alzahakar

Ok, my friend has a 86 Z31 turbo. He recently had the motor replaced after the old motor developed a rod knock. He looked into rebuilding the stock motor, but decided to just have it replaced with a low mileage JDM VG30ET as it ended up being about two grand cheaper than any rebuild he was quoted. After the swap, the exhaust smoked at startup, but quickly went away as the car was driven and warmed up. The shop ensured him it was just from the motor sitting in the shipping container and would go away with some miles. He's driven the car in excess of 150 miles since and has had the oil changed. The car has a new cat and a new exhaust. When I watched the car warm up, I noticed alot of condensation coming out of the tailpipe with the A/C off. I'm thinking the motor has a bad head gasket and it's leaking coolant into one of the cylinders, but I would like a confirmation before we go tearing the heads off the thing. Here's the video, lemme know what you guys think.

YouTube - 300zx smoking problems

**edit**
BTW, the engine runs strong, doesn't stumble or idle bad.

S14DB

You do a compression and leak down test? What year is the motor(pre 88)?

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alzahakar

Not too sure on the motor year. Know how to find out? The shop told him the compression and leakdown were good. Motor supposedly has 32k miles. It drives better than the old motor. It makes boost at like 1700rpm. It's sick.

S14DB

I wouldn't believe the shop if it's doing that. Get it tested.

Does it have a T3 or T25?

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alzahakar

Not too sure. I haven't been under the hood much. I've almost completely rewired it, but nothing mechanically. I'll have to go over to his place tomorrow and take some good underhood pics.

S14DB

It only does it when the car is warmed up or all the time?

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alzahakar

Does it from cold start up til shortly after it's warm. It does seem to take longer for it to stop smoking if you let the car sit and idle than it does if you take a short drive or rev the engine up.

alzahakar

I ordered a LDT setup. I needed it anyway. As soon as I got this car over to my place, I started checking it out. It is a 86 motor(written across the tensioner bracket in white paint marker) and indeed has a T3 turbo. Taking it to a friend's shop to get the leak down done tomorrow since my setup won't be in a for a couple of days.

alzahakar

Did the compression test. Numbers ranged from 119-138. Tested twice. I found some compression numbers on hybridz or z32.org that said they should be around 170-180 on a fresh rebuild and 150-160 on an aged engine.