PSI for block testing

[V8guy]

What is the recommended PSI for pressure testing for block testing ?
Thanks

[glennpm]

My opinion, 10 or 15 psi and then if you use a pressure radiator cap, keep it at 8psi.

Do not test this with only air. You have a very dangerous "bomb" if it fails. Fill with water and then either air or water pressure or the top

[flatjack9]

I fill with water and test at 50 psi.

[flatford8]

I’ve been reading about pressure testing blocks for a few years......this is the first time I’ve seen anything about filling them with water first......Mark

[sugarmaker]

Folks,
Well, for sure I am not a expert to speak on this subject. Only stood by when my B block was air presure tested to 60 PSI at my machine shop. No water in block. That is only one ref point and no supporting data for appropriate testing methods of blocks.
Regards,
Chris

[Oldtmtech]

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Being an old tractor guy I can tell you all steam boilers are hydro tested meaning the boiler is filled with water then air pressure the reason being is because water does not compress so if you have a leak the pressure quickly drops because your air vessel is small
If you just filled it with air pressure and you have a leak it is like when you lose a hose off of your air compressor tank and the hose whips around for ever
Your air compressor tank is a certified pressure vessel your engine block is not
Kind of a crude explanation but I hope this helps
Todd

[Frank Miller]

I know a gut who stitches blocks and he tests to 30psi which is twice the pressure any pressurized system sees.
Air tanks I believe, are routinely tested with water but these are done at much higher pressures. I suppose testing with water in the block will help you identify any cracks by visible wet spots.

[Bored&Stroked]

I use air pressure at about 30 - 40 PSI. I like air as I then spray soapy water all over the block and into the ports to look for bubbles. Trust me, the bubbles will show you exactly where there is a hole, crack or other issue - and it is a very SAD experience to see them . . .

[D. Jones]

A friend gave me the basic motor I have in my truck because a guy that was going to buy it pressure tested it at 165 psi and blew a pea sized hole on the #5 intake valve-guide pocket. The fellow brought the motor back and told my friend what he had done. My friend was so mad he rolled the motor out on to the ground and left it there for about two years before he gave it to me. Fortunately I was able to engineer a repair that worked.

Pressure testing is good if not carried to extremes.

[glennpm]

Originally Posted by Oldtmtech

Being an old tractor guy I can tell you all steam boilers are hydro tested meaning the boiler is filled with water then air pressure the reason being is because water does not compress so if you have a leak the pressure quickly drops because your air vessel is small
If you just filled it with air pressure and you have a leak it is like when you lose a hose off of your air compressor tank and the hose whips around for ever
Your air compressor tank is a certified pressure vessel your engine block is not
Kind of a crude explanation but I hope this helps
Todd

Exactly correct Todd.

[Tim Ayers]

This is great info. I just bought a pressure testing kit and was wondering

[Yoyodyne]

How much pressure can you put in an early block without popping out the core plugs in the pan rail?

[Phil Gillespie]

Originally Posted by Yoyodyne

How much pressure can you put in an early block without popping out the core plugs in the pan rail?

1.5 times normal working pressure is a safe margin as I have been advised.
2 times normal working pressure would be the maximum for safety.
Phil NZ

[flatford8]

I have a pressure test kit from Speedway. I put a shutoff before the regulator, then my air fitting. I read that one of the well known contributors here (can’t remember which one) used 55lbs as his test pressure. I set my regulator at 55, shut off the supply and unhooked my airline. An hour and a half later it was still at 55lbs. Did both sides this way. As I said before, never read anything about filling the block with water first......Mark

[flatjack9]

Originally Posted by Yoyodyne

How much pressure can you put in an early block without popping out the core plugs in the pan rail?

I've never blown one with 50 psi in over 20 years.

[Frank Miller]

There are two completely different schools of thought going on here. Pressure testing steam boilers and air tanks is completely different than pressure testing a block.
A high pressure vessel like a steam boiler gets tested at extremely high pressure where a failure would be catastrophic with strictly air. Not to mention it is easy to achieve a much higher pressure with water - think hydraulic brakes - than it is with air.
A block that wil see no more than 15psi on a closed system will easily pass at 30psi.

nothing wrong with 50 either. Anything higher is completely unnecessary.