Ford Lehman smoking??

1980 Ford Lehman, 120 horse, 6 cly. diesel engine. Low hours maybe 2000 hours.
She smokes blue grey out the exhaust. When we drained the oil out of the fuel injector pump their was diesel in it??? Some neighbor say that it could be coming from the valve galley under the valve cover???
Any help would be great.
Kurt

Kurt, There is typically some diesel in the injector pump when you change the oil, especially if you have not changed it in the recommended time period. As for smoke, how long, under what RPMs? The 120 always smokes when you start it up and will continue until the engine warms. If it has not been run for some time, or worse yet, only run at the dock, you need to get it out and run it at wide open throttle for about five minutes or so and then see if the smoke clears. You may get lots of smoke running wide open for a while. Chuck

We have two 1973 vintage FL120s in our boat, something under 3000 hours. We've had the boat 14 years now. Both engines smoke (blue) on cold startup. If FL120s don't do this there is something wrong with them. The blue smoke on startup is the burning off of lube oil that has seeped down along the valve stems and gotten into the cylinders.

But the exhausts clean up after about three minutes or so. After that there is no smoke in the exhaust although on cooler, high-humidity days there is steam (white).

The CAV/Minemec/Simms in-line injection pumps use lube oil to lubricate the drive mechanism in the lower part of the pump. The injection plungers themselves are lubed in their bores by the fuel they are pumping. (Which is why fuel lubricity is so important to "jerk injection" engines like these.)

The injection plungers and the bores they run in wear over time. It's just the nature of the beast, although wear can be accelerated if the fuel has low lubricity. As the plungers and bores wear, a bit of the fuel they are sending to the injectors can leak down past the plungers at which point it ends up in the lube oil down below and starts to dilute it. The more the plungers and bores wear the more fuel leaks past and the more the lube oil gets diluted.

This is why there is a 50-hour injection pump oil change requirement in the manual. As the lube oil is diluted with fuel its lubrication qualities are diminished. The 50-hour oil change interval is intended to ensure that the pump's drive mechanism always has sufficient lubrication even if the fuel leak-down is approaching the "do something about it" point.

Because the plungers and their bore walls are wearing down, this is gradually reducing the "power" of the injection stroke. While you can't compress a fluid, it's as though the compression ratio in the top of the bore is being reduced due to the wear. So the "shots" going to the injectors get weaker and eventually this starts to manifest itself in various ways--- hard starting, uneven running, etc.

But...... the dilution of the lube oil itself in the injection pump will not have any effect on what is going on in the engine's six combustion chambers. if you are getting a serious amount of oil dilution this means the pump is nearing the need for an overhaul although I would be surprised if this was the case with an engine with only 2,000 hours on it, unless the engine has been abused. Also, if the pump oil has not been changed for a long, long time (as opposed to every 50 hours) the amount of fuel in the lube oil could be significant as it has been leaking down in tiny quantities for a long time.

Gray smoke indicates (I think) improper combustion. Blue smoke is lube oil being burned in the cylinders and black smoke is too much fuel being forced into the cylinders. Gray may indicate a bad injector pattern or something else that affects the even-ness or timing of the combustion process.

If it was our engines that were smoking gray while running I would be on the phone to our diesel shop to find out what the cause might be and get them to fix it.

With regards to your injection pump, is the lube oil being changed religiously every 50 hours? If it is and there is still a significant amount of fuel the oil come the next 50 hour change then the pump may need an overhaul. If the oil has not been changed religiously every 50 hours, start doing that and see how much dilution there is at the end of the first 50 hour interval. There will be some but it should not be much.

Bu the only relationship between the dilution of the lube oil in your injection pump and the gray smoke in your exhaust that I can think of is if the plungers and bores have worn so much in the pump that the injection pressure is starting to be affected and the combustion characteristics in one or more cylinders is not what it should be.

But with only 2,000 hours on what has a reputation for being a 12,000 to 14,000 hour engine in properly operated, properly serviced, properly maintained recreational boat service, I would suspect an issue with one or more injectors, not so much an issue with the pump.

