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Old 10-05-2010, 04:15 AM   #21
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RE: Coolant recovery

"I run it about 1 1/4" below the cap so there's plenty of air space for expansion ."

A header tank or the coolant recovery setup would give 25% better cooling for about $20.

The usual reason extra cooling is needed is the aging of coolant.

The modern diesels with exposed to the coolant cylinders (instead of pressed into the cast block, or as in a throwaway 3208 ) require anti freez to control cylinder erosion from cavitation.

The knocking sound diesels make frequently comes from the cylinder it self ringing like a bell.

The coolant in contact does not stay in contact with the cylinder and cavitation pitting and erosion results.

The anti freez folks solution is an addative that coats the cylinder walls , so the "green slyme" gets eaten by cavitation , not the cylinder wall.

Thats one of the differences between diesel antifreez and car stuff like Prestone.

Unfortuniatly the green slyme builds up on the entire cooling system inside the engine , and heat exchanger.

The MFG suggests a 2 part cleaning and rinse every 2 years ,
Not doing it can compromise the system enough so extra cooling ability is useful.

Good insurance for only $20. and a half hour of install, time.
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Old 10-05-2010, 09:48 AM   #22
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RE: Coolant recovery

"A header tank or the coolant recovery setup would give 25% better cooling for about $20."

I don't see how and you give no reason whatsoever. In my case the exhaust manifold is the "header tank". Like old cars w a large header tank on the top of the radiator. The advantage of the coolant recovery system as I recall is to limit oxygen in the coolant system and thereby reduce corrosion.


Marin,
If your Lehman cooling system is close to sucking air and causing "air pocket" problems when operated normally as Peter B describes you need to correct the bad design. A Murphy Switch and/or a coolant recovery system would be a high priority on such an engine. You check it every time you start??? Sounds like you're quite concerned. And when you install the recovery tank make sure it's above the cooling system (radiator) cap. Many of those things have trouble "sucking" coolant back UP to the header cap. So basically the higher the better.
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Old 10-05-2010, 10:46 AM   #23
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RE: Coolant recovery

Quote:
nomadwilly wrote:"And when you install the recovery tank make sure it's above the cooling system (radiator) cap. Many of those things have trouble "sucking" coolant back UP to the header cap. So basically the higher the better."
Good advice although I know you can't accomplish this on all boats.
My boat was designed and built with this thought in mind and my coolant recovery
tank resides under the salon settee. Overflow rises to the recovery tank and gravity
feeds back through the cap as the engine cools. The last time, in the past 4 years,
that I added coolant to the systrem was about 2.5 years ago when I replaced it.
When the engine is cold, the coolant recovery bottle has about 2 inches of coolant
in it.

The first photo shows a small hatch along side the salon settee.
The second photo shows the hatch closed
The third photo shows the hatch open, right above the coolant tank fill. (I know, I
know...anal as hell)




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Old 10-05-2010, 11:01 AM   #24
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RE: Coolant recovery

Quote:
nomadwilly wrote:

Marin,
If your Lehman cooling system is close to sucking air and causing "air pocket" problems when operated normally as Peter B describes you need to correct the bad design. .....And when you install the recovery tank make sure it's above the cooling system (radiator) cap. Many of those things have trouble "sucking" coolant back UP to the header cap. So basically the higher the better.
No, I think it's a long way from sucking air.* The header tank blows out a small amount of coolant when it's full and then it doesn't blow out any more after that.* I just like to keep things topped off is all.

Interestingly enough, Brian and Bob Smith at American Diesel have told me that they recommend that the recovery bottle be mounted very low in the engine room, considerably below the level of the header tank.* I don't believe this idea is the best and when I get around to mounting our tanks I'm going to mount them the same way they have been in every vehicle I have owned---- at the same height as the coolant tank so that the nomal "full" level in the tank is even with the 1/3 full level of the recovery bottle.

*
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Old 10-06-2010, 04:22 AM   #25
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RE: Coolant recovery

"I don't see how and you give no reason whatsoever."

Air is an insulator, removing the air and the system gets about 25% more efficient.

The modern recovery system does work.
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Old 10-06-2010, 11:18 AM   #26
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RE: Coolant recovery

FF,I don't think there's air in the system unless the coolant level is quite low. Air rises and should be at the top of the headed tank. If the flow through the header tank became strong enough of course air would be mixed in but I can't imagine engineers designing a system that would pump itself up w 25% air???


Marin,
Those American Diesel guys are (as you suspect) dead wrong. You need to get out more *....find some better sources of information. I recomend Harbor Marine in Everett or Gallery Marine in Seattle. Also the shop on Nickerson (where Norm Dibble used to work) I think is good. Nix on Stewarts in Ballard. Obviously level w the top of the header tank works fine as thats where it is on cars and there's lots of cars. But higher does work even better. In theory lower should work fine too but in practice it does not.


