blow by???/

[newtodsm's]

i am thinking that i have blow by. i did a cylinder leak doen test i could hear a leak near the throttle body. i am assuming that means my intake valves are leaking for that cylinder. when i do a boost leak test my dipstick will pop up. if you pull it out a little moreoil spray out of the tube like a watergose. is this blow by? if not what should i check next

 

[chico904]

A leak heard near the throttle body can easily be the throttle body seals, or gaskets.

 

[Calan]

Yes..that is blow-by. And it sounds like you may have some pretty worn piston rings or a worn out PCV valve. Are you burning any oil?

Do a compression test and add a capful of oil to each cylinder and see if the results change. That will give you some indication of the ring condition.

Edit:

Charlie's right, but if you have all the intake valves closed during the leak-down test, you shouldn't really see much air at the intake unless the valves are leaking, or it's finding it's way back through the crankcase and PCV system (aka blow-by). If one or more cylinder's valves are open, then the air will flow back up into the intake and out through any leaks of course.

Did you have the engine at TDC when doing the leak-down test? The article I linked to above has all the details for both a leak-down and compression test if you need more info.

 

[newtodsm's]

i just did my compression test its was 120 on each cylinder. im thinking thats low. i will go do a cap full of oil and report the results. its not burning any oil. it drives fine idles great. i was driving the other day and oil sprayed all over the engine from the dipstick tube. i did some research on here and found what to check. i have replaced the pcv valve and i had each cylinder on tdc. ill go do the compression test with oil right now

 

[Calan]

120 psi is definitely low. I believe factory spec for your car should be 178 psi, with a service limit of 133 psi. Was there a lot of variation from cylinder to cylinder, or is it pretty even across all of them?

If they are all reading around 120 psi, I would double-check your testing setup before assuming the worst. Make sure your battery is fully charged and the tester is reading accurately, etc etc.

BTW - you did warm the car up fully before doing the test... right?

 

[newtodsm's]

this might sound really bad but i didnt know it had to be warmed up. i drove it this morning then it sat for about 30 mins before i did it. i am pretty sure my tester is good i bought it this morning. and i didnt mention it has a 6 bolt swap

 

[Calan]

Nope.. it has to be warmed up due to the expansion of the rings, cylinders, pistons, etc. at running temperatures. It also helps make sure the battery is charged.

Click that link I gave you up there ^^^ for a refresher, and make sure you didn't over-look something else. There is nothing worse than trying to track down a problem while going down the wrong path due to troubleshooting errors.

For a stock 1G 6-bolt turbo, factory spec is 164 psi with a service limit of 121 psi.

 

[newtodsm's]

ok so i let it warm up and tryed it again. still 120 across the board. then when i put a cup of oil in cylnder 1 and 2 were 150 and 3 and 4 were still 120. so im assuming that the rings are bad.

 

[Calan]

It's a pretty good bet, but I'm still a bit leary of all 4 cylinders reading 120 psi. Have you done another (proper) leak-down test? If so, what kind of loss percentages are you seeing on each cylinder? And you meant a "cap" of oil... not a "cup"...right?

If you are truly at 120 psi on all cylinders because of bad rings, the car is gonna be burning oil and probably smoking like crazy. If you aren't seeing any bluish smoke while driving and it still has decent power, I think something is off with your compression results.

 

[newtodsm's]

sorry i did mean a cap full not a cup. i have never seen any bluish smoke. its doesnt burn oil. i have done the compression test three times with the same results everytime. i am thinking about changing the rings and going from there. is it possible to change them without pulling the motor. i was wondering if i could take the head off and the oil pan. then unbolt them and push them up. is this possible? while i have the head off im going to have it pressure checked and make sure everything with it is ok. thanks for all the help

 

[Calan]

Is the bottom end stock? Do you know how many miles are on it?

I'm sure some will disagree, but...

You can change the rings the way you said, but I would just pull the motor. To do it right, you need to have the cylinders honed anyway (and possibly the block checked and/or decked), and while it's out you could check everything else out and fix anything that you come across with not a lot more effort or cost.

It's still possible that it's mostly the valve seals as well, at least for the compression results. (You never mentioned the latest results of the leak-down test). As for the original dipstick popping problem during a boost leak test, that means that pressure is either getting past the rings, or into the crankcase through the PCV path from the IM. So if the valve seals are shot but not the rings, then you have another little problem as well.

My bet is that the motor has just seen some wear and tear, and probably needs rings, valve seals, and a good going-through.