Bodged repair...

simon_wall69

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Just got my car back from a Bosch diesel injection specialist place in Stoke - the car had a fuel leak on the IP and needed the seals renewed. This they did and there are no leaks.

However, since I have got the car back, it now only starts on four/five cylinders and takes a bit of revving to run on all six.

Also, the car hangs onto its gears until over four thousand revs before changing up. Then when driving, the slightest pressure on the accelarator and the gearbox kicksdown a gear.

I assume the gearbox issue is due to a vacuum pipe being knocked out. I don't understand the starting though, there is no more air in the fuel and the glow plugs are fine. What have they done to the car???

It is going back on Monday but I haven't great hopes as I doubt they are familiar with the none-injection bits of the car.

Thanks in advance for anyone who has been bothered to read all of this!

Car is w124 e300 td multivalve n/a estate.
 

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I am not good with diesels,,but would this not be just that if not running on all six the power will be down, upsetting the gear box changes,,sure they may have knocked off a vac pipe to the box
 

Alex Crow

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check they have correctly reconnected the 'kickdown cable' on top of the engine with the throttle linkage. also yes, it does sound like a vacuum pipe may have been left off. does the glow plug light come on and go out/stay out like it should??
 

Number_Cruncher

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I agree with AP, check the kickdown cable.

The bracket which holds the kickdown cable to the inlet manifold has quite a bit of slop in it, and if you just re-fit it and hope, there's a good chance the cable will be out of adjustment.

To check, simply pop the connector off the kickdown cable, and check that it sits without pressure next to its ball on the accelerator linkage. If not, tweak the adjuster accordingly.

As a hint to setting the cable correctly, with full throttle and kickdown, the car should change up somewhere near the dots on the speedo.

Running on a reduced number of cylinders at start up is a more complex problem. After the revving, does the car continue to run on all six, or, does it revert to 4 / 5 at idle? does the problem go away completely on a hot start? While running on 4 or 5, is there a lot of smoke from the exhaust?
 
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simon_wall69

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I agree with AP, check the kickdown cable.

The bracket which holds the kickdown cable to the inlet manifold has quite a bit of slop in it, and if you just re-fit it and hope, there's a good chance the cable will be out of adjustment.

To check, simply pop the connector off the kickdown cable, and check that it sits without pressure next to its ball on the accelerator linkage. If not, tweak the adjuster accordingly.

As a hint to setting the cable correctly, with full throttle and kickdown, the car should change up somewhere near the dots on the speedo.

Running on a reduced number of cylinders at start up is a more complex problem. After the revving, does the car continue to run on all six, or, does it revert to 4 / 5 at idle? does the problem go away completely on a hot start? While running on 4 or 5, is there a lot of smoke from the exhaust?

Yes, forgot about the kickdown cable.

It did revert to 4/5 at idle; when warm it ran and started on all six. There was a lot of smoke when not running on all cylinders.
 
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simon_wall69

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check they have correctly reconnected the 'kickdown cable' on top of the engine with the throttle linkage. also yes, it does sound like a vacuum pipe may have been left off. does the glow plug light come on and go out/stay out like it should??

The car went straight from a service to the injection place, as the mechanic noticed that the fuel pump had a fuel leak. The glow plugs were checked on the service and they are all fine. The glow plug light comes on and goes off exactly as it should.
 

Number_Cruncher

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>>There was a lot of smoke when not running on all cylinders.

This at least means that fuel is getting into the non-firing cylinders, but, it doesn't tell you that the injection is happening properly or, at the right times. If you can isolate which cylinders are missing - by slackening injector pipes and listening - you might find that repeating the delivery valve seal replacement on those pumping elements might help. Did the injection specialist also replace the copper crush washers?

Was the engine starting without any misfire prior to the injector pump work?

If this is an ongoing problem, it could be that those injectors aren't spraying well enough to fire under marginal conditions, but, sorry, it's also possible that you have a compression problem.

If you check the compressions, and find the rearmost cylinder(s) down, it will most probably be inlet valve seat recession - this can be confirmed by running with the inlet manifold off - you'll see exhaust smoke chuffing back out of the inlet ports.
 
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simon_wall69

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>>There was a lot of smoke when not running on all cylinders.

This at least means that fuel is getting into the non-firing cylinders, but, it doesn't tell you that the injection is happening properly or, at the right times. If you can isolate which cylinders are missing - by slackening injector pipes and listening - you might find that repeating the delivery valve seal replacement on those pumping elements might help. Did the injection specialist also replace the copper crush washers?

Was the engine starting without any misfire prior to the injector pump work?

