Intake Valley Pan Issues

[Michael Mahoney]

Hi all, I had a cylinder lose compression and was tearing down upper end, intake, heads, etc to check the cylinders (440-500 stroker). After removing the tunnel ram intake I noticed the valley pan had ballooned up. I have never encountered this before. Anyone have any thoughts as to what caused this. No explosions, loud bangs or anything. Just finished racing the last weekend on 1/8 mile track.

 

[440Coronet500]

Is your PCV system plugged up. It appears your engine is not venting properly. 440'

 

[4speed68rt]

Internal pressure!! Maybe it blew out the head gasket on the inside, or broke the cylinder on the inside. I have never seen this. Please let us know what you find.

 

[1968rt]

Im guessing a hole in that piston. Had it happen to me. Gas fumes get into the crankcase then bang.

 

[rbkt65]

excessive internal pressure. pcv not working as stated above. do you have a pan-o-vac kit on it? if not maybe look into it. we put the p-o-v on all our stuff and do not have any concerns like that.

 

[PurpleBeeper]

Dang...I'm betting you ignited some really rich blow by in the crank case. That "looks" like more than what a plugged PCV valve would do, even on a race motor......WOW

 

[steve340]

It does appear to be a minor explosion - I am not sure crankcase fumes pressure could do that.

 

[BSB67]

It wont take that much pressure. Several psi. The reason it looks so dramatic is because it was a tunnel ram verses a regular intake that would prevent it form looking like that.

 

[4speed68rt]

Maybe your fuel pump is leaking into the crankcase and the fumes ignited.

 

[Michael Mahoney]

Couple of things. Try to answer some of your suggestions, I have an external fuel pump, so no internal fuel leak unless thru carbs. No big explosions or loud bangs. I did find that the PCV valve could bottom out in its fixture and loose vacuum (fixed that by drilling out the bottom of the fixture so that the air flow could continue even if the PCV was pushed down).

Got the engine out and the oil pan off. Everything looks pretty uniform and oily clean. Took loose number six and slide it out, as soon as the ring lands hit air, parts started falling out of the cylinder. Piston lands are shot, all the rings broke. On the bright side, the bearings look good, connecting rods are good as well. No deep marks in the cylinder. So we will see. Now I have to find a machine shop.

 

[RemCharger]

Are those KB pistons?

 

[steve340]

Given the condition of that piston there would have been a lot of blow-by pressure.
Good luck with repairs.
Thanks for posting that

 

[Michael Mahoney]

Are those KB pistons?

Ross custom pistons.