I have a 1981 300D that runs great. I even had a mercedes master mechanic tell me for the miles,174k, that its the best he has driven. When we got our cold snap, single digits, the car had a real hard time starting. It was expected. For some strange reason I popped the hood and took off the crankcase vent into the air cleaner. Turned the key and started right up. It has worked 3 times now. Why? Dosen't make sense to me. Maybe I shouldn't question success.

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Mark B

81 300D

The time that it takes you to open the hood allows the engine to recover from the first couple of starting attempts...If you will glow the plugs 2-3 times for the full duration, it should start...I would also install a block heater. They make a WORLD of difference on the diesels.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Benzmac, I would agree but I did an experiment. monday morning low to mid 20s car was cranking and cranking would not start. Opened hood, removed the breather hose, started. Next morning, even colder, removed breather hose. Car started first time. Wednesday morning. did not remove breather hose. Cranked for 5 minutes with no success and then removed breather hose car started right up. Each time i would cycle the glow plugs 4 times. I have never heard of anything like this before. Any ideas at all. I like the fact I know it will start in cold weather, but would like to understand why.

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Mark B

81 300D

OK. You have a blockage, maybe some water is settleing in there and freezing? Have fun with this one. It would be a hard one for a shop to duplicate. I do know if the pipe is plugged, the car will not start. So start with the blocked possibility.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

This is very very interesting....
Crankcase breather hose blockage.
I would've never thought to check that when I was having problems couple weeks ago.
Now the car acts as if the problem never happened, even in similarily cold weather.
Next time there is a problem I'll have to check this.
Thanks.

Tonight I checked the hose for blockage and its clear. I am going to take off the aircleaner and check everything inside.
This one does have me baffled. I will report on what I find.

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Mark B

81 300D