MD11C seized inlet valve...bent pushrod...broken cam follower

[dur]

Well I started the engine last weekend to check it would be ok for hols next week and it would only run on the front cylinder. Investigation has revealed that the inlet valve was completely seized in its guide and needed to be soaked for a night and then very light but persistent tapping to get it moving enough to remove. It appears to have rusted into the guide but now nicely freed up and mercifully not bent as I feared it might be. The engine was decoked and valves lapped last winter and has hardly any use at all. It was running fine two weekends back.

Any suggestions please for why it should rust up and how to prevent a recurrence. I can't work out how the valve stems are lubricated so not sure whether their might be an oilway blocked.

The bent rod broke the cam follower - I have managed to fish the pieces out with a magnetic screwdriver but I am not sure how to lift out the bottom half of the follower which is still intact. It is not as free moving as the undamaged one - probably a bit out of shape. Also there is some gasket sealant or similar from the seal at the base of the block which is in the way. At the moment I am between a strong magnet - the telescopic type but I doubt it would have the pull to move the jammed follower or plan B maybe epoxy putty on a stick after a suitable clean up. http://i566.photobucket.com/albums/ss105/dur_photo/P1100870s.jpg shows the top of the broken follower and you can see the orange gasket material clearly. Any thoughts- better ideas how to get it out etc would be very welcome. - Thanks

 

[UncleAlbert]

The orange stuff is a polypropelyne or rubber type seal which is located in a rebate in the bottom of the cylinder block they seal the join between said block and crankcase. Looks like you may be into a head and block lifting situation. It will be possible once the head is off to lift the cylinder block up guided by the long studs which hold everything together. Make sure the piston in the bore involved is at the top of its throw, put some soft wood spacers, about 1 - 1.5 inch thick between cylinder block and crankcase so that you can get to the cam follower with out the piston coming out of the bore, you will probably need another pair of hands to assist with this part.You can thne replace teh seal and sort out the cam follower.

Look up the exploded view on http://www.marinepartseurope.com/en/volvo-penta-explodedview-7742230-21-15101.aspx

The seal is item 36.

How do I know all this? well I have rebuilt the top and mid portions of my MD11C so had all this apart. All done whilst engine in situ on a Centaur.

Reason for your failure is probably due to obstruction in the very thin oil feed pipe which supplies the top end (rockers and valves) . This pipe with its attendant banjo connection has to be carefully straightened to allow for head removal, take care!!!, and then bent back to about 90 degrees when reinstalled. Take even more care!!!!!!

Good luck.

 

[dur]

Thanks for that. As the o-ring is only a seal for that gallery I might see if I can push it out the way or trim it back a little. I know it is not a good idea but want to avoid lifting the block at the moment. Engine is being replaced next winter.

For the rocker oil feed to also feed the valve stem there would have to be an oil way between the rockers and the valve guide and I don't think there is. I would have thought that it would negate the need of the oil seal on the valve stem apart from anything else.

 

[dur]

By way of completeness...

I was able to trim the piece of excess seal with a scalpel taped to a stick. The broken cam follower came out with the magnetic gadget and it all went back together with second hand follower and pushrod. I spent a good while checking the water passages and flushed through via the drains. All quite clear so I started her up with no problems until...

Two days later... we set off for a few days on the boat. The engine was running really smoothly for about 20 minutes at about 1500 rpm when it slowed and started making an ominous ringing sound. When we pulled the stop there was huge thump as the engine abruptly stopped turning. The other cylinder had broken the exhaust valve spring and as the engine slowed to a stop dropped the valve into the cylinder.

After a very kind tow to where we could anchor we took the head off, removed the exhaust valve which was embedded in the top of the piston, stuck an m6 bolt in the valve hole with epoxy putty and held it there with garden wire, stuck more epoxy putty in the injector (seemed like a good idea at the time) and ran very smoothly and quietly on the other cylinder but with very little power and a lot of trepidation. Luckily there was a decent wind all week and with help from a friend when propulsion was required had a great week.

http://i566.photobucket.com/albums/ss105/dur_photo/MD11cexvalve.jpg

Cause? I suspect the result of a good sailing season where we had only used the engine for a few very short runs it had never warmed up properly and condensation had caused surface rust on the valve spring (and maybe the other valve to seize).

New engine this winter!

 

[VicS]

Yes first hand knowledge of the mess that a dropped valve can cause.

We kept it running making nasty noises as long as we could so a real mess. Luckily for me not mine . We ended up sailing home from the CIs... but that's another tale... and repairing the engine.. It was a good few years ago and spares were becoming difficult to obtain even then. A new engine might have been the sensible option but once repaired the old one outlasted the owner!

 

[Marsupial]

In general valves and guides are not lubricated, they are made from hard material that resist wear, in carburettor petrol engines some would put redex * into the fuel to help lubricate the valves; cant do that in a diesel.

Us old and often ridiculed engineers squirt WD40 or something like it into the inlet manifold (with the engine stopped) to drive away condensation and help prevent the corrosion and stuck valves you have encountered.

as an aside * All I can say is that in my experience engines with redex had less valve wear and more carbon deposit - so take your choice.

 

[dur]

Well actually I did some googling on this and (at risk of being shot down) there are those who adovcate using a small amount of cheap 2 stroke oil in the diesel as upper cylinder lube. If you google you can find many people saying this is a good move (not just one person being requoted over and over) and I reckon there is probably something in it and apart from a relatively small cost (it is a sailing boat after all) I can't see there is much to lose.

 

[UncleAlbert]

sorry to hear of the near demise of another MD11C. Dont let the engine installer take the old one away without marketing the spares yourself to defray the cost of the new lump. You never know I might be in need of some bits and bobs next year.

 

[Marsupial]

Well actually I did some googling on this and (at risk of being shot down) there are those who adovcate using a small amount of cheap 2 stroke oil in the diesel as upper cylinder lube. If you google you can find many people saying this is a good move (not just one person being requoted over and over) and I reckon there is probably something in it and apart from a relatively small cost (it is a sailing boat after all) I can't see there is much to lose.

It's a good move IMHO for piston rings but don't expect it to lubricate the inlet valve - the injector delivering the mix is either in the cylinder (direct injection) or in a combustion chamber (indirect injection) in nether case will the additive touch the inlet valve.

 

[cryan]

Valve stems will usually get a small amount of lubrication from the oil mist that is around the rockers and is often free flowing to that area from the crankcase and camshaft case.
One common cause of valve stem seizing is excessive use of Easy Start spray. This can remove all lubrication from the lower valve stems. Its ok to use a squirt or two now and then, especially in winter but iff you flood the intakes with it regularly valve damage occurs.