Ken/Alabama
Well-known member
I’ve got a block I want to pressure test. So what is the preferred method? Apply air pressure and spray soap and look for bubbles or fill the block with water and apply how much air pressure to it??
Pressure Testing a Block
- Thread starter Ken/Alabama
- Start date
Pete
BANNED
Either way works ok.
You can also submerge the whole block, pressurize it and look for bubbles.
I use 25 to 30 lb. pressure.
Bored&Stroked
Well-known member
I fill with air and spray a foamy soap solution all over the thing - making dang sure to spray inside the exhaust ports (top to bottom).
Ken/Alabama
Well-known member
I’ve got an 8BA block that has cracks in the intake and exhaust valve seat on the same cylinder. The crack in the exhaust is very short and runs up to the seat . The crack in the intake runs under the seat an over to the cylinder. I removed both seats and pinned the cracks . If it passes a pressure test I’ll install new seats and sleeve that one cylinder .
Bored&Stroked
Well-known member
Hey Ken, when you put the pins in, did you coat them with any sort of sealer - like locktite stud and bearing mount? This tends to help them not leak/weep a bit.
I've found that sometimes the pins will weep just a bit - so I always start the engine and use a water-glass ceramic seal product from Moroso for the initial break in. Sometimes I do it twice just for good measure. This stuff will seal up the IronTite pins if they are weeping.
Hopefully you can save the block!
I've found that sometimes the pins will weep just a bit - so I always start the engine and use a water-glass ceramic seal product from Moroso for the initial break in. Sometimes I do it twice just for good measure. This stuff will seal up the IronTite pins if they are weeping.
Hopefully you can save the block!
rockfla
Well-known member
I fill mine with air and have a pressure gauge on my water pump plate with an on/off valve and let it sit with 50psi of air and see IF it will hold 50 psi check it in the morning. IF its down, then re pressure the block and start with the water & soap spray bottle. IF still at 50 in the morning a shout of joy and a Fess Parker skippitdy do!!!
flatford8
Well-known member
I do this same procedure, but I only wait a couple hours before I start my happy dance........Mark
GB SISSON
Well-known member
I would be a bit wary with 50 lbs in a fairly thin walled cast iron block. When I blew out that 12 ply 'roller' tire at 30 lbs, the explosion was extremely violent and caused a most unfortunate permanent hearing loss that I live with today. That's way more pressure, and I would imagine schrapnel could be involved. (Never thought I'd be one of those safety guys).
Ken/Alabama
Well-known member
Yes I did use a sealer on the pins. I used a Lock n stitch kit and it has a ceramic sealer for the pins. I’m a little afraid of 50 lbs . The cracks were in the valve seat area. The intake ran over into the cylinder . The exhaust had a very short crack that ran under the valve seat but stopped there. If it checks good I’ll sleeve that one cylinder.
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GB SISSON
Well-known member
I had a freshly pinned and sleeved cylinder in a new rebuild that I bought. It leaked on startup. I used Kand N block seal and the instructions said to pull the plug on the affected cylinder before the run. It seemed like a good idea as the sealing wasn't working against compression. I have wondered if it might be a good idea to pressurize the block with the K W in it to drive it deep into any potential leak zones. Just a thought. Oh, and the sealer worked very well for me.
petehoovie
Well-known member
KiWinUS
Well-known member
Dale do you put the water glass in with the radiator you are going to keep with engine? We found with race cars it would ruin radiator if not rinsed out immediately after draining. The would not remove/ dissipate heat near as good
flatjack9
Well-known member
The engine encounters much higher pressures during when running.
Interesting, Jack. Never thought of it that way. How much pressure do think a motor sees while running?
rockfla
Well-known member
Tim
My good friend and Flathead (and A & B motors) specialist re-builder here in town runs his up well over 100. I believe he goes to 130psi.
GB SISSON
Well-known member
Are we talking pressure in the cooling system here? Don't most radiator caps have something like a 15 lb cap? I woulda thought that was 15 PSI, but maybe the terminology is different. If we are driving around with 100 psi in our radiators, no wonder it's such a ****show when we pull the cap before it cools down.