Issues with a SP135 Lehman engine.

[Jsta_Rebel]

About a month ago, I started the boats 1990 Lehman 135 engine to motor out of our anchorage and noticed upon start up that there was a popping sound coming from the air intake manifold of the engine. It only lasted a minute or so before going away, and did not come back until Sunday when we were coming back into the bay. It did not go away this time and was accompanied by valve tappet noise as well. My first though was a valve was not closing all of the way, so I did a valve adjustment today even going through the procedure twice to make sure I got it right but the popping sound coming through the air intake manifold is still there although the tappet noise went away. Anybody have any ideas? Motor starts right up, doesn't seem to be missing, no smoke on start up or while running.

[DougR]

Sounds like you might have had a stuck inlet valve which then freed up. Then it happened again and either didn't free up, or the valve kissed the piston and bent slightly, resulting in the tappet noise.

When you adjusted the valves did you find any excessive clearances? Or evidence of bent pushrods?

Maybe time for a compression check........

DougR

[sailorchic34]

Odd's are a burned valve. Run a compression check. Not the end of the world, but does require the head to come off and at least that valve / and maybe seat replaced. Of course while it's off have all the valves lapped.

Will not hurt the engine, running at way for a bit, but noisy.

So a head gasket, other gaskets, New valve, lapping compound and probably new hoses too while your working on it.

EDit; On second reading. Don't run the engine. That tappet noise, might be a valve stuck open a hair tapping the top of the piston. In that case, address it pronto.

When adjusting valves, better a thousands loose then a thousands too tight. (or so my dad said years ago)

[a64pilot]

I vote sticking valve, especially since it came and went. It will do that a few times, then come and stay, a dropped valve if your unlucky, a bent push rod if your lucky, or if your real, real lucky you catch it before it does harm.
I wouldn't even start it, I'd pull the head

Called morning sickness in Lycoming aircraft engines as it goes away as the airplane warms up, initially

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[model 10]

Take the cover back off and whack all the closed valves with rubber hammer. Turn the engine over enough times so you have whacked all the closed valves a bunch of times. Do both as you could be hearing an exhaust leak through an open intake valve. You can tell if it closing by the sound.

[Jsta_Rebel]

Originally Posted by Guy

Take the cover back off and whack all the closed valves with rubber hammer. Turn the engine over enough times so you have whacked all the closed valves a bunch of times. Do both as you could be hearing an exhaust leak through an open intake valve. You can tell if it closing by the sound.

I closed the off the stop valve on the injection pump so the engine wouldn't start and turned it over some. After seeing the all of the rocker arms were going up and down equally and was still hearing the popping, I started bumping the engine over and saw that the popping occurred when the #3 valve opened which I believe would be the intake valve for the #2 cylinder. I'm thinking that the exhaust valve on that cylinder isn't opening correctly and the excess gasses are exiting through the intake valve when it opens. Since I'm not a diesel mechanic, I'm just not sure. Does this sound right to you guys? the push rods would have to be ok since I adjusted the valves although as you asked, I did have more adjustment on #4 valve than the rest. Maybe a bent push rod and even after the adjustment it is flexing under load??

[Jsta_Rebel]

Originally Posted by a64pilot

I vote sticking valve, especially since it came and went. It will do that a few times, then come and stay, a dropped valve if your unlucky, a bent push rod if your lucky, or if your real, real lucky you catch it before it does harm.
I wouldn't even start it, I'd pull the head

Called morning sickness in Lycoming aircraft engines as it goes away as the airplane warms up, initially

Sent from my iPad Pro using Cruisers Sailing Forum

All good advice and that's what's bugging me. It came and went and then came back, but it came back after the engine was warm. I wish I could pull the head, but Anguilla on the hook with a low that just came off Africa late this afternoon and came off low at latitude 10 has me worried. I don't want to pull the head if it can be helped. I'm figuring if this storm develops a little I'll head out and sail to St.Thomas and work on everything there, but I'd sure like my motor to be available.. I know I have St. Martin real close, but I don't know any machine shops there, and I know Bruce Merced who runs the machine shop at IBY real well. Just bad timing for this to happen.. Anguilla unfortunately has no good mechanics that I know of and there are no machine shops here. Beautiful Island though.. Nice people, and hassle free anchorage.

[Jsta_Rebel]

Fact is, I'm going to try whacking the #4 exhaust valve a right not to see if I can free it up.. that sounds like a good plan..

[model 10]

It could very well be carbon on the exhaust valve stem and inside the valve guide. As the guide wears, the bottom of the guide gets bigger so there is more room for carbon to build up and so more carbon build up on the valve stem too. It can keep the valve from closing at some point. Kind of like a wedge.
I've heard of removing the valve spring and putting a hose over the end of the valve guide and forcing a serious solvent through and working the valve around. Who knows, it might work for a little while.

[sony2000]

Double check, but I doubt an old Lehman's extended valve will reach the piston.
In your geographical situation, forcing a decarbonizer down between the valve stem and the valve guide may yield results.
On the islands, look for an aerosol of carb cleaner from any mechanic or a can of Seafoam using a syringe to deliver the distillate to the valve guide(s).
Its easy. Do all of them.
Then put the Seafoam in the crankcase.

[topmast]

Is the valve spring intact ? Some older fords can lose lub to rocker arm shaft and not follow the pushrod easily Fault is a little rubber grommet on the oil line

[Defeverboat]

Call American Diesel 804 435 3107 for expert help Talk to Bryan before you do anything!

[Jsta_Rebel]

I'd like to thank everyone for their input on my problem. After running out of things to try in resolving my issues, I decided I needed to pull the head and see what's going on in there. What I found was that the number 2 intake valve seat is bad and causing the popping back through the intake manifold. So it's time to "brake out another thousand" or in this case 2 and just rebuild the entire head with everything new and be done with it. Anyone have any ideas where I might find Ford Lehman parts other than Bomac Marine? I ask because I sent them an email requesting parts and got a replay stating; Push rods and tappet's? I can't believe they asked this question. I'm not a diesel mechanic, but know what push rods and tappet's are. Any ideas for parts would be greatly appreciated and again, THANKS.. for the responses to my problem here..

[sony2000]

Why not change the valve and reseat the seat. Or just reseat with grinding compound. That could be done locally. Add a new head gasket, and its over with for a while. How much would that cost? The rebuild is only as good as the rebuilder.

[topmast]

Some mechanics consider pushrods and tappets(lifters) a replaceable item. Seats are individually replaceable.Probly not reusable if it's been bouncing around. Lapping compound ?