I have a knock in my engine. I have a 1980 450 SL! The knock is coming from the right rear of the engine. I removed the valve cover to see if there is anything abnormal, it looks good so far. I'm planning on checking the valve settings tomorrow.

Does anybody have any other suggestions?

Carbon deposits?

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This car does not have adjustable valves, AFAIK. Maybe the cam or cam followers are worn. Have the oil tube fittings (above the cam towers) ever been changed?

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describe the situations in which you experience the knock and if it is sensitive to throttle input car speed, etc.

tom w

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Not to hi-jack this thread, but as mentioned in another topic (with no response), I also have an engine knock. It only can be heard between 1600-1900 rpms under acceleration. It seems to be coming from the right side of the engine. My car has 265K and I think it is a good chance that it is worn camshaft causing it. Also too, the lifters are making a little "clacking" noise on that side as well, but I can tell that the knocking sound is distinctively different than the lifters.

When I first bought my car, the mufflers were full of holes and the car was rather loud and I could not hear the knocking at all. It was only after I installed new mufflers that I noticed the knock. I have not heard it get any louder since I have owned it (since December 05'). However, it is still a big concern of mine. I really like my car, but I would like to know that my engine is not worn out.

If it is indeed the cam causing the knock, will it damage my engine to continue driving like this? Will it eventually quit running, or.....? The car is old and I did not pay much for it, so I really do not want to spend a lot of $$$$ on it. I have heard that camshaft replacement is very costly on these cars, so I do not think my car is worth the trouble. If I can get about 25000 more miles out of my car, I will be happy. It still does not leak, nor burn one drop of oil, which is a plus.

What exactly does a carbon knock sound like? Does it occur at all RPMS? What is the best "cure" for carbon knock if that is what it is, but knowing my luck, I doubt its that simple. I have the worst luck with cars.

Yellowdragon - he is right- it could be worn camshaft/camshafts.

Thanks in advance.

Worn cams will definetly make the engine loud - but usually the front of the cams wear before the rears.

86560SEL: Driving with bad cams isnt good in that you'll have worse fuel consumption and less power, and it'll be loud and probably misfire as they wear even more and inhibit proper combustion - I don't know what might happen if the exhaust lobe is worn but the intake isn't, but I don't think catastrophic engine failure is a result. If you DO have a bad cam, start looking around on eBay for them. Hell, I'd settle for a cam from any m116 or m117 with hydraulic studs if I were you. An old 4.5 cam, or a 420 cam may even give you more power?

What type of knock is it - octane knock or mechanical-sounding?