But talk to a good diesel shop that has a lot of experience with FL120s. Or you can call Bob or Brian Smith at American Diesel and see how they diagnose the possible causes of gray smoke in the exhaust. They're the world's Lehman experts.

Light smoke can also be an indication of a head gasket problem, but I'm thinking this would be manifesting itself in other ways, too, like coolant getting into the engine's lube oil and turning it to chocolate milk along with a coolant level reduction in the header tank.

Let us know what you find out.

Marin said:

With regards to your injection pump, is the lube oil being changed religiously every 50 hours? If it is and there is still a significant amount of fuel the oil come the next 50 hour change then the pump may need an overhaul. If the oil has not been changed religiously every 50 hours, start doing that and see how much dilution there is at the end of the first 50 hour interval. There will be some but it should not be much.

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Great post Marin. Question, what will the lube oil in the pump look like if there is excessive fuel in it? Or if it is really old? After 50 hours, what should the oil look like, black? Amber?

I just changed mine for the first time (80hp Lehman). There isn't much oil in the pump (maybe 1/3 of a quart). It came out Black with a hint of brown to it (I imagine that's the fuel?). I have to wonder how long it's been since it was replaced. Hopefully the PO, made this part of his routine.

Greetings,
Whenever I've changed the oil in the Lehman 120 injection pumps the old oil has always been amber colored. Of the three 120's that I have been quite intimate with, only one injection pump has experienced oil dilution with diesel and that engine had about 4500 hrs. on the clock. Due for a rebuild? Don't know.
Not wanting to get into an argument here but I asked B Smith Sr. about oil change intervals at a Mystic Trawlerfest and he stated that the 50 hr. change interval mentioned in the manual was a misprint and in fact one could go with 100 hr. intervals with no ill effects.
Has anyone here altered the drain on their pumps? I've tried MANY techniques, gadgets, funnels and gizmos to ease the torture of changing oil but I still manage to slop oil all over the place. What I am thinking is to drill and tap the drain for a 1/8 NPT and put on a 90 degree elbow with a 3" or 4" capped pipe nipple. Any thoughts?

RT Firefly said:

Greetings,
Whenever I've changed the oil in the Lehman 120 injection pumps the old oil has always been amber colored. Of the three 120's that I have been quite intimate with, only one injection pump has experienced oil dilution with diesel and that engine had about 4500 hrs. on the clock. Due for a rebuild? Don't know.
Not wanting to get into an argument here but I asked B Smith Sr. about oil change intervals at a Mystic Trawlerfest and he stated that the 50 hr. change interval mentioned in the manual was a misprint and in fact one could go with 100 hr. intervals with no ill effects.
Has anyone here altered the drain on their pumps? I've tried MANY techniques, gadgets, funnels and gizmos to ease the torture of changing oil but I still manage to slop oil all over the place. What I am thinking is to drill and tap the drain for a 1/8 NPT and put on a 90 degree elbow with a 3" or 4" capped pipe nipple. Any thoughts?

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Here is what I did. I used a plastic dust pan (kind where the hand duster fits into the handle). The handle is a grooved piece of plastic like a channel..... pulled the plug, let it drain onto the pan and down the handle where there is a hole (for hanging the dust pan). Down the hole into a paper cup. no mess. Not exactly what you wanted to hear, I'm sure, but it is effective.

Adelaide said:

Great post Marin. Question, what will the lube oil in the pump look like if there is excessive fuel in it? Or if it is really old? After 50 hours, what should the oil look like, black? Amber?

I just changed mine for the first time (80hp Lehman). There isn't much oil in the pump (maybe 1/3 of a quart). It came out Black with a hint of brown to it (I imagine that's the fuel?). I have to wonder how long it's been since it was replaced. Hopefully the PO, made this part of his routine.

