Dipstick popping up under boost - Finally done compression test!

[The Real Roadrunner]

basically
when the PCV is in operation (idle, cruise etc) air will be sucked INTO the cam covers.
when on throttle, PCV shuts, and any blowby will go OUT of the cam covers..

so on throttle, PCV has no effect.

Ummm, not so sure on the above, air should never be sucked into the camcovers unless its through the tube that runs to the intake pre turbo.

The PCV only works when manifold vacuum is greater than whats inside the engine, so from pretty much 0-30hgvac which means it will always be drawing air to the inlet manifold unless the engine is on boost in which case it will shut and then use whatever pressure difference there is in the tube from the cam cover to the pre turbo inlet (there will be a difference as im yet to see someone build a filter with 0 restriction).

Whitchy, HTFU and get a spring on the dipstick

cheers
linden

[oldcorollas]

Ummm, not so sure on the above, air should never be sucked into the camcovers unless its through the tube that runs to the intake pre turbo.

sorry, thats what i was meaning
pre-turbo-cam covers-crankcase-PCV-imlet manifold under vacuum....

so something liek that

[JZA70R_92]

how big are the hoses running to the catch can.....

[Ben Wilson]

Sit down, grab a cup of coffee and have a look at this, that is the only place I've ever seen it all spelled out.

[lexsmaz]

Does your catch can have a breather / filter on the top of it ? ... Most turbo's factory setups that i have seen, have a PCV hose system & also a breather hose to pre turbo piping, so you have basically only got one of the above unless you have a breather / filter setup actually on your catch can as well ..And as GA70H 92 mentioned how big is your catch can piping ? ...

You could try runing it on a dyno setup without any catch can piping & see what happens then ? But as has been said if you have got some smoke issues etc, it is possibly ring sealing related ..

[WHITCHY]

Thanks for that link Ben!
I'm not sure on the exact size of the hoses running to the catch can, but they are bigger than my heater hoses, maybe 12mm? Its whatever the factory size is as the cam covers have not been modified.
There is no other breather/filter on the can, just the one running pre-turbo.

[WHITCHY]

Ok, finally got off my arse and did a compression test!

Not as horrible as I thought it would be when I did the dry test, but there's a decent jump in compression when I did the wet test. Is it normal for there to be that much of a jump on a wet test? I used about 1.5 tablespoons of oil for the test.

Results were:
1) Dry 159 / Wet 220 = 61psi difference
2) Dry 161 / Wet 212 = 51psi difference
3) Dry 151 / Wet 199 = 48psi difference
4) Dry 151 / Wet 209 = 58psi difference

Do these results mean all my rings are fubared and thats definatley where the compression is getting into the sump? I have changed to a slightly thicker oil, so it doesn't seem to be consuming as much as before, but it still smokes a bit on boost.

Thanks for any help and info!

-Whitchy

[hosking1991]

with this sort of problem i think a leakdown test should be performed

[CrUZida]

1.5 tablespoon's of oil ?!?

Correct me if I'm wrong, but I've always thought it to be 'a few squirts of oil'

1.5 tablespoon's would raise the compression significantly by reducing the amount of space in the chamber?

[WHITCHY]

I searched the intahwebs for an answer on how much oil to use, and most results said 1-2 tablespoons. I only found one result that said 1-2 teaspoons, figured they are easy enough to get mixed up, go with the majority?
How much does everyone else use for a wet test?

Thanks!

-Whitchy-

[CrUZida]

Fair enough, I've only ever gone by word of mouth, never actually researched it.

[thechuckster]

you only want enough oil to wet the ring lands - 2 teaspoons sounds like a lot - i just dribble in a small amount (5ml?) with a syringe+long tube to avoid getting lots of oil/crap in the plug valley and/or plug threads.

~60psi increase from dry to wet does suggest you have a fair amount of blowby and will need to attend to it sometime soon.

[Hiro]

you only want enough oil to wet the ring lands - 2 teaspoons sounds like a lot - i just dribble in a small amount (5ml?)

A teaspoon is 5ml

[allencr]

That much oil probably bumped up your CR to about 15:1! Try testing it again after cranking it over for a second or two, it'll distribute more then enough oil all around and spray out the excess. That 'wet' test will be valid.

It needs enough oil to coat the cylinder & rings, 5-10cc, a few oil can squirts or about a1/3 of a cap full, then it is cranked over to spew out the excess. Do it one at a time or all together.
***************************
I meant 'Do it one at a time or all together' for for the oil in the cyls., not for removing a plug & checking each one individually!
If the plugs & test are done one at a time, the cranking speed might be too slow, it's extra wear & tear on the starter & battery, and you won't be able to hear the 3 or 4 'whomps' of the compression stroke into the tester from the cyl. being checked.
I don't care whether it is hot or cold, or care much if the throttle is jammed open a bit, since I'm usually looking for consistency rather then a specific number. Cranking speed is much lower then idle speed, so there's enough air getting in when there is an intake plenum or even with carbs/ITBs that also have a balance tube/ports.

[WHITCHY]

God dammit! It took me so long to stop being lazy and do the comp test on Sunday! I'll do it again in a few weeks when I can be farked pulling the coil packs and sparks out again.
Thanks heaps for those instructions Allen! I couldn't find anything specific like that in my searching.