Hey guys, I was wondering if someone else is having the same problem as me. My car seems to be having blow by. If I was to open the oil cap, there seem to be more pressure than normal. Anyone with a turbo on their tc's, can you test your car also with the oil cap off during idle and check if this is normal or could be just mine. I did a compression check and got 185 across the board. So, I am lost now. I thought that blow by was caused by bad rings or pistons. Please help if me if you can. Thanks scion community.

 

Did you do a leak down on your motor. That will tell you if there is a problem with your motor. With 185 across the board I think your ok . good luck

 

thanks for the reply. i havent done a leak down test yet, but i am going to do a leak down test soon.

 

Dont take your oil cap off while the engine is on. The vent on the drivers side of the vavle cover would be a safer place to check for that. Another thing, pull the dip stick while the car in on and feel for pressure coming out.

 

dont worry it is normal. get an oil catch can if you want to have one

 

Well heres what i was told by the mechanic that has been working on my car lately.

Blowby is caused by pressure going into the motor by the turbo (i think thats what he said LOL, any experienced people can chime in on this) What he did is install a blowby check valve, which prevents pressure to go back into the motor, instead it reverts it back (or so he told me).

Anyways if i were you id do a "cylinder leak down test" to confirm that everything is alright. When i did my test it came out "moderate" means my motor has some blowby.

 

well i have a perrin oil catch can. i thought this is all i need, but i guess there is something else. this is my second turbo from innovative and it is leaking out from the seals again. i dont think that the seals are bad, but i do believe that the blow by from the motor is seeping oil through the seals. i had the turbo on for about 20miles of driving without boost, just testing it, and when i popped off the intake from the compressor housing, there was a small puddle of oil build up. the first turbo was doing the same thing. i guess i will just have to do a compression leak down test to find out whats going on!!! thanks for all the help.

 

do you have lower comp pistons? because the compresion on the tc is 200 , check the piston rings

i think you are loosing compresion

 

finally, a reply that i can build from. no, i do not have lower compression pistons. if the stock compression should be at 200, i am definitely low. thanks for the reply, gerard. i will have a leak down test tomorrow and see whats wrong. thanks again!

 

from your first post i couldnt tell if you had one or not. blowby is normal but since you have a noticeable pool of oil the leak down test is the next thing to do as you stated. good luck.

 

Your second step would be to confirm what Gearard had to say.

 

There should be a little air puffing in and out of the filler cap from the pistons moving up and down. There should also be a little air being sucked into the cap depending upon how the crankcase vent valve is working or if it is blocked. At idle no load or gentile rev in meutral there should be a net vacuum from any blowby leaks since there is only a little bit or pressure in the cylinders and mostly vacuum for most of the crank revolution. Too much blowby and the oil vapors and blowby from the crank blows into your intake through the PCV valve and may deposit some oil in the intake. Valve stems can also leak into the oil from the intake and the exhaust sides.

 

By the way how full is your catch can?

 

repair manual says ideal compression is 189 psi (for 05). minimum is 145.

 

no, my catch can site tube is still pretty clear and low. that was what i checked out first. going to see a shop today to do a leak down test.

 

what were the results

 

Not true. Compression spec is a range from 145 - 189. 185 across all cylinders would be very normal.

 

my 06 tc did 200 psi just with bolt on parts like cat back, intake and unorthodox pulley and a good set up with an apexi neo afc but if you say 185 make sure is 185 in all pistons and it has to be exactly 185 any difference and you found the problem

 

Lower readings indicate less ring seal/more blowby and or less carbon buildup in the chambers and on the piston top. It may be acceptable but leaking more than really good sealing rings - it could also be variations in the compression tester and cranking speed. Adding a small shot of oil to the cylinders to increase ring seal after the initial pass on all cylinders would show an increase in pressure if the rings are leaking more than usual.

 

considering we are talking cylinder compression, i can't see what those parts you listed have anything to do with anything???

also, it does not have to be exact across the cylinders. A margin of 14 psi is allowed between cylinders..small differences are normal as well.