New Engine Shock Absorbers

I had new engine shock absorbers installed (new mounts as well) into an '85

300SD, and now the engine seems to shake slightly more when idling, does that make sense? When I turn the engine off, it turns off immediately but seems to shake a bit more stronger than with the old worn out shocks, is it possible and is it a good idea to adjust these shocks to make them more stiff? Is it bad when the car shakes a bit when the engine turns off? Sign of worn out engine?

Thanks in advance for any advice! cp

Reply to
cp
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A five cylinder engine is inherently unbalanced - thus the shock absorbers. IMHO you're feeling the engine's oscillations more now because the new motor mounts are not worn out or broken. The shake on shut down is normal, a badly worn out engine is smoother due to its low compression.

All that said, you CAN have your shop adjust the "rack damper pin" which is a spring loaded pin that prevents the injection pump's fuel rack from oscillating during idle. The fuel rack controls the engine's speed so when the rack oscillates the engine's speed rises and falls very quickly causing the shaking. A quarter to half turn IN of the rack damper should help.

Reply to
T.G. Lambach

Too far in and it'll stall intermittantly at low rpms though. Be careful.

Reply to
Richard J. Sexton (At work

Thank you for the advice!

Can the vibrations affect anything adversely? Like the transmission or its mounts?

?? So you're saying that this is a sign that the engine is now worn out? The mechanic says it feels tired (he does lots of these cars) but another mechanic (who does lots of these cars too) says that the engine is in great shape, and it has 300,000 miles. I think it accelerates just great, takes no oil whatsoever, driving it in the BC mountains is just joy, but the mechanic telling me that the engine is 'tired' (thus worn out) makes me want to sell it, so you are saying that its shaking shows it's not worn out yet? At idle the engine sounds great, works like a clock and nothing pings, and the car slighly shakes, from what I've described do you think my mechanic is right in saying it's tired?

Will try it, thanks for the advice!!

cp

Reply to
cp

I meant NOT worn out! :-)

Reply to
cp

Right, NOT worn out.

These old engines complain a lot before giving up the ghost. Hard starting, low power, oil consumption are the signs of the end. Your engine, despite its 300K miles sounds like it's in good shape - no doubt due to good prior maintenance.

I'd suggest you dump the mechanic who claims the engine is tired. He is looking at its mileage rather than at its condition. In his favor is that most engines of this mileage would need an overhaul by now. Yours is the exception that may go to 400K if you take good care of it.

By the way, with a 10 mm and either 12 mm or 14 mm wrench you can adjust the rack damper pin. It looks like a small bolt screwed into a nut (lock nut) on the aft end of the engine's injection pump. Look between the oil cooler lines at the back end of the injection pump.

The larger nut is a lock nut, the smaller bolt is the adjustment. Loosen the lock nut one half turn. Then screw in the bolt on half turn, hold that position with the wrench while you snug the lock nut tight. By tight I mean firmly snug, not tight as in all your might tight. This is an incremental adjustment, more may be needed but first drive the car for a while. Too much tightening will stall the engine, if so, back it off. If the bolt is screwed all the way in and no further adjustment is possible the pin ought to be replaced, the newer version has a stiffer spring and is more sensitive to adjustment.

My 300SD used to shake - a lot, particularly at a stop light after exiting the freeway. This adjustment and a new pin completely cured that.

Finally, the engine's shaking won't harm the transmission or its mount.

Reply to
T.G. Lambach

:-)

Starts the first time, before I finish turning the key.

Can do about 110-120mph

3 months after last oil change, can't see any change in level, carport always dry

You have given me hope! Maybe I should forget going to Germany to pick up a 124... hmm what's another cheap mercedes!

I shall, thanks A LOT for the advice, I will try adjusting the rack damper pin.

cp

Reply to
cp

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