Engine replacement

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Theduke1948

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Joined
Feb 5, 2018
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Location
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I am thinking of replacing a Ford Lehman 120 with a Yanmar 4jH110 common rail Diesel engine. The boat is a Blue Seas 36 at 12 tonnes. Any thoughts? Has anyone done this?
 
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Duke, I had to search to find West Lakes Shore.
What hp is the Yanmar, is it enough? Some Blue Seas of Lehman era came with twins, others like yours with a single.Problem in changing engines is not so much a different engine but all the hassle that goes with it, like electrical,changed engine mountings,prop shaft length,exhaust system.....have you given up on rebuilding the Lehman? Or finding another one? Or fitting a 135 which might drop right in? If I could make good the existing I don`t think I`d contemplate the swap.
 
Theduke1948 said:
I am thinking of replacing a Ford Lehman 120 with a Yanmar 4jH110 common rail Diesel engine. The boat is a Blue Seas 36 at 12 tonnes. Any thoughts? Has anyone done this?
Click to expand...
Not familiar with that Yanmar. Believe they run at a significantly higher rpm. You may have issues with getting tall enough gears (transmission ratio) to be able to use your existing propeller. Just another added cost to consider.

Ted
 
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You can totally rebuild your Lehman for about $20,000. The new Yanmar alone will cost that much, much less all of the changes required to install it.

The Yanmar will probably save you a little on fuel- maybe a few tenths of a gph at cruise speed.

The Yanmar is a 2 liter engine and the Lehman is a 5+ liter engine. The Lehman will last several times longer than the Yanmar.

I would stick with the Lehman.

David
 
I was looking at a NT32 w a 6cyl Yanmar a few years ago. It all looked good until I called the local distributor. I was on the phone for about 5 minutes before I located someone that had heard of it. Never did find a source of parts.
I had a small Yanmar that was a great engine having no problems at all. Many here don’t like high rpm but I don’t see it as even a small problem. One of the best Yanmars (4JH) has a bullit proof reputation and the developed their rated power at 3800rpm. I’m talking about the nat aspirated engine. Think they had/have higher output turbo engines also on that same 4JH block.
I’m fine w Yanmar but you better stay clear of that engine that has the parts problem. But then I repowered w a Mitsubishi over 10 yrs ago and haven’t needed any parts except oil filters.
 
Wow. I have a 4JH Turbo 110 in my NT 26. Although I usually cruise at 1800 to 2000 I would severely question the ability of this unit to power a 36 ft boat. Jim
 
Have you contacted AMerican Diesel.

http://americandieselcorp.com/

THey offered a drop in replacement. Maybe they still do. It was a different engine but the power characteristics were similar.
They marinized the original Lehmans so they knew what it would need to be a drop in.

Try contacting them to a least find out if it is still available.

I also agree that a good rebuild of your engine is likely the better way to go.

Talk to them about why you are thinking about an engine change.

Changing mounts, electrical, controls, shafts, exhaust and so on can sometimes double the cost of the engine alone.
 
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BruceK said:
Duke, I had to search to find West Lakes Shore.
What hp is the Yanmar, is it enough? Some Blue Seas of Lehman era came with twins, others like yours with a single.Problem in changing engines is not so much a different engine but all the hassle that goes with it, like electrical,changed engine mountings,prop shaft length,exhaust system.....have you given up on rebuilding the Lehman? Or finding another one? Or fitting a 135 which might drop right in? If I could make good the existing I don`t think I`d contemplate the swap.
Click to expand...

The Yanmar is 4cylinder 110hp. Our diesel mechanic has quoted approx $20,000 to overhaul the Ford Lehman or approx S30,000 to install a new Yanmar and gearbox. New price 18,000 plus 12,000 for the changes. This is Australian dollars. I am wondering whether a 4 cylinder higher revving modern 110hp motor will be better than the old 6 cylinder 120hp slow revving motor and if anyone has experience with making such a change.
 
