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Old 06-01-2002, 09:07 PM
Tim the Taxman
Posts: n/a
Unhappy 240D Smoke & Drive Problems - 2nd try

I would appreciate your advice on a couple of problems. I have a 1983 240D purchased 3 months ago with 133,000 miles on it. Problems:

1. There is a buzz connected to the clutch, driveline??? that is probably always there but very LOUD after 60 mph. It will stop and start almost instantly. Mechanic says to replace the clutch. I don't notice any clutch problems though. When the clutch is tapped when the buzz is on about half the time the buzz will instantly stop for a few seconds, then start again. Resting my foot on the clutch while buzzing, the pedal seems to vibrate more than when buzz is off. Motor and transmission mounts I am told are fine. Any ideas on what this is and how to solve it? How much should a new clutch cost?

2. There is a whole lot of black/dark grey smoke at idle and take-off or when pressing hard on the accelorator at speed. Not noticable at cruising speed. I am in the process of gauging how much oil I am using. Don't appear to have any noticable oil leaks. Mechanic says it needs valve guides (valve job). The air cleaner is clean. Mechacic said to hold off on the valve job for a long while and just keep adding oil to it and forget about the people behind me beathing the smoke. I don't want to spend money if I don't have to, but I am a little embarassed by all the smoke and feel bad for those people behind me, especially in stop and go traffic. Any ideas?? If a valve job is needed, what is the cost? What other repairs should be done at the same time when the head is off?

The car starts and runs fine, with similar acceleration as my 76, although it does chug more than my old 1976 240D. I get 27-28 mpg all the time. I love these cars but I'm beginning to wonder about this one, bought it for 2200 and in three months put another 1600 in it. If I fix the clutch and valve job what else will be going wrong about now! At 137,000 I thought the car was almost new!!

Thanks for any input,


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Old 06-01-2002, 11:15 PM
Registered User
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
Number one complaint I would guess is a bad throwout bearing... or a really gauled pilot bearing... both would normally be replaced on any clutch replacement...

Number two you might have some real improvement for the time being by putting in new valve stem seals... that is done from the top of the engine without taking the head off...

Your smoking problem may be unburned fuel... from bad timing or over rich condition. Fairly easy to check start of fuel delivery , but not exactly fun. I agree about holding off on the valve job... you can also check your precombustion chambers to see that nothing has clogged the seven critical size holes which fuel squirts through... Lots of things could be causing these symptoms before a valve job would be called for... particularly if that mileage is correct ... Greg
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Old 06-02-2002, 11:14 AM
Tim the Taxman
Posts: n/a
Thanks for the information, I was under the impression that these later years 240D's didn't use valve stem seals accessable from the top. Replacing the valve stem seals would help for how long before a full-blown valve job would be needed? Would injector pump timing or bad injectors cause the smoke? How are these adjusted?
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Old 06-02-2002, 12:27 PM
Registered User
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
I am pretty close to absolutely sure your engine has valve stem seals... not that there is not stuff in the way and you need an offset pusher deal and a protective cover on the valve when you install the seal... so as to not mess up the sealing surface when you put it on.... but the actual seals are really cheap..
Not knowing anything about the actual condition of your valve stems... that is pretty hard to estimate...
But in general these are very tough engines , if you keep the oil and filters chenged, and it would not surprise me to see you go another 20,50 or 100 K before you needed the valve job...
Those other items can certainly cause smoke ....anytime you have less than perfect burning of your fuel you are going to have smoke... so if the injection is too early then it has a cooling effect on the air being comopressed, which is what a diesel counts on to ignite the fuel... and the fuel has to be in a fine mist.. or it will not burn properly... so the cleanlyness of the injectors outlet... the precombustion chamber holes have to be the right size , pointed in the right direction, and clean.
There is a ' diesel purge ' sold for cleaning injectors which only involves feeding a can of this stuff into the injection pump which might help .... I have not tried it yet... but others swear by it...

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