W124 turbo diesel lifters

[300TDT]

I have a '94 3.0 turbo diesel - done about 250K miles. I've had it for the last 12 years so know it's history. The rocker cover (is it still called that?) has never been off and a loud tapping is now coming from that area. I've had it before but it normally disappears after a minute or 2 as the oil gets pumped around. I've always assumed it's the hydraulic valve lifters.

This time however, it's louder than usual and is there permanently.

Any clues?

My main concern is, is it likely to be damaging anything?

 

[turbopete]

does the tapping go off above 1200rpm? injectors are a common fault on the 606 engine. could just be that the tappets have given up or the aux belt tensioner! tappets and injectors will both make the engine run less efficiently

 

[300TDT]

Tks for reply turbopete - yes certainly up to 2000 rpm. Bit difficult to hear after that owing to other engine noises! My engine is the 603.960. it was not sold in the UK as far as I'm aware (I brought mine in from Germany, LHD).

 

[turbopete]

i have a uk 210 e300td and it rattles up to 1200 rpm. i know its the injectors as it takes air in the fuel when its revved up and if i leave it idling long enough i get more smoke than normal coming out of the exhaust as the air works its way out, and the rattle quietens down! rev it up/ drive for a while and rattle returns. mines a 606 engine, but diesels all run along similar principles! try pushing on the tensioner with a pole of some likd to put it under pressure against the belt. it will quieten down if its faulty

 

[300TDT]

Turbopete - I'll try that. Thanks

 

[Number_Cruncher]

The lifters are easy enough to check if you find it isn't the belt tensioner damper.

With the cam cover off, find the cylinders where the valves are closed, and the cams are pointing away from the lifters, and gently push down on the surface of the lifter with a soft, non-metallic rod or bar. You're looking for a lifter that's noticably softer than the others, and pushes down more easily. You'll probably need to slowly turn the engine over to allow the cam to rotate, to check all the valves.

Using an oil which is thin (or at least thinner than many oils) when cold, such as a 5W40 helps lifter noise considerably on these engines.

 

[300TDT]

Thanks Number Cruncher. I'll try that first - although probably ought to think about replacing the injectors and belt tensioner after 250,000 miles as well.

 

[Number_Cruncher]

It's the bushes in the end of the belt tensioner damper, or sometimes the damper itself that can make noise.

Number 332 in this link

http://www.detali.ru/cat/oem_mb2.as...GA=722.357&CT=M&cat=503&SID=20&SGR=045&SGN=03

With the engine running, push on the damper with a bar or pole, and see if the noise changes.

If you're concerned about an injector being the cause of the noise, one by one temporarily slacken the injector pipes while the engine is running. If one injector in particular causes the noise to stop, then, you know that you need to investigate that cylinder more closely. If you did find the noise suddenly stopped on one cylinder, I would then swap that injector with another, and see if the noise moves. If yes, it's the injector, if no, it's something more mechanical in that cylinder. Apart from the sealing washers under the injectors, this costs nowt!

 

[300TDT]

Thanks again. I'll try a bar on the tensioner first, then loosening the injector pipes. I like the idea of starting with the nil cost tests!