PeachParts Mercedes-Benz Forum - View Single Post - 350SD low idle problem... drops to 250rpm at idle, A/C shuts off, engine overheats...

Blevinsax · #1 08-09-2013, 07:20 PM

Hello all - long time no see...

For the last few months my 350SD has been idling too low - typically around 250rpm. It forces me to put it in idle with one foot on the accelerator and one on the brake when I have to stop at stoplights in order to keep it at normal idle speed. The low idle also causes one of the fans to stop and the engine will run hot. With the A/C on it starts blowing hot air and the engine really starts to overheat.

A non-diesel mechanic friend looked at it and when he jiggled a few wires/vacuum hoses under the intake manifold it temporarily corrected the problem. He used a zip-tie to pull the cables and hoses up together and the problem was resolved... again temporarily. The low idle is now back and jiggling the wires/hoses doesn't have any effect.

Otherwise the car runs fine - drives fine, no problems.

What could the source of this problem possibly be? I really need to know so I can just tell a mechanic what to do - otherwise they'll charge me thousands of dollars to 'figure it out' themselves and do a bunch of unnecessary stuff. Unfortunately I cannot seem to find a mechanic in Las Vegas who actually knows anything about working on these cars (and won't charge a fortune to do so) so if you know of a mechanic in Las Vegas who ACTUALLY knows what they're doing and cares to do a good job, please forward their information to me.