Popping on overrun & white smoke from exhaust

[Naso Grande]

Hi folks,

I've noticed that my GTO-3 is popping & banging a lot more on the overrun than it used to. The car is due a service soon but was hoping someone might be able to tell me if this is normal or the possible causes if not. The car is completely stock and I've done about 2000 miles since buying it about 8 months ago.

I've also noticed occasionally there is white smoke coming from the exhausts usually when in traffic. I'm already suspecting that the turbos may require a refurb (car has 11k on the clock) from what I've read on other posts. I've added about 1.5 litres of oil in the last 2000 miles and the boost is about 0.5 bar.

Any feedback would be appreciated.

Thanks,
Graeme

[Alpinestars]

Not an expert Graeme, but my understanding is as follows:

White smoke is oil burning in the exhaust ie, post engine as opposed to blue smoke (oil burning in the engine). It is therefore likely to be oil making it's way past the turbos.

The fact that the smoke appears more whilst standing with the engine warm may be a sign that oil is passing through the turbo seals and being burnt in the hot exhaust.

[saucyboy]

No expert myself, but could it be over fuelling, thus the popping on over run?

I know I get this and the car hasn't been burning any extra oil. In fact i recently had the exhaust fully off and checked the turbos at the same time. the shafts were tight and there was no sign of any leaks.

James

[F.C.]

Popping on the over run is usually a sign of an air leak in the exhaust system allowing unburned fuel (poss. over fuel as mentioned above) to ignite thus causing the popping noise.
White smoke is probably oil getting past the turbo "so called seal".
Have you changed you exhaust system to a dual box type (H&S, Roush etc)?
If so, according to the oem supplier of the Noble turbos the fact that the dual box type exhaust provides less back pressure, can lead to turbo "seal" bypass sooner than on the standard fitment exhaust. (Less pressure in the exhaust for the oil to fight to seep out).
F.C.

Edited by F.C. on Sunday 25th May 11:28

[Naso Grande]

Thanks Guys. I don't feel as though the oil consumption is high so prepared to live with it for the time being. Can the over-fuelling problem be solved by resetting the adaptive maps? The exhaust is standard factory fit.

Just been out for a quick run this morning and everything was fine.

Graeme

[Adrian W]

Hmmmm, think i might take that one with a pinch of salt!

When it's smoking on tickover put a white tissue over the end of the exhaust, if it's black it's oil if not it's water.

[Naso Grande]

Thanks Adrian,

On tickover there is no smoke from the exhausts. I only see it in the rear view mirror sometimes when I move off in traffic.

[mgbond]

I didn't think the MBE had addaptive mapping?

Bondy

[Adrian W]

mgbond said:

I didn't think the MBE had addaptive mapping?

Bondy

It does

[Adrian W]

Naso Grande said:

Thanks Adrian,

On tickover there is no smoke from the exhausts. I only see it in the rear view mirror sometimes when I move off in traffic.

Im such a sad git I clean the inside of the exhaust tips, if it's sooty its ok, turbo cars run a bit rich when they are poolding about, if it sticky it's oil, could be breathing and oil passing through the rings, on normal boost levels it's the first sign of the engine starting to get a bit tired (after all it is a pumped up Mondeo engine)also could be a warn turbo. If it's only a little bit of smoke I would ignore it untill it gets worse.

You can see if it's breathing by taking off the bottom left pipe from the intercooler and seeing if their is any oil in the pipe or inside the intercooler, it's one clip and is easy.

[peterguk V6 KWK]

Slightly O/T here but related to one or more posts above..

Exhaust back pressure.

I keep reading on this forum how reducing back pressure on Nobles is bad for the Turbo seals.

Now, i've been running an MR2 business for years and have built high boost engines using journal bearing and ball bearing turbos of all sizes, decat'ed, with the biggest, baddest exhausts Japan can make.

I've also been an active member of MR2 forums on both sides of the Atlantic, and the US forum especially, contains technical info that puts this and many other forums to shame.

Yet, i have yet to hear of any 3" straight through system being of any detriment to the turbo oil seals.

Example...We have TD-06 or T3/T4 turbo'ed cars, running 25 psi, and 20,000 miles later are as good as the day we built it..

We have OEM CT20B turbo'ed cars running 17 psi instead of stock 12 psi, decat'ed, and perfect after 30K...

So, can someone explain why Nobles are different, and can't last a couple of 000 miles with an eficient exhaust?

Edited by peterguk V6 KWK on Sunday 25th May 12:47

[wjs]

Had the same problem ,it turned out to be a leaking turbo seal on the front and rear turbo, also a small leak was found around hoses to thermostat housing.The white smoke turned out to be steam and was easily fixed, hope this helps.

[Naso Grande]

Thanks Will. Really enjoying the car by the way. Seems like the same problem again as I'm having to top up the coolant quite often as well.

Cheers,
Graeme

[NobleGuy]

If your coolant levels are dropping it could be head gaskets or more likely, as in my case, a couple of silly little leaks from the ageing hoses. Mine smokes significantly in traffic when still warming up for about a minute or two - never get smoke otherwise. I think my front turbo is getting a little worn out, but spoke to a chap who mentioned that the Noble exhaust is very good at building up condensation when warming up - my tissue test shows no black deposits.

Not sure what I'm trying to say really....
I guess if you're burning oil then worry a little about your turbos. Like mentioned, check the intercooler pipes for oil. If you're losing coolant check your hoses. If they're OK and you're still losing coolant then there might be an issue there.

[wjs]

Naso Grande said:

Hi folks,

I've noticed that my GTO-3 is popping & banging a lot more on the overrun than it used to. The car is due a service soon but was hoping someone might be able to tell me if this is normal or the possible causes if not. The car is completely stock and I've done about 2000 miles since buying it about 8 months ago.

I've also noticed occasionally there is white smoke coming from the exhausts usually when in traffic. I'm already suspecting that the turbos may require a refurb (car has 11k on the clock) from what I've read on other posts. I've added about 1.5 litres of oil in the last 2000 miles and the boost is about 0.5 bar.

Any feedback would be appreciated.

Thanks,
Graeme

[F.C.]

peterguk V6 KWK said:

Slightly O/T here but related to one or more posts above..

Exhaust back pressure.

I keep reading on this forum how reducing back pressure on Nobles is bad for the Turbo seals.

Now, i've been running an MR2 business for years and have built high boost engines using journal bearing and ball bearing turbos of all sizes, decat'ed, with the biggest, baddest exhausts Japan can make.

I've also been an active member of MR2 forums on both sides of the Atlantic, and the US forum especially, contains technical info that puts this and many other forums to shame.

Yet, i have yet to hear of any 3" straight through system being of any detriment to the turbo oil seals.

Example...We have TD-06 or T3/T4 turbo'ed cars, running 25 psi, and 20,000 miles later are as good as the day we built it..

We have OEM CT20B turbo'ed cars running 17 psi instead of stock 12 psi, decat'ed, and perfect after 30K...

So, can someone explain why Nobles are different, and can't last a couple of 000 miles with an eficient exhaust?

Edited by peterguk V6 KWK on Sunday 25th May 12:47

Grahame Page at Universal Turbos (oem supplier for Noble) suggests this seems to be the case.
I agree it doesn't really add up but there are a few Nobles out there that have had the need for turbo re-builds at relatively low mileages, mine included.
F.C.

Edited by F.C. on Thursday 29th May 00:15

[NobleGuy]

My turbo blew a large plume of smoke when I had the silencer off for about a week.
Certainly appears that the lack of back-pressure was the cause.