Mechanical Over Rev - What did I break?
12-26-2015, 09:33 AM
#21
Long story short, I'm a shitty driver and hit 1st instead of 3rd at WOT. The wheels skipped for less than a second or so before clutched in. The car seemed to go into some kind of limp mode where anything over 1/4 throttle would make it bog big time. After stopping, letting it idle, and listening for any kind of strange noises, the car seems to have it's power back. No odd noises that I can hear as of yet, maybe on a cold start it'll start rapping.
Why would it have done something like this? I refuse to believe it just fixed itself. I'm gonna do a compression test and a cylinder leak down on it this week but the way it lost all power and then was restored is very odd to me.
Why would it have done something like this? I refuse to believe it just fixed itself. I'm gonna do a compression test and a cylinder leak down on it this week but the way it lost all power and then was restored is very odd to me.
A compression test and a leak down as well as a peek in the cylinders with a borescope will give you an idea as to the condition of the valves.
I've kissed a few pistons on an over rev like yours (snagged 2nd instead of 4th) on a 350 and never knew it until I tore the engine down years later because it flattened a cam and saw the eyebrows on the piston tops.
12-26-2015, 10:34 PM
#22
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Took apart the car today. Pulled all the pushrods out, didn't find a bend or a kink in a single one. Car runs just fine with no noises, misfires, or CEL. A compression test may have been a good idea but I'm not really worried about it, seems like a waste of time.
12-27-2015, 07:30 AM
#23
Only way to tell if you tagged a piston with a valve. Not really a waste of time because if a valve head is bent it is being side loaded with each closing. If it fatigues and breaks off the end of the valve, the motor will be toast at that point.
12-31-2015, 06:07 AM
#25
I doubt a 1-second spin will hurt the rod bolts. If you bent a valve you'll have zero compression on the cylinder. I mean dead zero. Ask how I know.
Where it's possible to bend a pushrod is if they are relatively light and you have a lot of valve spring. It's not likely, but if it were my motor I would check.
Where it's possible to bend a pushrod is if they are relatively light and you have a lot of valve spring. It's not likely, but if it were my motor I would check.
I did this shortly after the first time owning a manual reverse valve body C-4. I had gotten in the habit with the AOD of popping it in neutral after crossing the line to bring the R's down. Well, one day that "instinct" came back & without conscious effort I lifted off the throttle & slapped the stick forward, & it back shifted alright, at 130mph... I had to clean my drawers after that.
Bent all 8 exhaust valves but it ran surprisingly well. When I hooked pressure to it you could here the air rushing into the header tube.
01-02-2016, 09:09 AM
#27
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03-10-2017, 01:29 PM
#28
I commented on this two years ago saying how my buddy did it. I think I bent a push rod doing it myself. Now I got this funny noise around 2k rpms and deceleration. Here is a video. You can hear the off noise best during the deceleration after the start up
yep I had the same exact noise, both check valves were in pieces. 
04-02-2017, 11:15 AM
#35
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This happened to me before and usually I see it accompanied by a CEL as we over ran the RPMs that the mapping was reading. Turned the car
off and back on 30 minutes later and no issue. Play on!
off and back on 30 minutes later and no issue. Play on!