Diesel engine sound.

I have a M Reg 300tdi with 230000 miles on the clock.

It idles a bit roughly with the engine vibrating a lot where others I look at idle smoothly. When I put my foot down there is a sort off sensation that it is missing, like a petrol engine missing a spark on one of the cylinders.

I have given it an oil service and run some injector cleaner through the tank with no improvement.

There is not any access black smoke and the water is fine so head gasket is ok.

Could it be a faulty injector? Or could the timing be out? I would be happy to get the engine to idle smoothly.

Also I had a squealing serpentine belt that I changed and at the same time I fitted an aircon belt that had been missing since I brought it. I ckecked the pully on the pump was not seized and it ran freely which it did.

Now the engine sounds different. There is a (not unpleasant) whirling sound that changes with the revs. It dwarfs the diesel clatter and gives the engine a pleasant humming sound as I go along. Not silly loud but just nice. Hard to describe without hearing it.

Is this normal for the 300tdi's with aircon? The aircon button lights up but switching it on makes no difference to the sound.

There are two separate issues here I reckon:

1. The aircon system - if when you select aircon there is no difference in the temp of air coming out the vents, the system is not working correctly. If you want it to work properly you will need to spend money. My advice? Take the belt off.

2. General poor tickover and running. At that mileage I would be putting a new cambelt kit on and in the process resetting the timing. Once that was done I would adjust the tappets.


Good luck

Dave

Cheers Dave. I was thinking about a timing belt change. Is it a fairly easy DIY job or are special tools required? I read something about a locking tool to lock the pulleys.

I have not checked if the air is cooling as I do not use it daily and when I have used the disco it's been freezing outside anyway so trying the aircon would be difficult to tell.

What I thought though was their would be a noise change from the compressor when switching it on and there was not.

If it don't work then I will leave the belt on as I prefer the noise it makes now to the diesel noise. It sounds very modern and efficient. Lol

Have you changed the fuel filter?

Yes, but I went to check the one under the chassis and the drain plug was sheared off. I want to get a set of o rings before I take the thing apart from the top to empty it.

Could this cause the rough running?

When I emptied the water from the bottom of the fuel filter there was only a little bit.

Brian S said:

Cheers Dave. I was thinking about a timing belt change. Is it a fairly easy DIY job or are special tools required? I read something about a locking tool to lock the pulleys.

What I thought though was their would be a noise change from the compressor when switching it on and there was not.

If it don't work then I will leave the belt on as I prefer the noise it makes now to the diesel noise. It sounds very modern and efficient. Lol

Click to expand...

If there is a change in the engine note when you switch the air-con on, the compressor is engaging. This means more drag on the engine, less performance and less mpg, but it's your choice of course.

Re the cambelt change I did one on my wife's car three weeks ago and these are the 'special' tools I used:

1. Deflecting bar torque wrench - for setting the new belt tension;

2. Six sided sockets for the pulley bolts that must be slackened off;

3. Timing pins for the injection pump and the flywheel plus puller for removing the crankshaft pulley:
12pc Timing Kit - 2.5D, 2.5TD, 200TDI, 300TDI (usually 58.00GBP)

My advice when doing the job? Don't skimp on removing stuff when doing the job. Some people do it without removing the radiator for example but I would not recommend that, you need good visual access to line up the timing marks.

This is the broad brush of how I do a TDi cambelt change:

1. Remove the radiator grill, the viscous fan, empty the cooling system and remove the radiator;

2. Remove the serpentine belt, the crankshaft bolt and pulley;

3. Prepare a piece of carton and mark the bolt positions on it as you remove the timing cover fixings, then remove the cover and install the two timing pins;

4. Undo the tensioner and idler fixings and the 3 injection pump bolts, to slacken the tension on the old belt then remove.

5. If replacing the idler and tensioner (recommended) now remove the old ones and lightly affix the new ones;

6. Install the new belt ensuring that the cambelt pulley is perfectly lined up with it's mark, tighten up the idler fixing, set the belt tension, tighten the injection pump pulley bolts and lightly tighten the tensioner fixing.

7. Remove the timing pins. Now using the crankshaft pulley bolt on the shaft, turn the engine over two complete revolutions, reinstall the pins then undo the injection pump pulley bolts and allowing to settle, then retighten. Check that the camshaft pulley is still perfectly aligned with it's mark.

8. Remove the pins and turn over two revolutions, insert pins, check cam pulley alignment and assuming all is correct tighten all fixing to their correct torque and reinstall the timing cover plate.

