This is a LO5 engine that in the cold never gets above 120 degrees so I never get heat and end up driving around freezing. I have replaced the thermostat now for the second time, first time was a stant 195 degree $7 one last winter and today I just tossed in the heavy duty $17.00 stant 195 with a lifetime warranty. Drove the truck for 45 minutes and the temp never got above 120 and the heat was mild at best. If I'm stopped with no airflow going over the radiator eventually the truck will warm up enough to get heat but it takes quite a while. The fan never kicks on and fuel mileage has suffered as well. At a loss what else to do here besides block off part of the radiator and attempt that....but the thermostat should not even allow coolant flow until the motor is much warmer regardless.


thoughts? I find it hard to believe that both thermostats are bad right out of the get go and am trying to figure out what the issue is. Typically on any other sbc I replace the thermostat and it fixes the issue, but this one won't. Years ago it had amazing heat and now it almost seems like the motor is overcooling. I'm about to just put cardboard in front of the radiator and call it a day but would like other suggestions.

 

something to look at is the cooling surface of the radiator. If it is a truck with a large grill, you may want to block off part of it. In cold weather with a radiator that gets alot of exposure can overcool your vehicle.

 

I agree with hotbird 89 you need a cover for your grill. Something like one of these will do the trick for you.

http://www.cabelas.com/cabelas/en/te...equestid=35205

 

i was trying to figure out how for 2 winters I had no issues with the vehicle getting up to temp and now it has popped up. Same motor/radiator/etc just a few flushes once a year difference is all. I'll just pop some cardboard in front of the radiator and see what happens. I was under the impression that the thermostat shouldn't open much until 195, and it seems that at 120 it's partially open already. I have a billet grill so the cover they offer and drilling holes to mount it won't work, but I'll see how the cardboard in front does instead.

 

You can check the thermostat by getting a bucket of water at its set temp (195*) dropping it in and you will be able to manually see it open. All of the tricks I know have to do with overheating, but I use to check the colant with a tester (the little tube thing with the diffrent color ***** in it) water does the heat transfer and colant just keeps it from freezing/evaporating. Most of the time I saw all/mostly water in the system the heater blew really hot. You can also pressure test the radiator cap to see if its still good. You said that you already checked your fan. Those are the first thing I check for overheating, just some food for thought. There was a debate among some of the local tunners about running lower than stock thermostats. They all agreed that lower would make more power but the debate was that engines were made to work at a certain temp usually 180*. All the components of the engine are made of diffrent metals eg. piston, rings, block, ect. We all know metal expands with heat but diffrent metals expand diffrent amounts at diffrent temps. The clearences were set up for thermostat temp. So before the engine reaches it the rings are tight with the block and cause more wear then they would at operating temp. This is why you hear that shorts trips where you dont get up to operating range are hard on an engine. Long story short, becareful driving an engine that does not reach operating temp becuase it could be causing lots of wear.

 

I test thermostats by putting in a pan of water and boiling the water on the stove with a thermometer in the pot - then I can see what temp (if any) it opens at.

 

i've been through this problem before and the only thermosats that i consider reliable are ac delco ones, all the ones from autoparts stores dont open as advertised

 

A thermostat is a thermostat. They are designed to BEGIN opening at the rated temperature, and be completely open about 25 degrees later. For example a thermostat rated at 195*F will begin to open then and be fully open by 220*F.

If the thermostat does not operate as described, then it needs to be replaced. I have had better luck with off brands that anything else, but that is just my luck. Anyway, that is just my .

 

i can't imagine two different ones are bad right out of the box, but I guess I'll have to swap it out again and see what happens.

 

I had this same trouble on my truck. (small block chevy) It turns out that the cheap chrome thermostat housing (O-ring style) wasn't holding down the thermostat to the intake manifold. Coolant was just going around the thermostat. I fixed it using a cast iron one (gasket type) I found in my junk drawer. Now it warms up quickly and I drive around all day at 180*-190*.

Try this. Remove the upper radiator hose from the thermostat housing. Use a screwdriver to see if the thermostat is snug against the manifold. If it is loose that could be your problem.

 

thanks red406, i'll have to try that, perhaps I'll just buy a new neck anyways, but for now I just tossed a big piece of cardboard in front of the radiator so i could drive the thing. Now I have to mess with some blend doors in the dash since the defroster setting isn't 100% it's blowing out the main vents as well. Not to mention I still want to hook up the rear heat as well.

 

I put some RTV on the intake manifold to seal the thermostat to the intake manifold so no water could get by. I did that when I lived in maine.

 

little update, bought another new water neck since all the spares i have around the house apparently are different outlet locations. Pulled off the mr. gasket chrome water neck again and looked for leaks, the thermostat sat fine into the intake, but there was a piece missing off the neck, looks like it was porous and is slowly breaking apart, guess that'll be my last cheapie water neck. This allowed coolant to flow past the thermostat, I didn't notice it last time when I replaced the thermostat. Now the motors stays around operating temp besides it still burping out some air here and there on the drive home.

 

Do a quick test at idle with the engine warm and heat on, say, floor vents - no AC.
Feel the heat from the vents at idle.
Hold the accelerator up to what is safe, say 2000-2500 RPM, and while holding the RPM, feel the heat from the vents.
Is the heat the same-ish, or Drastically hotter?
Now let the throttle off.
Does the heat drop-off quite a bit, or just a little?
If the heat dies when you let go of the throttle, your Heater Core is plugged or you have air in your System.

 

I've back flushed the heater core probably 3 months ago and it seems to flow rather well. I'm sure it's just air in the lines, but I'm going to mess with it after the sun comes up in a few hours.

 

Seems like you got it fixed.

 

Also when these problems occur can be result to a bad radiator cap not holding proper pressure and doesnt allow the coolant to pressurize to what it should.