Mazda Miata Cylinder Head Pressure Test

[serchmarc]

`do you use something in the middle of the plate and the head?like a gasket or some?

[fiatnutz]

@serchmarc - There is a rubber gasket seal.

[serchmarc]

hey off topic quest.. is it true?that cylinder head and blocks from toyota yaris for example are impossible to machine or resurface, I heard a myth about that yaris modern cylinder blocks cant be over bore cause of the material and! they just can be machined buy a special laser boring machine is it true?

[fiatnutz]

@serchmarc - Don't know the answer to your specific question, but if the cylinder is 'alusil' with sufficient thickness, we can hone it oversize. If, on the other hand it's Nikasil, it will have to be replated. Using a laser is just another way of removing material, I have known about their use on the manufacturing side for over 10 years. I will check with my friends at TRD to find out what they do.

[serchmarc]

@fiatnutz hey thanks ,you reply i thought you never replay back

[massebigpoppa]

è ovvio che perde se ci pompi dentro aria da quella parte...è una valvola che chiude nel senso opposto..!!!!!

it is obvious that it loses if pumps to us within air from that part… is a valve that closes in the opposite sense.!

[KLONIME1001]

sopy water worst to use use diesle fuel....

[RoberTastic]

when taking heads to a shop just for this test should I strip the heads completely down, or can i leave everything in?

[fiatnutz]

@RoberTastic -Disassembly of the head allows us to see inside the ports.

[XploiTee]

Dont u weld the water passage now ?

[makaveli200369]

Where did you spray air to get the bubbles to show up at the valve seats?

[fiatnutz]

Air is pumped into the water passage and soapy water is sprayed onto the exterior surface. The bubbles were coming from the long-side port walls. Caused: excessive porting.

[MrGuvEuroman]

Im surprised you'll repair that head! Normally people wont touch/repair other peoples mistakes : D

[RubixDesign]

That's right !

How will you repair that head ?

[jdmfreak1992]

He said get it off the machine and weld it up .

[zapwatt]

Good, that makes me feel better.

[zapwatt]

I wonder how common is it for aluminum heads to have these leaks.

[fiatnutz]

This one had been ported by someone and they took a little too much material out of the exhaust ports. When the head got really hot, the metal could not expand enough to keep things together. The aluminum exceeded its modulas of elasticity due to insufficient wall thickness. Noramlly these heads go for ever w/o problems.

[centracing]

@fiatnutz i think you mean ultimate tensile strength not modulus of elasticity

[ls6guy]

cool