Dead Lehman 120

boatmon said:

Okay. I backed off the plate covering the flywheel, not enough to have unlimited access due to the stuffing box. Only had about 2" of shaft that I could slide back. No pesky spring fragments anywhere that I could see....

We're pulling the engine early next week.

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Having owned a boat like yours with exact same engine, where the hour meter broke at about 3000 hrs, just after I bought her, yet was still humming beautifully when I sold her 16 years later, that engine of yours is theoretically barely run in for a Lehman 120hp. I agree with all the folk who recommended doing as little as possible to get that engine reconditioned and stick with the 120.

By the way, ours was a sedan like you have - or converted her to. I think that is now the best layout for sheer indoor/outdoor living, without the aft cabin so many were built with. Congrats on a great and clearly loving restoration/conversion. But if possible, hang onto that engine and just fix'erup..!

PS. There's no such thing as a 'dead' Lehman 120. Just one that's not running perfectly right now...ok?

This gentleman swapped out a six cylinder Perkins for a four cylinder. Not sure if this helps, but watching him restoring his old Monk is pretty enjoyable.

PS. There's no such thing as a 'dead' Lehman 120. Just one that's not running perfectly right now...ok?

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And some that need surgery. LOL

Hey me bruddah, sorry to hear about this. But Wabi will be up and running soon enough.
I know you remember what boat means.....

I would be willing to bet it is your dampner plate. Sounds just like a rod letting go or a dropped valve. If you have rust in bell housing even more proof.

The pieces fall between the block and flywheel.

Try turning crank backward, to see if it falls free.

Dampner plate is only good for 2500 hrs. Never heard of a Lehman failing catastrophically. Great engine.

Changed mine at 5000 hours, noise reduction was dramatic. Plate was completely shattered.

Choices, I tried up, down, left, right and with all my 253# on the crank bolt and nothing budges. Yeah, I've been told that the dampener springs make just like a frozen crank.

More will be revealed.

Hey Brudda Jay, upnort now?

Comodave said:

With my photos it seems to be a crap shoot if they load correctly or not so I gave up worrying about it. Sometimes no matter what I did they would load wrong.

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Como,
Are you guys taking pics w i-pads ect?
Been my experience that you must take the pic w the pad (or ?) oriented correctly. Need to take some test pics and take notes how the pad/camera was oriented. Then if you always hold the pad that same way all the pics on TF will be right side up. Or should I say right end up. The saying right side up is not right. Confusing anyway .... You don’t want the side up you want the top or bottom up. But there’s no word for that that includes both .. ???

Yeah, Peter B, mine was just like yours, except when I started to rebuild her, there was sooooo much water sandwiched between her glass sheathing you coulda wrung it out like a wet towel. All had to go. We wanted more salon, so I extended 18" and widened to full gunnel. All the 2 of us need as a floating... I'll try to add a pic, but it may be upside down....?

boatmon said:

Hey Brudda Jay, upnort now?

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Yes.

I have a link I'd like you to read but I'm at my son's home some distance to mine and using my tablet so I'll see if I can remember other threads I had link it to.

The short answer is bigger engine with higher horsepower might very well use less fuel. Think of the RPM's to get up to a given speed, let's say 7 knots, and the larger engine will use less RPM than the smaller engine and probably last longer as the smaller engine will be more stressed (heat) than the larger engine.

My boat is in for refit and repower and is being prepped as I type this to take the new engine and leg as it is a stern drive jobbie. I had to learn a wee bit as I made the switch. First I tried to match HP to HP with Volvo, but Volvo didn't want to play that game. You see my old engine was a 270 HP at the engine but really a 240 measured at the prop, which they do now compared to the days when Jesus was in diapers. The new Volvo engine I was interest in was a V6 but given the weight of my boat it would be under more stress and Volvo didn't want to warranty it under those circumstances.

So I got a larger engine, much larger (semidisplacement hull with shallow v bottom) that is 350 HP at the prop. It is a larger block V8 than my old engine. Part of my reasoning was that at a given speed, again lets say 7 knots, the rpm will be less and thus use less fuel, not more as you might guess because the hp is higher. The RPM's will be significantly lower, heat stress is significantly lower thus the engine will last longer if I don't use it a lot at WOT.

I don't know your circumstance but if you are older you may not care if the engine doesn't last significantly longer. My son knows he's inheriting my boat and I want to save him the task of repowering, really the expense of a rebuild at the very least. The stress on engines is much more significant moving a vessel through water than any land based vehicle engine experiences. Evening doing 75 mph on the interstate is less demanding; if you look at your car's rpm guage when travelling at that speed you'll observe that is only at about the 1/3rd mark of WOT.

When I talk to friends about the stresses of a marine engine I liken it to a very large container truck carrying potting soil (heavy) permantly driving up a very steep hill, that's your boat engine at work.

Only if you drive that way....I use well less than half the hp of my engine...sometimes down maybe a third.

So if I got an 80hp replacement I would still be in the operating recommended RPM for it and probably never wear it out either.

More people are worried that I am in danger of glazing my cylinders than anything.

120 hp

I would keep the 120 hp and rebuild. I had a smaller Lehman in a 36' boat (displacement hull) for a number of years, and it was faster than the speed of "heat"!
Very odd that 3000 hrs you would have a problem.

