Ford Lehman 120 Bad cylinder

mplangley said:

I'd be happy to just live with it (for a while) but I am worried about two things. 1) the oily mess it makes out the breather tube and filter but also 2.) more importantly what further damage it may due to the engine?

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A good "Pro Vent" catch can will help fix that problem

manyboats said:

I can't believe nobody has come up w a fix for the overheating #6 cylinder. If I had an FL I'd sure tru something.

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When Harbor Marine, Everett, WA rebuilds a FL, they drill and tap the block in the lower part of the number 6 water jacket and install a fitting which is the supply or return (I don't know which) for the hot water cabin heater. This is supposed to improve flow around number 6. For more info call Mike in the engine shop.

I think you're nuts to run it with a bad cylinder. If the cylinder is galled you can break rings or worse, have the piston seize, break a rod? Crap in the oil, you name it. Don't run it, don't use snake oil, take a good look at it before you bake the entire engine. Reliable? It's giving you all the warning possible before you have a catastrophic and you have to throw it away.

How about a sticking valves caused by water seeping into the back of the valve head and sticking the valve open? Because it has been HOT?
Check by using oil down injector port if compression improves its rings if it does not it could be a stuck valve, I think those engines are free runners???( the valve wont hit the piston top) maybe it will if it is stuck wide open?? There are better more experienced heads than mine on here!

Barney said:

How about a sticking valves caused by water seeping into the back of the valve head and sticking the valve open? Because it has been HOT?
Check by using oil down injector port if compression improves its rings if it does not it could be a stuck valve, I think those engines are free runners???( the valve wont hit the piston top) maybe it will if it is stuck wide open?? There are better more experienced heads than mine on here!

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Water can certainly make its way to the FL 120 #6 cylinder through the exhaust port. I have seen both raw water and coolant end up there.

Larry H said:

When Harbor Marine, Everett, WA rebuilds a FL, they drill and tap the block in the lower part of the number 6 water jacket and install a fitting which is the supply or return (I don't know which) for the hot water cabin heater. This is supposed to improve flow around number 6. For more info call Mike in the engine shop.

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Hi Larry,
Are you up the coast now?
Glad to see someone has done something about the FL cooling problem. Mike is very very well known in the PNW for his good work and occasional good joke. He/they rebuilt our BW.
Probably would be the return hose from the heater as that would probably be the "suction" side of the loop. I'm quite sure one of our hot water hoses goes basically directly to the water pump. Would very likely draw some hot coolant away from #6 cyl.

Barney said:

How about a sticking valves caused by water seeping into the back of the valve head and sticking the valve open? Because it has been HOT?
Check by using oil down injector port if compression improves its rings if it does not it could be a stuck valve, I think those engines are free runners???( the valve wont hit the piston top) maybe it will if it is stuck wide open?? There are better more experienced heads than mine on here!

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Not good advice to put oil down a injector hole in a diesel for compression check. Oil goes right into piston bowl and that alone changes the compression ratio. Of course the readings will go up.

Leaky valves will not cause the blowby flow to go up, leaky valves send compression into exh or intake, if the compression is coming out the crankcase vent, it IS leaking past the rings.

No harm in trying something like outboard ring free, but if any of the aluminum smeared near the rings, it will do nothing.

And running it further can turn a piston replacement and in site hone job into an engine replacement.

Does cylinder fire at all at 1700 under load? or is all the fuel coming out as smoke? If it is not firing, that hole is in really bad shape.

Do the compressed air into inj hole trick, see if pressure builds with valves closed.

Do diesels burn holes in their piston crowns like gas engines?

FL "Ticks" at all speeds

I have a FL 120 (one of a pair) on a President 41 Trawler. I have been driven to distraction by a constant "Ticking" sound in the after part of the top end of the engine. I have done all the expected things and cannot find a problem. Engine performs fine, no smoke to speak of, plenty of power but it still makes noise. This has gone on for about 2 years now. Engine has about 3300 hours. Oil analysis shows nothing out of the ordinary. Can someone advise on this. My best mechanic says maybe "Piston Slap".

manyboats said:

Do diesels burn holes in their piston crowns like gas engines?

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Yep, they do, but mostly in high output turbodiesels making 50+ hp/liter. On lower rated engines the piston crowns rarely burn, but if piston gets too hot it expands to eat up all clearance and then it starts to scuff. Damage there is usually limited to skirt and bore.

Mike W said:

I have a FL 120 (one of a pair) on a President 41 Trawler. I have been driven to distraction by a constant "Ticking" sound in the after part of the top end of the engine. I have done all the expected things and cannot find a problem. Engine performs fine, no smoke to speak of, plenty of power but it still makes noise. This has gone on for about 2 years now. Engine has about 3300 hours. Oil analysis shows nothing out of the ordinary. Can someone advise on this. My best mechanic says maybe "Piston Slap".

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Valve lash checked? Also try cracking individual inj lines and see if it is diesel knock. Slap will persist even with injector canceled.

Piston slap can come from too loose a fit between piston and bore. But it is generally harmless unless really excessive. If engine had a piston failure in the past and someone honed the crap out the bore to clean it up, you will have slap. But if no other symptoms, it can run dang near forever like that.

Provided it is slap.

On a Lehman #6 I would rather have piston fit too loose than too tight!!!

Thanks Ski

I have checked the lash as well as fuel system knocking. Both negative. Guess it will remain a mystery.

Ski, I think i am going to cancel my subscription in boatdiesel.com and simply ask ask you for your knowledgeable advice here and save some money to spend more in my boat!

Video piston slap 2714 #6

Sorry my video did no upload

Piston slap lehman 120 2714 #6 https://vimeo.com/166044459?utm_sou...vimeo-cliptranscode-201504&utm_campaign=29220

Thank. That is exactly what mine sounds like. Any recommendations or should I just live with it?

