Turbo Dodge Forums banner

Question on Pressurizing Cylinders -- Head Gasket Test

692 views 2 replies 3 participants last post by  moparracer 35 
#1 ·
Good Afternoon, All--

So this is probably a pretty dumb question with an obvious answer, but sometimes in the heat of battle with a car, obvious things can be missed!

For reasons I will not get into here at length, I wanted to check my head gasket by doing the cylinder pressurizing test, looking for bubbles to appear in the radiator fill neck.

The basic procedure -- as I took it -- was to ensure each piston, in turn, was at the top of it's compression stroke with both valves closed. Then, using a compression test hose in place of the spark plug, pressurize each cylinder and watch for bubbles to appear in the radiator fill neck.

My problem is that with high pressure air pumped in (95 psi, the max. on my compressor), the piston is pushed down until the exhaust valve opens, and all the air just escapes thru the exhaust, rather than putting the pressure against the various sealing surfaces in the combustion chamber. It's almost a simulated cylinder firing, with the crank rotation. I even tried putting the car in gear (manual) and setting the parking brake in that hopes that that would hold the crank relatively steady. It does not -- the entire drivetrain spins and the car "squats" as the parking brake attempts to hold the vehicle still.

With too low a volume of air, it just seeps past the rings and wafts out the dipstick tube.

I suspect I'm missing some really easy portion of this test that somehow allows me to pressurize the cylinder without having the car run me over in the process, and it could be as simple as getting a regulator and metering a certain PSI of air during the test.

Any thoughts? If there's a recommended PSI for this test, can someone chime in?

Thanks!
Dave
 
See less See more
#2 ·
1)I would recommend using a cylinder leak down tester so you can control and monitor actual air pressure and cylinder pressure.
2)After bringing the piston to TDC on a compression stroke place a socket with a breaker bar on the crank bolt and have a helper hold the crank in place while you pressurize the cylinder.
3)If unsure, rent a block tester from AZ, you have to buy the test fluid.
The fluid is blue and when exposed to exhaust gases it will turn yellow.
The kit comes with easy to follow directions.

CYLINDER LEAK DOWN TESTER
Super price on OTC Tools 5609 at ToolTopia.com

BLOCK TESTER
http://www.autozone.com/loan-a-tools/block-tester/oem-block-tester/391378_0_0/?checkfit=true

BLOCK TESTER FLUID
http://www.autozone.com/test-scan-a...k-tester-test-fluid/391381_0_0/?checkfit=true
 
#3 ·
I pressure check by removing the valve rockers (so the valves are always closed) and putting about 100psi of air in the cylinders. You can check head gasket, ring seal, and valves by this one method. Just be sure to loosen the radiator cap because if the head gasket leaks there can be a lot of pressure put into the cooling system.

You can remove the rockers by loosening the cam caps . Put caps back on before rotating the engine.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top