over revved 1995 E300 - PeachParts Mercedes-Benz Forum

wjjeng · #1 01-28-2008, 11:31 AM

I accidentally downshifted while at speed and may have over revved the engine of my 1995 E300. Seems to run fine when cold but will not go over 45 mph after 20 minutes of driving and white smoke comes out of tailpipe. Local deal does not have a technciian with much experience on this engine. Any ideas on what may have been damaged?

winmutt · #2 01-28-2008, 12:15 PM

What kind of white smoke? Coolant or diesel?

JimFreeh · #3 01-28-2008, 12:15 PM

I've got an OM603 300D out back with a runaway engine.
Zero compression, engine turns freely, cam still rotates.
I'm betting on bent valves on that one.

Jim

wjjeng · #4 01-28-2008, 12:49 PM

I do not know how to tell the difference in type of smoke. Only happens when going up hill - hard to get the opportunity to smell it.

If bent valves are a problem should I go to a dealer to have repaired or can any qualified diesel mechanic with good references do it?

TMAllison · #5 01-28-2008, 01:35 PM

What type of RPM?

I thought the trans wouldnt downshift to too low a gear regardless of shifter position if RPM's were too high??? I seem to remember my '90 2.5 turbo acting that way....?

Have you checked that the vacuum lines to the EGR valve and resonnance flaps are connected?

Hatterasguy · #6 01-28-2008, 01:37 PM

How? The trans won't dowshift if the RPM's are to high, and if you took it out of gear the IP would limit it. Not sure where the cut off on that 606 is, probably about 5,200.

pimpernell · #7 01-28-2008, 02:16 PM

Quote:

Originally Posted by wjjeng

I accidentally downshifted while at speed and may have over revved the engine of my 1995 E300. Seems to run fine when cold but will not go over 45 mph after 20 minutes of driving and white smoke comes out of tailpipe. Local deal does not have a technciian with much experience on this engine. Any ideas on what may have been damaged?

Seems to run fine when cold? Does it go over 45 mph when cold? Are there any noises that can be heard that were not there prior to your over revving? White smoke can be an indication of a head gasket problem, which will require extensive engine work. The link below tells of similar symptoms which turned out to be a couple of clogged fuel filters. Not saying that this is whats causing your problem, but it's worth a look see.

White smoke, lack of power, caused by clogged fuel filter!

wjjeng · #8 01-28-2008, 02:25 PM

Yes, it will go over 45 when cold. From a cold start it does seem to make more mechanical clattering than before. After 5 minutes sounds normal and will run normal at 70 mph. After about 20 minutes begins losing power and slowing down. Smoke only comes out on steeper hill when the car slows down to about 35-40 mph.

I believe I will try to get the 2 filters changed before going any deeper with this.

Thanks very much for everyone's input.

TMAllison · #9 01-28-2008, 02:29 PM

Why would the filter be restrictive only when warm?

You need to look at what changes after its warmed up. That's probably going to be air metering.

tankowner · #10 01-28-2008, 02:39 PM

Quote:

Originally Posted by wjjeng

Yes, it will go over 45 when cold. From a cold start it does seem to make more mechanical clattering than before. After 5 minutes sounds normal and will run normal at 70 mph. After about 20 minutes begins losing power and slowing down. Smoke only comes out on steeper hill when the car slows down to about 35-40 mph.

I believe I will try to get the 2 filters changed before going any deeper with this.

Thanks very much for everyone's input.

Are you saying that all of these symptoms are new after the accidental downshift? Also, you are saying that it will run fine once warmed up for approximately 15-20 minutes, and then begins losing power? And what do you mean by losing power - you cannot exceed a certain speed - cannot get beyond certain RPM? Finally, how fast were you going when you downshifted?

P.E.Haiges · #11 01-28-2008, 03:06 PM

Is it a Diesel?

P E H

2.5Turbo · #12 01-28-2008, 03:23 PM

Is there any check engine light on? This car has a computer controlled rack on the injection pump I believe. If the computer finds something wrong, it might limit engine output. I've known of cars that will throw a code and limit power if the driver tries to downshift at too high of a speed. Otherwise, I don't think the transmission on that car would let you do that. As has been stated earlier, the 722.4 in my 300D 2.5T won't let me do it. I think these cars have the 722.5, the last hydraulic auto before the electronic 722.6 in 97.

TMAllison · #13 01-28-2008, 03:33 PM

His trans ought to be the 722.438, same as the 96's.

wjjeng · #14 01-28-2008, 03:48 PM

OK, I will try to answer all of the quesitons:

Was going about 60 mph and shift level went into 2nd gear briefly, maybe 5 seconds
Car became unusually quiet briefly and was returned to Drive
Afterwar, car was a little sluggish above 60 mph
All symptons were new after the event and, over several weeks, performance has continually gotten worse to the point where I cannot go over about 45 when warmed up and will accelerate very slowly and sounds like it is missing when starting from a complete stop. Car surges with full power coming on and off.
Yes, it is a diesel (I think all E300s are diesels)
I don't know if the check engine light is on but will check that later today.

pawoSD · #15 01-28-2008, 04:51 PM

2nd on that car maxes out at like 50-55ish probably doesn't it? On my car 2nd is good till like 48.....but thats with a lower revving engine and higher diff (3.07)....The most rpms the engine on your car could have seen in 2nd at 60mph is probably 5300-5500 tops....shouldn't have hurt it for 5 seconds....especially if it wasn't under full load or anything.

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