I did the pressure test today. Filled the engine with water, closed the
cooling system and eliminated manifolds from the loop. Then applied 20 psi
pressure to the cooling system (water jacket). It held easily for 20 min. no
change (twice). The pressure dropped sligthly when I was cranking the engine
with plugs out while keeping cooling sys. pressurized.. Spoke with a local
rebuilder that suggested the above while canking the engine and watching for
water appearing in cylinders (coming out of plug sockets), crankcase or
elsewhere. Drained the oil and watched for water dripping from underneath.
Nada. Filled both manifolds (with raisers) with water to look for leaks.
None. I guess that I got to check them under pressure.
In summary, no obvious leaks. There may be some (tiny) there that might show
if the engine is warm. That would be my next step I guess. As advised here I
built a tool for pressure testing using a piece of plastic 3/4 inch pipe,
plastic screw-on cap and a tire valve that I installed in a cap. Worked
great. Used a small compressor (tire type) to apply pressure and since its
gauge was constanlty showing pressure changes I knew exactly what's
happening. Despite that there's no pregress locating the leak. Any ideas?


"rmcinnis" wrote in message
...

"basskisser" wrote in message


Why? All you need is a non-relieving cap with 1/4" nipple, available
at NAPA for less than $10, a low pressure gauge, and your air
compressor, even the little tiny ones will work.

I am not sure how you would make that tool. It wouldn't be hard to drill a
clearance hole in the outer bracket of the radiator cap. The pipe, as you
describe, would probably fit down the center of the pressure relief spring
okay. What I don't see is how you fasten the pipe to the seal surface
without destroying the sealing surface and/or gasket and make sure that it
doesn't become a source of leaks.

Since he would need to be jury-rigging the closed loop system he could
just
simply not use a radiator cap. Simply close the system with a pair of
hose
barbs fitted into regular old pipe. With a Tee and some reducer bushings
you could arrange for a tire valve and pressure guage with ease.

Just be real careful with the pressure if you don't have the pressure
relief
of the radiator cap. I would recommend a hand pump instead of an air
compressor.

Rod