Lehman 120 seized - where should I spend my next 10-20k?

Hello lehman experts,

I've been working hard on Voyager over the last year to rewire and refinish the interior, but at a slow pace as I have little time. As a result I have not taken the time to run the engine/transmission since a 50km relocating cruize 12 months ago.

I have great hopes for this great old boat...and now the engine is seized, the tanks are rusty, the engine stringer are rotten, the hull has blisters, the batteries need replacing, a windshield is cracked, the teak decks leak..I still love the boat.

Last year, on the most recent cruise, it ran well but tended to run hot between 200-220 indicated. Later, Brian at American Marine warned me that running it that hot would likely do havoc on #6. I thought 'good to know' and hope it didn't do any harm yet and that gauges were off.

Now, to my surprise this seems to have already turned into the worst case. I can NOT even bar it over one-degree by hand standing on a cheater bar, I verified the starter is kicking out a ton of torque and engaging/disengaging, but nothing can move the crank at all. It looks totally internally seized.

Fearing hydro-locking I pulled all of the injectors, but there is no sign of water in any cylinders. Oil was just changed before that last trip and it's still clean and clear. All of the valves move freely by hand except for the #6 exhaust valve which is frozen in an open position pic below.

Engine hours are less than 3,000 and the engine wasn't smoking or making any unusual noise. Given the weight of the head and my limited experience on the Lehman, I'm planning to have a mechanic come out and look at it. I don't think it's the damper. But I would love to see if anyone has ideas on what I did to it and how to utilize the mechanic. I'm willing to throw money at it but need to figure out where to start.

Did #6 break off and drop a valve? Can a borescope see that through the injector port? Any chance when it overheated did I just melt piston #6 to the sleeve? Can a repair be done onboard or should I have it towed to a yard where the engine can be pulled? Should I have a mechanic pull the head where it is to inspect, or is it inevitable that the engine needs to come out to repair?

I know the answer lies in having an assessment from a qualified mechanic, but don't we all like to speculate where I should spend some boat bucks?

Figuring out next steps since I have to move the boat one way or another for dredging that is starting in about a week. I can haul it over to the guest dock and have a mechanic look at it, or I can have Sea Tow take it straight to a boatyard and pull the whole engine out for repair, rebuild or repower?

Thx,

Captain Warfdog
Westpoint Harbor
San Francisco Bay

I would ask Brian how to proceed.

Comodave said:

I would ask Brian how to proceed.

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Agree. He predicted disaster, and appears right. Otherwise,pull the head, see what you find, and proceed from there.
The engines have a habit of silting the coolant passages around the no.6 cylinder furthest from the circulation pump.
If you see a path to fix it, you still need to discover why it was running at 200-220 degrees. Fixing the immediate cause of and the seizure itself won`t necessarily resolve running hot. Could be lots of things,heat exchanger, other coolers, blocked exhaust angle, impeller, raw water pump, etc, even poor circulation due to blocked cooling passages around no.6.

Before you pull the head, same suggestion I was given.
Pull the tranny and remove the damper. Then see if the engine turns over. My labour and $150 solved the seized engine issue.
The damper springs, known to fall apart jam the flywheel and give the same effect as a seized engine.

Thanks SteveK. That is possible, but given the frozen exhaust valve I have to figure out what happened to #6. Something is clearly wrong beyond a possible damper jam. That's why I initially ruled out the damper plate.

Thx
joe

Someone on this forum has 2 of the 120s for sale in San Diego. Perhaps an option to consider?

Have you attempted to bar the engine over a few degrees in the opposite direction? It’s a long shot but if #6 has dropped a valve seat and trapped the valve there may be no clearance to allow the piston to move over TDC. Have a gander with a bore scope after pulling the injector.

BeeJay said:

Have you attempted to bar the engine over a few degrees in the opposite direction? It’s a long shot but if #6 has dropped a valve seat and trapped the valve there may be no clearance to allow the piston to move over TDC. Have a gander with a bore scope after pulling the injector.

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Won’t budge either direction.[emoji35]

If engine was running fine the last time you shut it down, I doubt it was a dropped valve or damper plate issue. Those tend to be noticed when engine is running.

If it won't move in either direction, I suspect coolant weeped into a cylinder and has the piston stuck. Sort of supported by the stuck valve.

