Leaking intake valve?

[john_d]

I recently purchsed a PZJ70( 1990....153,000kms). I had the oils filters, timing belt and bearing replaced. I also had the valve clearence adjusted. 9 of the 10 shims were replaced.

Since the valve clearence adjustments there is a thumping noise emanating from the air filter box. I had the valve clearence redone at the toyota garage and then rechecked by anthoter garage. The thumping noise persists. I'm told by both garages that it's a leaking intake valve.

The compression pressure after the valve clearence adjustments are as follows:

cyl 1-4- 32kg/cm2
cyl 5 - 30 kg/cm2

Min/Max compression pressure according to the engine manual for the 1PZ is between 27-37kg/cm2.

How could I confirm that it is a leaking valve without opening the engine head and what other problems could lead to the thumping noise?


Thanks.

[roscoFJ73]

A power leak down test may identify the exact point where it is leaking.

Maybe you could also pull the manifolds off ,you can sort of see the valves from there.

Or remove the air filter tube from the manifold and see if it is louder


Normally when you do a compression test,if one is a little low and you want to ascertain whether it is a valve or ring problem,you tip a teaspoon of engine oil in through the glow plug hole.
If it is a ring problem the oil will increase the compression temporarily.
If its a valve problem it will not change the figures.