1976 K-10 runs hot down the highway

[warlok1469]

What could be pressurizing the system to make the cap vent? If it was a head gasket or a cracked head, wouldn't it do it at lower rpms too? I mean it's the difference of fine at 2800rpm and screwed at 3200 rpm. I'm really finding it hard to believe its a head or gasket. It just runs soooo good!!

If you kill a man, you're a murderer.....kill many, and you're a conquerer..... kill them all,..... YOU'RE A God!!

[DnStClr]

Have you changed the oil since the rebuld?

Don St.Clair
Culleoka Tn

[VileZambonie]

If it is lifting the 16lb spring off of the cap and venting you are building up too much pressure in the cooling system. Check for the presence of hydrocarbons at the radiator with a gas analyzer. Any decent shop will have one. Run the engine with the radiator cap off and if you are seeing HC's or Co's aboove the radiator neck you are leaking compression into the cooling system. This means bad headgasket sealing, or cracked combustion chamber etc. When you built the engine did you check your cylinder head mating surfaces with a precision straight edge?  

Edited by: VileZambonie  at: 3/10/07 8:48 am

[warlok1469]

I hoped you were wrong but I'm afraid you may be right. That is really the only way I can think of that it would pressurize like that. The oil has been changed since the rebuild and no water in it. When we rebuilt it, The block was decked and the heads were resurfaced and rebuilt with new parts. I'm hoping it's only a head gasket. I noticed that the new coolant looks kind of dirty (pretty quick too ). Ummmm.... @#%$!!!!!!

If you kill a man, you're a murderer.....kill many, and you're a conquerer..... kill them all,..... YOU'RE A God!!

[BILTUP]

Maybe try a coolant/rad flush first.  Pressure test the coolant system.

[Lt.Del]

Let us know the results.

SgtDel
aka "Andy"

www.delbridge.net

1979 Big 10 383 stroker
1991 Blu 'Burb 3/4 ton 4x4

[warlok1469]

Well........ Yesterday, I looked in my radiator and found a nice film of oil on top of the water and a nice coat of gunk (looked like green oil) on the walls. Kind of cemented the head gasket theory. So I flushed the cooling system (wow that worked great, spotless!!) and got to tearing down today. Found no obvious problem with the gasket. No cracks breaks etc. The only thing that is weird is one side looks blue and solid like the Fel Pro Permatorque and the other looks like perforated metal with flaky crap imbedded, kind of like an exhaust gasket if you know what I mean. No breaks but looks kind of junky. I cleaned up the surface and will puit new Fel pro's and hope all is well.
I'll post up after I test it out tomorrow.

If you kill a man, you're a murderer.....kill many, and you're a conquerer..... kill them all,..... YOU'RE A God!!

[VileZambonie]

Make sure the heads are not warped. If you don't have a precision straight edge run them to a machine shop and they'll check em for free for you.

[warlok1469]

OK.............. Here's what I found. The head gaskets had NO signs of any cracks or anything abnormal except they were 2 different styles. One was steel and blue like Fel Pro PT and one was an impregnated perforated core style. But no damage and both looked like they were sealing. No visual cracks/problems with the heads so I went to have the heads checked for cracks, turns out that they are 1.72 heads. (wonderful!!). So instead, I have a set of 1.94 heads that only have about 5K since rebuild so I brought them to make sure they are OK. Nope, int. valves on one are sucked into seats and sharp as a razor. So now, do I put the crap (but rebuilt and in good condition) 1.72's on and waste all the lost power, or do I sit and wait for my account (and wife) to agree on a rebuilt set of 1.94's for $300? Not to mention, I still don't know what was causing the overheating on the highway!!!

If you kill a man, you're a murderer.....kill many, and you're a conquerer..... kill them all,..... YOU'RE A God!!

[1976Scottsdale]

Did you use non-retorque gaskets and sealant on the head bolts?  Torqued to 75ish?  intake not warped?  Finally, did you have the heads magged?

[warlok1469]

Yes to all. The heads and block were mag'd, surfaced, torqued to 65'#. I'm kind of thinking the problem was one gasket was fel pro permatorque (no re-torque) and one was a impregnated perforated steel type that should have been retorqued and probably never was. However..........

This is hopefully all a moot point now. I traded a guitar and amp for a 2000 model 285hp crate 350 complete pan to intake from another friend. I know it ran perfect and I'm dropping it in tomorrow or wed. Hopefully no problems....... there's mud to be slung and rocks to crawl!!!!

If you kill a man, you're a murderer.....kill many, and you're a conquerer..... kill them all,..... YOU'RE A God!!