***SCARY**** My car ran away today

[mbonly]

87 300d turbo, 603 eng, 244k, #14 head, 90 deg with what felt like 300% humidity (hottest day of the year so far). I was pumping gas today and when i got back inside I tapped the accelerator pedal and the eng when strait to well over 5000 rpm and climbing- with the a/c on-, I was quick enough to turn off the ignition after a couple of seconds and when it turned off and I was back in my senses (after realizing I could've lost the engine or worse it could've happened in traffic) I saw it was the carpet that had moved over the accelerator some how. I placed it back where it goes and started the car again and guess what, it did it again, all the way to 6000 rpm or so and quicker this time since I didn't have the a/c on now, I can't believe how quick it got there. After shutting it off, a million thoughs went through my head, timing chain, vaccum pump (not the updated one), rods, valves ect, ect ect. I opened the hood and notice the cause, it was the accelerator linkage that had gotten stuck, I checked the acelerator cable and it had paly on it so I realized that wasn't the problem but I couldn't really see where it was binding so I worried that something internal in the pump or one of the other devices that the linkage moves was sticking. I had somebody pump the accelerator reapeately but couldn't duplicate the problem. The only thing I could attribute it to is the white lithium grease I sprayed on the joints in the linkage about 2 or 3 months ago. I noticed the other day that the grease kind of dries off I guess from the heat and maybe that was making something stick from too much friction so I sprayed some wd40 on all the joints and tested it again and carefully went home with my hand just inches from the key. Has anyone experienced this problem? is there something common that fails or is it just the grease? sorry for the long post folks but I'll really like to describe the problem and hear if others have had this problem and what the cause was, as you'll probably know I'm afraid every time I press the accelerator now.

[bennett]

Been there... done that on a gasser with my brother..

we were in traffic .... I call it the "magic carpet ride"

[mbonly]

really scary, What turned out to be your problem?

So the problem didn't start with the carpet wedged against the gas pedal?

There is quite a bit of pedal return resistance on mine, and doubt a carpet, even a heavy rubber mat could hold mine.

Did I understand you to say the cable is not binding, that it is the mechanical linkage? I know it connects to the cruise with a couple of short rods with ball sockets before connecting the IP, and I could see those rods possibly getting fouled up. Hope you find out fast, so this doesn't happen again and thanks for the heads up.

[mbonly]

No it wasn't the carpet, I think it's most likely that little roller that slides on a sort of cam in the linkage but am not sure.

[wols0003]

Could you feel a difference in the feeling of the pedal when you pushed it, before starting?

[mbonly]

Originally Posted by wols0003

Could you feel a difference in the feeling of the pedal when you pushed it, before starting?

No not at all, it felt the same, even the second time it did it.

[DieselAddict]

On my 87 300D I had the same experience after I incorrectly installed the glow plug wire harness underneath the intake manifold which caused the throttle linkage to stick. In your case the first thing I'd do is move the throttle linkage back and forth by hand and make sure it doesn't stick. You don't have to remove the intake manifold to do this, you can access the linkage through the gaps of the intake manifold.

[pberku]

Check your engine mounts. A bad engine mount will cause the engine to tilt, pulling the accelerator cable with it.

IN THE INTERIM, you may want to increase the slack in the accelerator cable to compensate.


Phil

[mbonly]

Originally Posted by DieselAddict

On my 87 300D I had the same experience after I incorrectly installed the glow plug wire harness underneath the intake manifold which caused the throttle linkage to stick. In your case the first thing I'd do is move the throttle linkage back and forth by hand and make sure it doesn't stick. You don't have to remove the intake manifold to do this, you can access the linkage through the gaps of the intake manifold.

It was so hot yesterday that I could only do limited check up, will try again today with the engine cold

[PatrickW]

There is the potential for a similar situation on some cars, but I don't know if it applies to yours:

There is a "damper" on the linkage - it looks like a little shock absorber, with a ball & socket joint on each end.

This "damper" can come loose from either end and get jammed in the throttle linkage, jaming it open...

Mine was like that, and I replaced it. Could probably live without it.

- Patrick

[mbonly]

Originally Posted by PatrickW

There is the potential for a similar situation on some cars, but I don't know if it applies to yours:

There is a "damper" on the linkage - it looks like a little shock absorber, with a ball & socket joint on each end.

This "damper" can come loose from either end and get jammed in the throttle linkage, jaming it open...

Mine was like that, and I replaced it. Could probably live without it.

- Patrick

Haven't seen one on mine, I do have my other 300d apart with the intake off and haven't seen it either so maybe this cars didn't use it.

[mbonly]

It did it again, it ran away today in another super hot day, but this time I think I know what the cause is. It was idling with the a/c on and my cousin was in the car while I was in the house and I heard it running full speed. I ran over and my cousin said it just started to run by it self but I didn't believe it. I restarted it while looking at the throttle linkage and after about 2 min of idling with the a/c on it started to run away again but I noticed that this time the linkage started to move by itself with nobody even touching the accelerator, so I suspect is the cruise control actuator being activated by itself. I want to disconnect it and look at it when the temp comes down, does anybody know where to disconnect the crise control?

[pberku]

It's unlikely to be your cruise control. There are just too many safety factors built-in to cause the cruise control to come on by itself.

I still think that its much more likely, and much more plausible for it to be a defective engine mount. (See my reply to you in post #9)

Phil

I've had bad engine mounts in my 87 300D that caused the whole engine to drop nearly an inch, my throttle was never effected!

If you think it's the cruise, than disconnect it! I'll try to post pictures of how to do that tomorrow.