IC hose sucking flat. New Turbo, Stumped!

[Madmac666]

Hi guys, have an odd problem with my 2011 319 V6 OM642 Sprinter and I'm a bit stumped with this one.

Sudden loss of power today after it was idling for 40 mins during the MOT, won't rev over 2600 and is painfully down on power (less than limp mode) felt like a turbo issue initially, no codes showing up at all. Got my colleague to rev it while i had a look through the engine bay and the hose from the resonator to the intercooler is sucking flat, so I assumed a turbo problem. Turbo shaft spins fine by hand and appeared to be spinning OK with the engine running and the intake pipe removed. Once i removed the turbo, I can't see any issue with the core at all.

Some background on the turbo

I had an ongoing issue with this turbo, it was re-cored last year and the characteristics changed in that there wasn't much boost below 2k then it was off like a scalded cat to the red line. MIL was always on, and when pulling around 2k it would start flashing and the engine pulled harder! I did occasionally get an underboost code, but it still pulled hard above 2k. The guy who rebuilt the turbo said he reckoned a vane setup issue when he re-cored it and would honour a fix, I just hadn't got round to removing the turbo to send it back.

Anyway, today after the loss of power I swapped the turbo out for a new one i had here, and the IC pipe is still collapsing indicating a restriction upstream of the pipe. I've checked there's no blockages, resinator and pipework is clear, air filter is good, I also ran it with open intake on the turbo, same problem. The turbo is the only thing upstream of this hose and I'm having the same problem despite replacing the turbo for a new one.

I checked for blockages/collapse in the exhaust in case a restriction in the exhaust was causing the turbo to not spin up (no dpf) and it's all clear.

I've used my scan tool to check throttle valve, EGR etc and they all appear to be working fine. Turbo vane control is moving fine on the actuator test with the engine running.

The only thing I can think of is a stuck EGR valve stopping the turbo spooling and subsequently restricting the intake flow, but on the EGR test the engine sound is changing as it should when I use the scan tool to force the EGR valve open and closed.

Still no codes, full scan, sensor check, raw data check etc turns up zero clues. Whatever is restricting flow to the intercooler is upstream of that hose, which should be under pressure, not collapsing.

Can anyone suggest anything I've missed? I'd appreciate some feedback because it's got me scratching my head!

Sorry for the long post, I felt all that might be relevant

 

[MrGreedy]

Just to check (I'm possibly slightly unfamiliar as I have the 2011 OM642 in the E class) is this the rubber intercooler pipe that exits the intercooler, goes up to the resonator, then into the silver aluminium charge pipe and into the turbo to feed air to the engine?

If pipes on the charge side are being sucked flat, this sounds like a charge pipe/path blockage problem and not a turbo problem. The turbo is supposed to be sucking.

Could the intercooler be blocked?

Making sure dust/dirt can't be sucked in, what happens if you disconnect the intercooler and just allow the turbo to suck air just from the charge pipe after the intercooler?

 

[Madmac666]

That's the correct pipe, on the pressure outlet of the turbo. With that disconnected from the turbo it runs better and doesn't flatten the pipe, obviously no boost though. It has to be the turbo restricting the flow, but I can't see the reason for that. With both turbos having the same problem, it has to be something else affecting the turbo flow - not spooling up would do this I guess

 

[MrGreedy]

Sorry, it was late and I was struggling with comprehension.

Having had some sleep and a cup of tea, these pipes lower around the engine should all be under pressure. Only the loose fitting rigid plastic ducting to the air filter and into the batwing and then turbo are under slight vacuum.

Then from the turbo outlet to the aluminium charge pipe, down to the resonator, the first intercooler hose and into the intercooler should be under pressure.
Like you, I'm not seeing how that pipe should be sucked flat when it should be under pressure.

 

[MrGreedy]

That's the correct pipe, on the pressure outlet of the turbo. With that disconnected from the turbo it runs better and doesn't flatten the pipe, obviously no boost though. It has to be the turbo restricting the flow, but I can't see the reason for that. With both turbos having the same problem, it has to be something else affecting the turbo flow - not spooling up would do this I guess

With this disconnected, or partially disconnected, are you noticing charge pressure coming from the turbo (disconnected intercooler pipe) when the engine is being revved?

