So last season I had a problem with blowing out the dipstick as well as burning oil....after doing some research I'm hoping it's just lack of correct pressure in the top end.

What I realized last night is that my PCV has a like a 4" U shaped hose that is plugged into the port directly next to it. My engine is a 94 and Shoebox's website only shows a 95-97 and on there the line goes from PCV up to under the TB. Is mine routed incorrectly? I have the port under my TB but it has 1 of those screw in caps on it.

p.s. compression test and leak down is on tomorrows agenda.

 

Your PCV valve is routed correctly. The 93/94 engines are different, using the U-shaped hose to connect to a vacuum port near the PCV valve, and not picking up the vacuum from the port under the throttle body.

I still have the OEM hose on my 94:

http://www.injuneer.com/images/photo.../DCP04270a.jpg

 

excellent...thank you

 

I assume since you are going to do testing, there is still a problem. Just fyi:

One very good but almost never performed test is crankcase vacuum. What I can't remember and I can't find in the manual is level. I'm thinking around 10 inches of water column but don't quote me. It's measured with a manometer. Water usually, but there are electronic ones also.

The PCV will go from somewhere that accesses the crankcase to the intake with a valve in the line. It vents only positive pressure created from the downward movement of the pistons. But doesn't allow (PCV is a check valve) the negative pressure created as the piston moves up to draw air into the crankcase. Thus a running engine has a negative crankcase (vacuum).

The first thing you should do is replace the PCV valve since they often go bad, they are normal tune-up items and there is seldom another reason for positive crankcase pressure. In fact the only other reasons would be blowby and you would know that as it would tend to foul plugs. Or an intake gasket problem but it would have it's own set of characteristics associated with that.

BTW if it were rings the compression test may not detect it but the leakdown test will always catch it. BUT I caution you. There will always be some sound coming from the crankcase by the rings. What many novices get confused on is how much is too much. The gage is there of course but a few are fooled. Careful !

 

well the motor has less than 1,000 miles and I get both the dipstick blowing out at WOT and oil consumption. I'm going to start with PCV replacement. The engine builder is telling me he doesn't think it is the rings....all I know is that at my last race I drove ~50 miles to and from the track and made about 6 passes. I burned 1-2 qt's of oil

I also drove out on pump gas and my first pass was almost a whole second slower than usual. Dumped 5 gals of 110 in her and she picked right back up to where she should have been. I either had some ****ty 91 octane in there or the 110 helped burn off the excess oil in the combustion chamber. (atleast that's my theory)

Maybe I'll get lucky and it will be an intake leak or a bad valve seal. I dunno.

 

Maybe I just need a valve cover breather?

 

The engine builder needs more than a WAG regarding the rings. If the engine has fewer than a grand, my guess is that the builder screwed up.

You might want to check your plugs to see if it is a specific cyl. and then perform a compression test.

Your rings should be seated by now, but sounds like you are either burning oil that is either coming from the top past the valve guides or from the crank case past your piston (s). If it is a boogered PCV and the pressure is pushing the oil down your valve stems, that could account for the excess oil consumption as well as the strange things that happen when the crank case cannot be adequately relieved of the pressure.

BTW, if your engine overheated during your racing, you might have glazed your cylinder and the rings may not have seated properly.

If your compression rings are bad, it is likely the cause of too much crank case pressure. If your oil control rings are shot or not seated, you may be getting blow-by and burning oil.

Obviously you need to narrow it down through diagnosis. Caveat: Racing=Breaking. JMHO

 

That would not be a solution for excessive blow-by. The stock PCV system is perfectly good for a normally aspirated engine. Sounds like you have a ring sealing problem.

 

the engine was overheated during a pass this year. Fairly early on though and the oil consumption seemed to really only get noticeable at the end of the season.

The dipstick blowing out has been happening in some form or fashion since the motor went back together last winter.

FYI - This is an N2O motor that I ran most of the year NA. I only ran maybe 1 - 1.5 bottles through it.

 

Cracked piston if it aint PCV. Say no more....JUICE is not nice to pistons. Particularly if you don't have it PERFECT. Cylinder pressure is your enemy.

Leak down with the precautions I mentioned.

 

Guess I'll find out tomorrow. Here's to hoping it isn't an f'ing piston or even a ring for that matter.

 

Where's the damn icon with the crossed fingers .....

 

One with some praying hands would be more like it.

 

Ok...

Speedy - you cross your fingers

Shoe - You pray

and I guess I'll pat my head and rub my belly at the same time while turning in circles jumping on 1 leg.

bouncing off rev limiter + N2O = not good. I did pop a head gasket and it did overheat but I didn't see anything else wrong when I replaced it. (other than the fact that I ordered but received and installed the wrong head gaskets on the car...standard SBC vs. LT1)

 

That's funny right there...uhm I mean uh I feel your pain....