Threaded heater hose connections on radiator?!

[someotherguy]

'93 C3500 dually 7.4/NV4500 - the radiator in this truck looks like it's from a GMT400 application (fit is correct in all visible ways including upper and lower radiator hose connections) but it's probably not original due to age/abuse. It does look old and possibly OEM, though.

The heater core isn't connected currently, suspect previous owner broke the quick connect on the intake as it's all gooped over in some plasticy crud I'll eventually have to chisel out and deal with what's left of the connector.

The heater connections on the passenger side radiator tank have me a little puzzled. There's two of them. One above, and one below, the upper transmission cooling line connection. And, they're threaded internally. One has a plastic plug similar to the drain plug on some aftermarket radiators, and the other has what looks like some type of aftermarket temperature sensor - plastic hex head and a single pin that doesn't look like any GM-style connector I've seen. Nothing was connected to it and there's no unclaimed wires nearby.

I had pulled the plugs out because I thought they might be some kind of previous owner hack, and they were weeping a tiny bit, so I was ready to remove them and cap the connections off until I deal with the heater. Surprised to see the threads in there. Anybody seen this?

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Richard

 

[Schurkey]

I don't recognize those fittings. Never seen 'em before.

Wild Guess: The sensor is for coolant level, not coolant temperature.

 

[Caman96]

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[someotherguy]

I don't recognize those fittings. Never seen 'em before.

Wild Guess: The sensor is for coolant level, not coolant temperature.

Wild guess = right on target. I wasn't even aware such a thing existed on these trucks, but Rock lists one for my application. GPD # 1712572 - from the application chart looks like this sensor was used in squarebodies and into early GMT400's ending in 1993.

Gonna have to do some searching in the engine compartment again and see if I can find any loose or damaged wiring. The only unaccounted for wiring I'd found so far was the A/C compressor clutch where the socket had been broken right off the back of the clutch so it wasn't immediately identifiable.

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Yep; had just found it in aftermarket (GPD) on Rock, part # above ^^^ but I wonder does anybody here have this on their truck? Does it operate a dash warning light or something? I may have to peel open the crusty owner's manual and see if it has any info.

Richard

 

[Schurkey]

I wonder if that was an option...or perhaps used on the Diesel trucks.

Neither of mine have a level sensor.

 

[Caman96]

I wonder if that was an option...or perhaps used on the Diesel trucks.

Neither of mine have a level sensor.

When you put his info in on RockAuto it does list a coolant level sensor. But then if you look at all the listed radiators, it doesn’t show any with that option.

 

[someotherguy]

Yeah, it's weird. I'm pretty sure it's not original to the truck. If you look at the 6.5td stuff there's a Liland radiator listed "with low coolant indicator" and another from Spectra that looks like it has the spot for it in the picture, but the pic is kinda small.

I think I'm through worrying about the mystery; it's probably indeed a radiator swapped from a diesel. It's old and I hope it just holds up through a few Houston summers before I have to replace it.

Richard

 

[smdk2500]

I know the 94+ diesels have a coolant level sensor but it is in the overflow tank on the firewall. Never looked at my buddys 93 when he had it. Also I know the radiators changed in 94 on the diesels they went to the pressurized overflow. Again on the diesel trucks there is a light on the dash. It just says low coolant. I don't know where to tell you to look since I don't have anything older then a 95 to look at anymore.