Pressure testing a head.

[ChrisM]

How do I DIY pressure test a head?

Does anyone have any pictures, as I have never seen this done? I’m quite happy to machine up a few bits and pieces.

Cheers - Chris.

[Hipwell]

You need a slab of Ali the same size or bigger than the head gasket ideally 3/4” thick, I guess 1/2” would easily do on a mini size head. bore the head stud holes and combustion chambers and make a rubber head gasket. You need some nuts and bolts To sandwich it all together, head studs and the right nuts would do.

Then you need to blank off any other coolant outlets with some thick Ali blanking plates and gaskets, or modify a stat housing and heater valve By welding or similar. Ideally you have a pressure gauge on one outlet maybe from a cheap tyre inflater dropped and tapped in and a shraeder valve on the other. A 5/8 unf bolt or old temp sender to blank that port is also needed and something to blank the external bypass if fitted. A foot pump or bike tyre pump can be used to pressure up the head. Some test at 2bar, company I use put 45psi on there. Some then have a big water vat to sink the head into to check for bubbles and some have a spray bottle with soapy water to spray over suspect areas.

You can also open up other areas of the aluminium test plate that maybe suspect, brass plugs etc in the head face, oil drilling’s etc.

There maybe better DIY solutions, but this is how some pros do it. It’s also possible to heat the heat casting and fill with hot water, you need to be careful not to hydraulic lock the air pump your using.

[ChrisM]

Perfect.

Thanks - I will have a rummage and see what I can rustle up.

Chris.

[1071bob]

Something like this, will need nuts and bolts to clamp it to the head etc.

[CooperTune]

A bore and honing stress plate will do nicely. I might suggest being careful with air pressure or could be wearing a freeze plug for a belly button. Steve (CTR)

[NicholasUpton]

Something like this, will need nuts and bolts to clamp it to the head etc.

This setup looks similar to the one a friends shop uses for keeping block at a spec temp during machining.

[ChrisM]

Great stuff guys.
Point taken about pressure and safety Steve.

[CooperTune]

Brings to mind a story from my Machine shop days. A fellow autocross/ Solo 2 competitor showed at the shop with his 240 Z block. In the bed of the truck was the stripped block with a stress plate and set up with a plate front and a plug in a rear freeze plug . He had a hose going to the front and one out the rear attached to a small hot water heater with a fish tank pump. He even included a temp gauge and had adjusted the heater to his desired temp. The request was we place the block in the Rottler plug in the heater and bring the system up to temp and then bore the block in firing order. Then move the assembly to the CK10 and complete once again in firing order.

At the machine shop we had a pressure testing bench with steel plates with rubber pads glued to one side, matching most 4, 6, V6, and V8 heads. Hard to believe I retired 20 years ago this coming spring. Steve (CTR)

[IanD1965]

I have a set up made years ago. I’ll dig it out and take some images. If anyone wants to borrow, just ask.
Ian

[ChrisM]

Very generous offer Ian.

On inspection I think it was thankfully a dodgy head gasket. There is a clear blow between the centre bores on the underside.

Will certainly make up a plate to check a few other heads in the future.

Cheers - Chris.