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300CEpimp 04-03-2003 10:24 PM

300CE Problem
I have a question for you tech guys. I have a 1988 300CE and it has a transmission problem I think. It happens when my car gets to its normal temp. When it idles it has a shake and my oil meter, and economy meter move back and forth along with my rpm gauge. Then when shifting it drops lower the 500 rmps and shakes really bad. Some help would be appreciated. Should I take to a dealership or try to fix it myself.
Thanks alot you guys.

acha3 04-03-2003 11:48 PM

This recomendation maybe have nothing to do with your problem but change all your fuses even if they look okay to you. hope that this would help in anyway;)
next check the engine and trans mounts
change the trans fluid and filter
check spark plug wires and spark plugs

300CEpimp 04-04-2003 09:40 AM

Thanx I will try that and see if it will work.

G-Benz 04-04-2003 12:31 PM

Your problem sounds more like an idle surge than a transmission problem to me...this will occur with the transmission in "Park" as well, but it's not as pronounced as when the engine is under load (i.e. with transmission engaged).

Your symptoms are while stopped with the transmission engaged, the idle speed oscillates, and you will note the corresponding actions with the tach and oil pressure gauge needles bouncing in unison (I don't have an economy gauge).

This is especially pronounced if you place the tranny in "R"...feels like you are playing with low-rider hydraulic suspension switches :rolleyes:.

The surge is caused by a number of factors, with the primary ones being a vacuum leak, a bad air mass sensor unit, or a bad coolant temperature sensor.

I have been tolerating my surge problem for about three years! :mad: I have replaced the air mass sensor (expensive $$$) and the coolant temp sensor, and the problem still persists. I have also replaced some broken vacuum actuators and sealed off suspected breaches, but so far, to no avail.

Replacing fuses might cure some other electrical ills you may already be having...but it won't cure this one.

I would hunt down vacuum leaks first. It's the cheapest route...

300CEpimp 04-04-2003 03:17 PM

Alright I will hunt down that vaccume leak, but where is it located and how do you tell if it is bad or not. Thanx for your info

G-Benz 04-04-2003 03:23 PM

I can't "pinpoint" the source of your vacuum leak, as you have a network of vacuum hoses to check.

The first places to check though is the "bellows" looking unit next to the air mass sensor...look for any signs of deterioration (cracks, etc.). Replace if necessary.

The large majority of leaks would probably reside near the intake area. Inspect the condition of the hose fittings and the smaller vacuum hoses.

Some here will run the car and spray starter fluid near these areas (sounds dangerous though). If the engine idle suddenly increases when you spray at a particular area, then you have found the source of the leak...this is the stage where I am currently at right now.

300CEpimp 04-22-2003 08:58 PM

I was wondering on how your repairs are going. Was it a vaccume leak?

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