Stuck Valve, Ford Lehman 120 - a bit dire.

[wilsod3]

Hi All - my firs post. My 40 year old Tayana 42 Pilothouse has finally given up on me. My mechanic says I need a head-job (who doesn't) to confirm and maybe fix. If there is more damage (he thinks there will be gulp) he'll need to pull the motor. Best case I'm looking at $5k worst case, $40k. Unfortunately, I don't want to sink that much more into her. Does anyone know any old-hand 'tricks' to unsticking a valve in situ?

Thanks in advance.

D.

[Rucksta]

Leeman is a robust engine and can be made to run in less than perfect condition if you are prepared to burn a bit more oil and produce less power.

Sticky valves can be due to carbon build up.

Steam cleaning by spraying water mist into the air intake of a running
engine can remove carbon.

More likely cause is a bent valve stem / worn valve guide

It is possible to remove the valve actuation gear and reassemble with the head on by retaining the valves with compressed air.

Effective diagnostic but not much you can do by way of remediation.

Have you considered disconnecting the injector on the offending cylinder and running on 5?

[acem]

That sounds awfully high priced to me. I work on non marine diesel engines. You can rebuild most small diesel engines for much less than $10K. That would not include removal and installation.

If a head job on a marine diesel pays $5-40K i need to change professions.

Thx-Ace

[Compass790]

Originally Posted by wilsod3

Hi All - my firs post. My 40 year old Tayana 42 Pilothouse has finally given up on me. My mechanic says I need a head-job (who doesn't) to confirm and maybe fix. If there is more damage (he thinks there will be gulp) he'll need to pull the motor. Best case I'm looking at $5k worst case, $40k. Unfortunately, I don't want to sink that much more into her. Does anyone know any old-hand 'tricks' to unsticking a valve in situ?

Thanks in advance.

D.

Welcome to the forum wilsod,
Was the engine left sitting for a while before the sticking valve showed up?
If so I'd try a good soak with penetrating oil for a start.
Can't imagine a 40k cost for a Ford rebuild but to be fair I dont know that engine. You should get replies from people who know that engine before long.

[wilsod3]

Rucksta - you are a freaking genius. "Have you considered disconnecting the injector on the offending cylinder and running on 5? No, I had not but I immediately see the benefit. My boat is not a ski boat so I don't care if I lose half a knot.

I am going to try this ASAP!

Any tips on doing this? Is it as simple as disconnecting and crimping the fuel line.

Many thanks Rucksta. This is exactly the type of advice I was looking for.

D.

[wilsod3]

Well, our mechnanics get paid pretty good down here (Australia).
Plus, Covid has put the boat industry on steroids - strange during a pandemic that boats and motorcycles have never been in such demand. D.

[Wotname]

OK, yes Aussie marine mechanics aren't cheap or so I have been told.

If it was me, I would first confirm what the mechanic has told you. Has he told which valve is stuck? If he doesn't know then he has just made a guess.

What are you fault symptoms? I.E. does it start; run rough; no power; makes horrible noises etc??

If you loosen off the injectors from the head and remove the valve cover, you should be able to rotate the engine by hand and observe the valves for normal operation. A stuck should be obvious although a 'sticky' one may not.

I would not crimp a injector pipe, there is a couple of thousand PSI in the pipe. If you must disable it, cap it.

[waterman46]

A friend and I removed the head on a Ford-Lehman 6 cyl diesel for the skipper of a boat we were crewing on. Neither of us is a pro mechanic or even close. He took it to be rebuilt by a diesel repair shop and then I helped him re-install it. I think the head recondition job cost about $500 in 1990 and re-installation was straightforward. Worked like a champ. We took that boat San Diego to Tahiti and did a lot of motoring (3 straight days in the doldrums). All good.

If you never removed and replaced a cylinder head, you can do it yourself but do read up a bit on the general issues and techniques. This, like most mechanical jobs on the boat, is not rocket science. Mechanics time on the boat is expensive so do that part yourself if you can.

Nice cruising boat. Fix an' go!

[skipmac]

First thought was the $5k-$40k sounded outrageous but if in Australian dollars then a little closer to correct but still high, at least in the US.

But I agree with the recommendation to pull the head and give it a go. On a marine diesel where you don't have remove a couple of miles of wires and hose to get the the heads it is not that difficult a job. Just make sure you can get the parts first, especially a new head gasket.

[Cheechako]

You should be able to get that head off in 45 minutes or so.
Take the head to a reputable shop that isn't a "marine" facility.. One that does head rebuilds, pressure testing etc. It should be $1000 US max to rebuild it, and that would be high.
That will also allow you to determine how much cylinder ridge there is etc also.
You'll never get a better engine than that Lehman.

[skipmac]

Originally Posted by Cheechako

You should be able to get that head off in 45 minutes or so.
Take the head to a reputable shop that isn't a "marine" facility.. One that does head rebuilds, pressure testing etc. It should be $1000 US max to rebuild it, and that would be high.
That will also allow you to determine how much cylinder ridge there is etc also.
You'll never get a better engine than that Lehman.

[jakkum]

I had a sticking valve in a Mercedes engine. Figured out which one it was and with the piston down, pushed it further than the cam did. Result is that the carbon built up is scraped off a bit. Tha. Sprayed pen. oil on the valve stem and pushed again and repeated till I had the idea it was free.
Than started the engine and ran it slow and sprayed again now on all stems one by one. Put the cover back on and Bob was my buy uncle.

[ussvdharma]

do you have any friend that is the army national guard, they use that engine and the 80hp in their generators...lots of parts...get myy drift DE w7kfi

[Lancerbye]

The engine does not not have to be pulled to do a head job. I am not a mechanic but am mechanically inclined. I have done this. A shop that specializes in redoing heads will decarbon it check it for trueness, and do a valve job. They will check the valve guides also. To reinstall you will need a new head gasket and a good torque wrench. The experience is great.

[mickand]

I have twin Ford Lehman 120's and have removed the cylinder heads on both.
The exhaust manifold should be removed first and bear in mind it by itself is heavy - better to have an assistant but I have done it by myself.
The head is also heavy and is also better managed off with a helper.
I would imagine any engine rebuild shop could renovate the head as necessary and Brian at American Diesel can supply any parts required.