Ford Lehman 120 raw water in coolant system

[AmericanVagrant]

The trawler I recently purchased has dual Lehman 120's - one of them underwent a significant service in September 2019 which included replacing the heat exchanger for the engine, oil and trans. Now, it's apparent that raw water is entering into the coolant system on that engine.


An engine oil analysis shows none is entering the oil system. Is this a pretty straightforward issue of the new exchanger being bad? There is a very slow drip out the coolant overflow cap (which holds good pressure) which is what led to my recognizing the issue.

 

[Marco Flamingo]

Is the slow drip out of the coolant overflow your only diagnostic? That could be caused by filling the coolant reservoir too full. Lehmans seem to be happiest with the reservoir only about half full.

 

[SoWhat]

What was the condition of the heat exchanger zinc? You should be able to remove end caps and test each tube to find a leaking one. If that is the problem I would be tempted to proactively replace all coolers. Engine or transmission oil coolers leaks can cause expensive probems.

 

[AmericanVagrant]

Is the slow drip out of the coolant overflow your only diagnostic? That could be caused by filling the coolant reservoir too full. Lehmans seem to be happiest with the reservoir only about half full.

It's definitely water ingress as the leak continues at all times (before, during and after running the engine, all day every day). Additionally, the coolant is significantly more diluted than the 50/50 water/coolant mix.

What was the condition of the heat exchanger zinc? You should be able to remove end caps and test each tube to find a leaking one. If that is the problem I would be tempted to proactively replace all coolers. Engine or transmission oil coolers leaks can cause expensive probems.

Not sure, I'll give it a look. Thanks for the tip.

 

[Comodave]

Call Brian at American Diesel. He is the guru and is very willing to help out. 804-435-3107

 

[Lepke]

Coolant usually has more pressure than the raw side in the heat exchanger. So you should loose coolant into the raw water. Not the other way around. Raw water is high flow, low pressure.

If the coolant to water exchanger is leaking, it may be a poorly soldered tube. Most radiator shops can fix it. I'd do a pressure test, most auto parts stores rent pressure testers that attach where the cap goes.
But if the cap is leaking with the engine off and cool, it may be some other problem if the engine cap is above the waterline.

 

[rgano]

Is the slow drip out of the coolant overflow your only diagnostic? That could be caused by filling the coolant reservoir too full. Lehmans seem to be happiest with the reservoir only about half full.

It is true that Lehmans want to run with about an inch or two of air space in the resevoir, UNLESS they have had the recommended modification to the filler neck whereby a double-acting radiator cap inconjunction with a recovery bottle results in a system like all modern cars have.

It is possible the OP could be overreacting to a bit of coolant escaping an old, unmodernized system, a condition I put up with for some years before modifying my own one afternoon.

 

[hobbystuff]

(1) How do you know it is raw water entering the cooling system?

(2) On a Ford Lehman, the only point at which raw water and coolant have an opportunity to mix is at the heat exchanger.

If in fact raw water is contaminating the coolant, I would start with having the heat exchanger pressure tested.

My experience, however, shows that if you have a leak at the heat exchanger, you are more likely to see coolant forming a slick out the exhaust due to the higher pressures in the cooling system (although not really that high a pressure). The coolant moves into the raw water. I suppose if the raw water pressure was high enough, maybe due to a blockage this could be reversed but who knows.

 

[SteveK]

coolant is being diluted.
When you replace the lost fluid are you adding a premix coolant?
Are you taking a coolant reading to verify dilution?
While adding fluid did you loosen the petcock on the manifold to bleed the air out?

 

[AmericanVagrant]

Thank you to all that have replied. I removed the heat exchanger and brought it into a local radiator shop that has experience dealing with them. They cleaned it, found a leak and sealed the offending areas/tube with putty. I'll reinstall and report back if I continue to experience the same issue.


For anyone in southern California, I used David's Radiator Service in Wilmington. Provided the repair holds, it was $125 vs the $700+ for a replacement. It seems the shops which advertise specifically to the marine community will charge a base price of $350 for the same service.

 

[catalinajack]

So now you have fewer tubes to do the cooling?

Thank you to all that have replied. I removed the heat exchanger and brought it into a local radiator shop that has experience dealing with them. They cleaned it, found a leak and sealed the offending areas/tube with putty. I'll reinstall and report back if I continue to experience the same issue.


For anyone in southern California, I used David's Radiator Service in Wilmington. Provided the repair holds, it was $125 vs the $700+ for a replacement. It seems the shops which advertise specifically to the marine community will charge a base price of $350 for the same service.

 

[AmericanVagrant]

So now you have fewer tubes to do the cooling?

Yes that's correct, 2-3. You could block off quite a few before noticing any difference in the ability to maintain normal operating temperature. Considering how many tubes there are - excessive scaling, water temperature and operating RPM will all have a much more significant effect.


I snapped this photo to illustrate my point (blocked tubes top center).

 

[AmericanVagrant]

As an update to anyone that may have this issue in the future, after reinstalling the heat exchanger I stopped seeing raw water weeping out the overflow. So it seems that that was in fact the issue.

