2 Problems - Engine Not Warming Up To Operating Temperature

[Ken K]

Have you replaced the radiator with aftermarket new? The reason I ask is some years of GM trucks used a pressurized recovery tank. Radiators had a thumb sized hose on the passengers side. The hole was plugged and coolant would not circulate correctly, never getting hot. There is a TSB on this issue. I don't feel well today, but don't remember the year of truck. Maybe the beginning of the "LS" engine stuff. I noticed that Eastwood is selling seal tape for fittings / housings now. It is a butyl rope that sticks to the heater core and A/C housing during service to eliminate air leaks. We used to have that stuff everywhere for years. Camper shell tape works well in many spots for air leaks as well.

 

[454cid]

Have you replaced the radiator with aftermarket new? The reason I ask is some years of GM trucks used a pressurized recovery tank. Radiators had a thumb sized hose on the passengers side. The hole was plugged and coolant would not circulate correctly, never getting hot. There is a TSB on this issue. I don't feel well today, but don't remember the year of truck. Maybe the beginning of the "LS" engine stuff. I noticed that Eastwood is selling seal tape for fittings / housings now. It is a butyl rope that sticks to the heater core and A/C housing during service to eliminate air leaks. We used to have that stuff everywhere for years. Camper shell tape works well in many spots for air leaks as well.

The only GMT-400's I've seen that used a pressurized tank, are those with the diesel engine.

 

[Schurkey]

I have a 1994 GMC Yukon. Engine is a L31R crate (based on 96+ vortec) that is stock aside from aluminum intake and headers. I live in Canada where it's normal to get -30 c / -22 f.

I'm having a hard time getting it up to operating temperature in the winter.

What water pump are you using? Far as I know, the Vortec pump/pulley doesn't line up with TBI pulleys. I have a photo of a Vortec pump and a TBI pump side by side:

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Note the height of the "worn" belt-travel area of the pulleys.

Also, if you're using the TBI water pump on the Vortec short-block, I hope you drilled the bypass hole in the block on the right side under the water opening. The Vortec blocks don't get drilled for the bypass, but the TBI water pumps are drilled. With no bypass in to the pump, the Vortec needs a different bypass system.

 

[Craig]

What water pump are you using? Far as I know, the Vortec pump/pulley doesn't line up with TBI pulleys. I have a photo of a Vortec pump and a TBI pump side by side:


Note the height of the "worn" belt-travel area of the pulleys.

Also, if you're using the TBI water pump on the Vortec short-block, I hope you drilled the bypass hole in the block on the right side under the water opening. The Vortec blocks don't get drilled for the bypass, but the TBI water pumps are drilled. With no bypass in to the pump, the Vortec needs a different bypass system.

It has the TBI pump. Not sure if a bypass was drilled in but it should be installed properly as I believe that installation was done at a GM dealership.

I blocked off the front grille and bagged the transmission cooler. Seems to have helped a lot. Used an IR gun and the gauge is reading pretty accurate. Also checked temperature sensor.

My truck is getting to temperature but then the thermostat opens and goes back down really quick. I'm now thinking it's a mix of all of the cold temperature, all of the aluminum accessories and coolers dissipating heat too quickly. Which was great in the summer when I'd be stuck in traffic with the A/C blasted on a +30c day and not overheating, but not so much in the winter.

Still trying to figure out what's wrong with the outside air coming into the cab on defrost. Looking through the receipts, it looks like the blend door actuator was done. I'll probably have to start taking a couple things apart to get a closer look.

 

[Ken K]

You may have a good blend door actuator but some restriction on the blend door itself. I have seen half pencil falls, drinking straw, plastic toys fall into the defrost duct work and stop the blend door from closing. One model would suck stuff out of the glove box when the blower fan was on high, so a check for blockage should be easy.
Also, if you replace the actuator, make sure to connect it to the door and electrical before turning on the key. The system will do a "Self" test with fuses removed and cycle the actuators. If the motor is not hooked up, it will damage the internal gears.
NOTE; The D.O.T. requires that all HVAC systems default to defrost during a system failure regardless of type unless it is cable operated.

 

[c1500deathtrap]

Still using the thermostatic air cleaner as well?