C lectric said:
Have you contacted American Diesel.

http://americandieselcorp.com/

They offered a drop in replacement. Maybe they still do. It was a different engine but the power characteristics were similar.
They marinized the original Lehmans so they knew what it would need to be a drop in....
Click to expand...
The OP is in Australia, whole engine import is an expensive option. I got a new FW pump came from Wagga Wagga Tractor in NSW,it fitted a long list of trucks, tractors etc, I`d say the Ford parts are available.Marinizing parts could be imported from the usual suspects, ADC, Bomac, fredwarner1,etc.
 
I am not familiar with the Blue Seas boat. Is it a semi displacement hull? Second, you don’t say why the Lehman needs rebuilding. Are you absolutely sure it needs rebuilding? If it does, I would be very hesitant to put a lightweight high RPM engine in place of a heavy slow turning engine. You have been quoted $30k for the replacement. Is that price guaranteed or is it an estimate? If it is an estimate then be prepared for the price to escalate once the mechanic gets into it. The tranny, engine mounts, exhaust and a lot of electrical need to be changed. A couple of missed items in the estimate or something that goes badly and you can kiss the estimate goodbye. And in the end are you absolutely sure the lightweight high RPM engine will perform the way you want and need it to? How did the boat perform with the Lehman? Personally I would rebuild the Lehman and it will run for the rest of our lives if you take care of it.
 
Comodave said:
I am not familiar with the Blue Seas boat. Is it a semi displacement hull? Second, you don’t say why the Lehman needs rebuilding. Are you absolutely sure it needs rebuilding? If it does, I would be very hesitant to put a lightweight high RPM engine in place of a heavy slow turning engine. You have been quoted $30k for the replacement. Is that price guaranteed or is it an estimate? If it is an estimate then be prepared for the price to escalate once the mechanic gets into it. The tranny, engine mounts, exhaust and a lot of electrical need to be changed. A couple of missed items in the estimate or something that goes badly and you can kiss the estimate goodbye. And in the end are you absolutely sure the lightweight high RPM engine will perform the way you want and need it to? How did the boat perform with the Lehman? Personally I would rebuild the Lehman and it will run for the rest of our lives if you take care of it.
Click to expand...
I am looking at purchasing the Blue Seas 36. It has sat idle for 6 years and needs a lot of work. The engine which was running fine when last used will not now turn over. The mechanic believes water maay have found its way into the cylinders. Unfortunately we will not know what is wrong until it is pulled apart which is why I am looking at all options. I will not make an offer on the boat until I am well aware of what it may cost repair and repaint the boat. A Blue Seas 36 is a Europa style displacement trawler built in Taiwan in 1982.
 
Duke, if it is the boat advertised in SA,the advert says Ford Lees. Same basic engine to overhaul but different marinizer. Of necessity I follow Lehman parts, but not Lees.
 
For a displacement boat the Ford was way oversized.

If a log is available researching the fuel burn per hour will give a rough estimate of the actual HP needed to cruise the boat.

Figure 15 HP from each GPH , so a 3 GPH fuel burn would equal about 45HP.

The replacement engine should be perhaps 75 HP so there is some extra for punching into high waves and wind.

A non turbo engine is less complex , and engine speed at cruise will be determined by the old shaft speed at cruise .

Gear the new engine for the same shaft speed , and the prop and shaft will work fine.

Should you be able to somehow obtain a BMEP or fuel map for the new engine the HP/ RPM for cruise will be easy to see.

Lowest cost would be to pull the head on the Ford and see what is wrong .

IF the engine can be lifted enough to drop the crank , the cylinders can be re honed, and new rings installed.

New bearings at the same time would add little to the bill.
 
