Test valves for leakage?

[Guest]

I know I've seen it on here, but now I can't find it.

At least twice I have heard of the dirty way of checking the valve clearance by flipping the head over and filling it with XXXXX liquid (kerosene?) and then see if any leaks through/around the valve.

Any thoughts on this?

Ultimately I'm going to put it on and check clearances and compression, but want to know if something is way off before I button it all back up, find soft compression, take it all back down.......etc.

[Brendan W]

I know I've seen it on here, but now I can't find it.

At least twice I have heard of the dirty way of checking the valve clearance by flipping the head over and filling it with XXXXX liquid (kerosene?) and then see if any leaks through/around the valve.

Any thoughts on this?

Ultimately I'm going to put it on and check clearances and compression, but want to know if something is way off before I button it all back up, find soft compression, take it all back down.......etc.

Nothing ' dirty' about it. It works. I would use petrol (gas - how can you guys over there call a liquid, gas) as thinner fluids find smaller holes.
Being pedantic now but you're not checking clearances, you're checking valve seat integrity.

[eil]

You can use just about anything but kerosene and gas (short for gasoline :P) are popular choices.

[Jedz123]

Yeah gas is short for gasoline...

I know my shop performed a blow by test using compressed air... It was expensive ($350) but they wanted to makes sure the valve seats weren't bad...

I say just check the valve clearence and run it...

[DimitriT]

I've done it with kerosene and it does find leaks. Just put it in a big pan or basin and keep it level.
Gas works too but it evaporates so may not give an accurate indication.
Give it time to work. I left it overnight. I then gave the seats a light lapping and repeated the test.
Much better results after the lapping.