# Not Poor - But Non-Existent "Performance"



## Spins (Sep 11, 2009)

I wonder if any members can advise me on a virtually none performance problem. 

The engine of my motor home is a re-conditioned Mercedes 307D (T1 OM616.934 with a 4 speed box. No turbo) which has astoundingly poor performance. (I think it's a re-con engine, it's painted blue) 

It's best (foot to the floor!) speed during acceleration is about 35mph. Given time it will achieve 45 mph and has never bettered 60mph downhill. During a recent trip to Devon I had to resort to first gear to climb a couple of not very steep hills. Any type of an incline means a shift down to third and then probably second. 

Having the weight checked at my local weighbridge before going to Devon, all up, including myself, wife and our Jack Russell it was 3005kg (Max 3500kg). So I don't think overloading is the problem. 

My only observations are that the throttle linkage appears to be be loose but I don't know if that is normal? and I have read, on an American forum, that there is a fuel return valve which pumps excess fuel back to the tank. It appears that the spring compresses after time and reduces the amount of fuel supplied to the injectors. The fuel consumption has been reasonable so I wonder if the engine is being starved of diesel? I don't know if the re-con engine had the original fuel return valve re-fitted. Other than that I don't have a clue what the cause of problem may be. 

I would be extremely grateful if anyone out there could help. Being overtaken by cyclists is not funny! 





All that it takes for evil to succeed is that good men do nothing.


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## jeffro (Jan 13, 2009)

Hi had one of these years ago. good van but only realy good for about sixty would do seventy but the engine would scream it done all the usual things crawl up hills etc but wasnt as bad as yours sounds sorry cant help any further sounds like you need a good diesel mec all the best jeffro


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## CliveMott (Mar 10, 2008)

Pull the carpet out from under the accelerator helps a bit!

C.


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## Penquin (Oct 15, 2007)

It would help people make suggestions of suitable people to ask if we knew where you are located; it sounds as if the engine may not be set up properly but it would take a mechanic plus perhaps a computerwith the appropriate diagnostic tools to check what is happening.

Spcialist mechanics would be able to give advice I am sure, a lot of owners know who they trust in their area.

Dave


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## JohnsCrossMotorHomes (Jul 21, 2007)

Have you by chance checked the fuel filter, restricted flow will affect power.

Peter


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## Mike48 (May 1, 2005)

I had similar symptoms to these an a car and it turned out to be valve timing. It happened after a reconditioned engine was fitted when the mechanic lined up the timing marks incorrectly.

Fuel of course is another possibility or anyhing to do with engine management. This problem is best solved by a garage with appropriate diagnostic equipment.


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## G2EWS (May 1, 2006)

Hi Spins,

Excuse my ignorance but I am going to assume this is a turbo diesel engine.

I had a similar problem on Claire's BMW 530D which flat out was only just about getting to 70mph. Took it to the garage and they knew exactly what the problem was. The air filter on the turbo was blocked. Happens all the time they said!

Regards

Chris


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## Otto-de-froste (May 20, 2005)

I'm not technical, but I think it would be difficult to provide any definitive answers without knowing the age of the vehicle, age and mileage of current engine, who reconditioned it, and whether it was done properly

I speak from experience of building a few engines on bangers when I was a student, and from memory never made a good 'un

My experience of non turbo Mercedes is mostly with PSV, and they would flat out at about 60
Autos were a bit more sprightly than manuals, which needed the delay between changes that you would expect from larger vehicles

That said, they were 5 speed with 1st as a 'crawler'

Hills were not much of a problem, but the lack of a turbo will surely impose on performance

Sounds like you need to get a diesel mechanic to run some tests, but even so I wouldn't expect it to fly up hills

Hope you get it sorted though; I know how frustrating it can be
Otto


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## gaspode (May 9, 2005)

It sounds to me as if the pump timing needs advancing (I assume it's a mechanical pump). This can be quite easy to do on some engines, dunno about yours but I've done it before on land rovers. Basically you just release the pump and turn it slightly as you would with the distributor on a petrol engine. Mark the start point so you can return it to that point if required.


