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How To Fluid Test a 4G63 Cylinder Head


Proven Member
Jul 1, 2009
Pensacola, Florida
How to fluid test a 4G63 Head

This is a simple and quick way to check for seat and valve seal.

First clean the head by the method of your choosing.

Remove the cams and fLOLlowers so the valves are fully closed.

Once the head is cleaned, blow the runners out with compressed air to remove any carbon, oil or crud that can give a "false" seal.

Next lay the head with the runners up, and the valves facing you. I am starting on the intake side.

Now get a jug of fluid, I am using water.

Now here is the hard part..... Pour the fluid in the runners, one at a time.

Now that all four runners are filled with fluid.

Now look at the valves in the combustion chamber, no fluid. All is dry. This side is good and the intakes are sealed well.

Now flip the head over, and fill the exhaust runners.

Take note that you will have to plug the EGR passage so the fluid will stay in the runner.

Look at the fluid pour out past the valve, there is an issue that needs to be looked into. It is a bent valve.

Notice how the runner on the left of the divider still holds fluid, but the one on the right is empty. This is cylinder #4. If the left side will not hold fluid, check to make sure you have blocked off the EGR passage.

If you used water, blow the excessive water out with compressed air.

Then with WD-40

Spray WD-40 in the runners to inhibit rust formation on the valve stems.

Now at this point any valve sealing issues can be addressed and fixed.
Last edited by a moderator:

ontario AWD

Proven Member
May 27, 2008
North Bay, ON_Canada
My dad taught me that trick back in the day.On my small engines,i usually turn the head upside down and fill the cc with wd-40 and watch to see if it leaks out.:thumb:


Proven Member
Jul 1, 2009
Pensacola, Florida
It is not really a trick, but a common pratice in machine shops and repair shops.


Probationary Member
Jan 13, 2011
Evanston, Wyoming
dang very helpful i did this process i was told by my friend to do this but i didnt use water i used gasoline, i now realize all valves are bent they all leaked on intake and exhaust side but a few. My suoer tech kit is wothless now. i was not told to clean the inside of the head so i didnt do that step would not cleaning head before checking the valves possibly give a false reading? I installed head and realized my oil pump siezed up and it sheaded the timing belt.


Proven Member
Apr 8, 2010
Atlanta, Georgia
I just tried doing this with water. After the first a few minutes, i started seeing some droplets forming. However, i let the water sit there for some time and didn't really notice the fluid level diminishing in the runners.

Does this sound acceptable?

Thank you


Proven Member
Apr 19, 2011
miami, Florida
Next time you are going to check by taking the valve cover off rotate the engine by hand and observe if all the valves are coming up to the same height or if any springs are lagging behind.

Looks like you will have bent valves, pistons dont look too bad, just clean out the high spots.

I use alcohol for those test mentioned.

Cheapest insurance new rod and mains bearings if you have gone this far
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