If this is an ongoing problem, it could be that those injectors aren't spraying well enough to fire under marginal conditions, but, sorry, it's also possible that you have a compression problem.

If you check the compressions, and find the rearmost cylinder(s) down, it will most probably be inlet valve seat recession - this can be confirmed by running with the inlet manifold off - you'll see exhaust smoke chuffing back out of the inlet ports.

The problem is new.

I assume that the compression is fine, as when the inlet manifold was off, I did the test as you describe - that was about 500 miles ago.

Before was fine; could they have altered the injection timing when doing the seals? They did the job with the pump in situ, so I don't see how this could have happened.

I have had injector problem before so this could be it, and it is just coincidence. I will have to ask about the crush washers.
 

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Pump in situ? Could they have dropped some crud into the bores?
 

Number_Cruncher

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OK, so, there's no compression problem - that's good news!

Yes, dirt or leaks in the area of the delivery valve can easily cause problems - it's because of this type of risk that I usually advise against DIYing this job - however, I'm sorry to see that you are in this situation having gone to an injection specialist. However, I hope that their guarantee of their work, will cover you - what gurantee do they offer? What's written on your bill?

Part of the function of the delivery valve is to give a smart, sharp, well timed, start and end of injection. If the valve leaks then injection may be much later then it should be, which would produce rough running and smoke.

There's also a seal between the top of the plunger bore and the lower edge of the delivery valve holder which is subject to full injection pressure - any leakage here will reduce the "jerk", the sudden increase in pressure which in conjunction with the delivery valve gives a sharp beginning of injection.

The seals both of the delivery valve itself, and the seal between the top of the plunger bore and the delivery valve holder have no gaskets or rubber seals, they rely upon an accurate "lapped" surface finish of the steel parts themselves. The tiniest spec of dirt will ruin this seal.

The rubber seals which were originally leaking between the outlet flange and the injector pump only seals against lift pump pressure, 30 psi or so as against the 2000 psi or so of injection pressure being sealed by nothing other than good metal surface finish.

If there has been any dirt caught between the top of the plunger bore and the delivery valve, then, if that dirt has embedded into the metal, it may be difficult to ever get a good seal there again without replacing the entire pumping element.

I hope that the injection specialist behave honourably towards you in rectifying this problem.
 

stu2009

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A friend of mine had this problem on his 300d. It would run rough for about 30 seconds in the morning with lots of smoke and then it would be ok. It turned out to be the glow plug. The wiring had been bodged at some time in the past.
 

Alex Crow

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another possibility to add is that one of the plastic fuel line clips - which ALWAYS break - has fallen into an inlet port and slightly bent a valve. this has been known to happen before!! also beware the 2x flaps in the intake system, they also break and can get into the wrong places, although generally will be in bigger pieces than the inlet runner diameter.
 

Number_Cruncher

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another possibility to add is that one of the plastic fuel line clips - which ALWAYS break - has fallen into an inlet port and slightly bent a valve. this has been known to happen before!! also beware the 2x flaps in the intake system, they also break and can get into the wrong places, although generally will be in bigger pieces than the inlet runner diameter.

That's a very fair point AP, and a distinct possibility.

I take the view that all right thinking mechanics would either plug the ports with rag, or run a length of duct tape across the open inlet ports whilst the manifold is off.
 
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simon_wall69

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Well, took the car back today - flat out it would do 55mph on the way there.

When I arrived, the engineer who had dealt with the car was adamant it was nothing to do with him and the issues already existed. I showed him the receipt for the service, and the car had done 15miles since then. We went on a test drive and he accepted there was a problem but was adamant he had done nothing to the car that could have created the issues.

Three hours later there was a phone call: they had adjusted the kickdown cable but there was little improvement. I explained that I held them for full liability, that the issues were created by them and demanded, in polite but firm tones, that I would not accept the car until it was fixed fully at their expense.

One hour later, another phone call: everything was sorted, ready to be picked up.

As a doubting Thomas, I turned up expecting the car to still be knackered; however, miraculously, everything was fixed. The cold engine fired up on all six, took it for a test drive: smooth changes about 2,000rpm, went up a steepish hill without needing to kickdown. I went back to the garage to thank them for fixing it promptly.

The mechanic claimed to have only adjusted the kickdown cable. I don't think he wanted to admit he hadn't put everything back together again properly.

Anyway, all sorted. The car cruised past 100 (kph of course) on the M6.

Big thanks to Number Cruncher and Alexander Patient for their selfless imput, without whom I don't think I could have put a case to the place whereby I would have sounded like I knew what I was talking about!
 


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