Make sure it is piston slap I did a oil analyst and had high amounts of aluminum and other metals in the report. I've been told a bad injector can make a similar sound. http://www.trawlerforum.com/forums/s6/lehman-120-piston-slap-17797.html

Busterbrown said:

Make sure it is piston slap I did a oil analyst and had high amounts of aluminum and other metals in the report. I've been told a bad injector can make a similar sound. http://www.trawlerforum.com/forums/s6/lehman-120-piston-slap-17797.html

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So, it's been almost a year now for yours. Hows ole #6 holding up for you?

Mr Barnacles It is running great no more knocking and the oil looks good I have put 80 hours on the engine and will change the oil soon l will send out a sample for an oil analysis and post the results

Thats very reassuring. I will before too long also repair a #6, and was hoping to follow your method.

Oh, and I'm glad for you too. LOL

Well - I finally have the necessity for further exploration of my "bad cylinder" problem.

One fine evening a couple of weeks back while leaving the harbor my engine seized. At least thats what appears to have happened.

I have removed my head expecting to find either a damaged #6 piston/cylinder or a stuck valve (causing all my smoke( but as far as I can see there is no apparent damage - at least not to the piston head and not stuck valve. Of course as fate would have it numbers 1 and 6 are at the very top of their cycle so I cannot see either cylinder . On those I can only see the piston heads which look fine though the $6 seems to have more carbon than #1.

Im trying to figure out next steps and what could be causing the engine to not turn over. My connections are all good and the start is definitely attempting to turn the engine. Ive tried wrenching it over on the flywheel but no luck there either.

Any ideas about what I should look at next? My current theory is that its either a bearing or a piece of broken transmission is gumming up the works.

Ive attached some photos of the head bottom (valves). I don't have a lot of experience so I am not sure if it looks good bad or ugly.

The mech that looked at mine in Wilmington, NC said no problem rebuilding in place on my boat, but lots of space around a single.

bummer.

disconnect the shift cable and see if you can move the shift lever through the gears easily. make sure you feel it pass thru the detents. Then put it in neutral and see if the engine rolls over.

The #4 looks like it has rust, and thats not good. If the engine hydrolocked while under power it could have bent some connecting rods.

If you cant roll the engine over in neutral then you have to beat the siezed pistons out. Then if you have enough sleeve left to bore out its time for that.

Me, personally, I wouldnt stick another nickel in it. Replace it with a cummins natually aspirated. Way cheaper, rugged, and parts are everywhere for far less than lehmans. I am putting this one in my boat. I pet it everytime I am at the storage....



http://www.trawlerforum.com/forums/s9/cummins-6b5-9-m-diesel-29258.html

Amazing you got it to run for all this time. I think it is number 6 - very well-known failure. Lots of information on that, number 6 fails and rubs on the cylinder wall, destroying the piston and the cylinder wall. I would pull that piston out, dollars to doughnuts its only number 6 and that's why it seized.

Did you call Industrial engines? They will sell you a long block and you get to buy it with Loonies.

You still don't know if its the engine or the transmission but its rare to be that. Better find that out first, the transmission will have to come off anyway although you can haul it out with it attached. Did it overheat or just stop? Yes, you can rebuild it in place but if you haul it up into the salon it will be much easier to manipulate. And, if you get it into the salon you can just slide it out the rear door and get it done in a real shop. Or replace it.

Seized engine - FL-120

Mike,

Sorry to hear the engine seized.

With the head off, can you move the crank with a breaker bar in any direction at all ?
Try soaking the rings while the head is off with some solvent & then again to attempt to move crankshaft forward then back several times.

Usually when this happens in a FL diesel it is the piston seized in the cylinder bore. Metal transfer from the piston to the cylinder walls will lock it up solid. Often you do more damage to block when removing the piston when still in the boat.

major internal damage can happen.

Your engine was overhauled not that long ago. Do you have any history or info on that, as to the what happened & how it was repaired, what parts installed, etc.. ?

Does not sound good for this engine. Some guys can bore the block in place, but not that I would recommend that, as to do a proper hone job you have to hone cylinders with a machine like the "Sunnen CK-10" or the newest one that is now called the " Sunnen SV-10 " cylinder hone machine to make the bore as close to perfect so it does not happen again. Other wise history may repeat itself.



Let me know if I can help as I am local.


As soon as my wife is better we can pull the FL-120 out of my boat & you can use that good one.

Thanks.

Alfa Mike

Could be a failed damper plate. The springs fail and get jammed between the plate and block. You need to slide the trans back to check it out. You just need enough room to get a mirror in there. If you have the head off and can't turn the crank I'd bet on the plate.

meridian said:

Could be a failed damper plate. The springs fail and get jammed between the plate and block. You need to slide the trans back to check it out. You just need enough room to get a mirror in there. If you have the head off and can't turn the crank I'd bet on the plate.

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Just went through all that myself...but pretty sure it was my dampner plate in North Carolina acting up, engine siezed up about 600 miles and 200 hrs later.....pulled tranny, yep.

Did the head gasket afterward though for a slight combustion to coolant leak if that thread comes up.

Makes me wonder if there isnt an hour rating for damper plates.

what_barnacles said:

Makes me wonder if there isnt an hour rating for damper plates.

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Trouble is the older design ones with springs corrode to failure to a point....plus if you have a lot of vibration at low rpms and have to sit there (as in bridges and locks), that shortens its life.

But the feeling I got with my research is 2500 to 3000 hours is expected, over that is anyones guess.

Because my engine was a rebuilt, I have no idea what the PO put in new at the time...it failed at 2900.