puzzled up North

[Myros]

Our C280 normally sounds like a fine swiss watch , very quiet, very measured. In the last week or so it has developed what I can only describe as a tappety noise, especially noticeable when hot. I had the bonnet up in the car park this am on getting to work, and it's louder on the exhaust side of the engine, rhythmic tap-tap-tapping in time with the revs.
I run her on 5w-40 fully synth, had an oil and filter change about 1,000 miles ago. The engine is a M104 24 valver straight six 2.8.110,00 miles.1994

Any ideas as to whether it is a tappet, and if so, what am I in for? I read the other threads on tappets and mine seems perverse, as it's quiet on start-up, but noisy when warm.

All help gratefully received.

 

[television]

Two things, when oil is warm it becomes thinner, when the engine is warm, other components expand. Is the noise really loud, don't forget that if parked near buildings etc, this can amplify the sound.

malcolm

 

[Myros]

Malcolm, loud enough for me to hear it outside the car

but just, and I mean just loud enough to hear it inside, radio off. No buildings around to echo off. Quite loud with the bonnet up. Definitely just the one noise though, not a whole bunch of them rattling like a bag of spanners on a cold morning. at idle speed of 750r.p.m. the frequency is about 2hz.

 

[johnnycapone]

If it were a tappet, you could take the rocker cover off and place a screw driver or length of small diameter steel and place the end on each rocker.
If the tappet is amiss you should be able to feel the vibration through the length of the steel. Just be careful not to put it in any moving parts. It is a very old practice but it does work.
Regards
John

 

[C220GJS]

If it's coming from down on the exhaust side check you don't have a leak from the manifold or downpipe, also listen at the drive for aircon compressor.
Johnny; I wouldn't start this engine with the cambox off unless you really fancy a shower in oil, also no rockers, hydraulic cam followers.
Cheers, Geo.

 

[Myros]

thanks for the input so far chaps

I can rule out the aircon, as I don't have it. I don't have any of the other symptoms associated with manifold leaks, such as backfiring etc., just this annoying tapping. I do have a couple of stethoscopes ( oooooh-err Matron). I'll call one of them the car's and have listen to the top of the engine, with all the doings still mantled up.
I first noticed it faintly a few weeks ago when getting out of the car to operate a barrier. Did the same barrier today and it is definitely louder.

 

[johnnycapone]

Thanks for that Geo, mine is obviously a lot older car than this one where you can have the cover off. But the (oooooh er matrons) should still give a good idea where the noise (vibration) is coming from even with the cover fitted.
Cheers
John

 

[cubicincubi]

hope it aint the little ends mate.

 

[turnipsock]

Did the noise start with the oil change?

How is the oil pressure?

 

[Myros]

Can't tell about the oil pressure

don't have a gauge. As far as I can tell, I only heard the noise a couple of weeks ago, which is well after the oil change ( I've been using the SL a lot as well, so not doing so many miles in the C)
However, it is me that is being perverse, as the noise is there on cold start up, just a lot faster with the higher idle and partly masked by the air pump.
Nearly 30 years of motoring experience tells me it sounds like a tappet.
Over to my mechie for a listen I think. Thanks for all the help guys. I fit hadn't been for the security guy at work not lifting the barrier that morning, and making me do it myself, I'd never have noticed at all.

 

[Myros]

so I did my Dr Kildare bit

with the stethoscope, and the noise seems confined to no6 cylinder, back at the firewall, equally on both sides of the cam cover. My mechie says sticking tappet, so I did an engine flush, oil and filter change, and it's still there, I reckon it's been there a bout 1000miles, as I last changed the oil in March,and have only done about 1500 since.
Any more ideas, oh helpful virtual chums?

 

[turnipsock]

a working theory

It may be something restricing the oil flow to the tappets around No.6. Something could have got stirred up when you did the oil change.

The oil flow through the tappets is very small and it is unlikely that the oil would have drained out of them during the oil change.

I changed the tappets on my 230TE a while back, there will be a thread about it somewhere.

 

[turnipsock]

http://forums.mercedesclub.org.uk/showthread.php?t=16058&highlight=Tappety+noise

here it is, like you I wouldn't have noticed if I didn't get out the car with the engine running.

Clive Williams came up with the working theory I post above.

 

[clive williams]

http://forums.mercedesclub.org.uk/showthread.php?t=16058&highlight=Tappety+noise

here it is, like you I wouldn't have noticed if I didn't get out the car with the engine running.

Clive Williams came up with the working theory I post above.

Hi,

Yep! I think we got the same problem here. New oil in dislodges muck from elsewhere and blocks tappet. The lifter (tappet) runs dry and prematurely wears - hence the noise. I would not run the engine but change the lifter soonest before the cam's knackered. The lifter is relatively easy and cheap to replace, the cam's not (a new cam will mean all new lifters anyway). Don't forget to re-shim it and be prepared for thicker shims to take up the slack as the cam will have some wear on it. Also, use a good quality cam building lube when you put the new lifter in as it will take some time to get the oil up. If you can't find cam lube then use Wynns Gear Oil additive in the tube.

Clive

500E
E320CDIT210

 

[turnipsock]

When I did mine, I had the old fashioned oil can and squirted engine oil all over the cam lobe area. I sat the cam cover on and fired up.

I didn't know there was such a thing as "Cam Building Lube"...I think I'll ask the experts at hellfords "Where is the cam building lube mate?"

You learn something new every day and there is only 45 mins to go.

 

[Myros]

Thanks fellas

It looks like I'm off to ECP on the way home then. Should I just do the four lifters on no6 or all 24 on all cylinders?

 

[Myros]

so ECP let me down

they don't do the lifters for the 6 cylinder engines. MB have them at £12.60 +VAT.
I'm assuming I'll need to do all four on No6 to be certain. Is it the same procedure for the 24 valve head as it is for the 4 cylinder engines. Presumable I'll have to disconect the ignition ( carefuly labelling all the parts and taking photographs to aid re-mantling) and then just have the cam cover off.
Will the "thingies" just drift out as you described in your article.

I must get on to MB about the shims as well.

On a different note, I am now trying to get used to the W124 300TE we bought as a family hack. Big is the word that springs to mind initially.

 

[turnipsock]

MB have them at £12.60 +VAT.

Ouch!

mine were about £7 each from the dealer, but I only had to do eight of them on the 230TE.

It might be worth taking them out and giving them a clean. Then reprime them and try again. As the problem only occured when you did an oil change it may not be wear that is causing the problem.

 

[Myros]

Thanks Turnip

but I've had to order four "thingies" from MB any way, just to be safe, as I don't want to be stranded without them. Of course, they have to come from Germany, so won't arrive until Saturday, and I can't get the job rolling until Weds,
Just as well I've joined the w124 T model fraternity, Lot's of room for hauling thingies about in.