Looking for help with a Lehman 120

[nmuir]

I have a new-to-me boat with twin Lehmans. I am looking to get some input/comments from the community as experienced Lehman mechanics are hard to find in Mataró Spain where the boat is! I will keep trying to track one down but in the interim am attempting to do some initial diagnostics from afar (I am over 5,000 miles away from the boat now).

The engines have an estimated 5,000+ hours on them (no meters) so there is a distinct possibility they need quite a bit of work.

I include a link to a short video of the port engine. https://youtu.be/BgEwBLKqLqk This is from when the engine was started from cold, so unless there is no thermostat in the engine the header tank coolant should be still. It isn't.

You can see the coolant is murky, and with the bubbles I am thinking that the head gasket is gone. The engine oil is ok.

I also wonder about the knocking and worry it is piston slap. It is definitely from the front of the engine (ie near cylinder 1 not 6). It may be hopeful thinking but could a shot head gasket or mis-adjusted valve train make that much knocking?

*If* it is piston slap do you think that the engine is about to expire? I have heard some people say Lehamns can run for quite a while with piston slap.

Oil samples should be back in about 4 weeks - the longer turnaround due to covid.....

Helpful comments from those with experience are welcome! Thanks in advance.

 

[Comodave]

The person I would ask is Brian at American Diesel. His dad Bob was the driving force on marinizing the Ford engine for Lehman. He is a wonderful source of information. 804-435-3107

 

[nmuir]

Thanks. I have heard American Diesel has a great reputation.


I have another short video of the engine sound if it helps. https://youtu.be/cRrR2Ivy0j8


Any more thoughts from anyone?

 

[Comodave]

I can work on most things on the boat but internal engine things are not in my field. Maybe PM Ski, he is really good on engines.

 

[bayview]

You are probably correct. Does it smell like exhaust? More bubbles when you race the engine?
Rental exhaust detectors are reported available at some auto shops

 

[catalinajack]

My advice for this and all boating issues is not to jump to the worst conclusion first, in this case, piston slap. Yes, you do have a problem with bubbles in the coolant. As for the noise, that may be an unrelated problem. When we purchased our boat with Lehman 120s, one of the engines was clattering loudly. The valves needed adjusting. Valves adjusted, noise gone. So, perhaps you should solve the coolant problem first. If it is a head gasket problem, you will have to adjust the valves anyway. If the head does not have to be removed, you MUST retorque the heads BEFORE adjusting the valves. It sounds like the valves should be adjusted regardless. The valves on FL120s should be adjusted every 1,000 hours according to Brian at American Diesel.

There are others on this forum who will have good knowledge of the "bubbles issue". I do not.

 

[psneeld]

I have had either soot or oil (hard to determine because havent sent it off to analysis) in my coolant expansion tank with a small but steady stream of bubbles when running.


Have had bubbles for years before (can't be sure but I will bet) a head gasket change/head rebuild 4 years ago at 2700 hrs (now 3700). The bubbles stopped for about 100 hrs after gasket change but came back.


My guess is the block wasn't as even as I thought (also an expert mechanic).


Even after 1000 hrs after the bubbles came back, my oil analysis is still great (Blackstone).



Every (probably at least 6) mechanic, marine engineer have said...you could try another gasket change (looking harder at the block) or just run it with bubbles till the oil analysis say something of significance. The more experience the mechanic, the less they were alarmed.


The also chuckled under their breath....there are probably thousands of marine engines out there with the same issue and the owners are clueless.

 

[Ski in NC]

Engine sounds about normal to me. Motion in coolant may be due to stuck open thermostat, it is right under tank. May have a drilled vent hole causing some flow. I did not see active bubbles. Fill tank a bit more to see if you are getting air added to system. That will be a bit messy as as engine warms the thermal expansion of the fluid will normally cause some to be expelled.

Some knocking is normal from diesel combustion. To separate that from piston slap, rev engine to say 1500 and snatch back throttle to idle. Listen to engine as it coasts down. If it is diesel knock, that will quit as engine is not fueling on coast down. If it is piston slap, you will still hear it.

If you take the tank off to get to the tstat, flush out that nasty coolant and renew. Green car coolant is fine in these.

Also make sure the vent fitting from the tank cap fitting is not clogged.

