Overrevving and cutoff

[na2ub]

My cruise control cable got dislodged and caused my car to get stuck at wide open throttle. It revved, then cut off, then revved ... etc... about 6 times, at which I turned off the ignition. I was stuck in the middle of the road, so I turned it back on and peeled out into a side street, probably 3 more overrevvs. I fixed the cable, which I will probably be cutting off, shortly, as the cruise does not work anyway. There was a lot of burnt rubber smell, but I don't think it is all from my tires. Maybe the clutch?

Question is what is my damage? Car drove fine after I relieved the cruise cable.

Thanks,
Doug

[Joe Bob]

You're probably OK but a leak down and/or compression test would give an indication of engine condition.

[na2ub]

Good thing is, the engine was up to temp before this happened. If it was cold, I would be really worried. How do I disconnect the cruise cable without cutting it?

[safe]

Your engine will be fine, you can't really hurt it that way. You must rev it past the revlimit, like missshift.

[dshepp806]

Happened to me once,..scared the sheeit out of me,....I can assure you that it only took ONE out of control situation before I hit the ignition,..I couldn't imagine 6 or more of these events! All bow to the damned rev limiter to save yo' arse.....

I've often wondered: ( experts will chime)....Why is it that the rev limiter catches RPMs headed "upwards".....but (apparently) doesn't limit revs in a "missed shift" (or "downshift") condition?

Why is this?

BEST!

Doyle

[Eagledriver]

Why this is, is because on a downshift over-rev the rear wheels are turning the engine instead of the engine turning the rear wheels. There is no rev-limiter on the rear wheels.

-Andy

[redstrosekNic]

Originally Posted by Eagledriver

Why this is, is because on a downshift over-rev the rear wheels are turning the engine instead of the engine turning the rear wheels. There is no rev-limiter on the rear wheels.

-Andy

+1
I believe the term for this is "mechanical over-rev". Mechanical, meaning it's the mechanical motion of the engine, without the ignition. The rev limiter is doing what it is supposed to do either cutting ignition, fuel, or both, but this doesn't keep the engine from mechanically moving.

[Tincanguy]

Originally Posted by redstrosekNic

+1
I believe the term for this is "mechanical over-rev". Mechanical, meaning it's the mechanical motion of the engine, without the ignition. The rev limiter is doing what it is supposed to do either cutting ignition, fuel, or both, but this doesn't keep the engine from mechanically moving.

Went on vacation back in the late 1980s and let a relative use my 78 Targa. When I returned, he told me that it was "running funny". I said it was running fine when I left. He then said he thought he may have over revved it. I said, no, it is protected by a rev limiter. I fired it up and it ran rough as a cob and smoked badly. I said, "you didn't by chance miss a shift did you?" He confessed that he had red lined it in third, meant to shift to fourth but missed the gate and went back into second. When he popped the clutch, in his words, "all hell broke loose". Lots of bent valves and nicked piston tops. The piston tops were polished out but the valves had to be replaced. Chris Powell did the top end repair for less than two thou (remember, it was the 1980s). Same job today would be more like 5 grand.

[dshepp806]

Originally Posted by redstrosekNic

+1
I believe the term for this is "mechanical over-rev". Mechanical, meaning it's the mechanical motion of the engine, without the ignition. The rev limiter is doing what it is supposed to do either cutting ignition, fuel, or both, but this doesn't keep the engine from mechanically moving.

Got it. Thanks for info....makes sense.

Best!

Doyle