Leak Down Test

[Don Dada]

Hi guys

I couldn't find anyone locally to do a leak down test for me so i went ahead and bought a tester to it myself.

Couple things i want to verify tho....

I know the whole process of finding tdc using a piston stopper and whatever but....

Is there anyway of telling if the engine is on its compression stroke??? and if it is not, its just a matter of turning the crank 360* to get it there right???

Am i correct in saying that if it is on tdc on the exhaust stroke i should hear some leakage through the intake as well because the intake valve will be slightly opened already???

Also will there be any corresponding pistons that will also be at tdc on the comp stroke at the same time to make my life any easier?

[blind_elk]

Yes, if a particular cylinder is at TDC on the exhaust stroke, then air pressure will be leaking out the inlet valve as well (except perhaps R32 GT-R, which doesn't have any valve overlap).

The following pairs will be at TDC together, one on compression, one on exhaust:

1,6

2,5

3,4

[DVS JEZ]

take off rocker covers and compression stroke is when the cam lobes are not pushing on the valves, so only base circle will be touching

[Don Dada]

Yeah....nice way to know, but the less work to do the better for me!

Its a R33 Rb26 btw

[blind_elk]

On all GT-R RB26s, on the exhaust stroke, exhaust valve is actually closed at TDC, and inlet valve is just starting to open. So if you are at TDC ex, then pressure will be released through the inlet only.

[rob82]

Best way to find it is to cut a 30cm length of fuel hose and put it down over the spark plug hole and hold your finger over the end while turning over once it starts to pressurise you know its on compression - keep going until you get to TDC on the balancer.

[White GTS-T]

And then just do the test in the firing order 1-5-3-6-2-4.