Walt,
All I can see of the salon settee is the cushions. Sounds like a good place though. As long as there's not much horizontal run of the tube.
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Old 10-06-2010, 11:34 AM   #27
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RE: Coolant recovery

Quote:
nomadwilly wrote:


Marin,
Those American Diesel guys are (as you suspect) dead wrong. You need to get out more *....find some better sources of information...


*
Eric--- The Smiths at American Diesel know a lot of stuff about Lehmans, which is logical since Bob Smith did much of the original marinization work on the Ford of England base engine when he worked at Lehman Bros.* But they have some "practices" that I don't adhere to or believe are the best practices.* Their coolant recovery bottle placement recommendation is one of them.

I tend to use my own logic, the experience I've had with other kinds of engines over the years, and advice from our diesel shop and people I know in the marine engine manufacturing business in addition to advice from Bob Smith.* There is also a lot of first-hand experience information about these engines on the Grand Banks owners forum as most of the older GBs have Lehman engines in them.* So as you say, there's a lot of information out there and I agree that taking advantage of as much of it as possible is a good idea.

In our boat the tops of the header tanks on the engines are right under the main cabin sole.* So it's not possible to mount the bottles higher than the header tanks.* But it is possible to mount them even with them.* I see that as a much better position than somewhere down low as AD recommends.

*
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Old 10-06-2010, 11:39 AM   #28
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RE: Coolant recovery

I'm missing something in the placement of the coolant recovery bottle debate.* I thought the coolant was pulled back into the header tank by the vacuum caused by the contraction of the liquid as it cooled.* So it would not matter at all where the recovery bottle was located.

What?
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Old 10-06-2010, 11:52 AM   #29
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RE: Coolant recovery

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I thought the coolant was pulled back into the header tank by the vacuum caused by the contraction of the liquid as it cooled.* So it would not matter at all where the recovery bottle was located.
In theory you are correct.* However, from what I've been told the easier you make it for the coolant to flow back into the system the better because the power of the vacuum pulling the fluid back can vary due to factors like cap seal, hose to tank seals, etc.

If the bottle is mounted above or even with the header tank, you actually don't need any vacuum at all to return the coolant to the tank.* In some of my vehicles, for example, there is no conventional radiator cap.* When changing the coolant there is a small plug that you remove from the top of the radiator and then you fill the system through the expansion tank.* Coolant flows by gravity into the radiator until the "full" mark is reached on the expansion tank at which point there is the correct level of coolant in the radiator.

So while American Diesel's recommendation to mount the recovery bottle low in the engine room is okay in theory, I don't believe it takes into account what may be reality if a cap or hose seal becomes a bit "iffy."

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Old 10-06-2010, 02:31 PM   #30
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RE: Coolant recovery

Quote:
Marin wrote:In theory you are correct.* However, from what I've been told the easier you make it for the coolant to flow back into the system the better because the power of the vacuum pulling the fluid back can vary due to factors like cap seal, hose to tank seals, etc.

That sounds reasonable.* Redundancy - if the vacuum fails, maybe gravity will work.

I have the same issue as you though, the tank us right up against the underside of the access hatch.

*
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Old 10-06-2010, 07:04 PM   #31
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RE: Coolant recovery

I have a coolant recovery bottle mounted low. Unless I wanted to move a bunch of stuff that was where it went, 20 years ago. I tried it, it worked, I left it.

The only time it fails to pull back the purged coolant is when it is time to change the recovery cap. That happened this weekend. It pulled all the purged coolant back after the new cap was put on.

If low is the only reasonable place to put it, do it and see what happens. The bigger if, is how good is the seal between the hose and the fittings. Any air leakage, even if no coolant gets out, will cause poor or no pull back. If it fails to work properly then look at the hose and fittings.

Yes, I believe that mounting the bottle level with the header tank is better but it will usually work mounted low. If not and you are sure there is not another problem then try raising it.
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Old 10-06-2010, 09:59 PM   #32
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RE: Coolant recovery

As Walt and I have pointed out there are other places other than the engine compartment foe the expansion tank. Under a helm seat if it's boxed in. in/under a seetee seat w the overflow tube going back to the eng comp. You can put it most anywhere the surge tank will fit and you can route the two small plastic tubes to and from. I can't understand not making an easy modification to a cooling system that will make it work better and I do think it will work better 1 to 2' higher than the top of the header tank.
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Old 10-07-2010, 07:07 AM   #33
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RE: Coolant recovery

Marin, I'm not clear as to why, (assuming I got motivated, and wanted to convert the dreaded L120 header so it would suck the coolant back), why just replacing the cap with one of the same relief pressure, but the right return valve assembly, would not work. After all, the coolant forces its way out past the lower seal, is trapped under the top of the cap in the neck, so flows out the tube in the neck and down and in my (our) case, out into the fresh air, or your bottles. Why would it not just be sucked back, retracing its route out, as it were, with the proper type of cap, and a tube from the outlet into a vented bottle? Why does the tank neck need the extra sleeve?
I'm sure you will have a good explanation - it's just I can't imagine why so far.
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Old 10-07-2010, 09:22 AM   #34
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RE: Coolant recovery

