blowby on new motor.

[tsitalon1]

Hey guys,
I gotta another stumper. First some history.

1990 gsx symptoms were:

Large amounts of blowby through valve cover breather. even at idle. Could not tune car out. Had 180psi across all 4 and 1-3% leakdown.

Decided to pull head. Found 7 hairline cracks in the head around sparkplug holes. Trashed head.

Decided to completely rebuild 6-bolt motor with 95 pistons, Arp head studs, Arp rod bolts, original block. Rebuilt used head. No balance shafts.

Well, 1 year later and 1500 miles on new motor I still have large amounts of blowby. You can feel large amounts of blowby through valve cover vent at idle. I can't seem to keep knock down above 14 psi. Fuel pressure not droping. Verified with fp gauge.

Here are the mods:
dsmchips ecu
720 injectors
supra TT pump rewired
Fts Afpr @ 41psi no vacumn
Maf translator
Sbr Gt-12 turbo 55lbs/min
Idrc fmic
5 deg base timing
Cold air intake in fender
evo exh manifold


The only reused parts from the old motor to the new rebuild are Pistons, block, turbo, valve cover, Intake manifold, crank and rods.


Any ideas?
James

 

[set3422]

maybe stucked PCV.

Originally posted by tsitalon1
Hey guys,
I gotta another stumper. First some history.

1990 gsx symptoms were:

Large amounts of blowby through valve cover breather. even at idle. Could not tune car out. Had 180psi across all 4 and 1-3% leakdown.

Decided to pull head. Found 7 hairline cracks in the head around sparkplug holes. Trashed head.

Decided to completely rebuild 6-bolt motor with 95 pistons, Arp head studs, Arp rod bolts, original block. Rebuilt used head. No balance shafts.

Well, 1 year later and 1500 miles on new motor I still have large amounts of blowby. You can feel large amounts of blowby through valve cover vent at idle. I can't seem to keep knock down above 14 psi. Fuel pressure not droping. Verified with fp gauge.

Here are the mods:
dsmchips ecu
720 injectors
supra TT pump rewired
Fts Afpr @ 41psi no vacumn
Maf translator
Sbr Gt-12 turbo 55lbs/min
Idrc fmic
5 deg base timing
Cold air intake in fender
evo exh manifold


The only reused parts from the old motor to the new rebuild are Pistons, block, turbo, valve cover, Intake manifold, crank and rods.


Any ideas?
James

 

[ballagsx]

I have herd a few horror stories about people rebuilding there whole engine and still getting alot of what they thought was blowby. when all it was was a $12 pcv valve that went bad.

 

[Amar1995]

Have you tried ditching the stock emissions and breathing system with the diagram used at Taboo Speed shop??? I can't remember either exactly how to do it, but I know alot of guys with more seriuos setups that had to add additional breather lines to skirt of the block. Call Shepard, extreme, ect. They should have more info for ya

 

[talon1979]

I may be wrong, but aren't you suppose to get blowby on a new motor until it has had a few thousand miles on it and things have worn in? I would also not use synthetic oil until the motor has around 5k miles on the new motor.