scary: popped off oil filler cap?

[rrubel]

I'm running a set of ProForm centerbolt valve covers with the standard push-in oil cap that comes with them; no provision I can see for a push/twist one.

Anyway, I was, um, trying to make it through a green light (ok, I was a full block away, but there were no cars...) so I whomped on it. Didn't make it and had to slam the brakes hard. As I sat at the light, I saw smoke curling around the headlights (this was at night) but it wasn't a lot and all the gauges seemed normal so I didn't think twice about it. Got home later, popped the hood, and saw that the oil cap had come off and was (fortunately) wedged between the fender and the headers. Some small amount of oil had come out of the valve cover and gotten on the headers, hence the smoke.

However, WHY would the cap have come off? I know it was on because I saw it this afternoon. I didn't think an engine could build up enough pressure to push one out; the breather tube was still in place and it's a jury-rig job. However, since I plan on racing the car, this is NOT something I want to happen on a regular basis.

Any suggestions/thoughts?

Thanks.
[RICHR]

 

[Ken]

That's why they mandate screw in fill caps in the NHRA, Rich. There's always a possibility it'll come loose and fall off, as you've discovered.

Why it came off is unknown to me; maybe it was simply loose enough that all it took was one good run to finally cause it to come off. The engine shouldn't be building that much pressure, not in your case. A Pro Stocker maybe, but not a street engine.

 

[sothpaw]

However, since I plan on racing the car, this is NOT something I want to happen on a regular basis.

Any suggestions/thoughts?

Thanks.
[RICHR]

Get a screw on style if this is not. I think if you are like me you will have enough problems racing (road racing & auto-x).

I am finding the details of what racing does to a car, the kinds of things that get messed up/ need service before & after. Brake fluid. Power steering fluid (steering rack & ps pump gets waisted especially from tight auto-x courses). High rpm wastes timing chains, even ps hose. Then there's rad. hoses. Not to mention tires. Sticking calipers...

... and the worst: Misc. wiring getting fried. Not easy to diagnose, I am finding.

I see now why my car was one of the oldest at the Pocono gathering (except the Panteras). I think you really have to do it all yourself. Guys with newer cars will not waste some of these things.