Blown Head Gasket....or not?

[dapiper]

Late fall took my bud out for a ride at moderate boost 16 psig, made a few sustained 5-10 sec at full boost in high gear, nothing unusual or extreme. After exiting freeway did a run through the gears and then thar she blows with a plume of steam under the hood after stopping at light. Drove 2 mi home and observed coolant dripping out near rear of block on manif side. Lost half of coolant, but did not begin to overheat yet.

 

Just pulled head and gasket was intact with o-ring pinch grooves in fire rings all preserved. Did notice some fiber loss on head side of gasket near galleys around all cyl, especially #5, and 6. Could have been erosion. There was a trench groove from one galley on #6 near the head bolt on the manif side to atmos. 50% Coolant was less than year old.

 

Also upon cleaning head observed some pitting around the galleys outlined by the gasket punched holes, i.e wherever head surface was exposed to coolant. This pitting is noticably more extensive than I ever observed.

 

Perhaps coolant became acidic due to exposure to combustion gases. I did observe what appeared to be slight foaming at the rad cap, but no loss of coolant. This over protacted period of several months. Also noticed variation of AFR during repeated runs to and from work, where it would run lean 0.7 AFR. Perhaps this was the steam offsetting the AFR. Using Innovate LM-1. Did notice steam in exh but only during warm up. #5 head cyl did clean up easier, perhaps due to steam cleaning. Will check pH of coolant.

 

Although head surface pitted along plug side galleys, why did it blow back at #5 or 6? Could be where greatest coolant back press exists?

 

I suspect the head gasket, the current OEM with graphite composite, since first time used. It appears to be flakey, literally. Can anyone supply the orig OEM asbestos laminate gasket?

 

Think I can reuse this head or is it the pits, literally?

 

Will this gasket benifit from coatings like Hi-Tack, Copper Coat or Hylomar?

 

I can post pix if you tell me how.

 

What say?

[Clifton]

I wouldn't use Hi-tack, ect on a fiber gasket. You are having a sealing issue with combustion pressure and a coating won't help that. I would run a MLS gasket. On engines prone to blowing head gaskets (7m's), they are the only thing that works. Even graphite gaskets with studs don't hold very long on them.

[BRAAP]

Pics would be very helpful.

 

Here is a “how to post pics on

HybridZ” thread.

 

Click ME for "How to post pics on HybridZ"