Pressure testing block

john in illinois

john in illinois

Well-known member
I have read the threads on pressure testing. Some recommended air pressure only and others suggested filling the block with water to pressure test so you visually see leaks. Would it be worth doing both? I am not sure which way to go.

John
 
Water is almost like GPS.......it gives an exact, visual location. Air ONLY could be hard to track down, especially if a small, slow leak in an obscure location. When ya think about it, water leaks are what you're testing for. DD
 
That makes sense. testing for cracks so water won't leak is the purpose. What pressure should I use? Seems that I read 40psi was good.

John
 
I'd think 40 PSI would be plenty, as that is about ten times the pressure that old rotten radiator is probably good for. DD
 
I have never had a problem finding the leak with a soapy water spray bottle the same as finding an AC leak.
 
If your using water you can add food coloring to the water. Letting set for a couple of days you'll find any leaks. Or you can purchase radiator leak detector and find it with a florestent light.
 
I've done a lot of pressure checking. In a machine shop setting, using an Irontite pressure check system, I tried to get 30 lb. of air. I would use a spray bottle with a soap like solution to look for bubbles. I believe this to be much more effective than using water, a slow leak with the water method will be very hard to spot.

I find that with my home made block off plate I can use 80 lb. pressure or more. I use this high pressure as a finish to the 30 lb. soapy water search.

Karl
 
The only place where a leak is hard to find is in the exh port from the valve to the exh manifold port, I would think submerging the block in a tank of water like an inner tube and putting air to block would be the best way. Walt
 
Walt Dupont--Me. said:
The only place where a leak is hard to find is in the exh port from the valve to the exh manifold port, I would think submerging the block in a tank of water like an inner tube and putting air to block would be the best way. Walt
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Or, block off the exhaust on the side of the block and fill the exhaust with water... look for bubbles. (Air pressure in block.) Have not found one with crack there yet, sure could see how it could happen, all the heat there.

Karl
 
Binx said:
Or cracking it with the wrong sized head bolt

Lonnie
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I had an engine one time that someone had put a to long head bolt in the top center head and pocked a hole right into the center exh. port. Also a friend built flathead and water came out of one of the exh ports, I don't know witch port hole but he had the head off a couple of time and couldn't find crack down in the exh port. Walt
 
40 psi and air will get it done.Go to a good machine shop and tell them you want to get your flathead pressure tested with water and see what their response is."lol".
Stop trying to re invent the wheel and use air.

R
 
40 psi air and some window cleaner will find most of them. Here are a couple I have found recently with that method. Don't forget to shoot soapy water or window cleaner in the center exhaust port and shoot a lite in there. Also all of the cylinder walls.
 

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29avee8,

do you use something under the plexglass for a seal? Great idea and pics. Thanks

Fourdy
 
I test exactly like 29AVEE8 - has worked very well for me. I use the same kit. I also use it on original Ardun heads - has found a few issues that needed to be fixed!

Dale
 
Fourdy said:
29avee8,

do you use something under the plexglass for a seal? Great idea and pics. Thanks

Fourdy
Click to expand...

I use rubber sheeting... called Marley, used as a dance floor cover in theaters- expensive and hard to buy in small quantities... about 1/16" thick. It's pretty tough.

Karl
 
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