250 with idle problems

[veggy tastic]

hello again!
whilst sitting in traffic the other day i noticed that the car was idleing really lumpily. the whole car was rocking as though there was a misfire. when i rev the engine it settles out and revs fine but on idle its lumpy and makes quite a loud tapping noise. i cant decide whether its from the diesel pump or the engine. but fairly sure its coming from the engine.
Does anyone know know if these cars burn valves out eaily. the car has done 200+k miles and is a five cylinder.
if worst comes to the worst im going to take the head off and rebuild it as i have to drive it to croatia in september on a £100 charity banger rally.
any advise would be much appreciated!!
thanks

 

[veggy tastic]

well...
i just had the cam cover off to see if there was anything that looked suspicious ie: cam or tappet damage. which there wasn't then put everything back together. i still get the tapping noise on idle but cant figure out which end of the engine it is at???? im starting to think its a tappet that could be worn out?
if it is, is it a big job to change one?

 

[GEORGEROV]

Do you think your problem could be with running it on veggie oil?. Quality of fuel could be the issue. Seen diesels that are noisey on normal derv but so much quieter on BP Ultimate for example. Imagine that they would be even worse on veggie!.

 

[wireman]

Are the engine mounts OK? dud ones allow the engine to bounce about for fun. Dont buy the £25 cheapies they do not have the fluid filling of the MB units. When my mounts were changed the fan sat in the middle of its cowl, prior to this it sat low in the cowl.

The tappet noise is a common problem that usualy goes away at engine speeds above idle once the running temperature gets high enough, so is the thermost in good order ie does it run at above 80 deg? if not put a new stat in and prepare to be surprised by how much better it runs when properly hot.
Some engines benifit from flushing the oil, there are oil additives for tappet troubles and I have heard (but not tried) that adding a good dolop of ATF to the oil for a short time before an oil change can cure gummy tappets.
If its only on tickover that there is a clatter it probably will be harmless.

I have not seen a burnt valve on this model but if you do change exhaust valves the old ones must be disposed of with some care, their stems are sodium filled and will spontaneously ignite (violently or even explode) if cut open and exposed to air/water.

And if you do remove the head take great care not to break the camshaft by not removing it by the correct proceedure, you must not just release the cam bearings they must be removed in the correct sequence.

 

[steptoe]

I had a noise like this on my 270K mile 250TD last year - My noise was a sealing washer under one of the injectors.