Nearly Blew Up my TD! Help! - PeachParts Mercedes-Benz Forum

diesel don · #1 04-01-2003, 09:53 PM

I just had the most bizzare experience and it scared the crap out of me!

I need to know if this was a 1 in a million freak occurance or if anyone has heard of it happening.

My daughter had just driven my TD home from a group meeting when I went to pick up my son from driver's ed. I decided that I'd drive home and not him.

As I went to exit the drive of the training area, I noticed that when I took my foot off the accelerator, that the engine didn't retard or brake but that the rpm's stayed constant. Thinking that the accelerator was stuck, I put it in neutral and punched the pedal to loosen it. Huge mistake!

The engine went to wide open and we started freaking out. I told him to get out of the car and I reached down to pull up the pedal, but it was not the pedal that was stuck. It was dark out and I pulled the hood release and jumped out of the car (thankfully it was level as it was still in neutral). Remembering Larry Bible's post I began reaching for the linkage mechanism to shut it down. Nothing. I was pulling up and down but still it was wide open and screaming. Surrounded by smoke and thinking it was going to blow any minute I started pushing another direction (towards the passenger side of the compartment.

Fortunately, it acted like I was starving it and it shut back down to idle. Later, we replayed the action and guessed that it was wide open for 20-30 seconds which seemed like an eternity.

Grabbing a flashlight I began to investigate and found the following:

1. The tiny clip that holds the rod that travels back to the firewall had come off.

2. This made that mechanism (the one you take off on the drivers side of the valve cover) to move towards the firewall

3. This forced two of the linkage rods on top of the valve cover to cross (they normally run in parallel)

4. When they crossed, one bent and held there. It bent at about 35 degrees which I can't even believe.

My question is.....HAS ANYONE EVER HEARD OF SUCH A THING. SEEMS HIGHLY BIZZARE TO ME AND VERY UNLIKELY.

I cringe to think that my daughter had just been driving the car.

Advice please?

Don

P.E.Haiges · #2 04-01-2003, 10:20 PM

Diesel Don,

Yes, happened to my '80 300SD in AZ on a freeway. I drove to right side of freeway and stopped with engine racing. Opened the hood and pushed the red stop lever and engine stopped.

The rod that goes to the transmission slipped off and jammed the throttle linkage. The rod was held on by a horseshoe clip which of course was gone. So I moved the transmission rod away from where it could jam the throttle linkage and drove away. Transmission would upshift at the lowest speeds so to get any power I had to use the shift lever to keep in a lower gears.

This was a few years ago and there doesn't seem to be any damage to the engine. Actually a Diesel can't over rev because the injection pump controls the top speed of the engine. I was glad it didn't happen to my wife because she wouldn't know what to do.

P E H

diesel don · #3 04-01-2003, 10:28 PM

P.E.H.

Thanks for the response. I think I'm still shaking a bit. The noise was crazy but the thought of my daughter....oh well.

I found another similar clip that wasn't doing much and transfered it over. I just went out a minute ago to tweek everything and the car started fine, etc.

If a car can't over-rev, what happened to Larry's to cause it to blow? I assume mine would have blown in another minute or two, or am I wrong?

Don

diesel don · #4 04-01-2003, 10:37 PM

Tx:

What is the fuel rack?

Don

P.E.Haiges · #5 04-01-2003, 10:51 PM

The fuel rack is inside the injection pump. It controls how much fuel is injected in to the engine.

Yes, if the fuel rack was not connected the engine could overspeed and something could "blow". Most likely a rod would break, punch a hole in the side of the engine and some parts might go thru the oil pan. The engine would continue trying to run. If other rods didn't break, the engine would eventually sieze from lack of oil.

P E H

leathermang · #6 04-02-2003, 02:00 AM

I have never understood why MB did not put a cable to the manual shut off so one would not have to exit the car , open the hood and get inside the compartment to do an emergency shutdown....

diesel don · #7 04-02-2003, 07:22 AM

Dieseldiehard:

The culprit was definately the horseshoe clip that came off. After that it allowed the linkage to gradually slip into the wrong position and when I punched the accelerator, it got stuck.

Don

mk240d · #8 04-02-2003, 09:19 AM

I had a similar problem occur in a 78 240d... on the highway the car would speed up once a certain point was reached on the accelerater pedal, almost as if it had cruise control wide open. but it didn't have cruise control. I finally located a problem with the linkage on the manifold side of the engine. linkage joint had worn and was sloppy and was jamming open. I had to remove it and re-peen the press fit and that was the end of problem. it wasn't obvious at first since the symptom only occured at speed. the only other similar problems have been with linkage needing lube even at the ip. hope all is well. cheers mark

lrg · #9 04-02-2003, 01:40 PM

We should all remember that lubricating the "throttle" linkage joints is a regularly scheduled maintenance item. If the joints are allowed to go completely dry eventually you will have a problem. I'm sure that there are a number of lubricant choices but I use white lithium gease that tends not to liquify and run out when it gets hot.