Best of luck

J

Seen some video's of older (and larger) diesel engines in inland waterway vessels in Europe. (Deutz, MAN, Brons, etc.) Many of these have a sequence of things to be done before starting and one of them is to pump the lub oil (which has been sitting at the bottom of the engine) throughout the engine with a manual pump. I would not know if one could do that with a Lehman, never heard of it, but hey, not too old to learn. Good luck and yes, my money would be on a rebuild, those Lehmans are amazingly reliable engines.

Ahoy all. The engine is coming out on Wednesday. Wabi Sabi will be drydocked as we have the seized Lehman evaluated and most likely rebuilt.

More will be revealed then. I will keep you all posted.

Capt Harry

boatmon said:

Ahoy all. The engine is coming out on Wednesday. Wabi Sabi will be drydocked as we have the seized Lehman evaluated and most likely rebuilt.

More will be revealed then. I will keep you all posted.

Capt Harry

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I hope it is nothing too expensive nor time consuming...
I think you will be happy reinstalling the original (rebuilt) engine. No surprises.

Nomad Willy said:

Como,
Are you guys taking pics w i-pads ect?
Been my experience that you must take the pic w the pad (or ?) oriented correctly. Need to take some test pics and take notes how the pad/camera was oriented. Then if you always hold the pad that same way all the pics on TF will be right side up. Or should I say right end up. The saying right side up is not right. Confusing anyway .... You don’t want the side up you want the top or bottom up. But there’s no word for that that includes both .. ???

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Usually I use an iPhone and mostly keep it the same way. Some photos taken at the same time and orientation willupload differently. Don’t know, I am not a computer expert by any means.

Choices said:

I would be willing to bet it is your dampner plate. Sounds just like a rod letting go or a dropped valve. If you have rust in bell housing even more proof.

The pieces fall between the block and flywheel.

Try turning crank backward, to see if it falls free.

Dampner plate is only good for 2500 hrs. Never heard of a Lehman failing catastrophically. Great engine.

Changed mine at 5000 hours, noise reduction was dramatic. Plate was completely shattered.

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It is never a good idea to turn a motor backwards...

Exhaust back wash

I am wondering how it seized. Were you driving along and it suddenly stopped or was it seized when you went to start it after it had been turn of for a few days.
I had the misfortune of buying my boat and the motors (120 Lehman's) ran fine but the time before that engine run, it got a guts full of sea water as a result of an unacceptable exhaust system, and when it was run for me it pumped that water through the engine. After I took possession one of the motors wouldn't start as it was seized and what actually stopped the motor from turning over was salt on the mains that was left there after the water evaporated from the engine heat. The motor was still tight until I took the last main bearing off. I probably could have used the original bearings as there was no engine damage or bearing damage but decided to replace anyway while the motor was down, the rings were okay as was everything else.
I must stress that it was impossible to turn the motor at all until all the big ends were off and half the mains and even then it was very very tight.
This info is redundant if you had and oil or heat related seizure
good luck

Juggerknot said:

It is never a good idea to turn a motor backwards...

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A slight attempt to rock the engine to get the crank turn seems pretty common in the Lehman world.


Is there something in particular with this engine that a half rotation in the opposite direction will hurt?


I understand that on some engines it can be a problem depending how many rotations are done.

psneeld said:

A slight attempt to rock the engine to get the crank turn seems pretty common in the Lehman world.


Is there something in particular with this engine that a half rotation in the opposite direction will hurt?


I understand that on some engines it can be a problem depending how many rotations are done.

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Where and how is it a problem? I've never heard of it being an issue either.

Post #46 triggered my post.

psneeld said:

Post #46 triggered my post.

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Many diesels will take a 1/4 to a 1/2 turn backwards on their own when shut down. At least the older ones.

Cigatoo said:

Many diesels will take a 1/4 to a 1/2 turn backwards on their own when shut down. At least the older ones.

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I've seen a few degrees at shut down on my old Dodge truck Cummins, but never 1/4 turn (90 degrees).

jleonard said:

I've seen a few degrees at shut down on my old Dodge truck Cummins, but never 1/4 turn (90 degrees).

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I never measured.

Possibly I'm alone. I do not find it odd that a +40 year old diesel, of unknown previous maintenance and having sat for 6 years - failed. Yes, 3,000 hours seems low for a Lehman, but not necessarily a good singular measuring point.

I wonder if an exhaust valve was partially hanging open and over the course of the run it slowly sucked water back into a cylinder and seized the engine. I have seen this on gas engines before. It's the main reason marine engines run cams with no overlap if the exhaust is water cooled.

psneeld said:

Is there something in particular with this engine that a half rotation in the opposite direction will hurt

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The only way to bar a Lehman is a 1 1/4" nut holding the pulley on to the crank. Turning it backwards on a seized engine will simply unscrew the nut. But other than that issue, no problem in rotating backwards

Look what I just brought home today.... Still not sure why engine seized. Pulled the dampener plate off when I got home and all is as it should be.

More will be revealed when I start taking this one apart. We decided on having a new rebuilt 120 going back in. What the heck, it's only money!

Boatmon where will you be getting your newly rebuilt from and what are they charging for one if you don't mind. I have the same engine and have always been curious.

That is what boats are for, to give you a place to use all your excess money...

The Lehman's are pretty basic. Most all diesel rebuilders could do one. I've been quoted from $7K to $11K.