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## weldted (May 1, 2005)

*performance or lack of it*

hi i would start with the cheapest options first!! This was never going to be a stunning performance power unit even from new, but i would start by first check the hand brake/rear linings are not binding it was known for the handbrake linkage to seized and cause binding of the linings to the drum, its a simple check and a bit of wd 40!! Is the air filter clean, usually if this is blocked you would get some black smoke but not always, try removing it temporally and a quick run down the road will tell. check the vent to the fuel tank on this model it does not have a pressurised tank like the newer ones. If air cannot get in fuel can't get out. The next step would be to take it to a diesel fuel specialist as they would have the test equipment to check it properly, if the timing belt has been fitted incorrectly they will be able to tell because the spill timing will be out, and they will be able to check the fuel metering valve. good luck hope this helps.


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## weldted (May 1, 2005)

*performance or lack of it*

hi i would start with the cheapest options first!! This was never going to be a stunning performance power unit even from new, but i would start by first check the hand brake/rear linings are not binding it was known for the handbrake linkage to seized and cause binding of the linings to the drum, its a simple check and a bit of wd 40!! Is the air filter clean, usually if this is blocked you would get some black smoke but not always, try removing it temporally and a quick run down the road will tell. check the vent to the fuel tank on this model it does not have a pressurised tank like the newer ones. If air cannot get in fuel can't get out. The next step would be to take it to a diesel fuel specialist as they would have the test equipment to check it properly, if the timing belt has been fitted incorrectly they will be able to tell because the spill timing will be out, and they will be able to check the fuel metering valve. good luck hope this helps.


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## teemyob (Nov 22, 2005)

*307*

I used to drive one of those when I was 16.

Do you know the engine power is only around 65-78 bhp with a new engine? and as you say, non turbo (the current BMW Mini One has 75bhp!)

Nippy on setting off when unladen but when they have any weight on, won't pull the skin of a rice pudding.

TM


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## vardy (Sep 1, 2006)

Comments about 1987 307D on Carsurvey.org (I was trawling for info on the same subject, as my Talbot has an identical performance to your Merc:

'Purchased as campervan - man it's sooo slow!'

'Weird ultra low 1st gear only needed when heavily loaded'

'Sloppy gearchange'

'Economy not bad 25-35mpg'

'Uncomfortable to drive - heavy steering, noisy engine'

'Any more than 65 and it sounds as if a rod is going to pop through the engine'

'Reliable, starts first crank, even when freezing'

Is this one of your own posts? - because it sounds very similar! My van only improved when new clutch fitted but it's never going to keep up in fast traffic.

Do you sneak around the faster roads at 5 in the morning when setting off too? - If so, give me a wave, there's a few of us about!!! :lol: :lol: :lol: 

- Helena.


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## rogerandveronica (Aug 11, 2008)

Like jeffro, I had a similar truck up to five years ago. 65 on the flat absolute max, but 23 to the gallon, 168,000 miles on orginal engine with no major attention. Very nice to drive provided you had patience. Very very safe.

I sounds as though you have one if the following
Fuel limiting through bad filter or lift pump
Air limiting through blocked air filter (mine once had leaves in the inlet duct).
Wrong injection timing.
Lack of full travel of the actuating arm on the injector pump. This is the most likely. If the vehicle will not reach 60+ mph foot right down when desending a long, reasonable steep hill, then this is the most likely cause. It is easily checked on the vehicle without the engine running, just get someone to push the throttle right down whilst you check the movement on the injector pump arm, if you can turn the arm more than a snippet further, you are suffering lack of travel which would expalain you problem.
Good luck, rogerandveronica


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## Spins (Sep 11, 2009)

*Non Performance*

Many thanks to all of you that responded to my questions. To answer some comments:

I'm afraid I don't know who re-conditioned the engine (if indeed it is a re-con engine but I don't think it would be painted blue when new) The mileage is 32000 'ish but I did find an invoice for a speedo head and the van was first registered in 1982.

