New For Me 1985 Silverado 20 6.2 Diesel

Craig Nedrow said:

Not having fun with the fuel system as the PO really did a number on the wiring underneath, but I think I got the new switch in right. Reinstalled all the dash but the pad, put in LED bulbs, brightened it up dramatically. I have to install the switching valve, and the tanks. I am using the old pigtail as it was previously wired, don't know if it's right, but it is quick and dirty. Very disappointed that we cannot take the truck on our Kentucky trip, pooh, really wanted to do that, but running out of time as we leave next Wed. To many other things going on. I should not have done the heads on the IH truck, took more time then I thought which put me behind. We will take Mom 2018 GMC instead.

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Holy fook! That would be a bonus. Or a disappointment IMo. I can’t imagine a cross country trip in a slow stinky cramped squeaky old truck if I had a suitable newer quieter, more comfortable, faster means of transportation!

Grit dog said:

Just read this, but commenting on fuel gelling.
Not sure why there are so many misconceptions, but generally any and all diesel fuel sold commercially in any area that gets cold weather is treated to prevent gelling at the rack for seasonal low temperatures.
The only times fuel gelling is usually an issue is when old summer fuel is being used, or same fuel from a hot area makes it to cold weather (think leaving Las Vegas and heading to Utah. There are actually signs on the highway about it….), or when an extreme cold snap gets down well below the treatment level of the fuel (ie: you wake up in the morning in Selah and it’s -29deg. Fuel in E WA probably isn’t treated for that low of temp).
It’s simply not an issue for everyday cold weather diesel engines. Unless the unlikely situations above present themselves.
Certainly no reason to be spending extra money dumping unnecessary additives into perfectly good treated diesel. Someone already did that for you.

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Usually "winter blend" is a lot of kerosene.

I've had it happen on a couple of occasions from an unexpected cold snap, right around 15° every time. After that I started using additives in the winter.

Somewhat more recently, like twenty years recently, I started using additives all the time. Not just for the anti-gel, but for lubricity and cetane boost.

The fuel quality in this country has been cr@p since 1994, and got worse in 2007. YMMV, but your fuel system's life will be much shorter on pump diesel.

Blue Ox said:

Usually "winter blend" is a lot of kerosene.

I've had it happen on a couple of occasions from an unexpected cold snap, right around 15° every time. After that I started using additives in the winter.

Somewhat more recently, like twenty years recently, I started using additives all the time. Not just for the anti-gel, but for lubricity and cetane boost.

The fuel quality in this country has been cr@p since 1994, and got worse in 2007. YMMV, but your fuel system's life will be much shorter on pump diesel.

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You’re referencing a 20-30 years ago issue?
+15F is the approx cloud point of straight #2 diesel. So no surprise there, you weren’t using winter blend….
Maybe the suppliers in NY weren’t doing the right thing or maybe this was before pretty much all diesel was winter blended for the conditions. I recall some of our diesels gelling back around 1990 when I was just beginning to work on vehicles and drive.
But since the early 2000s when I started running diesel pickups full time, everywhere from the Southern Rockies to Prudhoe Bay, I can think of 2 occasions in 20+ years where diesel has gelled unexpectedly and rarely/never added anti gel. Both were in Colorado and both times it was about -30F, extreme cold snap, and the blends for that area weren’t stout enough to go that low. Crippled all the diesels in Denver one morning, lol.
Same goes for the 1000s of med and heavy diesel engines I have been around in the same timespan.
Bottom line your 30 year old diesel gelling assumptions are false and have been for a long time.

And yes diesel lubricity has gone down along with sulpher content, also right on schedule with your statement. Yet it’s amazing how many millions of diesel engines run for 10,000’s of hours with no lube additives and original pumps and injectors. Don’t doubt the ULSD (way after the early 90s switch to lsd) affects fuel system wear n tear, but there’s also a lot of hype around what one “must do” to preserve their fuel system wear components.

And winter blend is sometimes #1, sometimes additive packages. Most of the time you won’t know what it is at the pump.
In extreme temps #1 is used more than additives due to cost.

Geez Todd, I took my 53 five window, all stock with a 235 engine all the way to Gainesville Florida, Via Bakersfield. That is the truck, after it was painted and motor swap. That is the original motor, it is brand new now, with a little Isky cam. I plan on upping the compression, single four barrel intake and run a Holly 350, split the manifold myself, and "split" the intake on the head. Should be about 150 hp, with a five speed. The rear is a Dana 60 W/4:56 gears. It will be amazing quick for short distances. I used to race it on the "AVE" with 4 speed Muncie, different rear end but same ratio, beat alot of V8 sleds. BTW, I sold that black truck, so to stop confusion, I will put it in this green truck.

