On Sun, 19 Apr 2015 00:19:07 -0700, "Snuffy \"Hub Cap\" McKinney"
wrote:

wrote in message ...
On Sat, 18 Apr 2015 18:40:29 -0700 (PDT), bob haller
wrote:

On Saturday, April 18, 2015 at 9:03:19 PM UTC-4, Ashton Crusher wrote:
On Fri, 17 Apr 2015 22:50:00 -0700, "Snuffy \"Hub Cap\" McKinney"
wrote:

This is more of a Sherlock Holmes type mystery than a practical matter.

Neighbor has a leaking head gasket in his Buick bad enough so that the engine runs rough all the time. Watch does with it is not my concern.

When driving it runs cool. When sitting idling the temp increases rapidly. If he puts in neutral and revs the engine, he says it drops to normal quickly. Radiator, fan clutch, thermostat, water pump all checked out and working normally.

I'm wondering .... when the engine is turning slowly, if the the coolant pressure drops, which could be letting more exhaust leak into the coolant and raise the temp? Says when the temp goes high, he can smell antifreeze, probably blowing out the overflow.

What he should do is go buy some "block seal" in a can and follow the
instructions exactly. That stuff sometimes actually works. The worst
that can happen is you are out the $30 for the stuff. At this point
he has nothing to lose but the $30.

but it will clog the heater.........
I wouldn't say it WILL clog the heater. There is a chance it will
plug the heater. For the uber-cautious, it's generally not hard to
bypass the heater core and even the heater valve untill the leak is
sealed.

Thanks guys. How long would you expect it to take to know if block seal works?

Engine & heads are cast iron.
Generally it works in less than half an hour or it doesn't work.
Still hjave not told us what year/model/engine. Cast iron heads and
block pretty much means it is an old technology engine?? You might
have a cracked head instead of a bad gasket, but the engine sealer can
address that too in most cases.