Pressure Test Engine Block

[TeeJay]

Can anyone please advise of the maximum air pressure used to test an engine block?

I have searched, but could not find any specific answers, but did find loads of other interesting articles.

I recently completed an Ultrasound test on my block, again thanking forum member for their comments and in particular Rohan. Very relieved at the comments on the results.

As I have Leak down pressure test equipment, I purchased materials to make up some test plates and completed a test at 20 psi, to check all connections and fittings.

All are ok, so now looking for comments to complete the pressure tests.
Thanking you for any comments.

[nmauduit]

20 psi would fit the regular use for water passages but for the oil galleries I would push at least to 100psi - though if there is a crack you can probably find it at a lower pressure. Some shops test pressure at temperature, which is not easy for the enthusiast (I've recycled an old electric oven as a cheap furnace, but a block is too big for it).

[Barney]

Shouldn't you be testing with as much of the volume as possible being an incompressible fluid? (i.e. Water). Any leak would then be quicker to be apparent and also be safer?

This is not any speciality of mine just adding my two pennyworth.

[Chancer]

Yes indeed as a general safety principle especially when dealing with higher pressures, however there is little danger in air testing an engine block at 1.5 times its max operating pressure.

And yes again, the leaks are much easier to see and the pressure will drop immediately assuming all air evacuated, a tiny leak can take hours to show with air and you can never be sure that its not the coupling, valve etc.

[promotor]

I always test mine with water and usually go up to 60psi in increments.

However, 20-25psi is more than enough though as you shouldn't ever get to that much pressure as the radiator cap will blow off way before then if working correctly.

Once finished if you are leaving the block upside down to drain it out keep checking machined faces aren't being affected/surface corroded by any lingering drops of water (that is if you've got a freshly skimmed block).

[TeeJay]

Thanks gents for the very constructive comments. Again shows how the members make this a great forum.

Yes agreed that water would be the safer and a better medium to use, but for first use I needed to check all the connections from block to compressor.

but for the oil galleries I would push at least to 100psi

Thank you for the useful addition on testing the oil galleries at progressively up to 100 psi.

While using air, I decided to do an inverse Air under Water check, i.e. as the block was on the engine stand, turned it upside down and filled a cylinder with water.
This was done one cylinder at a time, draining the water from one before filling the next. Each was left for 15 mins, observing all the time for bubbles. Pleased that no bubbles were observed.

On reflection, I could have filled all four cylinders and observed for say 30 mins for bubbles, so making the total elapsed time shorter. But I have left the test plates attached so I can complete any further tests.

keep checking machined faces aren't being affected/surface corroded by any lingering drops of water

Re the comment on water and cast iron, yes when I emptied the water, all surfaces where dried off first with clean lint free cloths, warmed with a hot air gun and sprayed with engine oil.

I learned this lesson many years ago by default.

[Mike Ostrov]

Hi, Tee Jay. I have pressure checked many of my alloy Coventry Climax blocks and heads as they do have some porosity issues.

I start with 15 psi and increase in 10 psi increments to 75 psi, our max oil pressure.

All testing done on an engine stand and I use some red #3 food coloring and plain water. Any leakage, pin holes, etc are notably visible.

I also have a few 250/500 watt red heat lamps and bring the block up to close to operating temperature (75C) as possible during the testing.

For some of the blocks with minor porosity issues, I have been successful with Sodium Silicate or "Liquid Glass".

Nothing is more irritating then to drain the sump and have water come out first or wonder why the radiator fluid (plain water as it is the best liquid for heat transfer) and water wetter from Red Line level decline and the sump liquid level increase.

The same procedure is done for my Twin Cam blocks and heads.

Hope this is useful. Cheers. Mike. PS: if you wish to chat just ring me 510-232-7764 Richmond, CA (near Berkeley, across from SF).

[TeeJay]

Hi Mike.
Thank you for your comments, appreciated.

I have noted the new interesting comments re:-

All testing done on an engine stand and I use some red #3 food coloring and plain water. Any leakage, pin holes, etc are notably visible.

I also have a few 250/500 watt red heat lamps and bring the block up to close to operating temperature (75C) as possible during the testing.

All my tests have indicated that the block is sound, so I can begin to clean everything prior to re assembly.

Prior to my pressure testing I had completed a full ultrasonic Bore Wall thickness check, which also had positive results, so i was hopeful that the block would be sound.

Thanks again

So this block will not require porosity correction, but I have noted the use of Sodium Silicate for any minor porosity issues.