Cost to overhaul Ford Lehman 120 HP?

As we continue our boat search for an older trawler we often see boats with Ford Lehman 12 HP engines.

Does anyone have any recent experience with the cost of a full overhaul of one of these should it be necessary?

Last year Harbor Marine in Everett was quoting $17,000 plus a core. Try them or North Harbor in Anacortes for current prices.

About $10-11K. We had a SP135 done 2.5 years ago by Bomac Marine. We pulled and reinstalled the engine. Less than a day for each. Here's a link for pretty much what he did:

http://bomacmarine.com/pdf/Suggested-Parts-Kit-for-Lehman-Ford.pdf

Ask Brian at American Diesel, the go to place for all things Lehman. They don't do overhauls but should know who does.


$17,000 sounds steep but may be reality. At that price I would look hard at repowering with a factory remanned Cummins 6BT 210 hp. New factory warranty and a newer design. Probably low $20,000s for bobtail engine and will take more work on engine mounts to make it work, but if you need to pull the engine for overhaul you are 80% of the way there.



But don't start your boat search assuming that any Lehman or similar engine may need to be overhauled. It takes a catastrophic event: loss of cooling or oil to cause enough damage to require overhauling. Most old Lehmans just need TLC and maybe a few marinization items replaced. American Diesel has all of the parts you need.


David

If the Lehman's in the boat you are looking at survey clean I wouldn't worry about them. There are a lot of them out there still running strong with over 10,000 hours. As one poster said the only thing that will kill them is overheating and loss of oil.

Marinized by Lehman they are a simple piece of steel based on a industrial engine built by Ford. I would rather have a old Lehman without all the computer and electronics crap on them than a newer power plant where you need a degree in electronic engineering to work on the.

Is the Lehman a direct injection design though? If not that would be a big reason to modernize. Which you can do with out computers in a Cummins.

Trusty old engines easy to repair yourself. Simple, efficient. Parts are available for a realistic price. After service from American diesel is excellent advice is free and parts are reasonable. Pulled my own engines changed oil pumps. Also pulled engines and changed camshaft and followers. In line six's with no electronics. Everything so simple, you have diesel? You have air. You have cranking power. The engine starts!
My current / new boat has cat 3208's NA again no electronics. Just love the KISS principal. And adored my Lehmans 120hp.

rjwilliams11741 said:

If the Lehman's in the boat you are looking at survey clean I wouldn't worry about them. There are a lot of them out there still running strong with over 10,000 hours...

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The only reason we rebuilt our Lehman at 8400 hours was we had to remove it from Hobo to get the fuel tanks out. The last oil analysis, as the previous ones, were perfect.

Thank you all for your input. I agree Ford - Lehman's are as near bullet proof as you can get. Simple, inline 6, all mechanical, naturally aspirated. What's not to like.

But, I'm realistic and want to manage financial risks as well as maritime risks. Hence the request for overhaul prices.

If my 225’s ever need to be rebuilt, I will be finding used ones to buy.

If using a local rebuilder , I would shop for the best "speed shop" in the area.

They are usually used to doing unique engines and should (ask) have the best equipment for the job.

They should be able to line bore the block for crank & cam shafts. Straighten the crank as required.

Most important would be their skills with balancing the reciprocating parts.

Matching piston weight , con rods end for end etc. is seldom done on a low RPM boat motor but it is not expensive and can make a Huge difference in the smoothness felt on board.

Since we boat for pleasure and an inline 6 is smooth to start with , why Shake Rattle and Roll just because the boat engine started out with tractor specs?

djmarchand said:

Ask Brian at American Diesel, the go to place for all things Lehman. They don't do overhauls but should know who does.


$17,000 sounds steep but may be reality. At that price I would look hard at repowering with a factory remanned Cummins 6BT 210 hp. New factory warranty and a newer design. Probably low $20,000s for bobtail engine and will take more work on engine mounts to make it work, but if you need to pull the engine for overhaul you are 80% of the way there.



But don't start your boat search assuming that any Lehman or similar engine may need to be overhauled. It takes a catastrophic event: loss of cooling or oil to cause enough damage to require overhauling. Most old Lehmans just need TLC and maybe a few marinization items replaced. American Diesel has all of the parts you need.


