I have a 1988 420 SEL. Upon changing the plugs, the passenger side were all in good condition, BUT all four dirver's side were very foulded up. The scope check seemed normal, all pistons firing. My mechanic said it is not the fuel distributor (?) but could need rings replace Ouch, but on 1 side only? Doubt it for sure. I know all the rocker arms were replaced on the passenger side, but not the driver side. Could this cause the problem? Maybe need a valve adjustment or replacement? She is not using any oil at all, and has 173,000 km. on it. Responses welcome and appreciated before I throw money in the wrong direction.
Frank - 13 Dec 2007 20:31 GMT
> I have a 1988 420 SEL. Upon changing the plugs, the passenger side were all in good condition, BUT all four dirver's side were very foulded up. The scope check seemed normal, all pistons firing. My mechanic said it is not the fuel distributor (?) but could need rings replace Ouch, but on 1 side only? Doubt it for sure. I know all the rocker arms were replaced on the passenger side, but not the driver side. Could this cause the problem? Maybe need a valve adjustment or replacement? She is not using any oil at all, and has 173,000 km. on it. Responses welcome and appreciated before I throw money in the wrong direction.
Hi Tony
I doubt it very much that the rings would be at fault here... It
would be very strange to only have bad rings on one side only. You
may want to check to make sure the wire set is working fine and make
sure the PVC valve is replace, only a few $$ and makes a big
difference.
FV
www.ClubPlug.net
Your Source for Spark Plugs on the Net!
-->> T.G. Lambach <<-- - 13 Dec 2007 21:24 GMT
Rings needed only on one side?? Find another mechanic.
New rockers on the right side is the clue to this puzzle, IMHO.
Were those rockers replaced along with a new cam? Or were the valve
guide seals replaced or both? And is the same now needed on the left side?
If you get into the left side's cam, rockers and valve guide seals you
ought to confirm that both cams are in correct synchronization with the
crankshaft.
On the other hand, perhaps the easier and much much cheaper alternative
is to install four new, higher heat range, spark plugs on the left and
see if that improves the motor's performance.

Signature
© 2007 T.G.Lambach. Publication in any form requires prior written
permission.
Tiger - 14 Dec 2007 16:33 GMT
No way on all one side rings... Possible that your valve seals are bad on driver side, but you would definitely lose oil along with it...
Do a compression test and that will tell you the condition of the engine.