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blown head gasket

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waltesefalcon

waltesefalcon

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Ok here's the deal. I'm stumped. My 1500 Spitfire blew a head gasket a week or so ago because the new thermostat didn't open and it overheated badly. I pulled all the tricks I could out of my sleeve but it still overheated to dangerous levels. Anyway I get the new head gasket on it today. Last week I took the thermostat out and took the radiator in to the shop to have it checked out, just to make sure my whole cooling system was in good shape. Radiator passed with flying colours, and it has about a four month old water pump in it. So I figure everything is hunky dory and take it out for a drive this evening to see how it runs, and it runs great no problems. I get confident and run it up to 3000 rpms no problems temp holding steady and running great. So I come home and pulling a hill about 1/4 from the hours and pulling about 2500 rpms the head gasket blows, as confirmed by the large plume of steam coming out of my tail pipe. So I say a few expletives and coast it into the drive after it dies. Anyone else have this happen to them before? I have decided to go ahead and pull the motor now for a rebuild instead of waiting till the fall like I was gonning to do. But I am still not sure about the cause of this second gasket blowing. Any advice would be nice.
 
Walter, after you cooked the first one, did you check the head for warpage? And, I'm assuming that you did reinstall the thermostat.
When I change head gaskets on mine, I liberally use the spray on Coppercoat sealer, and have had no problems on the 13.9:1 compression race engine.
Jeff /ubbthreads/images/graemlins/hammer.gif
 
Aloha Walter,

I think Jeff is right, the severe overheating may have warped the head. I just finish replacing some valves in my MG, one of the checks the shop did was make sure the head was flat. A machine shop should be able to check the head and skim it if necessary to give you a nice flat surface. The copper coat gasket sealer is also good, I like the spray because you don't have to worry about lumps. Don't forget to follow the shop manual in tightening the head nuts in the proper sequence. Also you may want to check that the head studs are not stretched. A quick test is that you should be able to run a nut with your fingers easily all the way down the threads. Good luck.

Safety Fast,
Dave
 
Good advice above.

The only thing I'll add is to check the top of the block for straightness too.....mine was off a bit when I rebuilt it last Winter, so I had to skim it a bit (and I "skimmed" about 0.100" off the head /ubbthreads/images/graemlins/devilgrin.gif ).

When I run my car on the road, I use a 160 F themostat...even in the cooler weather, it seems OK.

For racing, I use a homemade "blanking plate" (an old themostat with the guts removed.....really, just a flat plate with the right size hole in it). Warmup is a bit slow, but no moving parts to fail!

Don't forget to check your lower radiator hose. It runs under suction and if it's old and soft, it can suck closed (causing overheating).

G'luck!
 
Jeff,
I don't know all that much about 1500's. Just how hot does it have to get to cause gasket leaks & why does the head warp so easily? Thanks,
D
 
Dave, I really don't know that the 1500 is any worse than anything else regarding head warpage. My comment was prompted by the fact that the gasket blew once, the engine overheated, and the replacement gasket blew shortly afterward.
My 1500 experience is limited to the race engines, where I typically have about .300" taken off the head to get a decent chamber volume. These will warp if the temp gets much above 250F. Of course a lot depends on compression pressures, etc. in this application, and doesn't necessarily correlate with the normal street usage.
When I was running compression ratios in excess of 16:1, I would blow a solid copper gasket until I resorted to putting a steel "O" ring in the block around each cylinder.
Generally considered beyond normal street stuff.
If you want to expand on this, PM me.
Thank you sir.
Jeff
 
Jeff,

The head was fine when I checked it, as was the lower radiator hose. And no I did not put the thermostat back in it. I figure since it gets kinda warm here in okieland, typical summer getting above 110 on some days, that in the summer running it minus the thermostat would be a plus. I hadn't thought about checking the block though thanks for the advice there Nial, I've never had a warped block on anything I built or worked on.
 
Oh yeah where are you guys getting the copper head gaskets?
 
Walter, running without a thermostat will just about guarantee you will overheat. Without the stat, the water will take the path of least resistance, and pretty much bypass all the places it needs to go. If you don't run a stat, you should run a blanking plate, or sleeve, that will provide enough resistance to allow pressure to build and coolant to flow through the entire system. In Okieville, I would be running a 160 stat in the summer, just like I do here or in California. A lower temp rating for the summer stat means that coolant will start flowing through the radiator earlier, so not as much heat has to be dissipated.
What are you running for coolant, a 50/50 mix of anti-freeze and water?
You may just have been a victim of circumstances, and there may be no damage done at all.
One thing I would do immediately though, is drain the oil. Anti freeze on a bearing will eat the bearing surface away quickly.
Incidentally, I get my solid copper head gaskets from "The Gasket Works". in Duarte, Ca. 818 358 1616. Mordy Dunst is the gentleman that runs the place. He races a TR4.
Those are pretty much a very high compression, competition only item though. At 13.9:1, I still run a stock gasket, liberally covered with "Coppercoat" sealant. A lot cheaper that a $130.00 solid copper one.
Jeff
 
Jeff,

Its okieland not okieville. Thanks for the advice. I am still going to rebuild the engine I did manage to bugger up my rings but I think that happened when the thermostat first got stuck anway it went well over the 250 mark that time. So its a good ole rebuild which is cool I wanted to replace my clutch anyway and slap a kent cam into it. probably shave .100" off the head and drop in some 9 to 1 flat top pistons. I was going to wait till the fall to do this but oh well why put off till tomarrow what you can do today right?

Cheers, /ubbthreads/images/graemlins/thirsty.gif /ubbthreads/images/graemlins/driving.gif
Walter

P.S. $130 for a gasket I think I just had a heart attack. copper coat it is for me.
 
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