David

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In 2008 I purchased a new Lehman 135 from American Diesel for $13,500. The estimate to overall the original FL120 was $8,500. I donated that engine to a marine educ. foundation and received a $1200 charitable deduction on my federal tax return. Problem with the engine was an out-of-round piston caused by over heating. The #6 cylinder is vulnerable to this problem...also referred to as "piston slap", it will sound like the engine needs a valve adjustment. American Diesel offers an external cooling modification to prevent this problem.

I looked over the items on the Bomar list posted above. If you were doing your own, or even having a good local shop do the work with your supervision, the costs should be quite a bit lower. There are a number of items on that list that can easily be avoided if you are careful in how you approach it.

Portage_Bay said:

Thank you all for your input. I agree Ford - Lehman's are as near bullet proof as you can get. Simple, inline 6, all mechanical, naturally aspirated. What's not to like.

But, I'm realistic and want to manage financial risks as well as maritime risks. Hence the request for overhaul prices.

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Makes sense to ask the question, but chances are if you acquire a boat with Lehmans you`ll never have to rebuild.
The main threat is blocked cooling passages around no.6 cylinder(furthest from the circulation pump) leading to overheat and piston failure. A blockage there can require some effort and persistence to clear.
I`m unaware of an ADC fix for this,I am aware of: 1) an ADC updated raw water pump to replace the original where the drive mechanism can fail without warning, and 2) a return overflow storage bottle system, the latter being more convenience than disaster prevention.

BruceK - What would cause a blockage of the cooling passage around #6 ?

Funny but Brian at ADC told me not to worry about the blckage issue as it has been way overblown.


May be time to recheck with him and Bomac.

While talking about FL #6 cyl overheating nwboater wrote;
“American Diesel offers an external cooling modification to prevent this problem.”

What does that consist of physically. Some plumbing I assume.

There are so many neglected boats with perfectly good engines. Like I said, I’d be looking for someone selling some Lehman’s for cheap.

psneeld said:

Funny but Brian at ADC told me not to worry about the blckage issue as it has been way overblown.
May be time to recheck with him and Bomac.

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Perhaps the diagnosis changed, but couple of years back I talked with him by email and it seemed real enough to him, I think he referred to "silting" around no.6 and the need to remove freeze plugs(which we call welsh plugs(apologies to the Welsh) to get the passages clean. As to the source of the "silt", not discussed. Maybe from coolant.
My mechanic got at the fw side with a patent cleaning product he worships, and got it clean.
When I read on TF of a major internal Lehman problem it`s usually no.6 piston failing,which as a non mechanic I associate with reduced cooling around no.6, be it silting or just furthest from the circulation pump, or both.

I talked to him about it 2 years ago I think, maybe 3. I wanted a freeze plug and he as usual asked " for what?". I told him andI believe he told me don't worry about it. It wasn't a big issue and with no symtoms and regular flushing it shouldn't be a problem.


While TFers keep talking about this rblem, my research into it didn't make it sound like the big deal made about it here.



I might call Bomac and see, they are rebuilders so they should have a good idea.

i would not pay over 7-9k to overhaul an old diesel when you can get more modern remaned engines for under 15k.

When my Perkins needs it i'll go Cummins. It's sad and wasteful but the support dwindles and I wouldn't want to invest in a dying platform.

We looked at re-powering instead of rebuilding. When we looked at the running gear, engine beds, shaft log, electrical panel, fuel system, etc., that would have to be changed or modified, the project costs more than tripled. We couldn’t justify it in a 30 plus year old boat.

How many hours are on the engine/s?

I rebuild will probably cost you as stated (10-17k). But that’s just the start of it. You would add on 3k for unspecified expenses (getting trannies redone/exhaust, motor mounts etc...)

I have a Lehman with 5800 hours. I put 3000 of those hours on in just 4 years. I do all required maintenance (even lash the valves) and spend the cash on the consumables like elbows/coolers etc.... I ran it at full throttle for about 2400 of those hours traveling. (It’s in a smaller 26foot downeast boat with a 2 to 1 reduction)

I am a worry wart by nature and, like you, figured my purchase of the boat with a rebuild cost. That damn engine just runs and runs. I think it even runs better now, than when I bought it.

