OK, here is a couple of videos showing my smokey Zed.

 

It only happens at idle from the right hand bank BUT it don't happen every time.

 

The PC Valves were changed and have now covered over 500 miles, its de-catted and has an aftermarket exhaust. I have a set of cats to put on it to see what happens.

 

Now I'm sure turbo seals are going to be commented about, all I ask is we look outside the box at other possibilities, ones that can be fixed on my driveway. Is it possible it could be oil deposits in the intercoolers, exhaust pipes etc?

 

 

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Cheerz, Rob

Edited July 13, 201115 yr by vodkashots
Embedding video

Embedded the videos for you bud.

looks like the start of turbo oil seal failure. could try changing the PCV valves, but i think you would still have the same problem.

Cheers buddy, PCV's are new so should be ok!!!!!!!!

i take it you renewed the PCV's due to a smoking issue? could be some residue oil being burned off from the exhaust.

I did yeah, the main reason was a number of boost leaks when the engine wasn't put back in properly, caused overfuelling and a lot of smoke. Done over 700 miles on the new valves now.

 

Jeff squared a lot away but it normally only happens in traffic which is quite embarrasing LOL

Put the cats back on - bet your smoking stops!! You have really lowered the back pressure by removing them and the tub seals are passing at idle and smoking.

 

From what I understand, decatting any turbo car especially old ones like ours is risky and many start to smoke afterwards! Its a 50/50 gamble.:headvswal

that is weird matey. my car does the same and i know my issue is the turbo. BUT my smoke is blue as the turbo oil seal will allow oil to pass into the exhaust which comes out as blue smoke. i see your smoke is white??? white smoke is water being burnt and it is still possible to be a turbo as the tubbies on our cars are water cooled also but there is also the thought there now that you might have a slight head gasket issue. but giving that it only happens when you come to an idle just like me i would say its still turbo related:)

 

It's a weird one mate, done the usual checks for head gasket and all clear, Jeff didn't highlight that as a problem either. Will try and put the cats off my UK car on it and fit the mongoose exhaust I have too. See what happens.

I would definately say the turbo seal is on the way out mate I'm afraid. Mine used to do this very occaisionally from one side and then I took the car off the road for 7 months or so and the car was up on stands while I did the timing belt and a few other jobs and then when the car was put back together after the icy weather the right hand turbo now smokes all the time and the left hand one has started doing it occaisionally. Mine is the same colour smoke as yours - white, hangs around for longer than steam would and smells of burning oil. Also noticed that on mine now you can see the oil leaking out of the elbow join on the drivers side turbo and the inside of the downpipes/elbow have a black glaze from oil leaking into the exhaust and being burnt. Try putting your cats back on might stop the seals leaking for a while but just be aware that its a sign they're well on their way :)

hmm... weird, mine done the same on idle only on the left side, i had cats on so i just always assumed it was the pcv's? where the new ones genuine nissan ones?? as i was told cheaper american aftermarket ones somtimes failed from the word go, or just didnt last very long.

Put the cats back on - bet your smoking stops!! You have really lowered the back pressure by removing them and the tub seals are passing at idle and smoking.

 

From what I understand, decatting any turbo car especially old ones like ours is risky and many start to smoke afterwards! Its a 50/50 gamble.:headvswal

 

Back pressure has nothing to do with it at all. Ever.

 

Putting the cats back on would do a little to mask the smoke, but nothing to remedy the problem.

 

Scrap the cats and put the money towards the part cost of a rebuild.

Cheers for the info guys. General opinion is the worst case scenario then. If it turns out to be tubs is it a simple job to do? I.e. Can it be done with the engine still in or is it an out job?

 

As far as I know the PCV were genuine new items, they came with the car when I bought it.

 

I'm going to put the cats back on, I realise this isn't a solution but if it might mask the smoke then it's worth doing, it's pretty embarrassing, a local thought it was on fire when I was at some lights LOL.

It can be done with the engine in, there's a thread somewhere on here debating if it is better to do it the hard way with the engine in and not disturb a working engine or if it is better to take the engine out and do it...the majority of people drop the engine especially if it is the right hand turbo as it is harder to do with it in....dig the thread up and have a read

Back pressure has nothing to do with it at all. Ever.

 

Putting the cats back on would do a little to mask the smoke, but nothing to remedy the problem.

 

Scrap the cats and put the money towards the part cost of a rebuild.

 

Will agree to disagree on that then. IMO back pressure / age of car has everything to do with it.

Surely cats on, no smoke no problem. If it stops smoking, its not masking a problem cos there is no problem. These cars were designed and built with chosen tubs and a manufacture design & tested exhaust system with a known back pressure. These cars are old, but can work perfectly for years without problem until we decide to start modding. Very often this can cause problems. In cases such as exhausts/decats/turbos it often does.

Bet many folk on here over the years have decatted to then find a smoke problem.

Sure I've seen a poll showing as much.

IIRC PCV smoke is more traditionally blue anyway. I cant completely remember why I think it's to do with the temperature it burns at i.e. PCV smoke goes into the intake side and is burned in the combustion process in the cylinder. The smoke from turbo oil seals is actually from the oil burning in the exhaust so never actually enters the engine making the smoke white. I could be completely wrong about this though :blink:

http://www.300zx.co.uk/forums/showthread.php?t=73665&highlight=decat+smoke

I've also had this problem for quite some time. I've still got the cats fitted, with a mongoose quad and it's only noticeable on idle. Both Jeff & Silverbullet have seen it and both concluded (several times I might add) that it's the turbo oil seals.