Peter,You'd think so of course but in practice a lot of the time to most of the time it dosn't suck up. It happens so very slowly that just the smallest air leak ruins the vacuum. I'm sure that must be the explanation but I think so in that I can't think of any other. Of course one could explain the origin of man (that nobody knows) or any number of can't quite explain things. If I really needed to know about the vacuum leak I could just install a vacuum gauge in the line and observe. Incidentally the vacuum leak theory is further supported by the fact that a lot of surge tanks work lower than the rad cap. I think the only dependable way to mount them is at or above the rad cap.
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Old 10-07-2010, 12:02 PM   #35
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RE: Coolant recovery

Quote:
Peter B wrote:

Marin, I'm not clear as to why, (assuming I got motivated, and wanted to convert the dreaded L120 header so it would suck the coolant back), why just replacing the cap with one of the same relief pressure, but the right return valve assembly, would not work.
From what I was told by the Smith's at AD, the issue is both the cap and the inside of the neck.* The original neck insert-- which you have to carefully cut out and remove at which point the new neck insert that comes with the kit is put in--- does not work with a return-flow cap.* The original system--- neck and cap--- only allows coolant to be blown out under pressure.* It will not allow coolant to flow back in under vacuum (or gravity).* So you have to replace both components.

It's been years, to be honest, since I looked at the components in the kit so I can't recite off exactly how the configurations differ.* But the new neck insert is as much a part of the conversion as the new cap is.* Simply putting a recovery bottle on the end of the existing overflow tube will not result in a recovery system.* All you'll do is fill the bottle over time.* In fact, I do recall that part of the installation instructions include blocking off the existing overflow tube.* So the recovery system doesn't even use that tube or connection at all.

*
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Old 10-08-2010, 04:48 AM   #36
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RE: Coolant recovery

Well I accept that's what they said, and it worked, in that you bought two kits. The fact you have not gone that extra step and hacked into the existing neck and put the kits on, suggests, like me....you are not completely convinced, and nor am I. I have carefully compared the set-up on the Lehman (ok - I'll wash my mouth out for using that name later), with the set-up on my car, and can really see no difference in basic geometry, other than the fact that the Lehman cap has just one simple spring-loaded pressure valve, without the return valve in the centre. I reckon if I can get a cap of the right pressure release, but with the centre return valve, attach a bottle, position it at, or (as Eric suggests), a little above the header tank, connect it with a suitable heat tolerant tube from the over-flow to the bottom of the bottle with vent hole drilled in the cap as well, to let air in as the fluid moves back and forth, it should work. Now because it's me doing it, it probably won't - at first, but that will not phase me, as that is my usual first result with anything I do on a boat, but by being persistent I usually get it done in the end. Watch this space.
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Old 10-08-2010, 04:56 AM   #37
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RE: Coolant recovery

Maybe it's different for the Lehman 135. I just added a coolant recovery kit and hooked it into the little relief tube coming out of the neck. It will allow coolant flow both ways. Did the same on my Westerbeke 8kw genset.
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Old 10-08-2010, 07:53 AM   #38
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RE: Coolant recovery

Keith:* Did you change the cap?

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Old 10-08-2010, 11:21 AM   #39
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RE: Coolant recovery

Quote:
Peter B wrote:

Well I accept that's what they said, and it worked, in that you bought two kits. The fact you have not gone that extra step and hacked into the existing neck and put the kits on, suggests, like me....you are not completely convinced,
I actually bought the kits on the recommendation of our local diesel shop which has installed tons of them on FL120s in our marina.* I haven't had them install ours since it's something I can do so why pay the labor charge?*

I haven't put them on yet, not because I'm skeptical of them working--- I've talked to people who have put them on or have had them put on and they work as advertised--- but simply because I've been too lazy to do it.* Installation requires removing the header tanks, and while this would be a great opportunity to sandblast and repaint them the ease of my bottle-in the-drip-pan recovery "system" has so far outweighed the effort required to install the proper setup.

I don't know about the FL135--- it's a different (and later) base engine than the FL120--- so for all I know it may have been manufactured by Ford of England with a recovery neck and cap from the outset.* But the FL120s' stock neck and cap will not allow coolant to return to the header tank, only blow out.* I know a couple of peolpe who thought they could get a closed system by simply feeding the overflow tube into a bottle with coolant in it.* It didn't work.

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Old 10-08-2010, 12:28 PM   #40
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RE: Coolant recovery

Who'd a thunk coolant recovery would rival twins-vs-single, anchors or dripless packing for endless discussion?*
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