I recently replaced the cylinder head gasket for a mate's 300tdi (head needed some filling and skimming). A few days later it started to billow white smoke especially at low revs and on overrun. The vehicle's owner thinks that it could be dislodged valve stem seals. I really wouldn't like to remove the head again unnecessarily. Is his theory a logical one? Is there enough space between the stem seals and the spring cap to allow the seals to get dislodged?
tetsu0san
Active Member
I would check the timing just in case as something may have changed and that is a very un-intrusive test. Failing that the gasket may have failed again? What sort of gasket did you fit?
I am not sure that a valve stem oil seal would do what you are experiencing.
Also, how bad was the head when it was removed?
I am not sure that a valve stem oil seal would do what you are experiencing.
Also, how bad was the head when it was removed?
He said it was smoke but he has a gut feeling that it is coolant. Head wasn't bad. There was some corrosion between the cylinders (where the head makes contact with the triangular waterways on the block). They were filled and skimmed. The vehicle's owner is suspecting an internal crack though.
cornish rattler
Well-Known Member
Could it be a faulty cyclone breather, when i did my s11a swb 200tdi conversion one of the bolt on bits i replaced as a matter of course was a new cyclone breather off ebay cheep one i think and that caused the landy to chuck out loads of white smoke, re-fitted the old one and everything was fine 
Verdict's out. Cracked head it is. New one on the way and should be here within a week or so. Couple of questions regarding valves. The new head only includes valve guides. we shall be using valves, etc out of the old head. The old head's valves were cut and lapped in when the head was skimmed. Since fitting the head, the engine has only run for about 2 hours. Do we need to do any work to the valves prior to fitting to the new head?
jamesmartin
Well-Known Member
yes lap valves to the new seats,personally id buy new valves(stems and guides wear) and lap them in, then check depth of valve head from head face using a straight edge .81 mm to 1.09 mm for inlet,.86 to 1.14mm for exhaust, dont forget to fit spring seat washer prior to fitting stem seals afte lapping valves in
jamesmartin
Well-Known Member
were was the crack usually they are visible
No idea James. Head is still fitted to the engine. There were no cracks when we removed it. There was some corrosion just above hte waterway in the block (where there are triangular cutouts in the gasket) which was filled and skimmed, the valve seats were ground, we re-fitted it, started up and it just got worse. An experienced mechanic said that the pressure applied when the seats were ground probably opened up the crack further.
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