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Based on discussions with others, including Bob Smith, we generally change the IP oil at around 100 hours, sometimes a little less. It always looks like clean oil with a hint of diesel smell. I suspect that if yours was black, you need to change it a bit more frequently for a while and see what comes out. If it continues to be black, you probably need the pump serviced. The pump doesn't hold much oil. Chuck

Capn Chuck said:

Based on discussions with others, including Bob Smith, we generally change the IP oil at around 100 hours, sometimes a little less. It always looks like clean oil with a hint of diesel smell. I suspect that if yours was black, you need to change it a bit more frequently for a while and see what comes out. If it continues to be black, you probably need the pump serviced. The pump doesn't hold much oil. Chuck

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Thanks Chuck. I suspect that it's been quite some time since it was replaced. My engine only has 1400 hours, so I am hopeful that a pump rebuild isn't in order.

Adelaide said:

Here is what I did. I used a plastic dust pan (kind where the hand duster fits into the handle). The handle is a grooved piece of plastic like a channel..... pulled the plug, let it drain onto the pan and down the handle where there is a hole (for hanging the dust pan). Down the hole into a paper cup. no mess. Not exactly what you wanted to hear, I'm sure, but it is effective.

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Ingenious !!

Adelaide said:

Question, what will the lube oil in the pump look like if there is excessive fuel in it? Or if it is really old? After 50 hours, what should the oil look like, black? Amber?

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The oil coming out of our two injection pumps at 50 hours looks just like the new oil going into our injection pumps. The only indication that there is some diesel in the oil is from the smell as described previously by Chuck. Since the oil in the pump never comes in contact with any combustion byproducts as does the lube oil in the engine's sump, there is really nothing influencing it to get dirty or change color other than perhaps heat.

While I have a great deal of respect for Bob Smith and he is certainly the authority when it comes to the the Lehman marinzations, I do not adhere to all his advice religiously. For example, he still advocates using Marvel Mystery Oil in diesel fuel when recent evaluations of fuel additives by the trucking industry have shown that MMO is actually one of the worst things you can put in your fuel if you are concerned about lubricity, which anyone with a jerk-injection diesel like the FL120 should be. MMO actually reduces fuel lubricity.

When it comes to operating and servicing our FL120s, with regards to the base Ford Dorset engine (which includes the injection pump) I follow the advice of an acquaintance in the UK who built a business and a career out of servicing, maintaining, repairing, exchanging, etc. Ford of England diesels over many decades, inclucing being an adviser to Ford of England's diesel engine division.. He's had a ton of experience with the Ford Dorset and feels that the injection pump oil can not be changed too often. He says it starts to dilute almost from day one when the engine is new and the rate slowly increases with use.

In his opinion that in-line injection pump was the single most troublesome component on the Dorset engine with--- for vehicular, industrial, and agricultural service--- an unfortunately short service life. It was one reason the engine proved to be a failure as a truck engine in over-the-road service. When I told him the Lehman manual said change the pump oil every 50 hours he said it sounded like a good idea to him.

Also, the Bob or Brian Smith told me directliy abut the 50 hour change interval not long after we got the boat. Why the story has changed from "do this" to "it's a misprint" I have no idea. This is the first I've ever heard of the misprint thing. So we will continue to change the oil on a 50 hour interval. It's easy, it's quick, it requires hardly any oil, and based on the advice given us by our UK Ford diesel expert, it's a good thing to be doing given the history and repuation of the pump.

We also follow our UK friend's recommedations for operating the engine--- idle times, loaded rpm range, and so on. Some of them are at odds with the recommendations of Bob Smith.

For the marinization items on the FL120--- pumps, manifold, raw water heat exchanger system, etc---- the Smiths are truly the experts and we have gotten and followed excellent advice from them that has improved the servicability and reliability of our engines immensely. But for the care and feeding of the base engine itself I put my faith in the fellow who spent a lifetime keeping them going in every kind of service imaginable.

That said, I am not suggesting that anyone else do what we do with regards to their FL120s. If they have operating parameters and service intervals they have faith in and have had good results from then they should continue to adhere to them.

