1JZ leak down test results, don't look so hot...

[Matt300ZXT]

This motor is the older twin turbo style that had been single converted and hasn't run since last March when the guy I bought it from sold his SC300. I had been trying to trade it/sell it and get something I could use more since I didn't want to tear down my daily driver SC300 when my 300ZX weekend car could use a perfectly good built motor.

Anyways, I ordered an OTC 5609 Leak Down Tester and broke out the air compressor today to get some numbers and see how this motor was. The motor is on a stand with no valve covers on it and no radiator obviously and no intake or exhaust manifold on it. These were done at 100 psi of air going into it on TDC on the compression stroke (had to stick my finger over the spark plug hole to listen for the whistle to know when it was on compression stroke) and I was able to tell if it was intake/exhaust side because I could put my hand up against or put my fingers in the intake/exhaust ports since no manifolds:

1:25% and was leaking on the intake side
2:60% and was leaking on the intake side
3:35% and was leaking on the intake side
4:35% and was leaking on the intake side
5:75% and was leaking hardcore on the exhaust side
6:22ish% and was leaking on the exhaust side

Now since I can't do a compression test to go along with these numbers, and the engine block wasn't warm so the rings would seal better, I know the numbers would vary slightly if it was in a car, but hot damn cylinders 2 and 5 look rough. Do these numbers seem indicative of rings, valves, or head gasket?

 

[hvyman]

Valves.

If it was rings air would be leaking into the crank case.

If it was hg air would be coming out of the cooling system.

 

[Matt300ZXT]

Well I don't have a radiator on it so I can't exactly check for bubbling coolant. I might do it again tomorrow and just feel for each cylinder if air is coming out of the dipstick hole as well. Also, if I have to pull the head to have it cleaned and a valve job done, I may as well just throw it on a 2jzge bottom end a local'ish guy is selling that only has 78k on it.

 

[hvyman]

You just need to feel or listen for air.

Personally I'd rather run the 1jz block. It's a lot stronger.

 

[Matt300ZXT]

You know any shops that are knowledgeable in the ways of the JZ and do stock rebuilds on 1JZ heads? No porting and polishing, just a valve job, stem seals, and cleaning the gunk off?

 

[zac101191]

The heads are easy to rebuild just put everything back where you got it. When i rebuilt mine I sent it to the shop for port and polish and I did the valves and seals myself. Just buy the toyo tool its worth every penny.

 

[f00g00]

Check your valve clearances too since there aren't any valve covers.

 

[SupraStoked]

You know any shops that are knowledgeable in the ways of the JZ and do stock rebuilds on 1JZ heads? No porting and polishing, just a valve job, stem seals, and cleaning the gunk off?

Hey Matt, I have rebuilt many heads already and have tons of already cleaned up spare parts (valves, springs, shims) for the jz heads. Let me know if your willing to work something out!