My point is, sure, calculate the rebuild costs, but don’t dwell on it. That engine will disappoint you in regards to any plans to rebuild it.

I had the number six cylinder in my port FL 120 suddenly develop a severe piston slap in 1987, about six months after I bought the boat.

I had recently reengineered the original muffler system from an all metal muffler place OVER THE TOP of the engine to a fiberglass lift system, but it was not soon enough.

The interior exhast pipe extended upward into the larger diameter "can" of the muffler to near its flat top. Water was injected into the can about midway up its side. Judging by the rust stains dribbling down the sides of the cylinder, the exhaust pipe had long ago rotted out inside the can allowing water to ingress the last cylinder after engine shutdown.

The most interesting fact was that the piston showed signs or "knurling" which is the shady practice of cross-hatching the skirts of the piston followed by smoothing to raise the overall surface back to original or higher. So somebody had previously removed this engine and had taken a shortcut.

For $6500, the engine was rebored, new larger diameter pistons installed along with new bearings, and four hours after getting underway from the FL dealer there in San Diego, the noise returned. The dealer identified the cause as "Bad" pistons and redid the job at his cost. Engine is still running like a champ in 2018 under the new-since-2015 owner.

We have twin 4 cylinder Lehmans in our 34' clipper. Found the dreaded coolent in the oil and we traced it to a failed liner.
To be honest any marine diesel mechanic locally was useless for this vintage, so we easily removed the engine ourself and sought assistance from a tractor repair shop. These guys knew the ford engine inside out, completed a full rebuild cheaply and sourced all the needed parts.

we just separated the cooling system and have sourced / serviced elsewhere.

I was keen to perform myself, and understood the theory with the engine being sio simple but didnt trust my practical skills and did not want to go to the trouble of refitting the engine only to find issues caused by my poor workshop skills..

Worth noting we are in Western Australia, so if you are in the US, likely you have skilled mechanics at your disposal.

All that being said, the lehmans are great, cheap to mainatain and repair, and if need cheap to rebuild. Our rebuild, including the fuel pump (1500 worth) and cooling system was about 6k australian.

Just had out 120 Lehman "serviced" at a total cost of $ 6000.00. (Pat's Marine Engines in Seattle) Oil changes, filter changes, impeller change, engine anodes changed, exhaust manifold removed and machined, new exhaust elbow fitted with new exhaust hose with better "flow". Heat exchange taken off and thoroughly cleaned and put back. (Made a big difference in the amount of cooling water out of wet exhaust!) Some new hoses, all fresh fluids and oils.
Not cheap, but hopefully good for another 50 years! Engine only has 3500 hrs on it. Service engineer stated that diesels need to run and run often!! Work still interferes with the hobby!!!!

GB3295 is there any chance you could post a video clip of how much water you are putting out of your exhaust at idle? I have the same engine and would love to compare.

av8r said:

Last year Harbor Marine in Everett was quoting $17,000 plus a core. Try them or North Harbor in Anacortes for current prices.

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I don't believe they are rebuilding Lehman engines any longer. Last year I was there for a motor mount casting and they said the fellow that did the rebuilding had health issues. But call them none the less, they are good people.

GB3295 said:

Just had out 120 Lehman "serviced" at a total cost of $ 6000.00. (Pat's Marine Engines in Seattle) Oil changes, filter changes, impeller change, engine anodes changed, exhaust manifold removed and machined, new exhaust elbow fitted with new exhaust hose with better "flow". Heat exchange taken off and thoroughly cleaned and put back. (Made a big difference in the amount of cooling water out of wet exhaust!) Some new hoses, all fresh fluids and oils.
Not cheap, but hopefully good for another 50 years! Engine only has 3500 hrs on it. Service engineer stated that diesels need to run and run often!! Work still interferes with the hobby!!!!

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I had work 10k$ worth of done at Pats several years ago. Most of the work was done well and I was pleased. Come to find out years later they repositioned the new motor mounts and changed the rear ones to being supported by the transmission. My shipwright in Port Townsend discovered this and said nobody does this. I called Pat and he denied doing it, which is weird. YMMV

Most smaller engines stateside have rear mounts on the gear, front mounts on the front of the engine block. It can be done on the engine only, that can be ok too. I can't imagine anyone changing it unless there is a driving need to do so. That is a lot of work.