I am working on a 83 300sd that has no fast idle when cold. Have checked and lubed the linkage. How does the pump know its cold and how do I go about a repair. I'm sure It has no effect but the Temp guage is broke always on cold.

i could be wrong but I really don't think the 617 has a cold idle swithch or function for that matter.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

You're not wrong, fast idle comes from applying pressure to the accelerator pedal with your foot. Older MB diesels have a knob on the dash for this.

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TXBill



Former owner of a few diesel MB cars
1998 Lexus ES 300 In Chicago We Trust

I totally forgot about that knob thing. I had an old 300D with one but it didn't work. So used to the SD now.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

I don't recall a fast idle circuit in either of my 126 SDs. The idle was fine after a cold start but there was no power for a minute or so. The SDL with electronic idle control behaves the same way the SDs did.

Sixto
95 S420
87 300SDL