Maybe Blow-by, HELP!

[TURB0]

Im considering purchasing a 1g GSX from a guy in my town. The car as some base mods and looks to be very well taken care of. It has 130k original miles with 13k on rebuilt engine and 9k on tranny. He let me drive the car and it all seemed to run fine and smooth. However, the dipstick was wired down when i looked under his hood. He said that under boost, it would pop out. Also, when I open the oil cap at idle, alot of air was coming out along with drips of oil. He has an oil catch can installed on the car as well. Im thinking a case of blow-by maybe? How serious is this to a dsm? What would I have to replace if anything? Or is there even anything that can be done short of rebuilding the engine? Any help would be apprectiated asap! Thanks.

 

[eviltalon1]

I have a freshly rebuilt motor with 175 psi worth of compression across the board. And under boost I still have a dipstick problem. If you are concerned about the health of the motor do a compression test and a leak down test. That will tell you the condition of the motor.

 

[ivanr4g63]

Yeah, a compression test should tell you more about the health of the motor, if thats your concern.

But I wouldn't be very worried about this, 'dipstick popping' happens to at least 50% maybe more of the turbo cars here, and yet they put good power to the wheels.

 

[xveganxcowboyx]

It could also be a bad PCV valve. (is that redundant?) Oldman will probably explain everything in detail at some point here My only concern is the fact that the dipstick was held down. As I understand it, that is the last safe place for the pressure to escape. If it can't get out there, what other damage could it have done while trying to escape?

I would guess it's not blow-by on an engine that new, but you never know. Just give an example, my compression is 110-120 across (very bad) and my dipstick doesn't pop (at least since I replaced my PCV)

 

[TotalEclipse112]

Ok I'll make this real simple, THE CAR IS FINE. Everything you described is completly normal with the exception of the wire on the dip stick, never seen anyone do that. But its fine. First off it's impossible to tell if there is blow by by taking off the oil cap and feeling for air. Its just not possible, the only way to tell if there is blow by is to do a compression or leak down test. The only way to feel blow by (and this is impossible) would be to stick you hand into the crankcase of a running motor and feel around the cylinder walls as the piston moves up and down and see if air/fuel mixture is escaping into the crankcase. Blow by goes into the crankcase not up into the valvetrain. Not only that but the valvetrain which is what you have access to by removing the oil cap is sealed off from the cylinders. The only way for cylinder pressure to get into it would be through the valve seals which is extremly unlikely. The pistons aren't right below the valve cover. So from what you described the motor's health is fine. As for oil under the valve cover and drips of oil, thats also completly normal. The lubrication throws a massive amount of oil at the valve train to reduce friction and aid in operation. The hydraulic lifers run on engine oil pressure, and I belive that the 4g63 runs about 60-70 psi of oil pressure (don't quote me on that I don't have the manual in front of me) to help keep them pumped up. As for the rest of the oil in the head it lubricates the cam's, lash adjusters, valve springs, and the valve stems. So with all that lubrication going on a ton of oil is needed so a couple of drops from the oil cover are no problem whatsoever. And as for the PCV its the Positive Crankcase Vent, its just a simple valve that vents crankcase pressure along with thinkgs the EPA says are bad, known as hydrocarbons and dumps them into the intake tract along with oil vapors and a bit of oil mist. Thats what a catch can is meant to prevent, they go there rather than into the intake. If you have ever taken the intake manifold off of one of these motors without a catch can, you probally noticed that black slimy crap in there thats from the PCV doing its job. The oil mist and othe rgarbages just finds something to sitck to on its way to the cylinder to be burned off. So in short my advice is buy the car it sounds fine, take it home, remove the wire from the dipstick and pinch it tight so it barely fits on the tube to stop it from popping out. Sorry for the long post but I thought it might be of some assistance, hope this helps.

 

[TURB0]

The compression test came back 151 149 157 152. Do DSM's just naturally have high crankcase pressure?

 

[eviltalon1]

Everyone that I have had.

 

[TotalEclipse112]

yup they sure do and your compression test looks good too

 

[jonseclipsegs]

What is going to happen when the boost is turned up from 14psi(where it has enough pressure to blow the dipstick out) up higher to say 18-20psi and more mods are added? More serious problems?

 

[ddavisaf]

Excessive crankcase pressure... I'm sure oldman'll be here soon....

Check and make sure that since he has a oil catch can, that he does NOT have a pcv. He should have a 1/8 npt straight fitting in it's place and still connected to the intake manifold.
If the motor is good (which the compression test says it is) then it will blow a bad dipstick out. If the motor is bad, it will blow a good dipstick out. Try replacing the dipstick with it's 2G couterpart.
Make sure you run a boost leak test also.