906 Sprinter 416CDI - turbo gone??

Chaps, not sure if you can help?

My 2001, 903 416CDI Sprinter-based motorhome suddenly developed a complete lack of power today whilst cruising the M25/M11 home today. Normally it has loads of power in reserve but as I left the Dartford tunnel it started becoming sluggish and despite a throttle pedal buried in the floor in fifth, it refused to accelerate up the hill and struggled to maintain the speed.

For the rest of the journey home, I was having to power down hill in order to make it up the other side. At the approach to the M25/M11 junction, am HGV nearly overtook me and going up past North Weald, I struggled to hit 39mph!!!

Once off the motorway, the van accelerates fine in 1st gear, once into second and when rpm hits 2,000 it's like driving through treacle. The van accelerates but only very slowly and appears to be labouring. None of the temps have increased and no strange noises.

However, yesterday on the motorway and on the overrun, I did hear a loud whining noise, which I assumed was the transmission but perhaps the turbo?

Had a look under the bonnet and saw a bit of pipe from the manifold to the turbo looking like it was loose but a bit of wiggling didn't confirm anything loose.

Question is, are these Sprinters known for lunching their turbos or could this be something else? Van has 34k on the clock and is on a 2001 plate.

Cheers

Doubt its turbo, as said above, prob a hose popped off- a boost one or even a tiny vacuum hose, or as I've had with other sprinters its gone into limp home mode for some reason, on one of mine (311) I never got to the bottom of it, but flicking ignituon on & off while driving would reset it if it did it. On another (312) it was a tiny electronic part cost about £20 but caused me low boost, I've also split boost hoses before, or had them come loose & spill boost pressure, but you can hear that.

These were all a lot lot higher miles than yours tho 250k+ so do get odd issues when they get far more leggy.

mine was similar fault, 413cdi was the boost valve under the air filter box. £120 from dealer goes fine now.

Hmmm, happened again on the A1(M) at Alconbury. Had been fine for the entire journey up to Stamford on the Friday night but failed today. Pulled onto the hard shoulder, turned off the ignition, waited 30secs and restarted and absolutely fine!

Just beforehand this time, there was a brief smell of burning before it happened, but not sure if it was the van or something I was following.

Anyway, will try and get it to a garage on Thurs to see what's up. Otherwise I'll have to cross my fingers for a trip up to Peak District on Friday!

Ok, so this problem is still ongoing......

Since the boost valve replacement, I've had a number of times the vehicle has gone into Limp Home Mode with seemingly no common theme which triggers it. I say that, only one thing I can think of is when I've had light throttle opening whilst going relatively slowly, or at low-ish engine speeds and I've made a demand on the throttle and then it kicks into LHM.

Back in July, Mercedes diagnosed a coked up turbo with kinked actuator rod. The third party warranty company offered to cover it, providing this was confirmed by their turbo specialist - Mercedes not wiling to stand by their diagnosis to the extent that I would have to underwrite all of Mercedes labour costs if the specialist confirmed no issue with the turbo. Therefore I took the van back to the motorhome dealer I got it from.

Their diagnostics came up with "Low Boost Pressure" and upon inspection, found the intercooler pipe to be detached. Re-attached the pipe, testdrove for 40miles, no issue and fault codes cleared.

I picked up the van on Friday and had three LHM episodes between Telford and Essex!

First one was at the M6 Toll booths southbound and to me sounded like a brief "pop" before it whistled and went into LHM. The time after that I was crawling in traffic at the M1/A14 junction - a bit boomy and agricultural the noise and then LHM. Same on the M11.

Each time, cycling the ignition cleared the fault and restored power.

I am now at a loss of what to do.

I am requesting the dealer underwrites the labour costs of having the turbo removed and inspected at Mercedes/Specialist in the hope a problem is found, I get a reconditioned turbo and the whole thing put back together. I also wonder whether replacing all the turbo hoses is something to consider. The van is 14yrs old - has only done 36k miles - but I guess things can perish?

What would you guys do? Any other recommendations?

I'm really stumped, because I absolutely love the van and when it"s running on song, its wonderful. But I can't keep having it go into LHM - I'm loosing all confidence in it.

Ok, so I've spent about 3hrs reading various posts dotted around the internet on the issue. It seems this issue is not limited to Sprinters but plenty of Mercedes applications - S, E & C classes where the Garrett GT22V VNT (variable nozzle turbo) was installed.

The fault code mine threw last time was "P1470-016" Low Boost Pressure, from what I've read, the diagnosis for which is suggested as the following:-

- check all vacuum & boost pipes (visually and pressure test)
- check EGR valve
- boost valve controller (turbo transducer), which I now understand is vacuum operated on my model year, only moving to electrical controllers from 2004.
- variable vane actuator

I'm presuming due to Mercedes taking a few hundred quid off me for a new turbo transducer in May, that the pipework has already been checked. But then again, the motorhome dealer found a disconnected intercooler hose when they saw the van. Which is fine, but clearly not the crux of the issue.

Anyway, all of the above and research undertaken suggests that the issue is with the variable vane actuator (as previously assumed). It turns out that it can become corroded or coked up (Mercedes original diagnostic), which leads to intermittent operation. I presume where a demand is made quickly for power, it struggles to move in time, which is what trips LHM. Although some suggest that it can be half disconnected, have GT85 applied and greased at the bottom of the pivot, the "proper" way of dealing with this is to replace the turbo, given the actuator rod has to be calibrated from factory.

Route I think I need to take this is firstly getting all the vacuum and boost pipes replaced (belt & braces approach) and then get the turbo sent away and looked at; ideally replaced with a reconditioned unit.

All of this makes me far more positive that this issue is resolvable.

So, as it seems to have turned out, it was the simplest of issues, now solved by All Klasse Autos in Bishops Stortford, about whom I have not a bad word!

Alex - the owner - took a good look at the van and was given the full story of what had happened so far, what I thought triggered the LHM and what the other garages had diagnosed. He then set about with his star machine doing a fault-finding exercise.

On the diagnosis, it came up only with the low boost pressure fault code, but nothing else. He checked the turbo actuator using the diagnostic tool and this moved freely and without any stiction unlike plenty of other Merc cars he said he'd seen. He then proceeded to go over the entire turbo circuit with a fine tooth comb - checked every hose and its connection for security and leaks. All good.

The one remaining item was the wiring for the boost pressure sensor. This was routed such that it was pulled very tight around some hoses across the engine bay. He rerouted the wiring with some slack and hey presto - seems to have done the trick!

So after all of that and Mercedes wanting to fit a new turbo, it turns out that the movement of the engine on its mounts under hard acceleration seems to have been pulling the plug slightly from the boost sensor and tripping LHM!

I have subsequently done almost 300miles with various driving - urban, a & b roads and motorway and, try as I might, have been unable to trip LHM in similar situations to before.

For £60, fantastic result!