Technical Runaway Turbo

[Mama Llama]

1.9 JTD 120 CV/88KW CF4 M88

THE PROBLEM: White-ish puffs of smoke on acceleration. Stopped at destination and revved her a bit. Huge plumes of smoke. Switched off engine. Waited a bit, debated calling my hubby as he has less love for Betsie than I do. Eventually called him. Restarted Betsie--- no smoke whatsoever --- hubby said to drive home carefully and then told me what to do if Turbo Runaway happens.. (Throw into 5th and dump clutch while standing on brakes) Drove home (3miles) no smoke until last 1/2 mile, not to much just kind of in puffs. Parked car.... revved her a bit... loads of smoke and trues-bob Turbo Runaway occurs. Crap myself but remember what hubby said to do and it worked. Now petrified I've seized the engine. Call hubby. Engine won't turn. I've killed her now haven't I. I go inside to mourn.

2 hours later: Hubby says I've killed her. I say no-way she's tough. Hubby opens and peers into bonnet... No oil leaks. No oil in coolant. No coolant in oil. Start her. Starts first time... no bangs or explosions.. just a perfectly happy Betsie. Hubby has to get back to work. Tells me not to rev her, to just drive her like a granny and I should be able to do the school run safely.

Three school run trips of 6 miles each done, with smoke only occurring last half mile of each trip, and not in huge amounts either. After last run engine light came on and code P0235

My traitorous hubby has now bought Peggy-(Peugeot 207) and brought her home for me use on the school runs until he can figure out what to do with Betsie.

WHAT WE'VE DONE SO FAR: Loads of googling. Spoken to a few mechanic family members. First suggestion was to check turbo return pipe wasn't blocked. Easy enough to check. So have ordered gasket seals and washers. And managed to find a used but sound return pipe in case that's got damage. Hubby is planning on getting up on stands tomorrow and having a proper look for leaks, cracked pipes etc.

Does anyone have any suggestions, hint, tips or anything before he gets under her? Anything to look out for? Has anyone encountered this issue before? Any advice and thoughts are welcome.

Hubby and I are generally mechanically able. We both grew up around cars, stock car racing, drag racing etc. So are pretty competent under the hood. Mostly.

 

[porta]

“Traitorous Hubby”
Maybe a headgasket if it’s wet n white smoke, my old six cylinder lump did it occasionally on number 5 cylinder…until I got it fixed two weeks later

 

[Mama Llama]

Good enough reason to buy a borescope according to hubby. Got one off Amazon for £30...ding dong delivery at 7am this morning

Jet washed the engine and had her idling for a while before hubby checked her over.

No visible leaks or cracked pipes...reset EML and took her for a run.

Half a mile out she started puffing bluish white smoke. And faint smell of oil... headed back home. EML back on...P0235 code.

Waiting for gaskets to arrive and will give turbo oil return pipe a check and clean.

Hubby is trying to be the voice of reason... about rehoming Betsie where she can have the freedom of open roads... humph... I already feel like I'm betraying Betsie coz Peggy is a nippy little thing whose heating kicks almost immediately...shhhh don't let Betsie hear me

 

[jackwhoo]

Does she has a dpf ?

 

[Mama Llama]

Does she has a dpf ?

Yes.

 

[jackwhoo]

Yes.

Could this be smoke from attempting to regenerate the dpf?

 

[Mama Llama]

Could this be smoke from attempting to regenerate the dpf?

I don't think DPF regen would cause runaway turbo.

 

[portland_bill]

A diesel runaway is usually due to burning its own oil, either through the breather system (rare), or from the turbo. Turbo shaft seals could be leaking, but I'd expect this to be present all the time, not just when hot, or after a short time.
Blocked oil drain could be an issue, it will allow build-up of oil in the turbo, and it has to go somewhere if the oil pump is still pushing.
Could be sucking oil into the cylinders through the head gasket, but that is unusual, as combustion pressure will normally push the other way.
What is P0235?

 

[Mama Llama]

A diesel runaway is usually due to burning its own oil, either through the breather system (rare), or from the turbo. Turbo shaft seals could be leaking, but I'd expect this to be present all the time, not just when hot, or after a short time.
Blocked oil drain could be an issue, it will allow build-up of oil in the turbo, and it has to go somewhere if the oil pump is still pushing.
Could be sucking oil into the cylinders through the head gasket, but that is unusual, as combustion pressure will normally push the other way.
What is P0235?

Blocked oil return seems most likely, have ordered gaskets and will check.

No visible leaks and not using oil so hoping that's the issue.

The meaning of fault code P0235 is: Turbocharger Boost Sensor A Circuit Malfunction.

 

[Mama Llama]

Hubby finally managed to jack up Betsie and get the turbo oil return pipe off.... and was really surprised how "clean" it was. So put all back together.... a lot of swearing and cussing as his "fingers are too fat and the angles are wrong" but eventually got the FOUR bolts back on. All turbo pipes checked.

Then decided to do an oil and filter change. Hubby says old oil is way too thin.... last oil change was 11/2021 (15k miles ago) and that degraded oil should be thick and/or sludgy and the oil he removed was very runny / very low viscosity. Also we have not had to top up the oil since the last oil change - the levels have remained constant. So no leaks at all.

After replacing oil and oil filter, tried to start her.... dead battery.... finally get her going …. mmmmm.... she sounds good.... ah I've missed her

Took her for a run.... got her up to temperature... she's driving like a dream... Got her revs up to 4-5k no problems.... no smoke...

So am even more at a loss as to what the problem was (is?)

So I've agreed to keep Peggy (Peugeot 207) on stand by and lets see how Betsie does on the school run next week.

 

[GettinBetter]

I'd be inclined to remove the air cooler, if the turbo bearings are leaking, they'll allow the oil to run to the bottom of the cooler and will build up till

1. There is no free path for the air to flow because the oil is blocking the way, in which case it will blast it through to the cyclinders, untill it clears the way.
2. The oil is cool and the viscosity is such that it stays at the bottom of the cooler untill it gets hot enough to be dragged through by the air blasting through.
3. Or a mixture of both.

It's a cheap and simple test, if there's no oil (or almost) it's not getting past the turbo bearings.

 

[Mama Llama]

I'd be inclined to remove the air cooler, if the turbo bearings are leaking, they'll allow the oil to run to the bottom of the cooler and will build up till

1. There is no free path for the air to flow because the oil is blocking the way, in which case it will blast it through to the cyclinders, untill it clears the way.
2. The oil is cool and the viscosity is such that it stays at the bottom of the cooler untill it gets hot enough to be dragged through by the air blasting through.
3. Or a mixture of both.

It's a cheap and simple test, if there's no oil (or almost) it's not getting past the turbo bearings.

Good evening,
Do you mean the intercooler?

 

[GettinBetter]

Do you mean the intercooler?

I certainly do.

 

[portland_bill]

During DPF regen, extra fuel is injected into the cylinders, on the exhaust stroke, so it passes directly into the exhaust, and is used to incinerate the soot in the DPF. A consequence of this, is that some fuel washes past the rings, into the sump, diluting the oil. The oil level therefore does not drop, even if the engine uses a little, and can overfill, but is of course, diluted. Probably too late now, but if the old oil smells of fuel, that'll be the reason. This is why most diesels have an 'oil change' warning, with the computer doing a calculated estimate of the oil quality based on use. (Short runs, long runs, temps reached, DPF regens, etc.) Needs an oil change at worst, annually, regardless of miles.