 

[Redhook98]

Mine had a slight tapping like yours. I switched from 15-40 oil to straight 30w. Noise went away with it. Engine runs quieter now.



Adjust your valves, retorque your head and change your oil and coolant. Re-assess after that.

 

[catalinajack]

The thermostat - if you get a Lehman thermostat from American Diesel ($30?) it will have an air bleed hole. A simple Stant thermostat can be drilled (1/8" or so) at a cost of less than $10.

Engine sounds about normal to me. Motion in coolant may be due to stuck open thermostat, it is right under tank. May have a drilled vent hole causing some flow. I did not see active bubbles. Fill tank a bit more to see if you are getting air added to system. That will be a bit messy as as engine warms the thermal expansion of the fluid will normally cause some to be expelled.

Some knocking is normal from diesel combustion. To separate that from piston slap, rev engine to say 1500 and snatch back throttle to idle. Listen to engine as it coasts down. If it is diesel knock, that will quit as engine is not fueling on coast down. If it is piston slap, you will still hear it.

If you take the tank off to get to the tstat, flush out that nasty coolant and renew. Green car coolant is fine in these.

Also make sure the vent fitting from the tank cap fitting is not clogged.

 

[rgano]

nmuir, I had a sudden onset of severe piston clank in the number six hole in one of my FL120s back in 1987. It was due to an incorrect muffle installation which I had changed, but not soon enough as it turned out. Believe me when I say the noise was disconcerting as on the flying bridge it sounded like somebody with an 8-inch monkey wrench was pounding on the engine. Scared hell out of me. Disassembly revealed that the PO had cheaped out using a knurled repair of the piston skirt to enlarge its diameter. Rebored the engine and put in all new pistons. You don't have anything like the noise I had. I owned that engine until 2015, and it and its unmolested twin are still running fine with probably 6000 hours on each by now.

A local acquaintance had an overheat of one of his FL120s with a subsequent knock in the forward part of the engine, but it continues to run fine.

It appears you do not have the modified reservoir filler neck on that engine which allows for a double acting radiator cap which allows you to better monitor coolant use/level with a recovery bottle. AsK Brian; he has kits.

That filthy coolant suggests neglect/exhaust input. A combustion leak detector sounds like a good investment at this point. Once you have a clue about that, you can decide about retorquing the head and adjusting the valves or taking the head off.

Hope your oil sample looks good. I am sure we will be interested to see that.

You plans for use of the boat should come into play as you consider what to do. Long range running? FIX it. Putzing around locally? Maybe live with it to see how it goes after a valve adjustment and coolant flush and neck modification and maybe a new stat, all easy things.

This post possibly aside, you are getting good advice here. I agree with all the other guy's comments.

 

[psneeld]

I tried a combustion leak detector (actually 2 different ones) and neither said I had a problem. Multiple tries....reread results and researched many times to no avail.


A great mechanic waiting for a reoccurance of noise in my dampner plate tested my system with a coolent pressure checker and confirmed a steady pressure rise the longer he left it on signalling a head gasket leak or possibly a cylinder leak ( I had ruled out the manifold with a pressure check).


So I am wary of the chemical combustion detectors...but can't say for sure how reliable or unreliable they are. Same place you can but a test kit will loan or rent a pressure checker.

 

[Xsbank]

It sounds like a Lehman to me.

A lot of good advice already here.

This is what I would do; before you panic, do the "normal" maintenance.
Change the oil
Change the coolant
Change (or look at) the raw water impeller
Change the anodes in the coolers
Change the oil in the Simms pump
Change the fuel filters
Set the valves

Now you have a baseline.

See how it runs now. Actually, you have 2, do the same to the other.
Look carefully at the drive belts, you will have to pull the front coolant hose off to change the belt, so do it while you change the coolant. What shape is the hose?
Look carefully at the injection port at the back of the exhaust manifold, they are failure items.

I agree that you should do the coolant tank mod, it saves a lot of mess and worry and is not expensive.

Once you've done all that and you see what the engine condition is, we can suggest some convenience mods to make your life easier.

Good luck. Spain (all of Europe) is prohibited for Canadians right now, must be frustrating?

 

[nmuir]

Got the oil samples back (faster than expected which is nice!)


I attach the port engine sample. The metals seem ok. If there was piston slap I might expect more aluminum, but bow to those with more knowledge than me!


Does the sample prompt any comments?

