The weather hasn’t been to cooperative lately 12 degrees this morning. It could be a combination of glow plug & compression, valves are past due for adjustment. Though usually if a valve is out of spec it seems to be to tight in my experience. Hopefully I can get it in a garage this weekend and check it out. I’m not sure when they start selling winter blend fuel around here, but son ran it out of fuel in late October early November. Fuel gauge isn’t accurate. I’ll post what I discover.

Based on this statement, I would bet your major problem is an in-tank filter partial clog. The filter picked up junk from the bottom of the tank.

12 degrees here today. Car wouldn’t start. Has started the rest of the week with temps ranging from upper 20s-30s in the morning. If it was the in tank filter caused by the tank running dry wouldn’t have been a problem before now since that happened about 3 months ago?

If temperature is the sole condition that seems to be determining whether or not the car starts, I'd start with a valve adjustment, then do a compression test. If you have tight valves from lack of adjustment, you'll lose a fair bit of compression, and that's more important the colder it gets. If it was starting fine in the 20s, your fuel lines and glow plugs are probably working properly.

I won’t be able to check the glow plugs until this afternoon. A local parts store has champion GP they can order the Bosch. But I need to try to fix it this weekend. Has anyone had much luck with the champions.

I replaced the glow plugs in my Volvo diesel with Champion brand plugs once. My experience taught me that Champions are good to buy if you want to get really good at changing the glow plugs quickly, because you will be changing them out again in short order. I had three fail outright within six or seven months. I realize that timing is an issue for you, but I'd never use them again. That said, a functioning Champion plug will start the car better than a dead plug manufactured by a better brand, so.....

Do yourself a favor and add a gallon of kerosene or a bottle of anti-gel additive to the tank before you go nuts with repairs. I think you're getting summer fuel from somewhere.

what engine oil are you running?

dramatic difference in cold starts going from 15w-40 to 5w-40

after checking everything else this can help for winter starting issues

Well checked the glow plugs. Three tested good (.8 ohms), ones reading kept jumping all over the place. So bad glow plug. Local parts store was able to order Bosch GPs from one of there other locations. Should have them for me tomorrow morning. JB3 I am running 5w40 oil. Hopefully this will take care of it then I can adjust the valves on a warmer weekend.

I went to full synthetic diesel oil on the 84 & 85SD. Starting is not a problem with either car when the battery is charged and glow plugs are working. Dino oil causes problems.

When near 0, I glow twice, turn the key to crank and keep it there. I tap the fuel pedal if it doesn't light almost immediately but crank once only. I'll keep the engine cranking until it starts or the battery dies. So far, this always works. There were times perhaps only with dino oil that the 2nd crank never worked when it was in the low teens or lower. I've read where others say you only have 1 crank.

Remember to check alternator voltage with the glow circuit disconnected when it's cold outside. I've had the parts store test rig condemn the alternator when the only issue was the GP circuit was energized.

Changed out all 4 GPs today. Started right up. Today’s temp is 40 degrees. Yesterday I started it so I could move it into the driveway to work on it today, it was about 35 degrees. Cycled the GPs 3 times before attempting to start it and still was hard to start. Would have never thought one glow plug could make that much of a different at above freezing temps.

I have another question about the the glow plug circuit. I have a short in the instrument cluster which causes the fuel & temp gauges to give erratic readings. It’s now causing the GP light to glow erratic too. Will that keep the plugs from glowing correctly? I can reach under the dash move around the wires & cluster and cause the light to change intensity.

That's not a short, shorts blow fuses or melt wires. You probably have a poor ground connection or broken solder joints somewhere in the cluster.

Sorry you are correct it is a poor ground. But the question still is when the orange light on the dash doesn’t glow or is dim does it keep the glow plugs from heating up? I ask because I know some vehicle charging systems will not charge if the light on the dash doesn’t work. Not sure if the glow plug circuit works the same way.

No, the glow plug light is just an indicator. The glow plug relay controls everything else, the light is just there to let you know when it's preheated long enough to start the engine.

You need to get a new fuel, oil pressure, temp gauge. This just happened to me and I ignored it for awhile until the fuse box completely melted and the alternator will not charge the battery if that pin is shorting out/ grounding out (whatever the correct term is) and u will end up stuck somewhere.

I had a guy on this forum willing to sell me one for $20 shipped. So id do that as well. Maybe your battery is not charging all the way and thus adding to this hard start problem