we did some racing today,and after a few laps i noticed that the crankcase pressure is getting higher every run .the last run i did the hose of the oil catch can popped loose.
I did reconected it to its place but suddenly the engine was stumbling when i placed in in to gear and died quickly.
My guess was that the supercharger was causing the blowby.
So i took of the blowerbelt and fired it up again.the pressure was stil there. the idle of the car looked o.k. but when i put it in drive it died.
strange thing is that above 1800 rpm everything works o.k.
There is no smoke coming from the exhaust at idle or driving,only the huge amount of air coming out of the valve cover which smels more like fuel then oil.
What could have gone wrong and cause this problem?,and what should be my first thing to check ?

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Perform a leak-down test on the motor when it's warm, it will tell you the condition of each cylinder and you will be able to compare the readings from cylinder to cylinder.

 

IMHO If you don't have the pistons and rings for a blown eng. you probably shoved a comp. ring down. I would check comp. pretty quick, a ring out of groove will wipe out a cyl. Danny Mc

 

You do realize that the crankcase should be under vacuum not pressure?

Check your PCV system.

 

The crankcase is never under vacuum.

 

O.K. i will perform a compression ,leakdown test next weekend.

Do you have better testing result when the engine is warm??

 

Sorry but it is always under vacuum when running, when the correct PCV system is used. The only time it has positive pressure is during cranking before it starts. Thus the reason for using a manometer. You are wrong.

Where do you think they got the term PCV. POSITIVE crankcase ventilation.

It vents the positive pressure during motion of the piston moving downward. Then the PCV Valve seals during the negative pressure of the piston moving upward.

Crankcase vacuum measurement is another way to measure the health of an engine.

Even lawnmower mechanics understand that.

I suggest you read a little more before you respond.

 

Sounds like when I broke the ring lands on my stock engine at 11Psi

I only broke three pistons no big

 

I am already a litlle bit afraid that it is the ringland issue,i did some reading on older post,and it sounds familiar.
Still i think it is amazing that the car performs "good" above 1800 rpm

 

Good is a factor of the other cyl's taking the load, you will probably [edit] up a cyl., hope not. Danny Mc

 

Mine would to. Hell it did not even miss....it would just pop the dipstick off the hood and hose down the engine with oil

 

You're the one who needs to do more reading. With the stock PCV setup the crankcase is NEVER under vacuum. The car sucks gases out of the crankcase through the pcv valve on the intake manifold, while at the same time fresh air comes in through the fresh air hose from the throttle body to the passenger side valve cover. And at full throttle since there is no vacuum in the intake manifold the crankcase gases are vented through the fresh air hose to the throttle body and through the pcv valve into the intake manifold. Why don't you go hook up a vacuum guage to your crankcase if you don't believe me.

 

The only way air will flow from the port in front of the throttle blades (fresh air supply to the passenger side valve cover) to the PCV valve, is if the pressure at the PCV valve is LOWER than the pressure in front of the throttle blades. The pressure in front of the throttle blades is already slightly negative, because atmospheric pressure has been reduced by the pressure losses through the air filter, air ducting, and MAF. Obviously, the PCV valve is under full manifold vacuum, which is typically 20"Hg at idle.

Given the fact that both the starting point of the PCV system, and the ending point of the PCV system are less than atmospheric pressure, which by definition consitutes a "vacuum", its very hard to understand how the crankcase can NEVER be under vacuum.

Looking forward to your explanation.

 

Hook a vacuum guage up to your crankcase and post how much vacuum it is under.

 

I am not a genius but if a cranksace was under a vacuum you could hook your brake booster to the valve cover and be good. What is vacuum anyways? I think it is a lack of atomosperic pressure. It wont hurt it to have a lil vacuum but not to much or you make suck all the oil out of the motor. They do run vacuum pumps on cars the have a bit to much blow by. I.E. blower cars,turbo, high compression that are worn out!!!.