I don't think the stuck valve has the whole engine stuck. Usually starter has enough grunt that a stuck valve will bend a pushrod or engine will still turn the other way.

Can also drain a qt of oil out of bottom of sump and see if there is any coolant present. If it got into a cylinder, some will drip past ring gaps. Only works if sump drain fitting is on the true bottom of the pan.

Since you already have the injectors out, try fishing a skinny poly tube down the injector hole and when it hits piston (actually might go in piston bowl), suck on it and see if you find coolant.

Can also get one of those cheap borescopes that plug into a phone. A skinny one can be fished into the injector hole.

Depending on what you find, I'm thinking pulling the head is likely.

If the damper plate is jammed, so will the exhaust valve be jammed.

Start there. Cheapest and the low-hanging fruit.

Don’t count that engine out!

I just finished rebuilding one of my SP275s.

Brian at American Diesel was very much a help—very!

You can remove the valve cover to see the condition of the valves.

Also, as has mentioned, broken damper plate will lock an engine up.

I would start there before yanking the head.

Much luck!

Pulling the head is the safest thing to do. If you want to play before doing that, you can try pouring mystery oil into that injector hole, letting it soak, adding some more occasionally, letting it soak some more, trying to bar the engine over occasionally, and seeing if it frees up.

Here is my own experience with one of my FL120s. At purchase, the 14-year old boat had mild steel mufflers mounter HIGHER than the engine. I quickly replaced them with lift mufflers. Not long after, while cruising down San Diego Bay, I became aware of a severe clanking sound for the port engine. Upon removal of the head, the cylinder walls displayed rust stains from water dribbling down the sides. Source was the muffler which had the rotted out inlet inside the can allowing water remaining after shut down to move on down to the number six cylinder. Fix was to remove and rebore the engine and all new pistons. At least it was not seized.

gkesden,
I’d think pouring SeaFoam instead.
Mystery oil is of course a mystery.

Xsbank said:

If the damper plate is jammed, so will the exhaust valve be jammed.
Start there. Cheapest and the low-hanging fruit.

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Those two parts have nothing in common.
The valve is being held open by something, assuming that the lash isn't excessive.
A stuck valve is fairly ominous and should be remedied by refurbishing the head.
In the course of doing that the reason for the seized crank will be revealed.

Moisture has probably migrated into the cylinders during storage. Easy access through exhaust manifold or intake. Rings could rust to side of cylinder, valve could rust to guide, anything is possible. I would start with a borescope and then flood the cylinders with lightweight penetrating oil.

If that doesn't work, the head needs to come off. (ps standing on a cheater bar is apt to break a ring and then the engine needs to come out)

With rotten stringers, rusty tanks, blistering, a seized engine and limited time, you might want to rethink this project. It will take years to complete. Wouldn't you rather be on the water now?

Thanks for all the ideas. No matter what, the next step has to be pulling the head to inspect and determine strategy.

Yes [SoWhat] - I get your point. I would love to have a better boat but I bought this one as a project and however long it takes I'm not ready to give up on it just yet.

I talked to Brian at AMC - I'll repeat what I have heard so many times, what a nice guy. He really didn't think that I toasted the engine since the alarm didn't sound. Probably never exceeded 200 deg.

We are going ahead to pull the head which needs to be done regardless since on valve is stuck. It's possible that it has been that way for a while. I am going to wishfully imagine that the cylinder bore is ok and the damper is locked up. Finding out later in the week when the head comes off.

It is so great to have this group to fall back on and of course Brian. Thanks all - I'll post the outcome and wish for the best.

Joe

That certainly is good news. Did Brian think that the engine was seized due to a broken damper plate. Or am I misunderstanding you?

Comodave said:

That certainly is good news. Did Brian think that the engine was seized due to a broken damper plate. Or am I misunderstanding you?

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Dave,

He doesn't know but speculated that either that or something dropping into the cylinder (huh-what? a valve or a metal-eating termite nest) or damper or something else on the flywheel. We'll see after we pull the head and follow the drivetrain from there...

My local mechanic also asked what oil I'm running and said that he has seen multiple older-diesels in the SF Bay Area self destruct or at least have valve train problems on Delo CX-4. I doubt that is really possible in less than 10-hours of running, but it may what we refilled the crankcase with last year.

