How much blow by is normal?

[Zink57]

Hey guys. I bought my TTA about 2 1/2 years ago with 21000 miles on it. Today I have a tic over 31000 miles on it.

My question: How much blow-by is considered normal on these engines? I haven't changed my coolant since owning the car and noticed that when I took off the radiator cap...that their was a ring of brown stuff (dime size) on the inside lip of the radiator opening and some indication of brown in the colant bottle--not much..just an indication...I can still see green calour in the overflow bottle I know that some blow-by is considered normal---esp for these boosted cars, esp not changing the coolant for this long...but is this an indication that the head gasket is failing???.. The oil looks 100% clean Mobil 1.

Again...it's not much brown stuff...just a dime sized amount floating and collecting at the lip of the radiator opening. Either than that...the car runs flawlessly at stock boost 16.5 lbs.

 

[BallisticV6]

no worry

I wouldnt worry about the brown stuff...
its probably tiny amounts of oxidation from the motor.

I see this stuff in all my cars when I open the radiator caps.

 

[BoostKillsStres]

Zink, when people speak of blowby there talking about blowby into the crankcase and out the breathers not into the coolant. And usually you won't see any blowby out the breathers unless things are really bad as a functioning pcv value will pull most all blowby back into the intake for burning. Any blowby into the coolant is abnormal. The brown is probably just oxidation. You could pressure test your coolant system if you think you have a HG issue however sometimes that won't reveal small leaks.
HTH

 

[Zink57]

Thanks guys
Today I changed out the coolant with distilled water and a gallon of prestone. I also dismounted the overflow jar and did the bottle brush clean job...looking like new. I guess I have been a bit paranoid due to my wife's 94 V-6 Camaro blowing a head gasket 2 weeks ago. To make me even MORE paranoid...the prestine 95 Trans Am LT1 that we bought her the other day ran into a water pump issue (and we hadn't had the car for more than 13 hrs!!!). That's the reason for the paranoia.

Now on a car that I just bought with 54 thousand miles...I'll be replacing the expensive $$ water pump on that vehicle. Oh boy.

 

[postal]

How much blow-by is considered normal on these engines?

If the oil dip stick stays in the tube your ok to up the boost another notch or two.

Jason