Now that i have my heater bypassed, will my AC still work?

 

Want to put it through its MOT before i replace the turbos so that i know about anything else that is wrong with it. With the smoke issues that it has because of the turbos it won't pass but turning on the AC raises the idle enough to deal with it most of the time.

 

Just don't want to fill the garage up with fumes.

The idle will still rise, it's governed by the ECU.

 

I've completely removed my aircon, relay & fuse too. When the switch is pressed, the AC flag is still activated and the idle speed increases as normal :)

Yup, mines removed and it does exactly as noz said. My tubs smoke a touch, I believe, but is disappears completly with the ac on. Do you still have your cats? And are your breathers all in good order etc. have a good read of the thread I put up yesterday.

 

- - - Updated - - -

 

Yup, mines removed and it does exactly as noz said. My tubs smoke a touch, I believe, but is disappears completly with the ac on. Do you still have your cats? And are your breathers all in good order etc. have a good read of the thread I put up yesterday.

 

Yup, mines removed and it does exactly as noz said. My tubs smoke a touch, I believe, but is disappears completly with the ac on. Do you still have your cats? And are your breathers all in good order etc. have a good read of the thread I put up yesterday.

 

I might have a temporary solution for your smoking issues. Is it only on idle, and are your breathers in the standard configuration?

 

Might work for you Cyberbean as well :)

Edited March 18, 201312 yr by Noz

Yes...go on lol, im currently considering venting the crankcase to astmosphere to relieve backpressure.

OK, grab a couple of one-way valves (found in most cars in the hose between brake servo & inlet manifold). These then need to be placed in the breather pipes from the cam covers to the turbo inlet 'elephant trunk'.

 

This allows the crankase pressure to still be vented (essential) but will prevent vacuum at idle causing low pressure in the turbo, which in conjunction with the reduced back pressure from the decats can cause oil to seep past the rear turbo seal. To check which way the valves flow, simply blow through them. It should be impossible to suck air through in the opposite direction. Make sure air can flow from cam covers to elephant trunk.

 

Fitting performance exhaust systems & decats is well-known to cause previously non-smoky turbos to smoke. This is just a trade-off for increased performance if your turbos aren't particularly new or in top shape. The same can occur if you leave a turbocharged car idling for very long periods which also causes low pressure in the turbo.

 

I've personally never had to use the One Way Valve trick, whenever I've had a turbo go down it's just an excuse to fit something much bigger :D

 

Give it a go and see if it helps at all. Bear in mind that it's a band-aid fix for tired turbos. The 200sx suffers from this when fitting aftermarket systems, and the OWV trick works well on those cars.

Yes...go on lol, im currently considering venting the crankcase to astmosphere to relieve backpressure.

 

ive been stressing this point for a long time...1st mod i carried out was to delete the PCV,s and have 4 points of exit via breathers on cam covers..all going to astmosphere with no drips of oil or condensation whatsoever.Gravity feed from tub oil return and its a big no no iff you have the slightest hint of positive crankcase pressure. One of the best mods ive carried out...

ive been stressing this point for a long time...1st mod i carried out was to delete the PCV,s and have 4 points of exit via breathers on cam covers..all going to astmosphere with no drips of oil or condensation whatsoever.Gravity feed from tub oil return and its a big no no iff you have the slightest hint of positive crankcase pressure. One of the best mods ive carried out...

 

Probably why I have never had the issue on any of my turbocharged cars, exactly what I do the moment I get a car. Who wants oily fumes being drawn through the intake? It's an emissions based configuration designed to save the world at the expense of your car's intake tract & octane number. The one pro about the system is that there is vacuum to help scavenge crankcase pressure on idle & overrun, but if you must, everything should be routed through a sealed catch can set up (separator) to prevent anything other than fuel & uncontaminated air being injested by the engine.

Probably why I have never had the issue on any of my turbocharged cars, exactly what I do the moment I get a car. Who wants oily fumes being drawn through the intake? It's an emissions based configuration designed to save the world at the expense of your car's intake tract & octane number. The one pro about the system is that there is vacuum to help scavenge crankcase pressure on idle & overrun, but if you must, everything should be routed through a sealed catch can set up (separator) to prevent anything other than fuel & uncontaminated air being injested by the engine.

 

I have this on every car i own Noel..LOL...goes back to my big bore biking days with monster GS and GSXR motors and always vented the oil filler plug with a 22mm braided pipe.

