Oil Cap Blew Off

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Oil Cap Blew Off

Post by GeoffInCarlsbad »

Hi everyone. Been awhile, but been back to tinkering to the '61.

Problem: My Oil Cap blew off over the weekend.

Recently, I've been getting some popping only when the engine is rather cool. Car starts fine, runs fine, put it in gear to pull out and inevitably
the engine has been popping 1 or 2 times only, then will act as if ready to stall upon a stop. Once the motor is heated up a bit, everthing runs great. Starts well, runs well, accelerates normally, et al.

A little background: Last year I replaced my autolite 4100 with and Edelbrock carb. I also run a PCV from the the intake manifold to a port on the carb. Have been doing that for over a year with no problem. Idle speed is good, timing on track (6 degrees), but I have her running a little rich.

So, the problem could be:
PCV Clogged
Oil in the crankcase being blown out, which means I my have a blow-by issue.
the former I will check today, but if it's not that, is a ring-job on the horizon? I have always feared I would need a rebuild on the nearly 60 year old motor, with unknown mileage. I can face that fact, but before I do, I'd like to get some ideas on other tests to diagnose this issue.

All help always welcome.

Best regards,

Geoff in Carlsbad CA
1961 T-Bird Convertible (in progress)
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Posts: 38
Joined: Thu Jan 03, 2019 5:49 pm

Re: Oil Cap Blew Off

Post by michaelperazzo »

I would warm the engine up to operating temp and pull out the PCV valve and open the cap on the other valve cover and see how bad the blowby is. Rev the motor and see how much smoke and pressure is coming out. Can cap off the vaccum line for the PCV valve first. A little is ok. A lot is a problem.
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Joined: Sun Sep 09, 2012 10:33 am

Re: Oil Cap Blew Off

Post by RAVEN »

You may have a bent push rod, causing a valve to not open and causing a pressure backfire (blow by). In a very remote possibility you have a choked exhaust on one bank, forcing exhaust to find a secondary escape path. This being the exhaust pipe cross over. Have seen this on a 454 chebie years back. The exhaust pipe internally collapsed, forcing the exhaust to find a path of least resistance and blowing the rocker cover gaskets. The compression pressure blew back thru the valve guides, and would blow the rocker covers. The internal crossover of the intake manifold could not handle the 8 cylinder volume of air under load. (Believe it or not but true.
Simple to check, might save you some grief

CDN Member since 1975 #2086
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1964 Sr Convertible "RAVEN"
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