Marin said:

While I have a great deal of respect for Bob Smith and he is certainly the authority when it comes to the the Lehman marinzations, I do not adhere to all his advice religiously. For example, he still advocates using Marvel Mystery Oil in diesel fuel when recent evaluations of fuel additives by the trucking industry have shown that MMO is actually one of the worst things you can put in your fuel if you are concerned about lubricity, which anyone with a jerk-injection diesel like the FL120 should be. MMO actually reduces fuel lubricity.

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Marin, 2 things....

1) Since I had black oil in my injector pump on this change, should I wait the 50 hours, or change it sooner to see what color I get?

2) are you using any additives in your diesel? I did not on this latest fill up. So many out there, not sure which is best, or any at all. I am in your area, so I assume we are probably getting similar diesel. Thanks for your help.

Do you know how long the oil went unchanged in the injection pump before you changed it this time? If it was a real long time-- several hundred hours or more---- I'd be inclined to see how it was after 50 hours. If it was a relatively short time--- 100 hours or so--- I'd be inclined to call our diesel shop, our retired acquaintance in the UK, or the Smiths at American Diesel. Or all of them

Actually, regardless of what anyone on an internet forum said, I'd be talking to someone in the engine business who has a lot of experience with FL120s to get their opinon on why the pump oil was so black. Because I can't imagine why it would get that way unless it's possible for dirt to get into the oil.

Actually, I just thought of something...... your engine hasn't been set up to run the engine's lube oil through the injection pump has it? It is possible to do this, the most common means being to send a feed from the oil filter plumbing. A few people on the Grand Banks owners forum have this setup on their FL120s. The advantage is that you don't have to change the pump oil separately and the fuel leak-down is absorbed into three gallons of oil instead of half a quart or so. In this case, the lube oil in the pump would look just like the oil in the engine's sump pan since that's where it came from. You'd know by the hoses or pipes connecting the injection pump to the oil filter plumbing. Just a thought......

As to additives, when talking to several people in the marine diesel business back when we bought our boat and and were asking basic questions like what kind of oil should we use and how often should we change it and what make of filters is best and what rpm should we cruise at, we were advised to use two additives. One is Hammonds Biobor, which is a bug killer. The other was Hammonds Select3, which was a stabilizer/lubricity additive. Hammonds has recently replaced Select3 with a newer product, so we use that now.

I have no idea if either of these products is making a difference or not. But 14 years after buying the boat the engines don't smoke any more at startup as they did in 1998, they start immediately and run smoothly just as they did in 1998, and they use no more oil today (1 qt or less every 100-150 hours) than they did in 1998. So if the additives aren't helping, they don't appear to be huring either.

Now the engines may both explode next week. But so far so good.

You can find any opinion on fuel additives you want on the internet. You need them, you don't need them, they're good for your engine, they're bad for your engine, they're absolutely necessary, they're totally unnecessary, low sulfur fuel has all the lubricity your ancient jerk-injection engines need, low sulfur fuel has totally insufficient lubricity for your old engines, and so on.

At some point you have to believe someone so we've chosen to believe people we know or have met who have made careers and reputations designing, manufacturing, servicing, and repairing diesel engines (propulsion and generator) for boats and that we feel are giving sound advice. The we feel part is the tough one to determine.

Just a little anecdote about the injection pump. I bought my MT 34 with a FL 120 in Long Island 3 years ago. I sailed it to Montreal where I live. The PO gave me a 5 minute crash course on the engine and told me how to change the fuel filter. And I was off for a few hundred miles (about 100 hours total). When I arrived home I took the time to read the engine manual and decided to do everything by the book. When I got to the injection pump I tried to locate the drain plug to change the oil as described in the manual. Couldn't locate the darn bolt under the pump. Thought I might have a different model than the one pictured in the book so I kept looking. I eventually located the bolt... in the bilge! It appears the bolt came loose and fell, draining the oil. From the look of the bolt, it had been there for quite a while (like a year or more). I talked with Bryan at American Diesel and to my surprise he explained that the pump can run without any oil in it but that would accelerate the wear of the internal parts. I've been monitoring that pump very closely since and I change the oil every 25 hours or so just to be on the safe side. It's been 3 years and I've had no problem with it. The oil always comes out as clean as new and the engine runs like new and doesn't smoke (apart from the normal smoke on start-up). In my mind this just shows how reliable and solid these engines can be.