 

[Madmac666]

There is air blowing out of the turbo on open pipe, not as much as I'd expect when I rev the engine though. I have to deduce something is stopping the turbo spooling therefore it's becoming a restriction to the inlet system.

I've given up on it for now as I'm away to Doune Hillclimb with the Evo for the weekend. I'll pull out the EGR valve and check it's not stuck open on Monday when I get back.

I'll update once I get that looked at. Appreciate the replies

 

[mersum1es]

What if your engine is at limp (and like you said it then prevents boosting), though your diagnostics cannot find a code (it is there but need SDS)?

 

[Madmac666]

Engine light is out. It only came on when I was driving,

 

[Madmac666]

Engine light is off since mot. It only came on when I was driving, but that wouldn't explain the intercooler pipe sucking itself flat. I'm convinced it's something to do with the EGR so I'll pull that out and have a look. It's never been out in 215,000 miles so chances are it's stuck open, hindering the turbo spinning up and restricting the intake

 

[MrGreedy]

There is air blowing out of the turbo on open pipe, not as much as I'd expect when I rev the engine though. I have to deduce something is stopping the turbo spooling therefore it's becoming a restriction to the inlet system.

Although I've never heard of this, a quick Google suggests it's not uncommon when a turbo isn't spooling up or providing enough pressure, and therefore the engine vacuum is sucking the intercooler hoses flat because the turbo isn't delivering enough air.

You've tried another (know good new turbo) and the problem persists, so it's probably something that affects the turbo, but not the turbo itself.

I think these are variable vane turbos, so could the vanes be stuck in a low boost position? Turbo actuator not working? Boost pressure sensor?
I'm not sure how EGR affects turbo performance and ppressue.

Some time looking at live data with a decent scan tool, or STAR, might help indicate the likely source of the problem.
What is the turbo actuator doing? What is the reported boost pressure, intake temp, EGR reported position, and the changes of these values with throttle application.

 

[ALFAitalia]

I can't see anyway the EGR could cause this. Are you sure it's not something as simple a a knackered hose....mine are virtually solid and I doubt I could squash them flat with just hand force.

 

[Jobsworth]

Generally if the EGR is stuck open there’s an unholy amount of smoke from the exhaust

 

[sweeper]

intake hoses being sucked flat, it can only be engine vacuum doing this and hence means a blockage so the engine can't get enough air and my guess would say it's on the intake side of the turbo, a blocked air filter or maybe a hose that has collapsed inside, think about what happens if you block the turbo intake, turbo can spin but can't suck any air, engine attempts to suck harder and any pipe between blockage and engine will suck in, iot will also attempt to suck air from anywhere else like engine breather pipes and of course there will be no power.

 

[ALFAitalia]

Seems unlikely to me... I think the blockage could only be between the turbo and the intake manifold on the heads.....although I still don't think there is a blockage or the engine would not run at all.
Both airfilters being blocked to that degree?....unlikely....and there isn't anything else to block between the intake at the grille and the turbo. It's a strange one for sure.

 

[Madmac666]

Appreciate your suggestions guys. If I disconnect turbo outlet pipe the hose doesn't collapse, so blockage is the turbo. I've discounted the air filter as I ran it with that off.

There is some white smoke from the exhaust

Am away this weekend but I'll get to the EGR when I get back and update

Cheers

 

[ALFAitalia]

How can a turbo be completely blocked.... and surely the engine would not run at all if it was?????

 

[Madmac666]

It can't be that the turbo is blocked. Both the old and new turbos are showing the same issues, so it has to be that the compressor isn't spinning fast enough and causing a restriction to the inlet. I'm deducing that if the EGR valve is stuck open then the exhaust pressure between the heads and turbo is bleeding off to the inlet and the turbo won't spool.

The engine runs, idles and takes some throttle. I can rev it to about 2600 but there's no power to drive. I limped the van home 20 miles, struggling on hills at 40mph but on the flat and downhills it reached 70mph

This was just after the MOT when it was idling for 45 minutes, which was maybe the last straw for the EGR valve. I'm hoping to get the EGR valve out tonight as I need the van tomorrow!