Lehman Injector Oil

Quick question for any of you guys that have the old simms injector pump on a Lehman. How often are you changing the injector oil? I know 50 hours is reccomended but the oil in mine always looks like new.

It really needs to be changed around 50 hours. The problem is that it gets diluted with diesel and loses some of it's lubricity.

Hey Troy,
*** I still change mine every 50 hours. I remove the level plug first and then the fill plug on top before I drain it. I make a note if any oil pours out the level plug. This is an indication if the injector pump valves are passing fuel into the reservoir. Bob Smith says eventually they will pass fuel and some is ok. Then ya have to start thinking about pump re-build. But.you may already know all this.
Ken

I change my two Simms pumps oil at 50-hour intervals too. I always looks good but smells like diesel. I replaced the drain plug with a pet**** to enable me to more easily drain the pumps.

I have a modified quart bottle I use as a funnel to direct the drain oil to a coffee can. Does your petrooster have a spot that a hose could be attached and then into a plastic quart container? That might be even easier.

Ken

Has anyone done any kind of oil analysis or experimented with longer intervals?
The reason why I ask is because on my boat there is no easy or clean way to change it.

Troy,
I don't think anyone will recommend running the Simms pump more than 50 hours before cleaning it out again.* No shortcuts here.* However, Rich had a good idea with using a petcock to replace the drain plug.* If you could add a hose to it you may find it's a lot easier to change, and you'll do it more often.

Keep in mind the injection pump is a megabuck item, so any way to coddle it is something to consider.

Mike

If I was smarter, I'd have figured out a way to rig a hose to the petcock, but alas and alack, I have not done so.

As others have said, the 50 hour oil change interval is best because it was the number derived at to ensure good lubricity in the pump's drive mechanism even with a fair amount of fuel dilution. The nature of Simms pumps is that they are wearing down their jerk-injection plungers and bores the moment you start the engine, so the fuel dilution rate*of the lube oil will gradually increase over time. Eventually it will reach the point where an overhaul is necessary. So the objective is to make "eventually" come as many hours in the future as you can.

The lube oil only lubes the pump's drive mechanism in the lower half of the pump. The injection plungers in the upper half of the pump (and the injectors themselves) are lubed by the fuel they are pumping, not the lube oil in the pump sump. This is why it's VERY important to have sufficient lubricity in the diesel fuel you run through an old-technology engine like the FL120. As they remove the sulphur from diesel fuel, you've got to add the lubricity back with an additive. Otherwise the Simms pump (and injectors) will wear out even faster.

If your FL120 has the original Jabsco raw water pump and Lehman drive unit, there is reasonable clearance between the pump body and the Simms pump drain to get a tube in there to collect the oil. I use a small plastic orange juice bottle with a short length of clear water hose--- the stuff with the criss-cross red "threads" in it--- jammed into the top of the bottle.

BUT..... if you change your Jabsco pumps and trouble-prone Lehman drive units for the new, more reliable Johnson pumps--- which we just did--- you will suddenly find that you have very little clearance between the raw water hose coming off the top of the pump and the Simms drain plug. If you have the smaller 3/4" Johnson pump, American Diesel told me the clearance issue can be solved by loosening the raw water pump's clamp screw and rotating the pump counterclockwisw to move the upper hose closer to the block.

If you have--- as we do--- the larger 1" Johnson pump, it turns out the upper hose sits a bit outboard of the Simms drain plug. So you can get at it with a wrench. I use the same juice bottle-hose arrangement but cut down the top couple of inches of the hose to be a half tube, not a full tube. I stick the half-tube end under the Simms drain to catch the oil and channel it down the rest of the tube into the bottle. Works great, no spills.

-- Edited by Marin at 16:31, 2007-10-29

I had a boat with a Sabre 120 engine that uses the same 380 cu in Ford engine. That engine was a real sweethart. It was pointed out to me that one of the advantages of the Sabre engine was that the Sabre used engine lube oil in the fuel injection system. Any diesel engine that I've known has lube oil that turns black very soon after changing. I've also been told that the black in lube oil is carbon and that the carbon is abrasive and the major cause of engine wear. Obviously changing engine oil also changed injector oil. I thought this could be a disadvantage rather than an advantage in that the injector system operated most all the time with high carbon oil.
Gasoline engines have lube oil that has additives to prevent gasoline from mixing with the oil. Does diesel engine lube oil have additives to prevent diesel from mixing with lube oil? What oil does Lehman recomend for the injection system? I would think it could or should be quite different from engine oil.

Willy
Thorne Bay AK

The Simms injection pump on a Lehman is supposed to use the same lube oil that's used in the engine. The manual recommends Delo 400. We use 30 wt in our climate in both the engine and the Simms pump.

As diesel fuel escapes past the injection plungers it thins out the lube oil down below. A newly overhauled Simms pump (or the virtually identical pump with the CAV label on it) will not dilute its lube oil at all, but it will start to pretty soon. It's the nature of the beast. Over time--- you hope a lot of time--- the plunger and bore wear will gradually increase until the point is reached when the pump has to be overhauled again. The greater the wear, the more fuel gets past the plungers and the faster the lube oil down below is diluted. As it dilutes, its lubrication effectiveness is reduced.