 

[catalinajack]

On a FL120, before adjusting the valves, the heads must be retoroqued. Not doing so risks head warpage.

It sounds like a Lehman to me.

A lot of good advice already here.

This is what I would do; before you panic, do the "normal" maintenance.
Change the oil
Change the coolant
Change (or look at) the raw water impeller
Change the anodes in the coolers
Change the oil in the Simms pump
Change the fuel filters
Set the valves

Now you have a baseline.

See how it runs now. Actually, you have 2, do the same to the other.
Look carefully at the drive belts, you will have to pull the front coolant hose off to change the belt, so do it while you change the coolant. What shape is the hose?
Look carefully at the injection port at the back of the exhaust manifold, they are failure items.

I agree that you should do the coolant tank mod, it saves a lot of mess and worry and is not expensive.

Once you've done all that and you see what the engine condition is, we can suggest some convenience mods to make your life easier.

Good luck. Spain (all of Europe) is prohibited for Canadians right now, must be frustrating?

 

[catalinajack]

Where are the viscosity and TBN ( Total Base Numbers)? Neither are required to determine the health of the engine but are essential to determining the health of the oil.

Got the oil samples back (faster than expected which is nice!)


I attach the port engine sample. The metals seem ok. If there was piston slap I might expect more aluminum, but bow to those with more knowledge than me!


Does the sample prompt any comments?

 

[nmuir]

Viscosity are the V100 and V40 numbers in the middle box. Not sure about TBN. They did say that as I did not know the oil information (age/brand/blend/viscosity/etc) that it 'inhibits evaluation'. The prior owner had no records.

 

[AusCan]

You are right, Neil. TBN and TAN aren't much use without the baseline data of fresh oil. These are used more for assessing oil condition rather than engine condition.

>1% water in the oil is the obvious concern. But it is odd that other readings such as sodium aren't high as well if coolant was getting into the crankcase. Perhaps the last oil change was done cold? Who knows.

As others mentioned - no need to panic. I'd change the oil and the coolant, adjust the valves and take another oil sample in 100 hours to get your baseline.

 

[Lepke]

Auto parts stores have test kits that will confirm combustion debris in the coolant. I wouldn't spend the time or money on regular maintenance items until confirming there is no combustion cross over. If the head has to come off, most likely you'll have to change fluids and filters when done. Changing oil and coolant now doesn't prove anything.

Bubbles in the coolant almost always mean combustion pressure and debris is crossing over from the cylinders to the coolant. The other common cause of bubbles is cavitation caused from very hot cylinder walls forming bubbles at the water jacket. Cavitation is ot a common problem in Lehmans running at normal rpms and hp, usually found in much higher hp engines under heavy load..
You should do a combustion-in-the-coolant test and a compression test. If either fail, pull the head. Send the head to a shop that specializes diesel heads. Tell them your problem so they do a pressure test before getting a lot of money into a damaged head. They'll also check your head bottom for warping and if there are no pressure leaks will probably take a minimum cut along the bottom to ensure the flatness.
Pulling the head and closely viewing the head and block surfaces should confirm or dispel a bad head gasket.

The rest the advise you're receiving is wishful thinking.

 

[rgano]

Got the oil samples back (faster than expected which is nice!)


I attach the port engine sample. The metals seem ok. If there was piston slap I might expect more aluminum, but bow to those with more knowledge than me!


Does the sample prompt any comments?

I can offer you the sample readings for my port Lehman 120 a mere four operating hours before the engine made so much slapping noise that I had it rebored and all new pistons and bearings put in. AND I can offer the oil analysis data for 103 operating hours after the overhaul.

Iron before/after 7/30 and remained in this 30 +/- regime for the next 28 years

Copper before/after 1/10 and remained consistent with post overhaul number for next 28 years

Al before/after 2/11 and remained consistent with "after" reading thereafter

Lead before/after 2/3 and ditto.

So to me looking at this data tells me nothing about impending doom.

 

[Choices]

I have a 135 and do not consider Lehmans to be quiet engines.

Getting everything adjusted will set a baseline. Mine seemed to have a lot of valve chatter. When I changed the damper plate the engine noise reduction was dramatic. Amazing.

We then set the valves and idle smoothed out a little. I drop down to 600 rpm when shifting, otherwise idle at 700-750.