Additional advice:

Good opportunity to flush out the radiator while it is dismounted; good opportunity to flush out the engine of any old crapp; good opportunity to put in new OAT antifreeze; good opportunity to put in a new thermostat - at about £4 why wouldn't you? Also check all coolant hoses and clips and replace as necessary.

Good luck

Dave

Cheers Dave. That's great advice.

It sounds quite straight forward. I will also get a cam cover gasket as a think it is leaking a little and check the tappets. Should be safe for a while then.

:beer:

Brian S said:

Cheers Dave. That's great advice.

It sounds quite straight forward. I will also get a cam cover gasket as a think it is leaking a little and check the tappets. Should be safe for a while then.

:beer:

Click to expand...

It is straightforward mate but please please don't do what I did the first time I did one.

I was trying to undo the injection pump pulley bolts (10mm from memory) and I couldn't shift one because someone previously had mullared the head by using 12 face sockets rather than 6 face. So I thought I would get away without undoing it.
NO!!!!!! Put everything back together, went on a testdrive - everything lovely for about 5 mls, then a bit of a ticking grew to a knocking and when I got back to my place there was a thwap! and the engine stopped.

The belt had moved, the cam pulley had come undone somehow and 4 pushrods and 1 rocker bit the dust.

So please, get the bolts undone, doing things logically, torque everything before putting the cover on and you'll be fine.

It always surprises me how much I learn when I muck up

I've learnt everything I know from cocking things up then doing it properly.

I am getting better though.

As a great man once said;

Every day, in every way, I'm getting better and better.

I want to do the belt on mine but I am still not sure how people manage to do the crank pully back up i dont really want to spend the 70 odd quid on the tool

Tuskenraider said:

I want to do the belt on mine but I am still not sure how people manage to do the crank pully back up i dont really want to spend the 70 odd quid on the tool

Click to expand...

200 or 300TDi?

His signiture says 300tdi.

Ah - dont read sigs (they is turned orf) - too much crap in them

The Mad Hat Man said:

Ah - dont read sigs (they is turned orf) - too much crap in them

Click to expand...

i agree ¬¬¬¬¬¬¬¬

I did not know you could turn them off.

Much better now.

Brian S said:

I have a M Reg 300tdi with 230000 miles on the clock.

It idles a bit roughly with the engine vibrating a lot where others I look at idle smoothly. When I put my foot down there is a sort off sensation that it is missing, like a petrol engine missing a spark on one of the cylinders.

I have given it an oil service and run some injector cleaner through the tank with no improvement.

There is not any access black smoke and the water is fine so head gasket is ok.

Could it be a faulty injector? Or could the timing be out? I would be happy to get the engine to idle smoothly.

Also I had a squealing serpentine belt that I changed and at the same time I fitted an aircon belt that had been missing since I brought it. I ckecked the pully on the pump was not seized and it ran freely which it did.

Now the engine sounds different. There is a (not unpleasant) whirling sound that changes with the revs. It dwarfs the diesel clatter and gives the engine a pleasant humming sound as I go along. Not silly loud but just nice. Hard to describe without hearing it.

Is this normal for the 300tdi's with aircon? The aircon button lights up but switching it on makes no difference to the sound.

Click to expand...

does it go VROOM? iif not, it should

It does now...

I have been having battery trouble lately, car not firing after a lots of cranking, until the battery dies, but firing straight away on a jumpstart.

After charging the battery last night and putting back on this morning (In the light) I noticed the earth cable goes to the chassis with a little clamp in the middle to bolt it to the body. This little clamp that was loose where the cable was soldered to it, obviously a lousy Earth.

I drilled through the cable and attched it directly to the clamp and cleaned and checked all the other earths and it now runs much much better.

Went to see a mate at Motormania for a charge test and the battery is giving out about 13v with engine off, then there is about 14v on idle, a little low but should be ok for a while. So I saved the cost of replacing the battery.

Its a lot smoother, still a bit rough on idle, but seems the idle speed has increased a little to help, but runs lovely. I run it around this afternoon, and when I was nearly home it started to stutter a bit going up a hill, so I guess there is still a fuel issue to address.

I am picking up some new o ring seals for the fuel sedimenter on Saturday so I can clean that out and I am sure it will be good.

So at the moment I am very happy.

Just got to sort out the soggy suspension, noisy alternator, cambelt change, abs light... you get the idea...