 

[SteveK]

As an update to anyone that may have this issue in the future, after reinstalling the heat exchanger I stopped seeing raw water weeping out the overflow. So it seems that that was in fact the issue.

Post 1 said reinstall heat exchanger, now re install again? Please explain further, is this a new/different heat exchanger?

 

[AmericanVagrant]

Post 1 said reinstall heat exchanger, now re install again? Please explain further, is this a new/different heat exchanger?

It's the same exchanger which has been repaired, per post #10 & #12.

 

[SteveK]

Of Course, it went in for repair. Thanks

So not the head gasket.

 

[rgano]

Thanks for the update. As I said earlier and may have been buried in the noise, IF you do not have the coolant recovery bottle modifications to the engines, do yourself a huge favor and do it. American Diesel has the kits. You will thank me and quite possibly remember me in your will.

 

[hobbystuff]

So much this ^^

 

[jwag956]

Slightly old thread - but do you have a picture that shows what this modification looks like??

Thanks

 

[rgano]

Sure, I have photos of the mod. Here is a wide and close-in shot. Wide shot shows the the recovery bottle on th far side while the close-in shot shows the new filler neck glued into place with Marine Tex and the new smaller diameter radiator cap secured to it. The gray-colored Marine Tex is painted over with green engine paint. This FL120 engine was marinized by Grand Banks and thus painted this color vice the normal red.

 

[SteveK]

Sure, I have photos of the mod. Here is a wide and close-in shot. Wide shot shows the the recovery bottle on th far side while the close-in shot shows the new filler neck glued into place with Marine Tex and the new smaller diameter radiator cap secured to it. The gray-colored Marine Tex is painted over with green engine paint. This FL120 engine was marinized by Grand Banks and thus painted this color vice the normal red.

I now understand the mod everyone talks about. My Lehmans, both came with cast overflow tubes, never understood what was being added.

 

[rgano]

Get the kit with instructions from American Diesel.

 

[BruceK]

My mechanic fitted Mercruiser kits to the Lehmans of my previous boat. Seemed to work.

 

[FF]

The key is understanding the new style radiator cap is very different in operation from the old style.

It allows the system to get back fluid from the recovery tank to totally refill the system.

The new system is worth installing because it eventually clears all air from the coolant.

On vehicles this allows the radiator to be 25% smaller , saving billions every year.

On a boat it would help if for some reason you had to operate at full throttle for an extended time.

 

[Sweetypie]

Ford Lehman 2714E twins one with coolant in Oil

Hey Guys, seems this isn't a bad place to start as a few of you have had these issues before.

I recently Purchased a 1976 Grand Banks 36ft Aft Cabin here in Perth Western Australia, She has had most of the big ticket items done, Teak decks replaced with glass, Fuel tanks replaced with alloy and the engines and gearboxes rebuilt in 2018.

Now here my problem, my Port engine header tank is bubbling. I remove the head had it pressure tested. Tests perfect and valves seat like new, these engines only have 1600hours on them.

I have the exhaust elbow machines as it had a bit of pitting on the flange, Note I have read a lot about these gaskets failing. Which in turn leaks coolant into the oil via the exhaust. So I have been told while its apart just do it.

Now replaced all Oil coolers and heat exchanger as good measure, even though they are only 4 years old, New head gasket, Injectors serviced, new filter all round along with flushing the engines oil out 3 times !

I even replaced the Header tank and all hoses, Re-installed the head and manifold along with all new gaskets and seals, flushed the cooling system (coolant side) and ran the engine up to temp for half hour, re checked head bolts and all pipes fittings injector bolts the lot. Now after about an hour or 1000Rpm running the engine has used 1 or so litres of coolant (which I thought might be bleeding the system out) but the Oil has that look, slightly light in colour milky.


I am no Mechanic, (carpenter actually) but my understanding is for coolant to make its way into the oil it can either be Head Gasket, Exhaust elbow gasket, Front manifold gasket, Cracked head, Cracked Manifold or Cracked Block.

Am I right in saying that I should not being looking anywhere else ?

Im confident it wasn't the head gasket in the first place as when I pulled the head the gasket surfaces on the Head and Block has no broken visible seals.

I thought it may be the exhaust elbow as it was pitted and looked a little corroded, I am reasonably confident it now wasn't this or the front Coolant flange gasket.


Im looking for my next option here. Do I pressure test the header tank and listen for Air ? do I get a compression test done on each cylinder ? do I re do the 2 manifold gaskets.

Can I someone maybe run a video camera in the Manifold while doing a coolant pressure test to see this, Or does the engine need to be running and have exhaust pressure ?

I could pull the fuel kill switch and just pump the starter for a minute or so ?


I did notice the port side of the Port engine's block to look a little Porous compared to any other part of either engine (Just under the exhaust gasket)

Could of other things to note, I believe this engine may have had some electrolysis damage since 2018 as it used to share the common Ground/Earth Cable with the generator which was disconnected in 2018 and since then has not been earth with the rest of the boat.

