Thread: 300tdi valve lash caps disintegrating

If they are wearing out that quick you have serious oil feed problems to the rocker/vale train, remove rocker cover and see if you are getting oil to the rockers, alternatively check your cam lobes for excessive wear, could also be rocker arm/rocker arm shaft wear Regards Frank.

pull the rocker shaft and rockers, inspect the tops of the valves and the pads on the rocker arms.

if they are marked then they will just cut the caps to shreds.

My guess is there isn't enough oil getting fed through to the rocker assembly.

Try Dave ( Blknight.aus ) he would be a good person to ask about this. never mind he's already on the job.

Having the last motor that I renovated set up on a test bed, using the starter motor, I had it turning over without the head on and was surprised to find a hard lump of crud come out of the hole that feeds into the oil galley in the head.
Given that the size of the hole in the head gasket is smaller than the oil galley, as soon as the oil flow lifted a bit that hole may have been blocked, if the head was put on first that lump would have still been in the oil galley in the block.
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Just checked the rocker arm pads, some are pitted and the hard facing has worn, on some of the valves the was small speckles that looked like chrome flecks, so it looks like the hard facing has gone. The top of the valves are good though, at least they are ok.

as a short term trial fix you might get away with carefully sanding the pads back and beveling the edges off...

I had assumed that the oil flow rate was ok, since you're going to have the rockers and shaft out anyway, key it over on the starter and check the flow up to the head and check the internals of the rocker shaft/arms.

Checked oil flow and it is good. There is plenty coming up pushrods and going through rocker arms and flowing through where they run on the rockershaft, also plenty of oil around the base of valve springs. Takes a while for splash to get around the rocker pad area though. Put it all back together and took for a 5 min run and took oil filler cap off and there was plenty oil around the rocker pad/valve cap area, so oil flow is good, maybe the rocker pad hard facing is just getting thin after 360,000kms? So I have replaced the lash caps with some spares for the moment and I will replace all the rockers and lash caps and hopefully all will be good then.
Thanks for help

It appears to be a problem with some engines and can lead to a broken rocker arm.
I believe the case hardening even on LR replacement caps is suspect.

Originally Posted by pawl

Checked oil flow and it is good. There is plenty coming up pushrods and going through rocker arms and flowing through where they run on the rockershaft, also plenty of oil around the base of valve springs. Takes a while for splash to get around the rocker pad area though. Put it all back together and took for a 5 min run and took oil filler cap off and there was plenty oil around the rocker pad/valve cap area, so oil flow is good.

Do you have a oil pressure gauge fitted?
An engine that has done a lot of kilometres can drop it's pressure dramatically when it heats up and the oil thins out, this would starve the top end of sufficient lubrication .
If the readings do show this, it's time to also fit some new bearing shells.

The 300TDi do have a second thermostat ( part no ERC5923 ) that controls the oil flow through the oil cooler, if this is stuck closed the oil temperature can rise, again thinning the oil.