OK, grab a couple of one-way valves (found in most cars in the hose between brake servo & inlet manifold). These then need to be placed in the breather pipes from the cam covers to the turbo inlet 'elephant trunk'.

 

This allows the crankase pressure to still be vented (essential) but will prevent vacuum at idle causing low pressure in the turbo, which in conjunction with the reduced back pressure from the decats can cause oil to seep past the rear turbo seal. To check which way the valves flow, simply blow through them. It should be impossible to suck air through in the opposite direction. Make sure air can flow from cam covers to elephant trunk.

 

Fitting performance exhaust systems & decats is well-known to cause previously non-smoky turbos to smoke. This is just a trade-off for increased performance if your turbos aren't particularly new or in top shape. The same can occur if you leave a turbocharged car idling for very long periods which also causes low pressure in the turbo.

 

I've personally never had to use the One Way Valve trick, whenever I've had a turbo go down it's just an excuse to fit something much bigger :D

 

Give it a go and see if it helps at all. Bear in mind that it's a band-aid fix for tired turbos. The 200sx suffers from this when fitting aftermarket systems, and the OWV trick works well on those cars.

 

Ok can I ask a few questions on that basis as id been thinking about this in any event, you saying about low pressure in the turbo, I was under the impression that higher than atmospheric pressure in the sump, caused oil to back up/not flow freely into the sump, this then causes excessive oil levels in the turbo and the lower pressure of the exhaust system allows it to suck it out through there? My turbos arn't tired as such, there rebuilt, previously on idle they smoked like a trooper, since the rebuild they have improved 100 fold, and the issue only occurs when the car is HOT ie when you've given it some, then spend a prolonged time idling at the 900 or lower rpm range. I could drive around all day at 2k and youd never know, I could also take you around for 20 minutes on attest drive and you never see a thing, after an hour though it would rear its head, I assume this is because the oil in thinning out, making it easier to pass? I do wonder whether my choice oil has its part to play here.

oh and the car is fully decatted with divorced downpipes 2.5 all the way with 4" slashcut rear boxes so is extremely freeflowing, also not helping. the only three things I may have done wrong are, non oem pcvs, non oem ruber from the oil drain(may have shrunk internally) and my oil choice. I am being very picky as I say as the amount of smoke is like a cigarette not a factory chimney lol.

A PCV delete is something i have been looking into just want to get all this other stuff done first.

A PCV delete is something i have been looking into just want to get all this other stuff done first.

 

Yeh I'm just wondering if the pcv/crank ventilation is the root cause of your turbo woes. Could save you some serious time by trying it first.

I have a serious chimney going on and a few people have said it is deffo turbos. Got some rebuilt ones ready to go in just had to sort out my heater bypass before I could drop it into have the work done.

 

It was the usual story of better exhaust and decats that brought it out.

Ok can I ask a few questions on that basis as id been thinking about this in any event, you saying about low pressure in the turbo, I was under the impression that higher than atmospheric pressure in the sump, caused oil to back up/not flow freely into the sump, this then causes excessive oil levels in the turbo and the lower pressure of the exhaust system allows it to suck it out through there? My turbos arn't tired as such, there rebuilt, previously on idle they smoked like a trooper, since the rebuild they have improved 100 fold, and the issue only occurs when the car is HOT ie when you've given it some, then spend a prolonged time idling at the 900 or lower rpm range. I could drive around all day at 2k and youd never know, I could also take you around for 20 minutes on attest drive and you never see a thing, after an hour though it would rear its head, I assume this is because the oil in thinning out, making it easier to pass? I do wonder whether my choice oil has its part to play here.

 

Pressure in the sump builds because of blow-by on boost on this occasion, hence the breather system. If oil wasn't flowing freely, the top end would be the first victim. Or the big ends. Or the turbo bearings. Excessive oil levels in the turbo on idle (ie when the problem is happening) would be caused by an overfilled sump.

 

I've never looked into the OWV trick too deeply, I just know it's a cheap (pretty much free) & easy way to temporarily solve the issue before going for staggered seals. Both Garrett & TD give the lack of pressure within the turbo exacerbated by free-flowing exhausts as the root cause of weeping turbo seals. I've never experienced it because whenever I get a car, the stock breather system is binned for reasons given in my previous post. The OWV trick is from my S13-owning days, reported to work a charm even on knackered turbos. Some people claim it solved the issue for a couple of years! My VG is vented to atmosphere, so all blow-by gasses exit immediately, but I don't have the scavenging effect on idle or overrun. Small price to pay IMO.

