2.1td Erratic Running

[robmc52]

Don't know if this is a diesel or electrical problem to be honest,when it's at idle the revs are steady, when held at, say, 1500 rpm the revs will rise and fall by 2 or 3 hundred revs either way. When under way, it doesn't feel like hesitation as such but as if the air con compressor is cutting in and out.moments later as if the throttle has been opened slightly. Thinking it may be fuel starvation I've checked the tank filter which is clean, the fuel heater, which has been bypassed and the fuel filter which looks fine. (Was going to change it but the shop was shut) All the fuel pipes look ok with no leaks, a couple needed tightening up a bit but that hasn't had any effect. Is there anything else on the fuel side I should check? Or could it be something electrical?

cheers
Bob

[techmanagain]

With respect, it is no use checking for air leaks visually as the supply pipes from the tank are under negative pressure (i.e. vacuum). Make sure the pipes are flexible, particularly where the metal pipes from the tank joins the rubber pipe to the fuel filter. As a belt and braces measure, use Jubilee hose clips on all the visible and accessible fuel pipes in the engine bay; it's surprisingly effective.

[Peter.N.]

I would concur with techmanagain, but do change the filter if its any age, as that can cause the problem. You can check for fuel leaks by parking the car on a steep downward slope, so that the fuel tank is higher than the engine, with any luck you will see it leaking.

Peter.N.

[robmc52]

Thanks for the replies chaps, I take the point about the flexibility of the rubber pipes, they do feel ok, I'll try putting some clips on the ones that aren't already done and cut back and rejoin where it joins the metal pipe. Been to Newport in Wales today and back, the car ran for miles very smoothly and would then hesitate/accelerate for a while. Didn't really spoil my enjoyment though, a steadyish 3000 rpm there and back and that lovely ride made it very pleasurable.

cheers
Bob

[robmc52]

Right, the good news is it's running smoothly at last. Bought a new fuel filter today and discovered an extra o ring in the box that I couldn't find when I dismantled the filter assembly. It's the small one that goes on the little screw in drain thingy in the bottom part of the filter, about 4/5 mm in diameter. Just put it all back together and the car is as smooth as a very smooth thing. I can't believe that such small part could make that much difference.

Now for some more bad news. After having such a nice long distance drive yesterday, I hadn't gone more than ten feet down the road this morning when the most appallng racket started from underneath the front of the car. If you can imagine the sound of a heavy toolbox being dragged across a rough concrete floor then that's pretty much what it was like. At first I though it sounded like a knackered wheel bearing but after a few hundred yards it began to get quieter and then gradually disappeared only to reappear after I'd stopped and then pulled away from a junction. I checked the brakes when I got to work but they don't seem to be sticking on, I can push the car with ease with the parking brake off and it pulls up straight when brake tested. The only things I can think of would be the parking brake dragging slightly or maybe the driveshaft bearing under the engine starting to go. I'm stumped really, especially as there was no hint of this after driving 350 miles yesterday.

cheers
Bob

[Peter.N.]

Hi Bob

If the noise is increasing with road speed as opposed to engine speed and is having no noticable effect on the running of the car, I would suspect the centre bearing on the drivers side driveshaft.

Peter.N.

[robmc52]

Hi Peter

Turns out to be the o/s wheel bearing after all, and the ball joint is worn as well. That long run last weekend finished it off by the look of it! I was quite suprised to be honest, my limited experience of wheel bearing failure led me to think that they normally take a while to go, usually with plenty of warning. Oh well, the nice people at Medway Citroen are sorting it out so I may get the car back before the weekend.

Bob

[Peter.N.]

Hi Bob

Well, that's a new one on me, I have never had a wheel bearing fail that spectacularly. I have had them make a noise like a tram which has continued for thousands of miles until I eventually got fed up with it and replaced it. They will usually whine for many thousands of miles, but as I say, I have never had one fail completely. Anyway, pleased it was nothing more serious.

Peter.N.