Theduke1948 said:
The Yanmar is 4cylinder 110hp. Our diesel mechanic has quoted approx $20,000 to overhaul the Ford Lehman or approx S30,000 to install a new Yanmar and gearbox. New price 18,000 plus 12,000 for the changes. This is Australian dollars. I am wondering whether a 4 cylinder higher revving modern 110hp motor will be better than the old 6 cylinder 120hp slow revving motor and if anyone has experience with making such a change.
Click to expand...

Slow is always better. Better engine life, less noise, less vibration. Also the new Yanmar is an electronic, common rail injected, high output turbocharged engine. Lots more to maintain and to go wrong.

The only real benefits to the new Yanmar engine is lower exhaust emissions and better fuel economy.

David
 
While it probably won't make much of a difference at cruising speed, 6 cylinder engines are inherently smoother running at low rpm than 4 cylinder engines. My John Deere has counter rotating balance shafts, but it's still nowhere near as smooth as a 6 cylinder when idling or running just above idle.

Ted
 
Theduke1948 said:
I am thinking of replacing a Ford Lehman 120 with a Yanmat 4jH110 common rail Diesel engine. The boat is a Blue Seas 36 at 12 tonnes. Any thoughts? Has anyone done this?
Click to expand...

Why replace it? If it aint broke, keep the money in your wallet.
 
I would not want a 4cyl high rev motor in a trawler unless it has counter rotating balance shafts. The inherent second order vibe of a 4cyl can be very annoying at high rev, and to get to hull speed this thing will need to spin up pretty high.

I looked up the engine but could not find if it had balance shafts or not. I know the earlier 4jh did not.

Big difference in sound quality. A big six at 1500 just purrs. A little four at 2500 sounds like a chainsaw.

My vote is for a big heavy slow six with no computers. Even if locked up, a full reman may not be needed. I've unstuck several engines in my shop where water sat in a cyl. Beat out old piston, hone if not bad, bore if bad, some new parts and out the door for like $5k.
 
As far as the 4JH 110 having enough punch for a 36 at 12 tons, ask the Island Packet guys like CarDude. He’s got a 41 PY Cruiser at about the same weight. True, this is a 3500+ RPM engine and mating to a big prop would take some gear, but there’s plenty of parts around and even a good selection of used engines. There’s at least one or two 12 ton Krogen Manatees with 4 JH’s, but one should note that the original Volvos were also 3600 RPM engines, so gearing and props were fairly well matched.
 
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I have that Yanmar 110hp in my boat. It pushes it at about 7 knots at a comfortable RPM of 2000, but I have a pretty slippery sailboat type hull. It will push my boat 8 knots but that’s way too noisy for me at 3000 rpm.

My boat also weighs about 12 tons and has a waterline of 35’.

I don’t think you would be happy with the 110HP Yanmar. I would rather have a lower reviving, bigger displacement engine in a boat that size.
 
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I agree the 110hp engine will probably not be enough power. But that’s basing my opinion on Bruce’s opinion that the OP’s hull is like an IG.

My opinion is that the newer engines are better than the FL and would find one if it were me. MER in Seattle offered a JD that was intended to be a drop in unit for replacing the FL. Don’t know their prices and I do know one customer of theirs that was disapointed in MER. I liked him a lot but he was a bit of an odd duck.

But if the OP’s boat is a FD the 110 Yanmar would be at least close to ideal.
 
cardude01 said:
I have that Yanmar 110hp in my boat. It pushes it at about 7 knots at a comfortable RPM of 2000, but I have a pretty slippery sailboat type hull. It will push my boat 8 knots but that’s way too noisy for me at 3000 rpm.

My boat also weighs about 12 tons and has a waterline of 35’.

I don’t think you would be happy with the 110HP Yanmar. I would rather have a lower reviving, bigger displacement engine in a boat that size.
Click to expand...

Dude,
Is that the 3000rpm JH or the 3800rpm engine?
 
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Yeah, I realized too late that the O.P was in Australia.
It might still be worth asking American diesel for advice. The logistics of shipping may not be worth it but the advice could well be.
Try it.
 
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