This is the first post I have made on this subject, but it's nice to know I'm not the only one. Perhaps I should organise a rally!

Just after I bought it (last September) I had it serviced. They replaced gearbox and rear axle oil, both fuel filters, glowplugs, the air filter, oil and oil filter, the fuel pipe from pre filter to pump as well as both hand brake cables. The van passed it's MOT in December so I don't believe the brakes are binding.

I would like to pick up on a couple of points. The actuating arm. Is that attached to the throttle linkage? Because the whole shooting match seems to be loose. When the accelerator (Ha! there's a misnomer) is pressed fully down there is up to 1/4" play on one of the levers attached to (what I think is) the lift/injector pump. Do you know how it is adjusted?

Secondly when I bought the van there was no key for the filler cap so I bought a new one which looked the same as the original. Should there be a vent in the cap or is there a vent in the tank, if so do you know where it is?

I'm determined to solve this problem but just in case, we're based just outside Seaford in East Sussex so if anyone knows of a good, local diesel mechanic I'd be grateful.

If you are out and about and see a Mercedes Challenger Carlton struggling up a hill give me a push! I'm fed up with the wife and dog trying to look as if they're not with me!


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## rogerandveronica (Aug 11, 2008)

Thanks for your latest information. My similar vehicle was M reg and had a vent pipe fed back to the inlet manifild for pollution control. If you have a problem with tank venting you would probably have normal power when you started a journey and the power loss would slowly get worse. Also if you removed the cap after a loss of power you would hear and feel the release of the vacuum in the tank.
As for correcting the throttle slack, make sure that` the pedal is going right down and not "sitting" on carpet. 
As you stated the actuator arm is connected to the injector pump. The shaft vanishing into the injector pump should not wobble about much in its home. If it does you have a problem. The adjustment for slack in the throttle linkage on some vehicles is by mean of a screwed rod end or ends in one of the actuating rods, on some it is by means of slotted holes in a bracket on which is mounted a bellcrank (right-angled piece which rotates and changes the direction of movement by 90 degrees) on other vehicles it is normal to bend one of the actuating arms in the likage (not the one on the injector pump).
Good luck, rogerandveronica


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## Spins (Sep 11, 2009)

*Non Performance*

Hi rogerandveronica

Many thanks for the quick response.

The throttle pedal is a narrow plate hinged at the drivers end that pushes down onto another plate of a slightly smaller size therefore only allowing the pedal to travel so far. The carpet is under the lower plate and does not come into contact with the throttle pedal at all. So I have ruled out the carpet as the problem.

There is not a sudden in-rush of air when the fuel filler cap is removed so I don't think a vacuum is being created in the fuel tank.

I'll have another look at the throttle linkage over the weekend and report back.

Do you have any knowledge of the fuel return valve? and is it possible that a compressed spring may be sending too much diesel back to the fuel tank and therefore starving the engine?

Of all the things I've lost I miss my mind the most............ ozzy osbourne


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## rogerandveronica (Aug 11, 2008)

Spins - sorry< I have no knowledge of a non-return valve. If it is this valve causing a problem you would stil be able to get up to speed downhill and crawl uphill.

If your speed limitation occurs all the time it is a revs limit that is the actual problem which must be due to the governor system in the injector pump not allowing you to raise the revs any more perhaps due to the throttle linkage.

If the speed/revs limitation occurs whether it is uphill, downhill or on the flat it is very likely just the linkage. If someone has fiddled with the limit adjustments on the injector pump it could also affect you the same way. Do not re-adjust the limits, get it set up properly if it turns out to be this. 

But if it seems that you can you wizz downhill without effort but just crawl along the flat and uphill it is likely to be fuel delivery/air delivery/injector pump timing related. (i.e. a gross lack of power)

I think that the original engine and gearbox on my truck were painted grey - but it was some years ago. 

Good luck, rogerandveronica


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