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engine vibration

2K views 18 replies 6 participants last post by  123 Fever 
#1 ·
Here is the problem. After driving in stop and go traffic or highway speeds 75+ as I stop at light the car starts to shake noticeable. When switching from drive to park its all over the place. When cold no such problems and once again this is sporadic so sometimes you cant notice a thing the next day back to shaking? Any suggestions I did find the article about replacing Rack Damper Bolt. Will this help?
Any one else experiencing this?

thanks

Zoran
 
#3 ·
Could be intermittantly sucking air from a tired fuel hose. What rousch said about the injectors is also good advice, as is replacing the damper bolt. (MB SI says to screw in the new bolt fully, don't fool around with "adjusting" it.) Exhaust valves could be too tight. Sometimes with higher mileage, the delivery valves inside the injection pump wear out and don't seat properly...the pump looses it's calibration.

My '84 had a similar problem, doing all of the above (sans pump) helped a LOT, especially the injectors...along with a 1/2 quart of ATF on a full tank (some will advise against that though). Sometimes the only way to get them "perfect" is to remove the pump and send it to someone *competent* who can rebuild it. (There's only one guy I know who I'd consider competent.) But best to check and double check the basics before getting carried away. ;)

How many miles on the engine?
 
#5 ·
OK, if your pump timing is accurate, the opening pressures/spray patterns of the injectors are correct (and even between them), engine compression is normal/even, and there are no fuel lines drawing air into the system (check the lines under the car at the tank), your next step may be to try a rack damper bolt and a little ATF. Often, but not always, that will tone the vibration down to an acceptable level. If that doesn't cure it, it could be time for a pump. Just make sure to double check EVERYTHING before going that route, even the injectors...rebuilt pumps aren't cheap. I've seen guys replace them only to discover it was just a leaky hose, which can exhibit the EXACT symptoms of an IP with worn delivery valves.

If you decide to overhaul your pump and need a place to send it (and you're in the US)...the gentleman I know (an "old world" German) has built tens of them for me...including MFI pumps for gasser 6 cylinders and 6.3s, few are left who can build those.

Gus Pfister
Pacific Fuel Injection
650-588-8880
(So. San Francisco, CA)
 
#12 ·
zoran - 5/29/2004 11:55 PM

ok it has to be the pump. It's wild shake only after drving on the freeway. As soon as I am off it starts shaking. However I park the car go to the store come back 5min latter and it's gone!!!
Hmmmm I'm getting the same thing especially when it's warm out. Personally I believe it's not the pump, but some other gremlin, anyone have ideas[?]
 
#14 ·
zoran - 6/7/2004 7:35 PM

just got my valves adjusted, this helped a lot...
That's great to hear. Another thing I was going to post...Lubro Moly "Diesel High Test" is a
KICK-ASS fuel additive, the only one I've tried that actually does everything it says (and I've
tried Red Line, PS, etc...PS "Cetane Boost" can actually make your idle worse and very erratic).

A hundred miles or so into a can of LM, and your car will idle MUCH better and smoke less.
 
#16 ·
RE: engine vibration / 20w50 in a diesel engine

.yap... valves and also I changed my oil. I had rotella synth in and it seems this did cause problems with my engine. I found new (German!)mechanic and he only works on diesels. He said replace the oil and put in 20w50 !! I said what he said yes best oil for diesels. I was reluctant but I did and what a difference. Much smother and it seems faster as the old oil was chocking the engine. I usual use 15-45 but never 20w50. Rotella was in just over 1000mil. Next is rd bolt and I should be set.
 
#19 ·
I had the exact same engine symptoms. A mechanic chased it around too. No leaks, Valve adjust, New injectors and finally he wanted to replace the injector pump. I called BS and went to another old school/old timer machanic. He attempted to adjust the injector pump rack but it was not responding to his liking. When it was all the way in it was still shaking. So this is what he told me to do. He set the rack adjustment out abit about a half inch of thread exposed or less. Then he told me to fill up the fuel tank and leave some room to add a half a quart of transmission fluid and a half a quart of GASOLINE. Sounds crazy but I did this for about three fill ups. I then adusted the injector rack bolt a bit in and the problem is completely corrected. It has been four years and I have not even had a hint of the problem. To this day I do this for one fill up about once a year. The reason is the injector system can get sticky. By leaving the rack bolt out abit you give it room to move. The Trans fluid has alot of cleaning properties and the gasoline thins the fuel and raises the C-tane rating to help clean the injectors.
I hope this helps
 
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