Smoking exhaust - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

alzahakar · 12-31-2008, 10:39 PM

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*** · 12-31-2008, 10:57 PM

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

alzahakar · 12-31-2008, 11:02 PM

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*** · 12-31-2008, 11:09 PM

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

Does it have a T3 or T25?

alzahakar · 01-01-2009, 12:25 AM

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*** · 01-01-2009, 12:42 AM

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

alzahakar · 01-01-2009, 12:54 AM

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 · 01-02-2009, 01:53 AM

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 · 01-03-2009, 03:36 PM

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.

12-31-2008, 10:39 PM	#1
alzahakar Zilvia Member Join Date: Aug 2008 Location: San Antonio, TX Age: 42 Posts: 196 Trader Rating: (4) Feedback Score: 4 reviews	Smoking exhaust 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. Last edited by alzahakar; 12-31-2008 at 10:45 PM.. Reason: more info

12-31-2008, 10:57 PM	#2
*S14DB* AFC #1 Join Date: Oct 2003 Location: 昨晩あなたのお母さんの家 Posts: 20,181 Trader Rating: (3) Feedback Score: 3 reviews	You do a compression and leak down test? What year is the motor(pre 88)? __________________ Comments should be taken as Opinions not as Statements of Fact

12-31-2008, 11:09 PM	#4
*S14DB* AFC #1 Join Date: Oct 2003 Location: 昨晩あなたのお母さんの家 Posts: 20,181 Trader Rating: (3) Feedback Score: 3 reviews	I wouldn't believe the shop if it's doing that. Get it tested. Does it have a T3 or T25? __________________ Comments should be taken as Opinions not as Statements of Fact

01-01-2009, 12:42 AM	#6
*S14DB* AFC #1 Join Date: Oct 2003 Location: 昨晩あなたのお母さんの家 Posts: 20,181 Trader Rating: (3) Feedback Score: 3 reviews	It only does it when the car is warmed up or all the time? __________________ Comments should be taken as Opinions not as Statements of Fact

12-31-2008, 11:02 PM	#3
alzahakar Zilvia Member Join Date: Aug 2008 Location: San Antonio, TX Age: 42 Posts: 196 Trader Rating: (4) Feedback Score: 4 reviews	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.

01-01-2009, 12:25 AM	#5
alzahakar Zilvia Member Join Date: Aug 2008 Location: San Antonio, TX Age: 42 Posts: 196 Trader Rating: (4) Feedback Score: 4 reviews	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.

01-01-2009, 12:54 AM	#7
alzahakar Zilvia Member Join Date: Aug 2008 Location: San Antonio, TX Age: 42 Posts: 196 Trader Rating: (4) Feedback Score: 4 reviews	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.

01-02-2009, 01:53 AM	#8
alzahakar Zilvia Member Join Date: Aug 2008 Location: San Antonio, TX Age: 42 Posts: 196 Trader Rating: (4) Feedback Score: 4 reviews	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.

01-03-2009, 03:36 PM	#9
alzahakar Zilvia Member Join Date: Aug 2008 Location: San Antonio, TX Age: 42 Posts: 196 Trader Rating: (4) Feedback Score: 4 reviews	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.