Another thing to mention is the coolant was blackish and not clean in the engine. Starboard engine coolant looks like its just came out of the bottle and I have no issues with this engine what so ever.


Sorry to drag this out, If it is the Block do I need to remove it to get it tested and if the block is cracked where would it be cracked ? if the coolant header tank is bubbling then I assume its within the combustion chambers and not the crank case ? The coolant and oil are well mixed together.

Thanks in advance. Few photos attached

[/IMG]
https://imgur.com/ti8ifPr
https://imgur.com/hsQ5M8O

[/IMG]

 

[Bmarler]

you might think about making some plates you could bolt onto the block to seal it up so you can pressurize the coolant passages. a nice flat steel or alloy plate with a rubber or silicone sheet for gasket. use the head bolt locations to attach it. drill the plate for a fitting you can pump some air into it and monitor for leaks using a good quality pressure gauge. install a "t" fitting in the plate where a cooling passage is, with the gauge pointing out one side, a valve and inlet fitting on the other leg so you can pressurize it and shut the valve. watch the gauge for pressure drop over time. i double the working pressure of the system as the starting point. if you use a 7 psi cap, test at 14.
i like to do this sort of thing with everything removed form the block that can be removed so you only have one thing being tested. if the block holds pressure, test each bolt-on piece separately using the same method.

 

[rgano]

You are speaking of black color in solution with the coolant and not black lube oil floating on coolant, correct? Black coolant sounds like carbon getting mixed in. Carbon = exhaust. Head gasket? Compression test will tell. Problem at the mixer? Maybe a coolant system pressure test will help you figure it out. How about doing an exhaust gas test of the coolant system?

 

[Sweetypie]

you might think about making some plates you could bolt onto the block to seal it up so you can pressurize the coolant passages. a nice flat steel or alloy plate with a rubber or silicone sheet for gasket. use the head bolt locations to attach it. drill the plate for a fitting you can pump some air into it and monitor for leaks using a good quality pressure gauge. install a "t" fitting in the plate where a cooling passage is, with the gauge pointing out one side, a valve and inlet fitting on the other leg so you can pressurize it and shut the valve. watch the gauge for pressure drop over time. i double the working pressure of the system as the starting point. if you use a 7 psi cap, test at 14.
i like to do this sort of thing with everything removed form the block that can be removed so you only have one thing being tested. if the block holds pressure, test each bolt-on piece separately using the same method.

This is really good advice, I wish I had of asked before I put the head back on.

I will order another Gasket set. Do you think if I take a head gasket to a CNC shop I could get them to just cut a metal sheet for me to suit the head bolts.?

 

[Sweetypie]

You are speaking of black color in solution with the coolant and not black lube oil floating on coolant, correct? Black coolant sounds like carbon getting mixed in. Carbon = exhaust. Head gasket? Compression test will tell. Problem at the mixer? Maybe a coolant system pressure test will help you figure it out. How about doing an exhaust gas test of the coolant system?

Thanks for your response, How do you think I could test the exhaust gas in the coolant ?

I think ill buy a radiator cap pressure tester today. I love these Engines already for the simplicity. Although I haven't fixed this engine yet!

No oil in coolant, The coolant was dirty I think Carbon would be a good way of describing it yes. Can I send some coolant off for testing this ?

 

[Sweetypie]

Alright,

So today I can the engine again after changing the oil, filter, and with the radiator cap on (these engines have overflow bottles)

after 20 minutes in Gear and at temperature I could see coolant in the oil again, While running the engine the overflow bottle was bubbling.


Ive been given some advice to pressure test the manifold which I will do this coming week.

Couple more things I should Add in here, Cylinder 2 when the engine was disassembled was far cleaner than the rest. Clean like you'd expect when you have a blown gasket, although the gasket was fine and both the Head and Block looks fine.

Knowing what I know now I would approach this slower than I have. I thought the issue was the exhaust elbow flange being pitted and corroded.

Because the engine sits on a slight angle in the boat Aft is lowest, If it was the exhaust elbow is would likely leak into cylinder 6 or 5 I believe ?

Also if the manifold has cracked I would assume a similar thing to happen here.

If the manifold was cracked could the exhaust really build up enough pressure in the manifold to make the overflow tank bubble ? I am thinking not.

Im currently thinking it must be the Head Gasket or the Block, if its the block it must be around cylinder 2.

So maybe a pressure test on cylinder 2 with the piston in multiple positions while watching the header tanks/overflow bottle for bubbles may work ?

If I get bubbles then off the head comes again. and Ill have to inspect the block closer. If I cannot find anything then build this Pressure testing plate Bmarla suggested.


Before I dive back into it any suggestions ?


I have drained the oil, poured 2 or 3 litres of clean oil over rocker arms and valve springs while slowly turning the engine over. So I think it should be ok for a week or two.



Next topic will be if I need to removing the engine from the boat. ... advice on this will be a god send I am sure someone has done this in a Grand banks before ?