Fotoman said:

Just a little anecdote about the injection pump. I bought my MT 34 with a FL 120 in Long Island 3 years ago. I sailed it to Montreal where I live. The PO gave me a 5 minute crash course on the engine and told me how to change the fuel filter. And I was off for a few hundred miles (about 100 hours total). When I arrived home I took the time to read the engine manual and decided to do everything by the book. When I got to the injection pump I tried to locate the drain plug to change the oil as described in the manual. Couldn't locate the darn bolt under the pump. Thought I might have a different model than the one pictured in the book so I kept looking. I eventually located the bolt... in the bilge! It appears the bolt came loose and fell, draining the oil. From the look of the bolt, it had been there for quite a while (like a year or more). I talked with Bryan at American Diesel and to my surprise he explained that the pump can run without any oil in it but that would accelerate the wear of the internal parts. I've been monitoring that pump very closely since and I change the oil every 25 hours or so just to be on the safe side. It's been 3 years and I've had no problem with it. The oil always comes out as clean as new and the engine runs like new and doesn't smoke (apart from the normal smoke on start-up). In my mind this just shows how reliable and solid these engines can be.

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great info! the real strength of the internet forum is finding out info you may never find any place else.

Adelaide said:

Since I had black oil in my injector pump on this change, should I wait the 50 hours, or change it sooner to see what color I get?

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First confirm which pump you have. Unless I am mistaken, the Dover based engines produced after the mid 80s used a pump that is lubricated from the engine lube oil system.

If it is engine lubricated, the oil will most likely be black. Lube oil becomes black from its carbon load and there is no easy way for carbon to get inside an injection pump.

RickB said:

First confirm which pump you have. Unless I am mistaken, the Dover based engines produced after the mid 80s used a pump that is lubricated from the engine lube oil system.

If it is engine lubricated, the oil will most likely be black. Lube oil becomes black from its carbon load and there is no easy way for carbon to get inside an injection pump.

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You and Marin bring up a good point. I'll check that out tomorrow. My Tung Hwa is an 83, but you never know. Thanks to everyone for the advice, this forum is great.

Fotoman said:

Just a little anecdote about the injection pump. I bought my MT 34 with a FL 120 in Long Island 3 years ago. I sailed it to Montreal where I live. The PO gave me a 5 minute crash course on the engine and told me how to change the fuel filter. And I was off for a few hundred miles (about 100 hours total). When I arrived home I took the time to read the engine manual and decided to do everything by the book. When I got to the injection pump I tried to locate the drain plug to change the oil as described in the manual. Couldn't locate the darn bolt under the pump. Thought I might have a different model than the one pictured in the book so I kept looking. I eventually located the bolt... in the bilge! It appears the bolt came loose and fell, draining the oil. From the look of the bolt, it had been there for quite a while (like a year or more). I talked with Bryan at American Diesel and to my surprise he explained that the pump can run without any oil in it but that would accelerate the wear of the internal parts. I've been monitoring that pump very closely since and I change the oil every 25 hours or so just to be on the safe side. It's been 3 years and I've had no problem with it. The oil always comes out as clean as new and the engine runs like new and doesn't smoke (apart from the normal smoke on start-up). In my mind this just shows how reliable and solid these engines can be.

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Well, that is pretty amazing and a testament to the Ford Lehman Engine. To think that the so called "weak link" of the engine could live through that.... no wonder these engines are still running strong 30-40 years in.

Adelaide said:

To think that the so called "weak link" of the engine could live through that...

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Or you could look at it the other way ... those pumps leak so much they don't need no stinkin' lube oil.

Adelaide said:

Well, that is pretty amazing and a testament to the Ford Lehman Engine. To think that the so called "weak link" of the engine could live through that.... no wonder these engines are still running strong 30-40 years in.

