Compression & Leakdown test results

[Mike Marnik]

Oh well i have been having a problem with excessive crankcase pressure lately when i would perform a boost leak test. The breather vent on the passenger side of the valve cover would have alot of air coming out. This worried me beciase my frieds 91 tsi has no air comin out during a boost leak test. I checked the pcv valve and it seals great under boost so that is not the problem. So today i did a leak down test and compression test here are the results Starting on the passenger side
146 psi 40% loss on leak down
150 psi 35% loss
145 psi 50% loss
145 psi 50% loss
from those results teh compression is great but im not sure what bad pressure loss on a leak down test would be. Also i burn about 1/4-1/2 a quart of oil a week. Also after a boost leak test the car will smoke (blue from oil) for about 10-30 secconds. Im thinking it has to do with bad valve seals my dad had mentioned a burn valve but the car runs great and pulls great.

 

[underpressure25]

When you did the leakdown test did you make sure that that the cylinder stayed at top dead center of compression stroke? Did you listen to hear where the air was escaping from? If you pull the dipstick and you hear air escaping its your rings.
If air is escaping out your exhaust its your exhaust valves. If coming from intake intake valves. If youl pull the coolant cap and air is bubbling out or it sprays out ita a headgasket, unless your car is still hot from running.
Good Luck

 

[Mike Marnik]

i made sure the cylinder was at tdc i did this while the engine was warm. The air was coming out of the breather valve but it wasnt hot air like it went down threw the crankcase/block first more like it was coming threw the head. the car doesnt over heat the car doesnt visibly burn oil and my compression test was great meaning good rings.

 

[Mike Marnik]

Update i did another leak down test and checked at teh tb elbow and i can definatly feel air coming out there and i also sealed off the exhaust with a bag and it inflated so i move the cylinders around a little bit o see if they were off but they werent. So im assuming this means my valves are sealing very well and i need to rebuild my head? aslo theres no coolat and oil mixing.

 

[91tsirasinhell]

Yes if you are getting air comming out of your intake and exhaust then you deffinatly have a problem with your valves.

 

[Mike Marnik]

thank god i finnaly nailed it down. as for the oil i was thinking i was burning it because i wasnt seeing any spots under my car anymore but thats becuase there was so many previous spots . we are moving and i was parked at the new house and sure engough when i pulle dout of the garage there was a spot of oil on the ground guess i will have to track that down.