Pressure testing coolant sys

[WEEZER]

What's the normal length of time to pressure test a 350 Chevy Small block coolant system. I know any engine will loose some pressure but what's the guidelines, pressurize to 15 lbs for 20 minutes with a loss of 1 lb????

[RickFigure8]

An engine should not have any pressure loss of the coolant. Radiator, hoses, heater core, head gasket are all a solid seal. I think you're confusing it with a cylinder compression leakdown test, which will have leakage.

Rick

[RebelMtrspts29]

Anthony,
That sounds normal, you have to take into consideration coolant hoses, and if this is not your racecar, heater hoses and any crossover pipes for any normal street vehicle. A pressure test of 15-18psi should hold that pressure fairly well. A drop in 1 or 2 pounds with a steady hold afterwards is acceptable.
If you are trying to test head gaskets, see if you can get your hands on a hydrocarbon/coolant test kit. Or drop me a message and maybe i can help.

Brian Obiedzenski #29

[WEEZER]

Hi Brian, yes it is my race car, unfortunately two weeks ago I found water mixed with the oil, wishfully thinking, I was hoping it was condensation because it sat all winter, but probably not, I change the oil and ran it for 30 min and have been checking the oil and all seems ok so far, it is holding pressure in the coolant sys but I guess I'll find out when I beat on it at riverhead. I overheated the last race last year and had pete c. (thanks pete) check it out (sniffed the coolant, re align the belts and stuff) and all was well until two weeks ago. Hopefully the worst is it will need head gaskets.

[richardpetey]

Generally, if you really cook a chevy small block usually you crack a head......................:eek:
Hopefully, you covered your carb. throat so water couldn't run into your motor and lay on top of your pistons, run past the rings and eventually get into the crankcase...................:help:
If you think that happened pull all the spark plugs before you turn over the motor(hydrolock).....................:(
If you really want to pressure test your cooling system, run motor and bring it to operating temperature first, then pressure test while the system is still hot.......................:D
Pull out all the spark plugs and check for vapor or water leaking into your compression chambers/cylinders while the tester is still hooked up to your cooling system.................;)
Some head gasket/cracked head leaks won't show up until motor is very hot...............................:confused:
UNCLE PETEY....................:wave: :wave: :wave: :wave: :wave:

[WEEZER]

Hi Petey, thanks for the tips, the car was in my garage all winter, I did'nt think to pressure test after running it hot, thanks, the thing is, is that it runs fine, no miss or anything and like I said for the last two weeks the oil has been fine and I did'nt run it much all winter, today I ran it for 25 min in the garage and my temp gauge was at 100 degrees making me think the gauge was junk, but as soon as I shut it down (obviously) the gauge went up to about 120 making me think the gauge is working??