Sounds like a bus

[Marjani]

I have a 1998 E Class 300TD current mileage is 100k. I have owned the car for one year and have put 40k on it. It has one previous owner. It has FSH with main dealers and a non franchised specialist. It has averaged 37mpg and if I am careful it will still do 42 mpg.
I have recently changed the glow plugs, serpentine belt and damper; I fitted new return fuel lines whilst I was there.
Shortly after I completed this work the engine at idle sounds like a bus from the inside of the car but only when hot say after 3 miles. I cant seem to identify anything noisy under the bonnet. It starts and runs fine and is not noisy off idle or on load.
It sounds like a transit has pulled up behind me.

Any ideas?

 

[turbopete]

how on earth do you manage those kinds of fuel figures? i have to be exceptionally careful to get over 35mpg (39.2 is my record!) i have what i think could be a similar noise all the time though. stealer reckons its injectors and apparrently its common on these. ive got air getting into my fuel though so im sorting that (hopefully) first as mine quietens down occasionally and it seems to coincide with less air in the fuel!. incidentally, does the noise disappear with revs, above say 1200rpm?

 

[DesM]

I'm also amazed as I get 32 pretty much regardless how I drive.
Anyhow, I have had a similar sounding feature on my 99 E300TD for the last year and have done 15k trouble free miles since it appeared. She sounds like a tobacco tin full of rusty nails at the lights but is fine above 1000 rpm. I believe that this may be wear in the (I'm not sure of the correct term) stabiliser bar that is bolted to the head at the front of the engine. I think there is a bush in there and in mine I think its just worn. Way to tell is to gently wedge a screwdriver against it at tick-over and if the noise goes away then Robert is your mother's brother. I'm going to have to deal with mine sooner or later so if anyone has any guidance on how to do it then this somewhat useless mechanic would appreciate the counsel. Des

 

[Marjani]

Hi Guy's
Firstly the fuel consumption, it's no secret as you can see 40k in one year is a lot of miles and these are almost all motorway or dual carriagway, and on these road I keep it to 70MPH!!
The noise disappears when the revs or load is increased. It's still smooth and quiet on the road.
I don't think it's the damper as I have just replaced it, but I will check this weekend.
Thanks for your advice, I will keep looking.