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The reliability issues with the Dorset engine's in-line injection pump we have been told about were not due to its lubrication system but it's frequent failure under constantly changing rpm. According to our UK acquaintance, some of the components in the pump are fairly weak and had a high failure rate at high rpm and constantly varying rpm. Which of course is what life for an engine is like in an over-the-road truck which is one of the reasons the Dorset engine proved to be a total failure in this application, which ironically is what it was designed for in the first place.

Ford of England came close to discontinuing the Dorset altogether but it was tried as an industrial engine in stationary, constant rpm, relatively low load applications like cranes, pumps, and generators. In this capacity it proved to be a very good powerplant. So Ford continued its production and the same properties that made it good for industrial use also made it good for agricultural use, primarily as an engine for combines. And of course, the same properties that made it good for these constant rpm, lower load applications made it ideal (at the time) for marine use. A number of companies marinized them. Lehman in New Jersey was the best known and perhaps provided the most marinization kits, but there were companies in the UK and other countries which marinized a fair number of these engines as well.

The later Ford of England Dover engine is the base engine for the Ford Lehman 135. This engine uses the engine's lube oil to lube the injection pump so there is no need to change the pump oil at all.

BTW, the reason Ford of England engines got such widespread use, even in this country in tractors and the like, is that back in those days ALL Ford's diesel engines for heavy truck, industrial, and agricultural use were made by Ford of England even if the piece of equipment they were going into was made in the US.

The Simms pumps on our FL120s don't leak oil at all. What they did do, however, is blow oil out the breather vent tube on the side of the pump. This was partly due to the slanted-back mounting of the engine. When the pump is filled to the correct level it actually puts more oil in the pump that's needed. So the excess gets blown out the breather on the side of the pump into the drip pan. One of the improvements Bob Smith suggested that I make to our pumps is to remove the breather altogether and blank it off with a nut and a pair of soft metal washers. Then, he said, drill a tiny hole in the middle of the large oil fill plug in the top of the pump.

I did this and found that the filler plugs on our two pumps had already been drilled. So no more oil being blown down into the drip pan.

I called American Diesel and talked to john. He 'thought' the drain plug was M8 metric. I don't understand the metric system so I don't know what that means. The next time someone has the plug out can they take it to a machine shop and check it out? I was looking for a metric petcock and found nothing on the web.
Terry

Don't know why the FL120's injection pump drain plug would be metric. England was not on the metric system in the 50s, 60s, and 70s when this engine was being manufactured. I bought a new Land Rover Series III-88 in 1973 (and still have it) and there is not a metric fastener on it anywhere including the engine, transmission, etc.

Marin said:

The later Ford of England Dover engine is the base engine for the Ford Lehman 135.

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And the 90.

Our 1973 engine manual covers three engines--- the 4-cylinder 80 hp, the six-cylinder 120hp, and a turbo version of the 120 hp engine that developed 150hp. According to the manual, all three engines are derivatives of the same generation engine. So far as I know, Lehman never marinzed the turbo version of the Dorset.

The slightly more powerful Dover engine came out some time after the Dorset. I assume this engine was also available in four and six cylinder versions, too, with the four-cylinder version being the FL90. I've not had any experience with the Dover/FL135 engine.

This may help FL users,though off topic (but which one?). I replaced my original type,probably the originals,4 PSI coolant tank ("radiator") caps. The overflow,and need to top up, decreased so much so I may not bother fitting recovery tanks.
BruceK

The overflow,and need to top up, decreased so much so I may not bother fitting recovery tanks.

However the recovery tank is a required part of the system.

The concept is to remove all the air in the coolant system , which the cap and recovery tank does.

Removing ALL the air makes the cooling system about 25% more efficient .

Not bad for a couple of bucks worth of plastic.

FF

FF said:

However the recovery tank is a required part of the system.

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Not with the FL120--- they did not have them as fitted stock. Don't confuse an automotive-style recovery tank--- the usually plastic remote bottle or tank that takes the overflow from the engine's cooling system when the engine heats up and then allows it to be pulled back into the engine as the engine cools down---- with the metal header or expansion tank on the front of every FL120. The header tank is a required component as it serves as the reservoir for the coolant, same as the upper chamber of a vehicle's radiator.