Thx
Joe

American Diesel recommendation is 30 weight oil. My boat had been using 15-40 for the previous 15 years so I stuck with it. We use Rotella oil.

The choice of oil did not cause your engine trouble. Some might be better than others in small ways, but did not cause this.

Ski in NC said:

The choice of oil did not cause your engine trouble. Some might be better than others in small ways, but did not cause this.

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Agree, This low stressed venerable Ford engine is used in all sorts of applications, unless you used something really oddball oil choice is an unlikely issue.Can`t wait to hear what you find on pulling the head.

Greetings,
Mr. w. I am NOT a mechanic but I agree with Mr. Ski. Not the oil. Interesting you suggest the valve may have been stuck for a while and you didn't notice it (your post #18).



I am jealous of those who can listen to an engine running and just from the sound, diagnose a noisy tappet (s), an engine knock or a stuck valve. Even when my hearing was half-way decent, the best I could tell was an engine was either running or it was not.


When I go into our ER it sounds like 300 monkeys shaking cans of marbles up and down...(twin Lehman 120's).

RT Firefly said:

Greetings,
Mr. w. I am NOT a mechanic but I agree with Mr. Ski. Not the oil. Interesting you suggest the valve may have been stuck for a while and you didn't notice it (your post #18).



I am jealous of those who can listen to an engine running and just from the sound, diagnose a noisy tappet (s), an engine knock or a stuck valve. Even when my hearing was half-way decent, the best I could tell was an engine was either running or it was not.


When I go into our ER it sounds like 300 monkeys shaking cans of marbles up and down...(twin Lehman 120's).

Click to expand...

RT I was reading this and thinking to myself “of course I can hear what MY engines are doing” but then I got to the part about 300 monkeys shaking cans of marbles up and down and I think you’re onto something. That’s exactly what they sound like!

Ken

warfdog said:

Dave,

He doesn't know but speculated that either that or something dropping into the cylinder (huh-what? a valve or a metal-eating termite nest) or damper or something else on the flywheel. We'll see after we pull the head and follow the drivetrain from there...

My local mechanic also asked what oil I'm running and said that he has seen multiple older-diesels in the SF Bay Area self destruct or at least have valve train problems on Delo CX-4. I doubt that is really possible in less than 10-hours of running, but it may what we refilled the crankcase with last year.

Thx
Joe

Click to expand...

Have you already removed the rocker assembly to notice the exhaust valve is frozen open?

Please explain why you prefer to go the longer, more expensive way first and not eliminate the damper as the cause. Are you planning a head rebuild for instance.
Brian at AM has often been quoted check the damper, they do not last forever and have caused this lockup more often than a #6 issue. The labor time involved in re&re the head must be 4 times re&re the damper that needs changing on some regular basis.

Capt. Warfdog,
Soo-Valley has a good point me thinks.
Something I’m going to add is that if you do a lot of very slow running in gear like trolling for salmon it’s very likely the damper plate. Also you can add adjusting the idle speed too low can also promote damper plate problems. Both = double trouble.
So if you do lots of fishing or any more of the above check the DP.

kchace said:

RT I was reading this and thinking to myself “of course I can hear what MY engines are doing” but then I got to the part about 300 monkeys shaking cans of marbles up and down and I think you’re onto something. That’s exactly what they sound like!

Ken

Click to expand...

Beauty can be in the ear of the hearer, but I think my 120s(2270hrs) had a sweet sound running, even when in the ER, between them. Now about that earwax buildup.......no, really, I think they sound ok, so have others.

Greetings,
Mr. BK. Our engines sound marvelous when running. I can easily tell when they've reached their "sweet spots" (1250 RPM and 1750 RPM) but as to picking up the sound of a stuck valve, for instance....Ah no. Not so much.

RT Firefly said:

Greetings,
Mr. BK. Our engines sound marvelous when running. I can easily tell when they've reached their "sweet spots" (1250 RPM and 1750 RPM) but as to picking up the sound of a stuck valve, for instance....Ah no. Not so much.

Click to expand...

It sounds something like this.

purrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr....thunk
purrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr....thunk
purrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr....thunk, thunk, thunk
purrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr....thunk
purrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr....thunk