So the zed is still off road. Still smokes on deceleration when warm only. No smoke on startup or when engine is cold, only starts smoking after 5-10mins of running.

 

Things done:

 

Whole new PCV system. OEM pcv valves and new silicone hoses from zcentre. I did swap restrictors on to the new hoses.

Compression test and leakdown test was done with very good results.

Changed oil to 10w40 semi synthetic.

Checked the turbos both sides, no sign on oil and no side movement on the shaft at all just a slight in and out movement but i believe that is normal.

all intake hoses checked. No sign of oil in hoses higher. Slight amount of oil down near the intercooler which i cleaned out now.

Changed intercoolers.

 

All that oil that was in the previous thread photos came from a leaking power steering which is rectified now. I was surprised how two points of leak on it basically covers the whole engine.

 

What else am i missing? I just want to go and enjoy my car

Hi! I'm no mech or specialist!

But isn't smoke from exhausts burning oil or water?

Who did ur compression test if that is good then could be a problem at the top of the engine?

If water getting into the exhausts then a compression test on the coolest system should help?

I will let other zedders with better skills make comments.

Hoping u get it sorted.

Hi - try putting 300zx smoke into google https://www.google.co.uk/search?q=300zx.co.uk+smoke&sourceid=ie7&rls=com.microsoft:en-GB:IE-Address&ie=&oe=&gfe_rd=cr&ei=2PWMVf7nF4GBcKi0gLgD&gws_rd=ssl loads of threads (many from this forum) depending on what colour smoke / when it appears.

 

The original one when this forum was the right colour http://www.300zx.co.uk/tech/SmokeDiag.htm

 

What colour is the smoke?

Valve stem oil seals

Sorry for misunderstanding it is blue smoke. It is oil. Wouldnt valve seals smoke on startup? I have done a compression test myself. With a brand new tool. I did notice a bit of sludge gathering in pcv hoses after a couple months of running but i put it down to short distance driving.

I have a MX5 and this was awful at start up for smoking, diagnosed it as valve stem seals as after a few mins the smoke cleared.

 

So this may not help you personally but I put some Forte seal conditioner in and the smoking stopped completely, recommended stuff.

Smoke on decel sounds like a seal in the turbo, but it could also be a valve stem seal. My ca18det started like that and I thought it was the turbo but after a short while it was smoking on idling, cruising under no load etc, turned out to be a valve seal.

But yours sound like it's turbo related since you have good compression and your leakdown test is good.

Mine has been smoking on deceleration for a little while now, only if I allow engine braking from 2500 rpm down to 2000rpm. Again, a good compression test, and OK turbos. Ive learned to drive around it and not allow it to decelerate between those rpms. It point itself to valve stem seals.

 

Driving on track is fine because its rare the revs are ever that low.

I'd go with valve stem seals too. Why? Here's my logic. Compression is good proven by leak down and conventional, this in theory proves combustion isn't leaking or consuming oil, il come back to that. Turbo failure tends to show one of two symptoms either white/grey smoke on prolonged idle, or as you move off or blue smoke on boost combined with oil over the intake tracts.

 

Valve stem seals typically leak over night causing blue smoke for the first minute or so. However, as the oil thins and it pools in the heads it can be sucked into the combustion chamber on the down stroke.

 

Whilst you might have good combustion at TDC you may be loosing it halfway through the stroke. Or the too rings ok and the bottom rings warn. Unlikely I recon.

 

It's very worth getting hold of a vac tester. This will show you what the vacuum is doing. If you google vaccu testing you will see what the results show you. You can also test valve stem seals with a leak down tester.

 

Also bear in mind if a lot of oil went into the exhaust it may take time to clear.

Over run smoking is usually piston related,id say ring land failure,on over run the crankcase pressures rise forcing oil up past the failed rings.This wont always show on a comp test.

From my experience hold the revs at 2000rpm for about 10-15 seconds ,if it starts to smoke that's the turbo seals .that's what I've learned from the club years ago.

Sorry for misunderstanding it is blue smoke. It is oil. Wouldnt valve seals smoke on startup? I have done a compression test myself. With a brand new tool. I did notice a bit of sludge gathering in pcv hoses after a couple months of running but i put it down to short distance driving.

 

yes as oil runs down the stem overnight then combusts on start up

So if the op said

Still smokes on deceleration when warm only. No smoke on startup or when engine is cold, only starts smoking after 5-10mins of running.

that's not smoking on start-up so prob not valve stem seals? If so, what is it?

So after a long long while. The car is almost done. Sills were rotten so bad after having them cut out i could see the inside of car. Thats now fixed and car is fully resprayed. Suspension was also rotten with springs starting to break while the car was still parked. All replaced with adjustable ones. All brake calipers had atleast one piston on them siezed. Even the rear subframe had to be replaced as it was not salvageable. And for the engine.... cracked piston, worn piston rings, worn crank bearings both main and conrod ones, one turbo had to be rebuilt, leaking power steering pump, clutch even tho still gripping, was worn to half a mil from limit. Surprisingly the car still ran and actually ran well not taking the smoke into consideration. If i knew what I was walking into i would have rather shot myself in a leg. But thats another UK zed saved. Pics to follow eventually

I am still shocked even to this day that any mechanic would take the credit for a vehicle like this.

Holy molly mate well done for sticking it out time to drive her and enjoy

What a nightmare, well done for saving him\her.

I though my build was bad, well done for seeing it through.