Start also looking for lose equipment, fan gaurds, etc.

 

[kchace]

Don't know about other engines, but for a Lehman the Iron is high at 25 as is Copper at 20, those are both wear metals. Aluminum is only very slightly elevated. Your report seems to indicate that the oil was not changed when the sample was taken? If so, I'd change it asap. Gotta get the water out and put in known oil.

Ken

 

[jjorgenson3]

+1 definitely on the oil and then the remaining advice given.

Good Luck,

Jim

 

[amapola]

Ditto Brian at American Diesel.

 

[Lepke]

The first thing you need to do is test for combustion gasses in the coolant.You can get a test kit at an auto parts store, or probably Amazon and ebay. If you run the engine long enough with a bad head gasket, the gasses can cut a path in the metal of the head or block.

If the test shows combustion gasses in the coolant, then do a compression test. That will show you where to inspect the casket.
Only if you don't have combustion gasses and debris in the coolant, change the coolant and oil. Otherwise you're just wasting new oil and coolant.

 

[bayview]

The first thing you need to do is test for combustion gasses in the coolant.You can get a test kit at an auto parts store, or probably Amazon and ebay. If you run the engine long enough with a bad head gasket, the gasses can cut a path in the metal of the head or block.

If the test shows combustion gasses in the coolant, then do a compression test. That will show you where to inspect the casket.
Only if you don't have combustion gasses and debris in the coolant, change the coolant and oil. Otherwise you're just wasting new oil and coolant.

+1

 

[Bryant]

FL 120s

I have a new-to-me boat with twin Lehmans. I am looking to get some input/comments from the community as experienced Lehman mechanics are hard to find in Mataró Spain where the boat is! I will keep trying to track one down but in the interim am attempting to do some initial diagnostics from afar (I am over 5,000 miles away from the boat now).

The engines have an estimated 5,000+ hours on them (no meters) so there is a distinct possibility they need quite a bit of work.

I include a link to a short video of the port engine. https://youtu.be/BgEwBLKqLqk This is from when the engine was started from cold, so unless there is no thermostat in the engine the header tank coolant should be still. It isn't.

You can see the coolant is murky, and with the bubbles I am thinking that the head gasket is gone. The engine oil is ok.

I also wonder about the knocking and worry it is piston slap. It is definitely from the front of the engine (ie near cylinder 1 not 6). It may be hopeful thinking but could a shot head gasket or mis-adjusted valve train make that much knocking?

*If* it is piston slap do you think that the engine is about to expire? I have heard some people say Lehamns can run for quite a while with piston slap.

Oil samples should be back in about 4 weeks - the longer turnaround due to covid.....

Helpful comments from those with experience are welcome! Thanks in advance.

Call American. They are the source for parts and info.
The FL 120 was originally a tractor engine so if there are any tractor mechs where you are, they might be of help.
My FL 120 has 7750 hours on it and it runs like a charm, but it has been very well maintained. A well maintained FL 120 will run for 10,000 hrs before needing serious attention, in most cases.

 

[PM]

I think it is the valves, get them adjusted. Then change all the engine fluids.

There definitely is movement in the water in the tank but the bubbles look to be pretty still. There is a good chance you have a thermostat issue, check it out. Does the engine temp come up when you run it?

When you remove the tank to check the thermostat be CERTAIN you get that slanted coolant tube on the starboard side of the engine filled with fluid. Your video does not show the port side of the engine but there should be an air bleed fitting to allow air out and let that tube fill. Otherwise you will get and air lock and overheating.

pete

 

[Comodave]

Bob Smith once told me that the local watermen would bring in their Lehmans at 20,000 hours for a preventive rebuild. So they will run forever if they are maintained.

 

[C lectric]

Pay attention to Ski's post #8. He is a Pro mechanic. Also call American Diesel.

Many stats have a small hole drilled in them, either by the mfgr or by an owner.
As Ski mentioned it could also be stuck open.

Could also be the previous owner removed the stat. which will cause the flow in the exchanger when the engine is still cold. Lots of people still think that is a good way to fix a problem instead of finding the actual problem cause, remove the stat.

In many engines that can actually cause an overheat since the water will go where ever it is easiest to go instead of where it must go to be cooled, the heat exchanger, as the engine warms up.

The water could be dirty because the coolant has not been changed in far to long. I've seen that enough times.