'81 300SD totally gutless until warmed up - PeachParts Mercedes-Benz Forum

tradonguy · #1 03-02-2006, 09:35 AM

My '81 300SD is totally gutless until it warms up to operating temperature. It is so bad that, if I try to drive it before it warms up, I could have an accident because I can't get out of the way of traffic until the engine is warm. Some of you are going to tell me to wait until it warms up and I do most of the time but there are those times I'm in a bit of a hurry. I don't think it's normal. There must be something I can do, like adjust the ALDA or something. If any of you has any good advice, please let me know. Thanks.

By the way, when it does warm up I have to watch I don't get a speeding ticket.

boneheaddoctor · #2 03-02-2006, 09:38 AM

When have you last checked your valve clearances? These turbodiesels are slugish for the first few minutes when its cold out (mostly in winter). but should be running well long before it gets up to operating temp.

tradonguy · #3 03-02-2006, 10:17 AM

I haven't had the valve clearances checked since I bought the car 2 years ago and I've put less than 2,000 miles on it since then for pleasure use only. The mechanic who had been servicing the car said it didn't need them checked but I haven't had much faith in his advice. He keeps telling me that I just have to live with the problems.

kerry · #4 03-02-2006, 10:24 AM

Given your location and the time of year you're posting, I'd say it's normal. Think of it this way, when you start it in winter, you've got 20 hp initially, then you get one additional horsepower for each degree for the first 100 degree of temperature increase.

boneheaddoctor · #5 03-02-2006, 10:27 AM

well when you get a chance check the valve clearances...you have no way of knowing what they are unless you checlk them THere is a good article on the DIY Atricles tab at top of screen.

But when its very cold out expect it to be a slug till the engine warms up a bit.

The fact it runs fine warn tells me you have no plugged banjo bolt. and your fuel filters are not an issue.

Trick is determining if your situation is within whats normal or if it excedes that.

I assume it starts easily in cold weather without a block heater....Is this the case?

tradonguy · #6 03-02-2006, 10:42 AM

Wow. You guys are great. I really appreciate your quick responses. It doesn't always start well in the winter so I have decided to purchase a 12 volt line heater to be hooked up with a second battery in the trunk to heat the fuel just before the injectors. This sounds like it is going to help solve part of the problem. See http://www.fattywagons.com/fwproducts.htm

Thanks very much guys.

Nate Stanley · #7 03-02-2006, 10:43 AM

These cars were built to run correctly when cold, though a tad slower until they warm up- but most diesels are like that. To blow this problem off by saying "live with it" is proof he really doesn't know these cars. My 300D can bark the tires in a 1-2 shift when cold, though I don't make it a practice.

I agree with BHD- check those valve clearances. Lots of previous owners may not have a clue about this requirement, especially if the PO was the 3rd or 4th owner of the car.

My own SD runs erratically when cold and smooths out when hot, but it's not on the road yet and I haven't even had time to pop off the valve cover. But I definitely will do a valve service before I start driving it.

boneheaddoctor · #8 03-02-2006, 10:44 AM

what sort of tempratures does it start ot be hard to start....this can speak volumes about compression etc.....

dannym · #9 03-02-2006, 10:53 AM

Are you running straight diesel or are you cutting it with Kerosene?

Ken300D · #10 03-02-2006, 11:06 AM

Valve Clearances.

This is not only the most likely issue, it's also a very inexpensive DIY job. There's the investment for the tools of course, but after that it's very cheap.

This is something everyone should do with every new purchase of this vintage MB, because most people don't even know the valves should have been adjusted and never have it done.

Ken300D

tradonguy · #11 03-02-2006, 11:24 AM

I am running straight diesel at this time with no biodiesel or kerosene in the tank. I just put in an additive to prevent gelling but that's all. I do use a few litres (quarts) of my own home-made biodiesel in the summertime. It is harder to start at temperatures significantly below 0c or 32f . And we get very cold temperatures in northern British Columbia.

boneheaddoctor · #12 03-02-2006, 11:36 AM

ok...Mine all start to about 10 degrees F without issue...haven't seen colder weather here since i got them.

at the temps you state its unlikely major wear issues or very low compression.

You could have one or maybe two glowplugs failed...or just a valve or two that is overly tight.

now if it was like 40 degrees F or higher then you would have far worse issues.

If its just 1 or 2 and at most 3 minutes when its that cold outside don't worry....mine is a slug for the first minute or two in sub freezing weather and runs like a strapped ape after that. Point of note...my car does idle smooth at startup at all temps....is your car rough right after it starts or smooth