'82 240D Idle Adjustment
#1
12-17-2010, 04:30 PM
'82 240D Idle Adjustment
I have a '82 240D that I cannot seem to get the idle adjustment correct. I have not had any problems until a few months ago when the level that it had been out for years was too low such that at stop signs the engine would die. I adjusted the idle screw so that with the A/C running it would not die on start up. However, this caused the engine to race after warming up and driving a few miles. At stop lights I have to turn the enigne off because it is racing so high. Any trouble shooting suggestions would be greatly appreciated. The engine runs fine, no smoke, no oil consumption. It is only the problem with the idle level that is casuing any problem.
#2
12-17-2010, 05:49 PM
Are you using only Diesel Fuel?
Other things that have an effect on idle:
The Fuel Supply pressure being too low due the Fuel Supply/Lift Pump being worn or the Fuel Pressure/Overflow Valve on the side of the Fuel Injection Pump is not holding at low pressures.
An Air leak on the suction side of the Fuel Supply/Lift Pump. Hoses or if you have the Old style shiny Aluminum bodied Hand Primer that is noted for causing Air leaks when it gets old.
Is the Valve Asjustment within specs?
The issue of the Idle being OK when you first start and not returning after you are running could be a Throttle Linkage isssue (is the return Spring still there?). Lube up the little ***** and Sockets on the Linkages.
In the attached thumbnail the circled part is the tip of the Stock Type Injectors. #14 and #15 are tiny drilled passages that over time plug up with Carbon. The little drilled pasages are there for the idle amounts of Fuel and the Fuel is supposed to squirt through them.
When they are plugged it has an effect on your idle. On my Engine it would shake a lot. When I installed new Injector Nozzles most of that shake went away. Adjusting the Valves also took away a good portion of the shaking.
Besides my Injectors most of the Injectors I have pulled at the Junk Yard were also plugged up.
While Injector Cleaner or more specific a Diesel Purge might keep the drilled passages clean if done on a regular basis. I do not believe either will clean out the passages if they are already completely plugged.
Other things that have an effect on idle:
The Fuel Supply pressure being too low due the Fuel Supply/Lift Pump being worn or the Fuel Pressure/Overflow Valve on the side of the Fuel Injection Pump is not holding at low pressures.
An Air leak on the suction side of the Fuel Supply/Lift Pump. Hoses or if you have the Old style shiny Aluminum bodied Hand Primer that is noted for causing Air leaks when it gets old.
Is the Valve Asjustment within specs?
The issue of the Idle being OK when you first start and not returning after you are running could be a Throttle Linkage isssue (is the return Spring still there?). Lube up the little ***** and Sockets on the Linkages.
In the attached thumbnail the circled part is the tip of the Stock Type Injectors. #14 and #15 are tiny drilled passages that over time plug up with Carbon. The little drilled pasages are there for the idle amounts of Fuel and the Fuel is supposed to squirt through them.
When they are plugged it has an effect on your idle. On my Engine it would shake a lot. When I installed new Injector Nozzles most of that shake went away. Adjusting the Valves also took away a good portion of the shaking.
Besides my Injectors most of the Injectors I have pulled at the Junk Yard were also plugged up.
While Injector Cleaner or more specific a Diesel Purge might keep the drilled passages clean if done on a regular basis. I do not believe either will clean out the passages if they are already completely plugged.
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