 

The smoke colour fluctuates a bit gray/blue and some days nothing out the back at all, it's only if I sit in traffic for about 5mins does it start.

 

The build up is on low rpm/idle, at any other rpm its gets blown out right. In other words, the seal is leaking all the time, just less visible at higher rpm's. Mine is unnoticeable after a blast, but I can't keep blasting after sitting in traffic - think it's time to get them sorted proper.

 

It looks like the culprit is the left/px side, and I understand that could be replaced with the engine still in. Thinking about it, a car with 90k miles on it, should probably have them both done anyway right?

It looks like the culprit is the left/px side, and I understand that could be replaced with the engine still in. Thinking about it, a car with 90k miles on it, should probably have them both done anyway right?

 

Its amazing that its lasted that long already!! If i was going to have the engine out, I'd also be thinking about a rebuild too. And if I didn't get it done when the turbos were replaced, then I'd be saving for a rebuild anyway.

 

We don't have many 'my car has just passed 100,00 miles' threads on here! That's not to say its impossible to do that mileage safely, but I'd say it seems increasingly unlikely based on recent trends.

 

As you rightly mentioned though - now Jeff can dislocate his fingers relatively easily, replacing the passenger turbo only, would be the quickest and cheapest option. It would also afford you some time to plan what to do if/when the inevitable happens.

 

And yes, the glass is always half empty!

Will agree to disagree on that then. IMO back pressure / age of car has everything to do with it.

Surely cats on, no smoke no problem. If it stops smoking, its not masking a problem cos there is no problem. These cars were designed and built with chosen tubs and a manufacture design & tested exhaust system with a known back pressure. These cars are old, but can work perfectly for years without problem until we decide to start modding. Very often this can cause problems. In cases such as exhausts/decats/turbos it often does.

Bet many folk on here over the years have decatted to then find a smoke problem.

Sure I've seen a poll showing as much.

 

the problems with zed turbos that i've read on here are usually people take the cats off and the car starts to smoke so people think removing cats causes the turbos to fail, this is not the case, it is the turbos were already failing but the extra bit of back pressure from the cats was holding the seals tight therefore stopped the oil leaking/burning there are plenty of zeds out there running decat some with new turbos other with originals and have no problems with smoking,

The smoking became pronounce on mine when I had the mongoose put on, and since that's a cat back only, does that change the back pressure much as well?

My point is that if the car has cats fitted and is NOT smoking then the tubs are (in that setup) working ok and have not failed. The seals in that instance are not leaking or else you would get smoke!

Now when the car is decatted, then smoking starts, the seals on the tubs have then failed, the reduction in back pressure is the cause. Think about it, a car is running in a particular configuration for 18years and 80,000miles and then suddenly something is suddenly changed - you can understand the failure.

I'm not doubting that the seals are weak and that changing the tubs is the solution to stopping the smoke, but I'm saying if the cats are put back and the smoke stops then the seals are obviously holding again otherwise the smoke would continue. The standard back pressure is essentially supporting the seals.

Now if people would rather spend £3k in new tubs rather than popping the cats back on then fair enough.

My point is that if the car has cats fitted and is NOT smoking then the tubs are (in that setup) working ok and have not failed. The seals in that instance are not leaking or else you would get smoke!

Now when the car is decatted, then smoking starts, the seals on the tubs have then failed, the reduction in back pressure is the cause. Think about it, a car is running in a particular configuration for 18years and 80,000miles and then suddenly something is suddenly changed - you can understand the failure.

I'm not doubting that the seals are weak and that changing the tubs is the solution to stopping the smoke, but I'm saying if the cats are put back and the smoke stops then the seals are obviously holding again otherwise the smoke would continue. The standard back pressure is essentially supporting the seals.

Now if people would rather spend £3k in new tubs rather than popping the cats back on then fair enough.

 

its always been my understanding thats imply putting the cats back in doesnt cause it to stop gaain once they let loose they let loose it may mask it slightly better but they are still gone. certyainly teh back pressure ftrom the cat seems to ensure a longer life syptom wise but the issue can still occur. anyways i think this sub coversation is starting to turn into a debate a drag away from the threads purpose.

It's always been my understanding thats simply putting the cats back in doesnt cause it to stop again, once they let loose they let loose it may mask it slightly better but they are still gone.

 

Exactly.

 

And in the spirit of keping this topic on-topic, consider the possibility of a leaky valve stem seal.

IIRC PCV smoke is more traditionally blue anyway. I cant completely remember why I think it's to do with the temperature it burns at i.e. PCV smoke goes into the intake side and is burned in the combustion process in the cylinder. The smoke from turbo oil seals is actually from the oil burning in the exhaust so never actually enters the engine making the smoke white. I could be completely wrong about this though :blink:

 

Spot on bud , this is what i found , from the PCVs it gets burnt , hence blue smoke from the rear tubo seal it gets vapourised in the red hot cast elbows hence white smoke . :scared:

So by reading all the posts it would seem I have a turbo on the way out.

 

Look forward to that expense !!!!!!!!!!!!!!

 

A bit of luck with a ZX just once would be nice.