 

Oil-wise, 10W40 semi synthetic seems to do well, I banged some Castrol in mine about a year ago after a flush and not had any reason to swap it since. About due a change now though. In my other cars I run Shell Helix 15W50 fully synth. It smells lovely....

I have a serious chimney going on and a few people have said it is deffo turbos. Got some rebuilt ones ready to go in just had to sort out my heater bypass before I could drop it into have the work done.

 

It was the usual story of better exhaust and decats that brought it out.

 

If I were you, there would be no reason not to vent the breathers to atmosphere to see if it helps at all.

If I were you, there would be no reason not to vent the breathers to atmosphere to see if it helps at all.

 

No real point as it is going to thursday. Deleteing the EGR and AIV so the breathers might go in the bin along with them

Pressure in the sump builds because of blow-by on boost on this occasion, hence the breather system. If oil wasn't flowing freely, the top end would be the first victim. Or the big ends. Or the turbo bearings. Excessive oil levels in the turbo on idle (ie when the problem is happening) would be caused by an overfilled sump.

 

I've never looked into the OWV trick too deeply, I just know it's a cheap (pretty much free) & easy way to temporarily solve the issue before going for staggered seals. Both Garrett & TD give the lack of pressure within the turbo exacerbated by free-flowing exhausts as the root cause of weeping turbo seals. I've never experienced it because whenever I get a car, the stock breather system is binned for reasons given in my previous post. The OWV trick is from my S13-owning days, reported to work a charm even on knackered turbos. Some people claim it solved the issue for a couple of years! My VG is vented to atmosphere, so all blow-by gasses exit immediately, but I don't have the scavenging effect on idle or overrun. Small price to pay IMO.

 

Oil-wise, 10W40 semi synthetic seems to do well, I banged some Castrol in mine about a year ago after a flush and not had any reason to swap it since. About due a change now though. In my other cars I run Shell Helix 15W50 fully synth. It smells lovely....

 

I really do appreciate the time your giving me with this one bud ive just done reading into the basic principals of crank case ventilation and now I understand that the pcv valve on our cars I sthe one responsible to removing oil at idle, and the one going into the corrugated turbo feed pipe is for WOT. This does however confuse me here the whole owv is concerned as sod all goes that way at idle due to the vacuum pressure in the plenum pulling it through that way. God im starting to get confused. In terms of venting to atmosphere only, you then loose the scavenging? effect that helps to remove problems with the crank and gasses that would cause it to chop the oil about. so that is a disadvange isn't it?

 

I think the issue ive got is sort of breather related in that there is bog all backpressure in the exhaust at idle and the pressure in the sump is higher than this causing it to pass. Part of me also questions if my oil level is correct or too high as reading the Nissan dipstick is nigh on impossible I find.

Penny just dropped, if the front cam cover ones have a one way check valve in place, then at idle this prevents a proportion of the air that is being scavenged into the intake by the pcvs being sourced directly from the intake. The non return ensures that the vacuum sources blow by gasses more efficiently, creating greater sump ventilation. I think I've just managed to unravel that mess of thoughts. If that's correct why the hell didn't Nissan do this to begin with....

Penny just dropped, if the front cam cover ones have a one way check valve in place, then at idle this prevents a proportion of the air that is being scavenged into the intake by the pcvs being sourced directly from the intake. The non return ensures that the vacuum sources blow by gasses more efficiently, creating greater sump ventilation. I think I've just managed to unravel that mess of thoughts. If that's correct why the hell didn't Nissan do this to begin with....

 

3 liters in a 6 cylinder set up produces a lot of "pushed air" in these small sumps..personaly i would,nt bother with a non-return system of any sort or description as its a step closer to a PVC system again. Like any 90,s car built they had to please the tree huggers more than the buying public to make these cars a winner and therefore had to ask for unrealistic and unreliable emission systems. I have 3 bucketfulls of rubber tubing..valves..canisters and metal pipework that nissan had to put on these engines to please pot growing lesbians and sweaters made from hemp wearing homo,s...No wonder they cost the same as a 3 bedroom house when they hit Nissan showrooms here:huh: