OM642 V6 induction noise?

[BTB 500]

The OM642 V6 in our Vito has started making a noise under hard acceleration that sounds like induction roar. It runs fine and is quiet at normal power levels, but at higher rpm and throttle settings the noise starts. It stops as soon as you lift off or the revs drop. I vaguely recollect there's a pipe/seal somewhere that can fail? The engine bay is very crowded - the only thing I could see this morning was an odd looking gap here:



Nothing is loose but I'm wondering if there was some sort of seal around this part that's come away??

Thanks in advance for any suggestions

 

[johnsco]

If the joint in your photo was leaking I would expect to see black oily residue around it.
I've dealing with a boost hose leak on the OM642 in my W211 .
Your Vito layout is rather different from mine.
However - If you can locate the intercooler, you probably have two large-diameter hoses (65mm-ish) to the inlet and outlet connections.
This is a place to look for any leakages ... the connections ... and the hoses themselves are prone to splitting .... and maybe even the intercooler.
There are numerous joints that can develop leaks.

 

[BTB 500]

Thanks I'll have a crawl around underneath to see if I can spot anything. The OM642 is a tight fit in there - the manifolds & turbo had to be replaced 4 years ago, and that was an engine-out job ...

The van is still running fine with no loss of power which made me think of an intake seal?

Local garage is booked up for over 2 weeks, and the nearest MB van dealership is a 50 km round trip.

 

[johnsco]

As you say - There's not a lot of room round your engine.
I'm waiting for the new intercooler hose from MB Leeds - Collect tomorrow.
See current thread:

E280 cdi Sports - 642920 Engine - Leakage from Boost Pipe at RHS Front of Engine Compartment | Engine

I've noticed oil mist contamination just behind the rad of the driver's side of the engine compartment. See photo ... It looks to be coming from point marked A. The shiny blacxk pipe is shiny 'cos I've just wiped it. It was heavily contaminated and so is the area round it. I've looked for the...

forums.mbclub.co.uk

The present hose has a split nearly 2 inches long.
You can feel the air blowing out when the car is only idling.
Heaven knows what it's like under load.
Strange that there is no noise ... No significant loss of power ... Perhaps a short delay when you put your foot down ... and not even an EML light.
Good luck.

 

[AndrewOl]

That little gap doesn’t look right and would be a good place to start. The little metal stirrup should be held in with a bolt. If you take it off you may be able to get it out to look at the seal in there. As you say it is super tight so you may have a wrestling match on your hands!

 

[BTB 500]

That little gap doesn’t look right and would be a good place to start. The little metal stirrup should be held in with a bolt. If you take it off you may be able to get it out to look at the seal in there. As you say it is super tight so you may have a wrestling match on your hands!

The gap looks wrong to me, but there's zero slack or movement there ... everything seems completely tight & secure. I did wonder if there'd been a big O ring or similar in the gap that had perished and come out completely, but I could be on completely the wrong track! Spoke to the nearest MB van dealership and the next available booking is April 20th.

 

[Bellow]

If that is part of the induction system and is leaking and is leaking when idling it will either draw air or expel it. Have a smoker or vaper blow some smoke/vape at it and see if it is swallowed or blown back. There could be a leak (there or elsewhere) that is only opening up under boost though.

Bear in mind any leak downstream of the filter can admit unfiltered air (off boost downstream of the turbo, at all times upstream of the turbo).

 

[BTB 500]

Yup potentially letting in unfiltered air is my concern ... there's no indication of loss of boost. Spoke to another local garage this afternoon - they wouldn't be able to look at it till after Easter. There's no access to anything from underneath without the van being on a lift, which makes things even more tricky.

 

[BTB 500]

Found this under-bonnet shot from 2008 ... it was a bit cleaner then! Unfortunately there's not enough resolution to see if anything has changed ... wondering about winding some electrical tape around there as a stop-gap.

 

[Martyn_n]

That joint looks ok to me; as johnsco stated if it were leaking there would be plenty of oily residue around it. Sounds more like an air leak upstream of the turbo, is the air filter housing(s) intact? Is all of the ducting properly connected / free of splits.
Personally I do like a bit of induction roar but probably not in keeping with a Vito!!

 

[BTB 500]

My initial guess was the turbo inlet seal, but unfortunately you can't see the turbo or any of the pipework (I assume there'd be some access from below with the van on a lift). Everything I can see on the top of the engine looks fine, other than that odd gap (I'm guessing that's the MAS housing).

I don't mind the noise but not keen on the idea of unfiltered air getting into the turbo & engine! It's crazy that all the garages are so booked up ... if I was a tradesman and relying on the van for work every day I'd be in big trouble. They are all blaming Covid (of course), but I recall having the same issue with the dealer in Reading back in 2018 - it often took a couple of weeks to get it seen then.

At 15 years old we'd ideally be replacing the van around now but low mileage used ones are in extremely short supply - I assume people have been buying them up due to problems getting hold of new ones. Was talking to our farrier this week and VW had just advised him it would be at least 12 months to get a new Transporter!

 

[Martyn_n]

I imagine the market in vans for conversion to campers is also pushing prices up now that "staycations" are the new thing.

 

[m80]

I imagine the market in vans for conversion to campers is also pushing prices up now that "staycations" are the new thing.

Things seem to be reverting to foreign hols again.

BTB the things I've suggested in post 6 here

Clk 320 oil smell | Engine

Hi all I have a 09 plate clk 320 cdi with 103000 miles and a full service history I’ve been covering around 500-700 miles a week and in the past month I’ve been smelling a sort off fresh oil smell coming from the air vents upon stopping and in traffic only sometimes tho it’s not consistent...

forums.mbclub.co.uk

may be worth a look.

All accessible from above.

 

[Bellow]

Found this under-bonnet shot from 2008 ... it was a bit cleaner then! Unfortunately there's not enough resolution to see if anything has changed ...

The early shot looks a lot like the later shot.

wondering about winding some electrical tape around there as a stop-gap.

Not before a rudimentary (smoke/vape) leak test! And even then, if upstream of the turbo I'd hesitate. You really don't want to end up removing ingested insulation tape from the compressor impellor.

 

[BTB 500]

Not before a rudimentary (smoke/vape) leak test!

No smokers or vapers here, unfortunately.

 

[BTB 500]

So after a bit of further investigation today (revving with the bonnet open) it didn't sound like the noise was coming from the engine bay. Had a look further back and the centre box on the exhaust has clearly seen better days:



Presumably that will be it, although it doesn't sound like any blowing exhaust I've ever had before Strange that the box is double-skinned (this is the original factory exhaust from 2007).

 

[DSM10000]

So after a bit of further investigation today (revving with the bonnet open) it didn't sound like the noise was coming from the engine bay. Had a look further back and the centre box on the exhaust has clearly seen better days:

View attachment 125473

Presumably that will be it, although it doesn't sound like any blowing exhaust I've ever had before Strange that the box is double-skinned (this is the original factory exhaust from 2007).

If it is only the sacrificial outer skin then peel it off and inspect the remaining structure. It may be perfectly sound.

 

[Bellow]

Unless you can see/hear a leak there I'd hesitate before assuming the culprit has been identified.

 

[Larkone]

The method I was always taught for checking for a blowing exhaust was to temporarily block the exhaust outlet to increase the pressure and it will show up any leaks very quickly.

 

[W1ghty]

The method I was always taught for checking for a blowing exhaust was to temporarily block the exhaust outlet to increase the pressure and it will show up any leaks very quickly.

The old palm of your hand trick ?