1. Home
  2. Mercedes Autos and SUVs
  3. 300E: #4Cylinder- Bad

300E: #4Cylinder- Bad

I hate to bother everyone again, but a compression test was done on my

300E- 1989 and all the cylinders were up near and over 190-200 except thr 4th, which was 130 lbs. He said "that cylinder shows heavy oil compsumption". But the car doesnt burn any oil, whith 119K on it. And it doesnt run hot or use coolant. Could a top end engine overhaul be done? Can I drive the car like this fir a while. The mechanic says i can drive it around like this. Hes had people with these cars, E s and S gas models run like this for 10+ years. Regards-Chuck
Reply to
Chuckyg
Loading thread data ...

The problem COULD be due to a defective valve guide seal on the #4 intake valve stem. In that instance lube oil would be sucked down the valve stem into the intake port where as Tiger previously suggested the oil gets "coked" or carbonized preventing the valve from fully closing - thus low compression. A dribbling #4 fuel injector could also be the cause.

You CAN drive the car until it fails an emissions test. The engine won't collapse.

If it were my car I'd try the following, in this order of cost and difficulty:

Install a new or rebuilt fuel injection nozzle in #4 cylinder. $60

Sequentially add two or three cans of Techron to the fuel. $8 each

Drive it a month or so.

If no improvement have your mechanic replace the valve stem seals on #4's valve stems. Guess about $250.

Thereafter, some doses of Techron to eliminate the coking in the valve's port.

If the problem still persists the cylinder head will need to be removed.

Reply to
T.G. Lambach

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.