High altitude = hard starting?
 

I took my '85, 300 SD to Lake Tahoe, about 6500 altitude last week and it took a long time, many tries, to get it started the next morning after a 40 degree night. Down at sea level it starts very easily. Any of you mountain folk have any suggestions for making the old girl start easier if I take it there again? By the way, FYI, there seemed to be no diesel stations on Tahoe North Shore or even on US 80 in the Truckee area.

I have driven from S.F. to Truckee a number of times and usually don't have a hard time getting going in Tahoe unless it's well below freezing. Be careful though driving up there with fuel from the valley because fuel sold in the valley is seldom winterized yet this time of year. I usually try to fill up in the mountains before I get where I am going because the stations there seem to get the winterized stuff earlier. You were probably getting a small amount of solids settling out in the cold with non winterized fuel. You're probably lucky because most times when that happens you can't get it started at all until it warms up. As to where to buy fuel, there are a few stations around the lake. I know of a Shell station in Incline Village and also another in Tahoe City. There aren't too many along route 80 because the truckers never fill up there, it's much cheaper just across the boarder in Nevada so most stations in Ca. don't bother to carry it for the few diesel heads like us.

LRG

Ron:

A 40 degree night shouldn't have been a problem.

Have you had your compression checked lately? At 6500 feet elevation the air is considerably thinner than down in the valley. A diesel that starts just fine in Sacramento or the Bay Area will continue to do so with reduced compression.
At 6500 feet (or higher) the molecules are not very close together and it becomes harder to compress them enough to get combustion. Having said that, the 40 degree night was a contributing factor in that the oil was thicker and the battery didn't have quite the same energy that it might at a higher temperature.

We're in Arizona at 3500 feet, but have a cabin in Alpine, AZ at 8000 feet. My '82 300D Turbo would start and run fine at the lower elevation and would continue to run OK at 8000 feet. However, starting it with anything short of a very warm engine was nearly impossible, even with a block heater. A rebuild solved the problem. The new compression causes it to start within the first revolution, even without the block heater. (We normally only use the block heater in the dead of winter when we can get sub-zero temperatures at Alpine.

Irg is correct regarding the use of #1 diesel. Try to either get that or else buy a "winterizing" additive and add it before you go up.

Wes

P.S. Lived in Nevada City for over 30 years and had no problems starting there or at Tahoe with a different diesel MB.

My '80SD didn't want to start at lake Tahoe either at about 30 F. Normally when I start the engine I step on the throttle about half way. For some unknown reason I tried starting it again without pressing on the accelerator and it started easily. After that I didn't step on the accelerator when starting and I had no further problems. I have no explanation why this worked. I was at Tahoe this year and had no trouble starting but it was warmer this time.

It does make sense that a Diesel would start harder at a high elevation. The air is thinner so there is less air in the cylinder to compress therefore the temperature inside the cylinder created by compressing the air will be lower. If an engine is leaking compression, high altitude will exacerbate the situation.

~~~~~~~~~~~~~~~~~~~~~~~PEH~~~~~~~~~~~~~~~~~~~~~~~~~~

Thanks for the advice, folks! My good neighbor also mentioned that perhaps I have a non functional glow plug that wouldn't cause me any problem at sea level. All suggested items will be checked.
I was also told that a good way to winterize diesel fuel is to add a gallon of gasoline to a full tank of diesel.

Ron:

Adding gasoline to diesel is for emergencies ONLY. You are far better off if you use additives made for the purpose (or, better yet, buy #1 diesel before heading into colder weather). With your temperate climate, I imagine #1 diesel is harder to find and you might have to go as far as Reno to find it. Most truck stops in colder states (even parts of Arizona) carry #1 diesel in winter.

Cheers,
Wes