Overcooling?

'93 Chevy G20 van w/305, no a/c. Purchased in spring of '03 from a small maintained fleet with the proviso that "You won't get much heat this winter". Well he was right. I do get SOME heat, but not much. My temp gauge
reads what I believe to be 140( 2nd hash mark on gauge). At first I thought low temp thermostat. I believe it was functioning properly, as I saw the gauge barely fluctuate from the mark, indicating the stat was opening and closing(?). I replaced that yesterday with new 195 stat. Old stat was found to be 195 too. Temp gauge is graduated from 100 to 260; 5 segments. I figure 180 must be the middle slash. After new stat install, my gauge still reads at the second hash(140?). Using a digital thermometer, I checked the water temp at the radiator fill and found it to be in the 140 range. Not wanting to, but needing to see if I could influence the gauge to a new reading, I put cardboard directly on 1/2 the radiator. I then took the van for a 7 mi loop on the interstate to test. That gauge never moved a whisker more from the 2nd hash mark than it had prior to the cardboard installation. Checked water at radiator after drive and found it to be in the 160 range. Using the thermometer on the drive, I tested air temp from the defrost vent(100ish), and the small vents in the doghouse(85). In comparison, my Buick LaSabre reads at almost 155 at the vent outlet. I guess my question is..., can a vehicle be overcooled? Does the factory ever oversize components in anticipation of installing extras, only to find that some models go out as *basics*? Why can't I get water temp up to the proper range? Thanks. -- jeff wald *Corduroy pillowcases make headlines*
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We had the same thing with our Blazer but when we got rid of the Dex-Cool and put in new stuff it went away. I'd probably try flushing the cooling system to see if that helps.
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"j Wald" wrote

gauge
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And you would be wrong for believing that the middle slash (or mark) is 180. Don't be fooled by factory guages, the marks and numbers on them do not necessarily translate into "actual" temperature readings. On your vehicle, the temp guage should be divided into four quarters, it's normal for the temp guage to read right at the "1st" quarter, that's where a 195 degree t/stat will read. Look elsewhere for your low heat from your heater problems.
Ian
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and
Ian, Ok, I can go with that. What temp should a thermometer read in the heater core return water in the radiator neck at full warm up? Mine sure isn't 195; more like 150. Why is the stat opening prior to 150? Why isn't the cardboard blockage raising the engine temp? Looking for answers. I'm freezing here. -- jeff wald *Corduroy pillowcases make headlines*
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j Wald wrote:

How do you measure temperature there without de-pressurizing the cooling system? I think a proper pressure cap needs to be on the radiator for the whole thing to work right.
---Bob Gross---
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I understand the pressurized system, but why would that make a difference when I check the temp of the coolant? I'm curious why I can get a proper temp reading on a thermometer. Am I taking the wrong approach using a digital thermometer in the return coolant from the heater to the radiator? Where then? Thanks.
-- jeff wald *Corduroy pillowcases make headlines*

whole
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Same principle as a pressure cooker. The liquid gets hotter and stays in a liquid form. It will not turn to steam and evaporate. That is also the purpose of an enclosed system. Once you crack the pressure, the liquid expands (sometimes violently) and nearly immediately looses temp.

the
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"j Wald" wrote

195;
cardboard
If you really want an accurate measurement of what the t/stat is doing...you would need to measure the temperature right at the t/stat housing. We use infra-red measuring tools (have you seen these, quite cool) and you can take a temp measurement off of whatever you point it at.
I would look at two things....heater core is plugged, (is there a large difference in temperature between the inlet and outlet hoses going to the heater core?) and your temp door is not moving all the way to the hot position. If you suspect the heater core, you could simply remove the two hoses and back flush the heater core with a garden hose and hot water. Remember that back flushing means that you want to send the water in the opposite direction of flow....so you want to force water through the hose that connects either to the radiator, or the water pump.....either of those positions will be the return hose.
Ian
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Re: Overcooling? Group: alt.autos.gm Date: Thu, Feb 5, 2004, 4:29am (CST+6) From: snipped-for-privacy@hotmail.com (shiden_Kai) "j Wald" wrote Ian, Ok, I can go with that. What temp should a thermometer read in the heater core return water in the radiator neck at full warm up? Mine sure isn't 195; more like 150. Why is the stat opening prior to 150? Why isn't the cardboard blockage raising the engine temp? Looking for answers. I'm freezing here. If you really want an accurate measurement of what the t/stat is doing...you would need to measure the temperature right at the t/stat housing. We use infra-red measuring tools (have you seen these, quite cool) and you can take a temp measurement off of whatever you point it at. I would look at two things....heater core is plugged, (is there a large difference in temperature between the inlet and outlet hoses going to the heater core?) and your temp door is not moving all the way to the hot position. If you suspect the heater core, you could simply remove the two hoses and back flush the heater core with a garden hose and hot water. Remember that back flushing means that you want to send the water in the opposite direction of flow....so you want to force water through the hose that connects either to the radiator, or the water pump.....either of those positions will be the return hose. Ian
Yep sounds like a restriction in your core...More than likely in your core.....This is what i tell everyone evertime this happens....When you flush it out and all is well you will still have deposits in your core....And even though it is summertime out you should still once a month turn you heater on for about ten minutes to allow the core to flush itself...Also once every six months flushing your entire system will also help.....especially if your using dexcool....As Ian stated heat it up and feel the hoses going to your core you will tell a temp difference by touch if it isn't flowing....If the outlet hose is cooler presto you have a blockage in your core...Id surely start there could save yourself alot of time and troubles .... Steve C
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gauge
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of the van thats plumbed in line with your front cab heater core. That 305 puts out good heat check heater cores also if a head gasket is leaking there will be poor heat.
Jim.J
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Had a '92 Buick Roadmaster (350) with *exactly* the same problem. Tried 3 different thermostats, flushing, nothing worked.
Turns out there was a "restrictor" between the heater core and the radiator that was missing. Put the restrictor in, bam. Heats me right out of the car when it's 10 below F.
Make **sure** your restrictor is there.
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