Any Disco experts out there?

Just forked out for a new tyre for the truck as I'm getting her sorted ready for the winter time, went to start it as I hadn't used it for a week, and got a loud knocking from the engine. Intermittent then it seemed to go away for a few seconds, then came back again. It seems to lessen with revs but I am reluctant to give her too much throttle until I know what it might be

I drove it round the yard and the noise was still a little intermittent. Seems to be worse when I drop the throttle so my fear is that the Big ends are the culprit

I'm not 100% and I always thought that they would give a gradual increas in noise and not go suddenly?

Anyhow, anyone got any ideas?

I might try and record the noise tommorrow and put it on here to let folks know what it sounds like.

Any help really appreciated.

Thanks guys & Gals

200tdi?
300tdi?
Td5?
TdCi?
Or petrol?

Service history?
any other symptoms such as smoke, loss of power, loss of coolant, loss of oil

Doh!! What a muppet, I am so miffed at it going wrong I forgot to say!

It's a 300TDi, was auto with EDC pump and fly-by-wire throttle, but I had so many issue with the elcronics, I replaced the pump with a mechanical one and fitted a cable throttle. She's been runnig fine since I did it, (last summer), but today started this knock

I have noticed it was down on poweer but seemd to be sweet enough running until now.

I do have to top up the coolant a fair bit but I put that down to the leak at the top of the thermostat housin (there is a cap that screws into it but I need to replace it). Not drastic but annoying.

JB

[Edited on 22/10/12 by Daddylonglegs]

Is it firing on all four cylinders ?
Stuck injector/s ?

quote:

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Originally posted by Wheels244
Is it firing on all four cylinders ?
Stuck injector/s ?

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That was going to be my first suggestion ref the miss-fire.

In my experience the injectors don't really give that much trouble.

Can you check the timing yourself?

These engines can often 'chuff' from the back of the cylinder head, it's a common place for gasket failure, it doesn't blow into the water jacket so doesn't manifest in overheating. at tickover it could be mistaken for a knock and at higher revs could go unnoticed due to the general increase in engine noise.

can you get under it when it is running? that would make it a lot easier to establish if it is a bottom end knock or not.

The easiest way would be to swap them over with a known good set to see if that's the problem.
Do you know anyone with the same engine that you could borrow a set from ?
Or whip them out and get them tested at a diesel specialist.

I've still got the set I had from the EDC engine setup, I guess I could try replacing them one at a time (the #4 is a special sensor injector so cannot use that one). I know they are OK because I had them tested when I had the original fault.

Have you got rid of the number 4 injector with the EDC wire that is an auto specific injector?

maybe you have a conflict with this injector and your manual pump? potential problem with the EDC wire maybe chaffing and causing a miss fire?

Yep, like I said, I changed the pump over from the EDC to a mechanical, and I also changed all the injectors for the reason you state. All the gear came out of a fully working non-EDC motor and has run fine since last summer.

Sod's law says it will play up just before the weather when I will probably need it on the road

As you've got a good set, I would try the swap first - cost neutral.
With a bit of luck that might sort it.
Keep us posted.

Will do, tommorrow's job sorted then...

Check if your turbo is leaking. A ruptured membrane in the turbo's valve will cause the symptoms you describe.

Steve, in the NLs

Well, it appears it's not quite as drastic as I first thought.

The noise seemed to be coming from quite high up in the engine, so I removed the aux belt and the noise stopped!

So, it's either alternator, water pump or power steering pump. I doubt that the water pump would make such a loud noise but cannot guarantee it. nothing seems to have excessive play, but I have had a squeaking for a few weeks which seems to have lessened so maybe a precursor to something related?


I found the power steering reservoir cap loose too so I must not have tightened it down last time I checked the fluid, and the reservoir was quite low, so now I am thinking that maybe I've foobarred the pump running it low? After I put the belt back on, the noise seemed to have gone, but then as the engine started to warm up a liittle it is still there occasionally. It seems worse on the overrun. With my hand on the alternator I can definitely feel the knocking, but that doesn't necessarily mean the alternator is at fault because the steering pump is directly mounted along with it so could be knocking through the bracket?

So, what is the general concensus, alternator or steering pump, and would the fluid being low (about 1" down in the reservoir) knack the pump?

cheers guys

tbh I can't imagine how either makes a knocking noise, does the noise get louder when you put on all the lights/heater/back window demister etc and load it up. Or the steering pump when you turn the wheel lock to lock?

Are all the aux belt pulleys on tight? None coming loose? Belt in good condition? (turn it inside out - did that to a cam belt once, and all the teeth were delaminating off the backing!)

quote:

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Originally posted by Mr Whippy
tbh I can't imagine how either makes a knocking noise, does the noise get louder when you put on all the lights/heater/back window demister etc and load it up. Or the steering pump when you turn the wheel lock to lock?

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