When we change the oil in our Simms pumps, the oil that comes out is pretty clean but it has been diluted to a certain degree. The pump on our port engine dilutes a bit more than the pump on our starboard engine.

The 50 hour oil-change interval for the Simms pump was arrived at because it ensures good lubrication of the pump's drive mechanism even with some degree of oil dilution.

The oil in the pump does not lubricate the injection plungers in their bores. They are lubed by the fuel they are pumping to the injectors. So circulating engine oil through the pump will have no effect on the rate of wear of the injection system. The lube oil only lubricates the pump's drive mechanism in the lower body of the pump. Given that virtually all diesel engines newer than the FL120 lubricate their injection pumps with engine oil, I would assume that even with whatever is in it that turns it black so fast, it's not been deemed a significant contributor to wear of a pump's drive mechanism.

The next-newer Lehman engine, the Ford Lehman 135, uses engine oil to lubricate its injection pump. It's only the FL120 (and its four cylinder variant, the FL 80) that has the in-line injection pump with an independent oil sump. Some FL120s use a rotary CAV injection pump instead of the inline pump, and I believe the rotary pump is lubed from the engine.

Willy -

I think that gasoline dilution is not a problem mostly due to the gas simply vaporizing as the oil heats up - doubt you could come up with any sort of additive to keep oil & gasoline from mixing.

Diesel's vaporization temp is high enough (though I can't remember what it is) that it won't vaporize at typical oil operating temps.

I don't have a Lehman/Sabre, but I'm pretty sure that the 120's injection pump oil is separate from the crankcase oil - so the carbon doesn't get in there. That's also why it needs changing so often - it's a small quantity of oil, so it doesn't take much fuel to compromise the lubricity.

Chris is correct regarding the Simms injection pump used on the FL120-- it's lube oil is separate from the crankcase oil. The injection pump is not part of the marinization kit, by the way, it's the injection pump installed by Ford of England when the engines were manufactured. The lube oil capacity of the Simms pump is about 2 cups (1 pint) of oil.

For anyone not familiar with the Simms pump on a Ford Lehman 120, here's what it looks like. The pump as built has an overflow/breather pipe on a banjo fitting on the side of the pump. Many of us, on the advice of American Diesel, remove the pipe and banjo fitting and block off the hole and drill a tiny breather hole in the center of the fill plug on the top of the pump (forward of the injector line connections).

Ya gotta change the injection pump oil on the 120's UNLESS you modified them to oil*like the 130's and 140's. If and when you decide to overhaul the pump (usually when the oil turns black in 25 hours) the pump can be modified. Not much more than drilling a hole and adding an oil line.

Marin wrote:

Chris is correct regarding the Simms injection pump used on the FL120-- it's lube oil is separate from the crankcase oil. The injection pump is not part of the marinization kit, by the way, it's the injection pump installed by Ford of England when the engines were manufactured. The lube oil capacity of the Simms pump is about 2 cups (1 pint) of oil.

For anyone not familiar with the Simms pump on a Ford Lehman 120, here's what it looks like. The pump as built has an overflow/breather pipe on a banjo fitting on the side of the pump. Many of us, on the advice of American Diesel, remove the pipe and banjo fitting and block off the hole and drill a tiny breather hole in the center of the fill plug on the top of the pump (forward of the injector line connections).

Click to expand...

Marin

Do you know if this mod is just for the 120 pump or do they reccomend this for the 80 pump also?

Troy---

If the FL80 uses a four-cylinder version of the Simms pump and it has the same breather/overflow arrangement as the FL120's pump, I see no reason why removing the banjo connection and pipe and drilling a small breather hole in the fill plug wouldn't be okay to do.

The reason people do this on the FL120's Simms pump is that because of the engine's rearward slant, the pump tends to burp oil out of the breather tube and it ends up in the engine pan or bilge. Also, on a pump that dilutes its oil at least a little bit--- which is just about all of them--- as the oil level comes up a bit, more of it goes out the breather pipe.

What Bob Smith at American Diesel advised me to do was to remove the pipe and its banjo fitting and then get a stainless nut just big enough to slip over the hollow bolt in place of the banjo fitting. The stainless nut covers the hole in the bolt and a soft washer (aluminum, brass) goes on each side of the nut to keep oil from seeping out from around it. Bob advises to keep the hollow bolt rather than replace it because its length is matched to whatever is inside the pump to ensure clearance.

The second part of the mod is to drill a tiny breather hole in the large oil fill bolt on top of the pump. Bob recommends driling the hole in the center of the bolt head down in the screw slot.

He told me that American Diesel makes these modifications to every pump they get for overhaul if it has not already been modified.

While I don't see any reason you couldn't do the same thing to an FL80 I would strongly suggest you contact American Diesel to confirm this. When it comes to diesel engines and diesel engine components, none of which are cheap to replace, I believe in confirming everything with the pros, not just taking a fellow boater's advice as gospel

PS-- If you're asking about the mod Rollsdoc mentioned, which is converting a Simms pump to use the engine's crankcase oil instead of having its own isolated lube oil supply, I've only seen a photo of this arrangement on a CAV version of the Simms pump-- I don't know exactly where holes are drilled, pipes are fastened, etc.* American Diesel would be the best source for that information.

-- Edited by Marin at 12:02, 2007-12-14

now it all makes since to me, thanks for the reply!