Block Heater Thermostat?

ArcticJ · December 6, 2005

First time here...great forum...here it goes

I just purchased an 06 Z71 Tahoe with the factory block heater. On the plug, according to the manual, is a thermostat that only allows the heater to operate at temperatures below 0 F, or -16 C. My wifes 05 Suburban has this also. I'm guessing the "thermostat" has something to do with the bulked up plug/round tumor located behind the metal prongs...just a thought. My 95 and 99 Tahoes and 02 Suburban had the heaters, but did not have the thermostats and operated flawlessly.

My question is what's the purpose of this thermostat? Is it just to keep one from plugging it in when it's 50 outside? Is it in reaction to someone damaging their block somehow? Or is there a part within the engine, introduced within the last year or two that can be damaged if the heater is used when the temp is above 0F?

The manual says not to use unless its below 32 F...makes sense. But then they go and do this, limiting the use to below 0 F, which is @%*^in cold...

Ultimately, could I lop off the old plug, replace it with an easy to locate orange one, rated for the watts and go ahead and use the heater as designed, at realistic temps such as 10-20 F without damaging anything?

Thanks for you thoughts.

8.1L · December 6, 2005

Interesting question. My manual (8.1L Yukon XL) says that in weather <0F, the block heater can 'help'. The 'coolant heater' should be plugged in at least 4 hours prior to starting the truck. At temps >32F, use of the heater is not required.

It then goes on to say that the vehicle may have an internal thermostat in the plug end of the cord (as you suspected), which will prevent operation of the coolant heater in temps >0F.

My guess is that since yours is set up this way, you won't need to use it above 0F. It won't, of course, help a weak battery. My son was a mechanical engineer in Chassis and Powertrain Development at GM for a while, and the way they test these vehicles and components, I'd go along with their recommendation. It is hard not to tinker, I will admit.

Don't know if that helps, but that's my $0.02.

Jim

fossil · December 6, 2005

I guess they want to save energy.

I lopped mine off. I like mine plugged in at -10C. Starting it up at those temperatures not plugged in just promotes more wear and tear which you end up paying for.

Wingnut · December 6, 2005

If I had one, I'd plug that sucker in when it got below 50F.

Yeah, I'm a wuss.

ArcticJ · December 6, 2005

I guess they want to save energy.
I lopped mine off. I like mine plugged in at -10C. Starting it up at those temperatures not plugged in just promotes more wear and tear which you end up paying for.

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Probably right...but I want to stay warm and reduce the wear on my engine...have you had any problems? Did you use any special plug, or just a basic hardware item?

Thanks for your input...apparently not very many people have experienced this or even know about it yet.

ArcticJ · December 6, 2005

If I had one, I'd plug that sucker in when it got below 50F.

Yeah, I'm a wuss.

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I'm with ya Wingnut...I don't want to wait until it's 0F outside...to darn cold

Shaners · December 7, 2005

My truck owners manual states that the cord may have the internal thermostat, but my Dmax supplement manual doesn't mention any thermostats.

So I plugged her in tonight ( temps around 20 in the garage tonight), and I'll see if it makes some difference tomorrow AM @ 5:30.

ArcticJ · December 7, 2005

My truck owners manual states that the cord may have the internal thermostat, but my Dmax supplement manual doesn't mention any thermostats.

So I plugged her in tonight ( temps around 20 in the garage tonight), and I'll see if it makes some difference tomorrow AM @ 5:30.

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Thanks Shaners...FYI the plug with a thermostat is a bit longer than normal with a circular tumor on one side where the wire meets the plug. If w/out the thermostat, the plug looks like a standard 3-prong plug...

Good luck...

Im waiting impatiently with my wire cutters and a new plug

Shaners · December 7, 2005

I just went out to the garage and there is a little warmth in the first 1" of my ext cord by the wall outlet, so I'm guessing that the heater is working.

Shaners · December 7, 2005

I just went out to the garage and there is a little warmth in the first 1" of my ext cord by the wall outlet, so I'm guessing that the heater is working.

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OK here is the results. The block/coolant heater in the Dmax definatly works regardless of the outside temp. I just popped the hood on my truck and I could feel the heat rolling out from under it when I unlatched it. Everything on the motor is warm, including the top radiator hose!!

dewfpo · December 7, 2005

Sounds like the block heater plugs are different on the diesels (no built in thermostat in the block heater wire) than for the gassers (built in thermostat in the B?H wire).

I park my truck in an unheated garage. Even thought it was -8F last night, the temp in the garage was +19F (since I used the truck last night) and it heated up the garage a little after shutdown.

At +19F the 8.1L BB in my truck turned over a bit slower than I'd like but it fired up pretty quickly.

I wonder what the P/N is for the diesel block heater wire/plug. I would think that I could just swap them out.

DEWFPO

Shaners · December 7, 2005

I wonder what the P/N is for the diesel block heater wire/plug. I would think that I could just swap them out.

DEWFPO

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I was wondering myself it it could just be swapped out for the people with gas motors that want to use the block heater before temps get to 0*.

I was also thinking about getting a heavy-duty outlet timer, so I can set it to turn the block heater on about 2 AM. As warm as it was under my hood this AM, I really don't thinki it needs plugged in for more than 3-4 hours.

fossil · December 8, 2005

Just used a regular plug from the hardware store

ArcticJ · December 9, 2005

Just used a regular plug from the hardware store

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I asked around with a couple of tech's in the chicago area about this thermostat controlled plug...one had no idea what I was talking about, one said it has always been that way (which it hasnt, my 95, 99 and 02 all worked regardless of temp) and finally the third guy said that he BELIEVES gm changed something internally in the engine and now does not want the block heater maintaining a constant 180 F when it is above 0 outside for fear of POSSIBLY damaging something internally...

Please, is there someone out there that can get a straight answer on this? I'm freezin here...

Gator81 · December 9, 2005

Installed an aftermarket heater on my '92 K2500. The towing package on it includes an oil cooler, which is great in the summer, but routing the engine oil through the radiator tank means it takes a very long time to come up to temp. On cold mornings, I was not getting much cab heat until I got to work (15 minutes). I figured that was doing bad things to my oil and my engine. Hence the block heater.

I plug it into a heavy duty timer that turns it on around 3am. By 6am, it's warm enough that the cab heater makes heat. The truck has always started easy, cold or not, but I think it's a lot better for it this way. And I know I like it better!

Regarding the thermostat, I would sure not like that. If it's colder than maybe 30F or so, I want that heater coming on to warm up the oil. Such a large portion of engine wear occurs at cold start-up, I don't care if I use a little electricity to help it out.