Sprinter/Hymer lack of power?

Plaides

I recently purchased a Hymer S520 on a Mercedes Sprinter 312D chassis. We have had a few trips in it and noticed a distinct lack of power especially on hills. I have not owned a motorhome before and therefore do not know if this is normal for campers.

When going up hills especially long ones, it loses power until one eventually has to change down to second gear. The water tank is typically 75% full and same with the fuel tank. Pushing the throttle down that extra bit seems to have no effect. The engine is 2.9 litre 5 cylinder and is easy to start and runs fine; no black or white smoke from the exhaust. Mileage is about 35K and 13 years old.

I do not feel that this is normal performance and the camper should have more power especially with a 2.9 litre engine. I have read that Sprinters can switch to 'limp home' mode if the ECU detects a problem, in order to protect the engine; but I don't know if it's in 'limp home' mode! Would anyone know if this is normal performance or whether I should investigate further by getting the ECU read, etc.

I would much appreciate any advice.
Thanks.

Aidan_M_M

It sounds like its down on power alright, could be the pressure sensor for the turbo.

+1 down on power.

Similar thread here.

If it's not the turbo I'd suspect air intake; air filter, MAF sensor, intake leak after MAF sensor (eg. unsecured hose), or EGR blockages (unlikely to be EGR on low mileage though)

Plaides

Thanks for the advice. I had read through the similar thread which is very interesting.

Looks like it is down on power then, so I'll check through those items and the fuel filter. The ECU light is not 'on' so I assume that there are no faults recorded but maybe that is not a valid assumption.

Wish it had a rev counter!

Plaides

The ECU should flag a broken MAF sensor. Maybe intermittent on one that's not long for this world.

Plaides wrote: »

Wish it had a rev counter!

You do! Ears!:D

paddyp

If its 2.9 is it not the old om602 engine with a mechanical pump in which case I'd be looking for a boost/vacuum leak.

paddyp

paddyp wrote: »

If its 2.9 is it not the old om602 engine with a mechanical pump in which case I'd be looking for a boost/vacuum leak.

Wouldn't that sound rough? Probably not significantly so on 5 cylinders but one could tune into a missing beat?

...sometimes it can just be a floor mat bunched up so that the accelerator isn't fully extending.

Aidan_M_M

Most of the ones I've done have had the vaccuum unit for the turbo faulty. Main dealer only part, easily fitted.

Plaides

Thanks for the help. I had checked if the floor mat was blocking the throttle pedal and it was clear. I haven't had a chance to check the other items yet.

Is there any simple check to find out if the vacuum unit for the turbo is faulty besides buying a new unit?

Thanks again.

Here's a suggestion but I'm not sure if it'll work on a diesel so best wait til somebody else verifies it or renounces it .
Spray around the vacuum intake on the turbo/head gasket with carburetor cleaner. The theory is that if you get an increase in revs or the engine idle smoothens out then you have a leak.
You may have to lock open the throttle to 50% for this for the turbo to kick in, again though I advise I'm not sure if this is necessary either.

Link

Aidan_M_M

I prefer to use WD40 , not as explosive . I don't really know how to rule out the vac unit without trying one , but they go very regularly.

gctest50

Sir Liamalot wrote: »

Here's a suggestion but I'm not sure if it'll work on a diesel so best wait til somebody else verifies it or renounces it .
Spray around the vacuum intake on the turbo/head gasket with carburetor cleaner. The theory is that if you get an increase in revs or the engine idle smoothens out then you have a leak.
You may have to lock open the throttle to 50% for this for the turbo to kick in, again though I advise I'm not sure if this is necessary either.

Link

Won't work that way - no throttle plate usually on a diesel so no depression in the intake manifold ( hence why there's a vacuum pump on the engine somewhere for the brake servo most times)

Aidan_M_M

Aidan_M_M wrote: »

I don't really know how to rule out the vac unit without trying one , but they go very regularly.

