Head gasket replacement....

markinnaples · #1 09-21-2017, 02:32 PM

OK, so it's been many, many years since I've done any major engine work on a car, but I'm going to attempt to fix a blown head gasket on my Camaro. The engine is a 1969 DZ302 with 13:1 compression, camel hump heads, tunnel ram, etc. but when it comes down to it, it's a pretty basic engine with no accessories.

I just plan on pulling the one head and replacing the gasket but I was wondering whether there are specific caveats or pitfalls I need to look out for? Or, are there any special tips or tricks that you can give me that will help? I just want to make sure I'm aware of any special things that I need to consider besides the normal pulling of the head and torqueing it down to factory specs, etc. I appreciate it.

VintageMusclecar · #2 09-21-2017, 03:53 PM

There's a reason it blew--you need to figure out what that reason is before putting it back together so it doesn't do it again.

Check the block deck surface for flatness as well as the head surface. Do NOT use a Roloc wheel to clean off old gasket residue, use a wire brush and a gasket scraper.

If the gasket blew between cylinders, look for damage between the bores on the block and the chambers on the head--the hot gasses can literally torch away material leaving a trough behind.

Replace the head bolts with quality replacements.

Measure the old head gasket thickness or look for a part number so you can replace it with the same part--or at least one with the same thickness. Composite gaskets go on dry. Steel shims go on after coating both sides with Copper Coat and letting it tack up a bit.

While it's apart, run a thread chaser through the head bolt holes, and the intake & exhaust manifold bolt holes to make reassembly easier. If you have to remove the rocker studs, don't forget to coat the threads with sealer before reinstalling.

markinnaples · #3 09-21-2017, 06:06 PM

Thank you. I think it may have blown due to having to use crap gas quite a few times when I couldn't make it to the engine shop but I will definitely check all of those things you've said.

**earntaz** · #4 09-21-2017, 08:05 PM

Mark -- if it were mine (but it ain't) ... I'd pull both heads and work over both sides. If one head gasket failed there is a good chance the other isn't far behind ... just my .02 worth ... TAZ

**SuperNovaSS** · #5 09-21-2017, 09:09 PM

Its a straight forward job. Just make sure everything is clean and true before reassembly.

Eric,

Why no Roloc disc on iron parts?

Jason

VintageMusclecar · #6 09-21-2017, 09:42 PM

I've seen more parts destroyed by those discs (--including iron and steel--) than I can begin to count--plus, the material that comes off them is abrasive, and if it finds its way into the engine it will wreak all sorts of havoc.

**JKZ27** · #7 09-22-2017, 01:52 AM

Quote:

Originally Posted by VintageMusclecar

I've seen more parts destroyed by those discs (--including iron and steel--) than I can begin to count--plus, the material that comes off them is abrasive, and if it finds its way into the engine it will wreak all sorts of havoc.

X2!!

**SuperNovaSS** · #8 09-22-2017, 02:25 AM

That's what I figured you were getting at. I think the gasket removing ones are a good products for removing the residue once the majority of the gasket material is removed. Any tool in the wrong hands can be problematic. Sticking with a gasket scraper is good advice.

Jason

**RPOLS3** · #9 09-22-2017, 01:46 PM

Also - maybe seems obvious - but make sure you change the oil when you are done before you start it back up.

VintageMusclecar · #10 09-22-2017, 02:25 PM

Quote:

Originally Posted by markinnaples

Thank you. I think it may have blown due to having to use crap gas quite a few times when I couldn't make it to the engine shop but I will definitely check all of those things you've said.

Re: the crap gas issue...

Be sure to carefully inspect the top of the pistons for any visible cracks or flaws, esp. around the outer perimeter above the top ring. Detonation/pre-ignition will often crack the piston resulting in catastrophic engine failure. Been there, done that--twice.

(not my pic)