Will you still hold pressure with a blown head gasket?

Kinda long post...

I'm pretty sure I have a blown head gasket. A lot of whitish antifreeze smelling smoke right at start up, over heating, constint loss of antifreeze with no visible sign of leaks and the ocassional blowning of anti out of the overflow bottle. The car has sat for a week and a half, I just opened the rad. cap and it released pressure? Shouldn't there be zero pressure left in the system? By the way the oil looks golden brown, no milkshake looks, unless you need to drain the oil to get a proper reading. Which test is better to do, compression, leak down, or both? What numbers should I see on the compression test? Do I remove all the spark plugs or do I test one open port at a time? If I do a leak down, I have a compressor ,but not sure what other tools are needed and how much air I am supposed to push in there? One last question, the block is bored .30 over, what are the chances of a cracked block? Unless there is discoloration on the pistons or the values, (I'm going to have the heads checked) I'm going to reuse all the parts, which are aftermarket. Does that sound safe or are thier parts that should be replaced? Thanks for your opinions.

I'd pull all the plugs and look for wet plug(s). If your oil looks fine, it sounds like you just blew a head gasket or 2. In that case, you can replace the head gaskets to get your car running. It would be good to know why your head gasket(s) blew? Pre-detonation is a likely cause or the heads were inproperly torqued down when the engine was rebuilt. If you don't eliminate the cause, it's going to happen again.

Thanks for your reply, the engine was rebuilt in 99'. I posted awhile ago about losing the coolant over time and it was mentioned that I might have a very small hole in the head gasket. The coolant would be burned without noticing smoke or any adverse affects. When my coolant blew through my overflow tank, 2 weeks ago, I only had enough coolant to refill it once (carry two jugs, just incase.). On the way home I had to stop about four times so the car could cool down, the temp. gauge hit red about four times as well. I figure the excessive heat made the hole bigger. On a side note, right before the problem happened. I was driving down a country road and floored it past another car. At that point the car developed a low end stutter. Made it about 20 miles and the overfill tank blew and it overheated all the way home, about 10 miles.

Sounds like a head gasket

Thanks, I hope that's all it is.

I blew a head gasket at about 60K, I think who ever had the car before me may have over heated it.

The way I determined I had a blown head gasket was using a cooling system pressure tester which I borrowed from Auto Zone. Pumped up the cooling system and sure enough the pressure would not hold. I actually forced coolant into a cylinder when doing the test and the engine wold not turn over (hydro locked) when I tried to start it after. When I inched it over and got it going much white sweet smelling smoke was coming out of the exhaust. How I thought to check my system was that my coolant was going down very slowly.

If you do a search there are actually a lot of posts on the board to do with blown head gaskets,, I think that with the two types of metal (cast iron block, aluminum heads on the LT1) we have to be careful with our cooling systems in that they are kept up in proper working order.

Changing the head gaskets on an LT1 is a fairly easy job, just take you time and keep everything organized.

One of LT1 buddies had a slow internal coolant leak, when he finally decidied to pull the heads to check it out, the coolant leak had erroded a large groove in the piston forcing a complete engine rebuild. Based on that experience, I would recommend changing head gaskets at the first sign of a blown head gasket, thereby saving an entire engine rebuild.