I read that if you try to pull off the vacuum lines to the turbo with the engine running and it's possible to remove them, then you have insufficient vacuum on them. If that's any help. Tbh I'm all outta useful suggestions on this one.

gctest50 wrote: »

Won't work that way - no throttle plate usually on a diesel so no depression in the intake manifold ( hence why there's a vacuum pump on the engine somewhere for the brake servo most times)

Nope, still don't understand that can you try explaining it again?

Plaides

I think that I may have found the problem. The turbo has a small unit mounted on the side with a short flexible pipe leading into the boost duct exit. There is also a control rod that comes from the middle of the unit and goes to a crank on the exhaust side of the turbo. There are no other connections either electrical or vacuum to the turbo. The arrangement looks similar to image 3 on this website - http://turbocentre.ie/en/index.php When I rev the engine, the crank does not move.

I am not familiar with turbos bit I assume that the unit is the wastegate actuator, and the crank should move to regulate the boost depending on engine revs. Assuming that the crank is jammed would anyone know if there is any way of freeing it, otherwise I assume that the turbo needs to be removed. Is this a common fault?

Aidan_M_M Most of the ones I've done have had the vaccuum unit for the turbo faulty. Main dealer only part, easily fitted.
21-06-2013 04:25

Aidan_M_M the vacuum unit I assume you refer to is the small double spherical reservoir and regulating valve by the left hand wheel arch (the vehicle is left hand drive). There is no pipe leading to the turbo from this.

I checked all the boost pipes and intercooler visually which appear in good condition. Also checked air filter which was ok, but I will replace the air and fuel filter.

Thanks again for your help.

Aidan_M_M

That actuator would only work under load. And no that sphere isn't the item, that's only a vacuum accumulator/buffer.

Plaides

Aidan_M_M wrote: »

That actuator would only work under load. And no that sphere isn't the item, that's only a vacuum accumulator/buffer.

I am not sure what you mean by the 'the vacuum unit for the turbo'. I would be very grateful if you could clarify please.

Many thanks.

paddyp

Sounds like your wastegate is actuated directly by the boost pressure so you have and old style turbo, check the the wastegate is closing properly then look for boost leaks, any slack in the throttle etc.

Aidan_M_M

Plaides wrote: »

I am not sure what you mean by the 'the vacuum unit for the turbo'. I would be very grateful if you could clarify please.

Many thanks.

It's a little unit that fits in the palm of your hand, on top of the front rhs chassis leg.

Plaides

I removed the wastegate valve actuator and discovered that the linkage between valve and actuator was seized. I freed it and refitted the actuator. Goes like a rocket now compared to how it was. Many thanks for all your help.

Kudos, happy days.

Aidan_M_M

Thats great news , and it's hard to beat the satisfaction of fixing it yourself!

rustynutz

I know this is an old thread but I am having the exact same problem with a Sprinter/Rimor motorhome I just bought, 100,000km on the clock. After reading this thread I had a look around the turbo and found what looks like a vacuum fed valve directly under the turbo, this has a rod coming out of it which seems to be connected to an arm coming from the exhaust down wind of the turbo. This arm neither moves by hand or when revving the engine, is this the unit you found was the issue op?

crabbypaddy

rustynutz wrote: »

I know this is an old thread but I am having the exact same problem with a Sprinter/Rimor motorhome I just bought, 100,000km on the clock. After reading this thread I had a look around the turbo and found what looks like a vacuum fed valve directly under the turbo, this has a rod coming out of it which seems to be connected to an arm coming from the exhaust down wind of the turbo. This arm neither moves by hand or when revving the engine, is this the unit you found was the issue op?

It's a waste gate its not supposed to open until you're in over boost which your unlikely to achieve stationary with no load on the engine. The manual force required to open would be somewhere around 15-20kg

If its a vacuum driven wastegate then stationary test requires a vacuum pump like a mityvac really. If you don't have one then disconnect the actuator rod and check if waste gate pivot is seized or stiff. You could also bypass the vacuum solenoid temporarily with a straight coupler to see if it opens.