Craig Nedrow said:

She alive!! drove to town worked great, except the glow plug relay wouldn't come on once, but tapped it with a rock and it worked? Anyway, busy waxing, and putting the canopy that doesn't fit right back on, and basically hope to take this to the World of Speed on Sept 6th to watch the races for a few days. I damaged my tailgate, here is the new one, bugger. Bonneville will run from Sept 6th through the 10th, incase anyone is interested. I will be going by myself, as Jan is not yet up to it, camping by the "turn in the road". Maybe I will se someone there?????

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Well, that turned out nice!! Good job.

HELP!!!!! Took my truck to town, 19 miles, purred like a kitten. Went out to start it after I was done, and no glow plugs... messed with the wires, tap, tap on relay, but to no avail, so buttercup rescued me. Next day, took the GMC and trailer down to load it up, and the truck started right up, glow plugs worked straightaway, and no problems. However this is nerve racking. It is not fuses, and it works when cool? the controller is new, but you all know how that goes, new bad parts, but it was GM. I think I will take that relay/controller off but? it is sealed, could grind the rivets and take it apart see if anything is wrong inside...What to do...

Was the engine still warm when you went to restart? The glowplugs don't function if the coolant is over 100°.

You know Derek, I was hot that day, and cranked it lots, got tailpipe smoke, but no fire. This truck will not start without turning on the glow plugs. Is their a wire and sensor to the block or the radiator, or does it work in conjunction with the temperature sender, which seems logical. I could unplug that I guess if it would cycle the glow plugs.

Craig Nedrow said:

You know Derek, I was hot that day, and cranked it lots, got tailpipe smoke, but no fire. This truck will not start without turning on the glow plugs. Is their a wire and sensor to the block or the radiator, or does it work in conjunction with the temperature sender, which seems logical. I could unplug that I guess if it would cycle the glow plugs.

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There is a switch on the pass side cylinder head. There's also a switch for the cold start timing advance and idle stepper. The problem is I don't remember which is which. I also don't remember the specifics of how it works, so I'd have to consult the manual, which I don't have handy.

If you want to trace the green wires from the injection pump you can at least dope out which switch it is. One is on the side of the head at the firewall end, and the other is screwed into the block off plate behind the intake manifold.

I'll be back at the shop on Tuesday if you still need me to look that up.

GM later offered a switch that disabled glow plugs at a higher temperature to aid in "warm starting."

There's another prospective issue, which is that a tired injection pump may not deliver enough fuel when it's hot to start the engine. Hard starting when hot is the first sign of a worn head & rotor assy.

The pump was rebuilt by a very good company, it all they do, and Thank You Derek for the timely info.

Is your electric advance working? Maybe your engine needs a timing bump too? Sometimes they need an advance bump when the injection pump gets to a certain level of wear, unless that's not good practice?

squaredeal91 said:

Is your electric advance working? Maybe your engine needs a timing bump too? Sometimes they need an advance bump when the injection pump gets to a certain level of wear, unless that's not good practice?

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Pump is brand new, just rebuilt, and seems like it's working like it should. I have not checked the timing, that is a good idea. What is initial, and total, anyone know?

I found the problem: A glow plug inhibit switch mounted in the passenger side cylinder head at the rear of the engine disables the glow plug controller if the engine coolant temperature is greater than 125 °F. This switch/sensor is a common failure point and is often disabled by owners as the OEM part numbers are becoming obsolete. Although its function is to prolong glow plug life by disabling the system when the engine is warm, it can be safely bypassed by simply splicing both connector wires together; it is a normally closed switch: from Diesel Hub.
So I think I will try splicing the wires together and see if that works because it seems to be the fix, cheap, and as long as the controller works, (it is,) the glow plugs will cycle and the truck will start.

I believe this is the culprit glow plug inhibit switch, pass side behind the glow plug. I did not pull to check, just made a jumper wire to connect both sides together. See pic 2. Drove the truck today, and no problems. Also both fuel gages are working, what a blessing!! I need to fix the window washer, as it does not work, and I have not spent any time diagnosing it. Also the left side blinker does not cancel, but don't want to pull the steering wheel off right now, maybe this winter. Working at finishing the K20 frame, will buy epoxy paint on Wednesday, Hope to paint maybe later this week, the weather is ideal to paint outside, my only option. I will paint chassis black after the primer, should be a thing of beauty. It will be nice to have the frame done and out of the shop, as I want to start on the cab. Most of the body work is complete, so stripping, a small amt. of body work then primer and color sand etc.