A recovery tank is an aftermarket add-on for the FL120 and requires some modification of the engine's header tank to use. It is not a requirement for the engine and offers no benefits to the actual cooling process. All it does is eliminate the need to top off the coolant periodically since the way the header tank deals with coolant expansion is to simply blow the excess out the overflow pipe into the drip pan or bilge.

Marin said:

Not with the FL120--- they did not have them as fitted stock.
............
A recovery tank is an aftermarket add-on for the FL120 and requires some modification of the engine's header tank to use. It is not a requirement for the engine and offers no benefits to the actual cooling process.
...........
.

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Well ..... yabbutt........

I dunno about your 120s Marin but there's a substantial difference in fluid volume hot and cold on mine. There was obviously some good reason to create the retrofit kit. Just because it wasn't original equipment doesn't mean that, were the engine marinized today, it wouldn't be. At the very least running without it will mean either a very messy bilge or significantly less coolant circulating in the engine. And that definitely offers some "benefits to the actual cooling process".

FF said:

However the recovery tank is a required part of the system.

The concept is to remove all the air in the coolant system , which the cap and recovery tank does.

Removing ALL the air makes the cooling system about 25% more efficient .

Not bad for a couple of bucks worth of plastic.

FF

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My FLs have bleed screws on the cooling system as original,you open the screws and top up until coolant comes out(reminds me of bleeding the cooling system on a rear engined Renault which otherwise overheated++, radiator was aft,heater radiator was forward, with long pipes in between).The Lehman engine manual says not bleeding is a common cause of overheating. I don`t think recovery bottles were original,though American Diesel does sell them,and a modified filler neck which takes a higher psi cap(8 instead of 4psi).
I agree retro-fitting recovery bottles makes sense, been on cars for years, and I may yet do it.BruceK

bobofthenorth said:

I dunno about your 120s Marin but there's a substantial difference in fluid volume hot and cold on mine. There was obviously some good reason to create the retrofit kit.

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Absolutely. And we bought a pair of them within a year of acquiring the boat. But we have yet to install them. Why? Because I'm lazy. So we have a "poor man's" recovery system on our engines. I put extension tubing on the coolant overflow pipe that comes out of the neck of the header tank on each engine and fed it into a cleaned out quart oil bottle that sits in each engine's drip pan. As the coolant heats up the excess is blown out of the tank and down into the bottle. When I do my engine room check before the next day's startup (or whenever the next cold startup is) it's a simple matter to pour the coolant from the quart bottle back into the header tank.

I also aways crack the petcock on top of the exhaust manifold before every cold start to make sure no air pocket has formed up there. NOTE--- The cap on the header tank usually has to be loosened or removed in order to get a flow out the manifold bleed petcock. If you don't do this the partial vacuum that can form in the top of the tank can prevent the coolant from exiting the petcock. And NEVER open the petcock if the engine and coolant is hot.

The FL120 header tank is part of the marinization kit and takes the place of the upper radiator tank that would have been in an automotive, industrial, or agricultural application of the base engine. But in the 50s and 60s and early 70s nobody cared about recovering stuff--- it was no big deal to simply let excess fluids be blown out onto the ground or into the bilge. And adding coolant to replace the coolant blown out of the header tank was no big deal either.

But today it makes a lot more sense to use a recovery system, either the proper kit as sold by American Diesel or our cheapo oil bottle system.

bobofthenorth said:

Well ..... yabbutt........

I dunno about your 120s Marin but there's a substantial difference in fluid volume hot and cold on mine. There was obviously some good reason to create the retrofit kit. Just because it wasn't original equipment doesn't mean that, were the engine marinized today, it wouldn't be. At the very least running without it will mean either a very messy bilge or significantly less coolant circulating in the engine. And that definitely offers some "benefits to the actual cooling process".

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My 135 Lehman is only 2 years old and no recovery system.