300tdi Acceleration problems, feels like clutch slip but isnt! Any ideas??

Hi All,

My 300tdi discovery has started to do the following, when the revs reach a certin amount (around 2000) the revs increces on there own, even if the accelerator is held in one position, at first thought it was the clutch slipping as revs would increase but truck wouldnt get faster, but even does it in neutral. have fitted a larger intercooler, could this have something to do with it (although it has been fine for 12 months or so).

Does anyone have any ideas, they would be greatly recived.

Possibly the boosting of the turbo coming in? You do not say if the road speed changes. (oops yes you did) go back to turbo coming in.

regards

Dave

The turbo boost coming in is correct tho isnt it? but that should come with extra power? For example if I put my foot down to overtake the car will speed up untill the revs reach around 2000 then revs will go up but the car speed doesnt increase, this happens by its self as soon as 2000rpm is reached and the revs continue to go up even if I stop acclerting only when I back off do revs go down, there seems to be no power with these extra revs! Know that sounds just like a clutch issue but does the same in neutral!!!

Quite simply, you cannot have an increase of revs whilst in gear without an increase in road speed, if you have then the clutch is slipping.

Try this, start engine, handbrake on real hard, select 5th gear and try to pull away with 2,500 + revs and make a serious attempt to drive away with the brakes on.

Do this when the car has been driven for half an hour or so. This will ensure that you are working a warm and well oiled engine. If the engine stalls then the clutch is not slipping, if you manage to get your foot off the clutch and the engine stays running then you need a new clutch.

This is very hard on the car and if the clutch is on the way out then this might finish it.

Incidentley, whilst out and about earlier this year running up some mountains I had some clutch slip, so when I got home I pulled the boxes out only to find a real cheap clutch had been fitted, I fitted a decent one along with a new fork (do this as a matter of course) and all is cool.

regards

Dave

benjiboy said:

Hi All,

My 300tdi discovery has started to do the following, when the revs reach a certin amount (around 2000) the revs increces on there own, even if the accelerator is held in one position, at first thought it was the clutch slipping as revs would increase but truck wouldnt get faster, but even does it in neutral. have fitted a larger intercooler, could this have something to do with it (although it has been fine for 12 months or so).

Does anyone have any ideas, they would be greatly recived.

Click to expand...

I take it you can hear the revs increasing and it's not an electrical fault in the alternator or the head. Don't exactly understand the neutral explanation, sitting still or moving. The turbo wont boost unless it's under load moving.

If the revs are raising and there is no change in speed then the clutch is slipping. Take it to an incline, and whilst it's moving dip the clutch slightly whilst the revs are held about 2500 in 4th, just for a second. When you release the clutch again, if it's fooked the drive will be lost for a few seconds as the plate attempts to get a grip. If it's well fooked you will have to back off the throttle a bit to get drive again.

You can also try this with the handbrake on, a stall test, but if you are not careful you are going to break something, and I have seen good clutches blown to bits.

you sure yer not accelerating with a slipping belt and it stops gripping at a certain rpm thus throwing the rev counter up but not your engine speed????

RAZ8550TDI said:

you sure yer not accelerating with a slipping belt and it stops gripping at a certain rpm thus throwing the rev counter up but not your engine speed????

Click to expand...

Now that's a good suggestion!!

regards

Dave

indeed, probably the most common to lead people into beliving its clutch slip aswell, looks like yer getting a boost of power but the only thing that is getting a boost of power is the reading the the rev counter!