Too much pressure in crankcase

[WD69FIREBIRD]

I just picked up my 69 Firebird after a 2 year rebuild yesterday. I keep blowing the dipstick out. Along with some oil. I locked the dipstick in and now blow oil out of the rear main. Too much pressure I thought so I checked the PCV valve to make sure it was hooked up and free. Appears fine and has suction on it. The rubber grommets is a baffle. Rubber plug has a slit in it the PCV valve goes into. Oil everywhere all under the car. It is a 455, hydraulic cam, edlebrock high performer heads. Motor was built a year ago so it did sit a few months before it was ran. The car made some rounds around town from the shop, to upholstery, to window tint, muffler shop etc...I ran it down the highway going from 40 to 80 about 15 times trying the seat the rings. Trying to get from high to low vacuum. I step on it and she blows its top. Any advice?

[WD69FIREBIRD]

Everything I see online says bad rings is why I'm getting blow back and the high pressure. But it's a brand new motor with 50 miles on it. Do you think this is the case and the rings are the issue? Or is possible I just have to take it easy and allow time for the rings to seat?

[David Pozzi]

The rings may have been installed upside down, or are wrong in some other way. I had an engine with a broken ring land section between top and second ring. It blew a piece of oil pan gasket out near the starter due to high crankcase pressures. It didn't show up doing a compression test or even a leak down test but once I got the piston a little bit past TDC one cilinder did show higher leak down.
David

[WD69FIREBIRD]

Thanks David. Your probably right as much as I hate to think i have to pull the motor after we jut finished it. But why would I think I was finished...always been something along the way.

[MrQuick]

they didn't happen to put in synthetic oil did they?

[joeelutz]

Other than the PCV valve is there a crankcase breather? It should let pressure out there before blowing seals. Could be a blown headgasket.

[WD69FIREBIRD]

they didn't happen to put in synthetic oil did they?

Originally no. After the shop ran it around they did change it and put in Valvoline Synthetic. Would that be the issue?

[WD69FIREBIRD]

Other than the PCV valve is there a crankcase breather? It should let pressure out there before blowing seals. Could be a blown headgasket.

The other valve cover has a breather on it. No oil is being pushed through that breather though.

[WD69FIREBIRD]

Other than the PCV valve is there a crankcase breather? It should let pressure out there before blowing seals. Could be a blown headgasket.

The other valve cover has a breather on it. No oil is being pushed through that breather though.

[WD69FIREBIRD]

I believe pontiac originally let it out of the valley pan under the manifold. We closed this up and used the PCV valve instead. Think it just makes to much pressure and I need to open the vlley pan back up?

[MrQuick]

Originally no. After the shop ran it around they did change it and put in Valvoline Synthetic. Would that be the issue?

if you are trying to seat rings, yes. I have seen it many times before. Did many re rings cause people make that mistake. Sometimes you can get lucky with a drain and refill with regular oil.
Old timers like to use non detergent 30w the first 1500 miles. I just run the cheapest stuff I can find.

[WD69FIREBIRD]

Well it's definitely worth a try. Off to get oil. Thank you.

[yellow1098Greg]

I made the mistake of putting synthetic in at first with my rebuilt and left it in for about 200 miles. Iv had some of the same problem with oil blowing everywhere and can't figure out the problem. Would that oil do some ireversible damage?

[MrQuick]

Pretty much, I was told by my engine builder that it rounds off the cross hatching and puts a glaze on the cylinder walls. Sometimes you can get lucky.

[Steve Chryssos]

Get some Valvo 10W30 oil non-synthetic and temporarily hook up a cheapie vacuum gauge such as Auto Meter 2337 along with 1/2 a bottle of Red Line Oil 81403 break-in additive. It's all about the vacuum gauge. There is no pre-determined number of miles to break-in. If there is, the number is closer to 500 miles. Before you yank the engine, put another 50 miles on it and see if the vacuum reading is increasing. As long as the vacuum is increasing, the rings are seating.

That is mojo imparted to me by a big cheese at Red Line Oil -- a synthetic oil manufacturer. If they're recommending non-synthetic for break-in, then you can believe it. It applies to any fresh hot rod engine build, not just the OP's.

Back to the engine in question, if you find that vacuum is increasing over the next 50 miles, keep going. But have a whiff of your oil. If it smells like fuel or nasty exhaust fume contamination (and it probably will), do one more Valvo 10W30 non synthetic oil change with the other half of that 81403 break in additive.

Good luck!
/Steevo

[JEFFTATE]

Yes , I agree , the vacuum gauge is " THE " tool to check the engine with ...
See what your intake manifold vacuum reading is .
Maybe do a cylinder leakdown test as well .

[MrQuick]

Get some Valvo 10W30 oil non-synthetic and temporarily hook up a cheapie vacuum gauge such as Auto Meter 2337 along with 1/2 a bottle of Red Line Oil 81403 break-in additive. It's all about the vacuum gauge. There is no pre-determined number of miles to break-in. If there is, the number is closer to 500 miles. Before you yank the engine, put another 50 miles on it and see if the vacuum reading is increasing. As long as the vacuum is increasing, the rings are seating.

That is mojo imparted to me by a big cheese at Red Line Oil -- a synthetic oil manufacturer. If they're recommending non-synthetic for break-in, then you can believe it. It applies to any fresh hot rod engine build, not just the OP's.

Back to the engine in question, if you find that vacuum is increasing over the next 50 miles, keep going. But have a whiff of your oil. If it smells like fuel or nasty exhaust fume contamination (and it probably will), do one more Valvo 10W30 non synthetic oil change with the other half of that 81403 break in additive.

Good luck!
/Steevo

yep, great point, it all comes down to machining,rings used and break in technique. Could be 20 min on a dyno.

[David Pozzi]

Make sure your dipstick & dipstick guide tube are the right length.

[yellow1098Greg]

Would you mind explaining the dipstick issue. I'm thinking this might be the problem Iv been having. What would the dipstick have to do with the oil issues.....thanks

[MrQuick]

Yep, wrong dip stick may cause one to add too much fluid.