Hi all.
I am getting a puff of blue smoke when the engine is started. I’ve read here that this is a common occurrence on a 1994 XJ6.
I have also read (while searching for seals) that these engines do not use an exhaust valve seal, only the intake seal is installed. Would there be a problen adding the exhaust valve stem seal?
Jaguar did not fit exhaust valve stem seals prior to engine serial number E163523 on the AJ6 engine but by the time your '94 was built they fitted seals to all 24 valves. [My '91 was engine serial number 143413.]
The same seal is used for both sets of valves - EBC3531. You can happily re- fit to both inlet and exhaust with no problem - except that you may find that the real cause of the puff of blue smoke on start-up is due to wear on the valve stems/ guides so the replacement new seals will only reduce the problem for a limited period. Worth doing that job nevertheless.
I have a 1990 4.0 litre that has been doing the puff of smoke every now and again for years , with no ill effects . Local dealer says when the head needs doing , that’s the time to repair it . My 2 cents worth . Mark
Mark,
Very true.That’s when I fitted 24 new seals on my car when I had to replace the head gasket because of the infamous cam feed oil leak. Prior to that there was no real problem - just a little embarrassment when on a cold start the twin puffs of blue smoke shot out of the exhaust, prompting a Merc driving neighbour to comment that he didn’t know Jaguar fitted diesel engines to those cars!
I worked at the Jag dealer in the 1990s and replaced stem seals as well as MANY head gaskets on the AJ6 engines. The head gaskets were updated every few years to attempt to stop the oil leak at the front right side of the head as Bryan alluded to.
Everyone in the shop pulled the head to renew the stem seal except me. I am not a large/heavy mechanic so I put pads and cardboard on the engine and fenders. I sat cross legged like a gnome and replaced them, cams removed with air pressure to keep the valves closed.
You need to put drilled blocks on the head or reinstall the cam caps and reinstall the head bolts (SNUG) to keep the head from lifting while applying air pressure to each cylinder.
Everyone has their own method of replacing the stem seals. I just did not want to pull all the stuff off the head. The fewer things you remove, the less chance of breaking (or losing) something.
If you need to replace the head gasket then I would replace the seals at that time.
bob