[DeTomaso] Bad head gasket question ?

[Konrad.Szwab at AlconLabs.com]

Thanks for the excellent advice !
 
I will replace the thermostat with a correct one, do the coolant filling procedure and then test again, then if needed proceed with the more advanced tests. 
 
I have great hopes that the thermostat is the issue.

________________________________

From: JDeRyke at aol.com [mailto:JDeRyke at aol.com]
Sent: Wed 7/25/2007 2:25 PM
To: Szwab,Konrad,HOUSTON,IT; DeTomaso at realbig.com
Subject: Re: [DeTomaso] Bad head gasket question ?



Konrad, it sounds like your water pump might not be circulating water thru
the whole system for some reason. With the engine running, you should be able to
see water flowing past the surge tank opening with its cap off. It may even
be desirable to go to your home & garden shop & purchase a 6" long piece of
1-1/4" dia transparent plastic (Tygon) hose and patch that into a radiator line-
temporarily! Tygon won't hold up to boiling water for more than a week or so-
its not a permanent installation. Then you can watch water flowing (or not!)
into or out-of the radiator. FWIW, 190-210F degrees MAX is normal for a good
running Pantera with 34-36 degrees total ignition advance. More advance normally
= trouble. Detonation from too much advance can pop a head gasket, especially
a stock 34-year-old one!

There are a couple of checks that can be done by good tune-up shops to
isolate other leak-problems. Such a shop can attach a device to the radiator cap,
then run the engine. Any leakage past a head gasket will always introduce carbon
monoxide to the cooling water which will be detected by the machine. In
addition, a persistently leaking head gasket or cracked head/block will make the
spark plug in that cylinder rusty. There are paper strips available with which
one can approximate this test at home.

A leak-down test can also be done, in which the cylinders are one-by-one
pressurized to 100 psi with air, then isolated. After 2 minutes, the remaining
pressure in that cylinder is noted and compared to other cylinders and other
engines, to give a rating on how well the engine as a whole is sealed. Further,
while the cylinder is sitting under pressure, a mechanic will listen for air
whistling in the carb throat (bad intake valve), in the exhaust pipes (bad
exhaust valve), in the radiator tank (blown head gasket) or in the valve cover
breather (leaky rings) to further define the probable cause before you tear the
engine down.  Well worth the money. IMHO, don't waste time with a compression
check- on a 351-C in a Pantera, its very difficult to run correctly, and at best
only gives a part of the info from a leak-down test.

In the less-probable-but-possible area, look closely at your radiator. One
was found in CA in which some cause had desoldered most of the folded finning
between the tubes in this rad, and two shops that worked on the radiator had
failed to notice it. Running a finger over the finning caused a small cloud of
lead dust to appear, so don't get your nose too close. The symptoms were, the
engine worked fine until the engine got hot, then water temp went up rapidly and
it boiled. The fix was a new radiator. Good luck- J deryke
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