Luke Warm Heat

[454cid]

I've got Motorads in both my Volvos, and they work well. I think my truck has a Stant, from before Motorad bought them. GM is availble too.... no idea who actually makes them.

 

[Komet]

I've pulled a Stant thermostat out of an AC Delco box before.

 

[Vikingdude]

I bought 2 genuine GM "stock temp", and both turned out to be 160*. Lots of amazon reviews notes the same thing about that part number (I got mine from rock auto). Stuck a motorad 195* in and heat (and open loop!) Improved instantly.

 

[L31MaxExpress]

The 383 is the first small block I have had that has had a 195F thermostat in many years. With cast iron heads I will still run a 170-180F.

 

[someotherguy]

No crappy heat in these trucks. I don't know about places where it gets REALLY cold, but here in Houston where every once in a while we flirt with temperatures in the teens and the occasional single digits (thankfully rare) a gmt400 with correctly functioning heat can still get uncomfortably hot if you want it.

The suggestions to backflush the heater core are spot on. The supply hose from the intake is the larger 3/4" hose, be careful as you wrangle with it as the original quick connect fitting on the intake, if it's still there, is undoubtedly corroded and will break off if you just look at it wrong. The return hose from the core back to the water pump (or radiator tank, depending on year) is the 5/8" hose. Garden hose spray nozzle into the 5/8" hose should flush any crud back out of the core into the supply hose, which hopefully you're able to disconnect without issue so that the crud can escape.

I just did a new heater core in my '93 today because it was leaking a little bit, and I was doing a lot of other cooling system work on the truck. After just running it enough to get hot and burp some air out of the system, I checked the temperature at the vents and it got up to 142F and was still climbing.

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Richard

 

[L31MaxExpress]

No crappy heat in these trucks. I don't know about places where it gets REALLY cold, but here in Houston where every once in a while we flirt with temperatures in the teens and the occasional single digits (thankfully rare) a gmt400 with correctly functioning heat can still get uncomfortably hot if you want it.

The suggestions to backflush the heater core are spot on. The supply hose from the intake is the larger 3/4" hose, be careful as you wrangle with it as the original quick connect fitting on the intake, if it's still there, is undoubtedly corroded and will break off if you just look at it wrong. The return hose from the core back to the water pump (or radiator tank, depending on year) is the 5/8" hose. Garden hose spray nozzle into the 5/8" hose should flush any crud back out of the core into the supply hose, which hopefully you're able to disconnect without issue so that the crud can escape.

I just did a new heater core in my '93 today because it was leaking a little bit, and I was doing a lot of other cooling system work on the truck. After just running it enough to get hot and burp some air out of the system, I checked the temperature at the vents and it got up to 142F and was still climbing.

You must be registered for see images attach

Richard

Right there with you on that opinon. These trucks have great heater and great ac when they are functioning correctly. The dash heater in my 99 4 door Tahoe (no rear heat in the Tahoe/Yukon like the Suburbans got) would heat the whole Tahoe with ease and the Express van has always had good heat too. That was with 170F thermostats in them too, engine running ~176F. You could not leave the temperature dial anywhere close to full heat even on a 0F day. I am a little more north in Texas than you are and it gets pretty dang cold in the early AM here.

With a 195F in the van on a recent 33F morning, the heater was blowing 150F and that was with the engine idling. When I drive it, it gets so hot the temp selector is no more than 1/2 way up and usually gets rotated even more to the cool side than that. 1-2 notches of the fan is enough to bake you out with the temp knob dialed way back. If anyone is riding in the back, I usually run the rear heater on low blower speed and often asked to turn it off. Weatherstripping is a highly ignored area of vehicles. I for one cannot stand a vehicle with whistles and wind noise as well as drafts of outside air blowing throughout. I recently replaced most of the weatherstripping on the van and it is as airtight as new.

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[L31MaxExpress]

I put a CarQuest (Advance Auto) (Motorad--made in Israel) thermostat in my '88. This is a 205 degree unit.

I've been dissatisfied with it ever since. Slow to open--temp is way past the "210" marked on the dash gauge--must be around 225 or more before it opens. Temp then drops way down. Back up...way down. Takes forever for it to stabilize--20 miles or more.

I'm likely to replace it someday, but I don't know what to use either. I've had good--and faulty--thermostats of pretty-much every brand.

There was a time that I really liked the concept of the Robertshaw 'stats. I have a shitload of them as part of an eBay purchase--started with an entire case, but I've resold about half of 'em. Problem with that case, is that they're 160-degree units. Nearly worthless in most of the country.

So far the Murray Ultra 195F high flow from the local Oreilly has been great in the van. It will spike the gauge ever so slightly (just under 210°F) before it opens the first time. The ECT shows it opens at ~194°F. The dash gauge will drop back to 1/4, but the ECT reading will stay around 190F. Then it stabilize out and stays very consistent. I have datalogged 100 mile road trips from the PCM data and the ECT shows the coolant holding steady between 194 and 198 for the whole trip. The gauge needle pretty much parks itself at 3/8 travel unless I am towing or idling in extremely hot weather at which point it will creep up to the middle of the gauge (210F) which causes the fan clutch to really ramp up. Fan clutch is set to get pretty stiff at 204F. At 210F the dash gauge and the ECT are almost dead on with each other. In other places they vary considerably.