Take the 2-minute tour ×
Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. It's 100% free, no registration required.

I have an 89 Mercedes 300 SE and recently the oil pressure needle has been stuck at the highest point when I accelerate. The values on the gauge are 0 to 3. When I take my foot off the gas the value goes down to 2 or less.

There was some knocking shaking sound this morning but after I turned the volume way up on the radio I couldn't hear it any more (bad joke). Also, if I let it idle for a minute or two it seemed to go away, no knocking or much less.

share|improve this question
    
Do you change your oil and filter often? Maybe restrictions or sludge in the valvetrain or a gummed up filter? –  Mike Saull May 1 '13 at 2:57

1 Answer 1

up vote 2 down vote accepted

Assuming that the Engine Oil Level is OK then you're gauge readings should resemble the following.

At idle, the gauge should be between 1.5 and 3 depending on how long the vehicle has been sitting and the temperature outside (there are some other things that factor in here. Just trying to not complicate things too much.)

Accelerating / Driving, the gauge, for the most part, should always peg at 3.

The gauge reading you're asking about seem to be correct. The knocking you're hearing is probably due to either using the incorrect oil weight (you should be using a 20-50 oil in that straight-6 or something like it. Also, Please double / tripple check to ensure that oil level is correct. And if needed, get your oil changed by a trustworthy mechanic.

share|improve this answer
    
My Acura manual states a minimum grade gasoline and going below will cause engine damage and knocking. Could that also be a possibility here to explain the knocking? –  Andy May 4 '13 at 19:35
    
Yes. The "will cause engine damage" is a bit extreme. But, it will without a doubt knock and eluminate the Check Engine Light. –  cinelli May 29 '13 at 8:47

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.