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Old 03-12-2011, 03:40 PM   #1
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Default Thermostat / Overheat

Setup: stock block & rad, t3/t4e tubular weld-el manifold, decrepit stand alone TEC3 EM. No coolant reroute.

Tried to start up last week after being buried in snow this winter. Charged battery, etc. Started and idled for a while - got distracted, (10 minutes?) heard odd sound, saw geyser from cap, shutdown engine. Bought a new rad cap and thermostat. Installed rad cap. Added water. Too cold to deal with anti-freeze.

Today start up car, idle a while. This time with computer connected. Watch engine parameters during warm up. Noticed that coolant temp was not rising as fast as normal. Sat around longer, still said the ecu coolant temp was only 20C. Got my lazy butt out of car, put hand on coolant sensor to check for myself. Sensor really was cold. (GM sensor installed in the heater loop away from the engine) But the radiator (top of now brown plastic POS) was real hot, I'd guess, hmm ~>50C. I could not leave my hand on it. Shut engine down. Like a I didn't really pay attention to the stock temp gauge, so I can't tell you what it was. Not like the stock gauge is accurate anyways.

Bad thermostat? Clogged jiggler (correct techno-term ) in the thermostat? Or normal? Thermostat is ~ 1 year old. Not sure if is thermo, or thermo + fan yet.

Crap, you all are going to tell me to stop being a pansy and change it. Yes? Or suggest something to try?
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Old 03-12-2011, 03:43 PM   #2
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Have you tried removing the Tstat and idling the car without it?
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Old 03-12-2011, 03:50 PM   #3
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Have you tried removing the Tstat and idling the car without it?
I'll try that. Will the tstat housing seal well enough without a gasket?
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Old 03-12-2011, 03:59 PM   #4
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I'll try that. Will the tstat housing seal well enough without a gasket?
It's been my experience that a gasket is needed.
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Old 03-12-2011, 05:03 PM   #5
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Saved the gasket, removed tstat. Rerun test. Remembered to unscrew cap before coolant got hot. Saw the water rise due to expansion. Since water was in the rad neck, couldn't tell if there was circulation. Recapped rad before overflow. It was close

Still a Cold heater loop, hot radiator :( . Stock temp sensor was at 11 o'clock and still rising. My last check was to unplug the GM temp sensor in the coolant loop to see if the TEC3 detected it. When GM temp sensor was unplugged, the TEC3 defaulted to hot temp, and the fan went on. At least the fan works.

So is this water pump, or heater core? Could it be anything else?

Heater core can be bypassed, but may have to sacrifice the hoses, right? The hoses were replaced last year, so maybe they can be removed without cutting? The core connections through the firewall are rather delicate.

Last edited by SlowRider; 03-12-2011 at 05:42 PM. Reason: removed stupid question
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Old 03-12-2011, 05:20 PM   #6
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What is the coolant strength and how cold is it there? Frozen rad?
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Old 03-12-2011, 05:39 PM   #7
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What is the coolant strength and how cold is it there? Frozen rad?
Coolant started out as 50/50. Has been diluted lately with water, but fortified with anti-freeze. Real answer: Don't actually know. I am not sure if I have an anti-freeze tester anymore.

It hasn't been cold enough lately to worry. This afternoon was 50F (~+10C), the morning was around 0C. Lots of anti-freeze in the system for those kind of temperatures, at least I think so.
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Old 03-12-2011, 06:52 PM   #8
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lol. looks like im not the only one in NH with overheating problems..
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Old 03-13-2011, 01:18 PM   #9
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Question Diagnostic for water pump

Now: no tstat in vehicle, 1.8L NA, stock cooling system
Observation: cold heater loop, hot top of radiator, stock temp sensor reads 11 o'clock and rising - heater water sensor shows cold and water really is cold there.

Is there a definitive test for the water pump? Since water pump replacement == timing belt + water pump, I don't want to do the replacement(s) if it really isn't required.

Anyone?
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Old 03-13-2011, 01:30 PM   #10
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Did the rad level go down when you took out the stat?

It is doubtful the pump has failed as in impeller falling off, it does happen, but not usual for a pressed on steel one like yours.

Just for the sake of easy diag, try draining the rad, if it wont drain it may be frozen, if it will you may have picked up some air, and need to burp the system.
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Old 03-13-2011, 06:05 PM   #11
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Yesterday, Radiator level went down when I removed the thermostat. Left rad cap on tight, cracked open tstat housing, globs of anti-freeze went all over the place. Cracked open the rad cap, more stuff comes out. Fortunately, I had a sort of mold-able funnel underneath the thermostat housing to guide it to a catch pan.

Put the thermostat housing back, (now without the thermostat) topped up system with water for now. Ran the test, Cold heater loop, sensor matched reality, heat in car blew cold air. Very hot rad, at least on top. Car / engine bay kind of smelled hot, maybe that was the ethylene glycol droplets boiling off. Shut down car.

This afternoon, checked water level for giggles, within 1/4 inch of the lowest radiator cap seal.

Average temp this week has been above freezing. The last couple of nights the low was 35-36F, the daytime has been 45-50F. Massive snow melt-off occurring. Doesn't seem like it is a freezing problem.

I'll try running it again for laughs. Never experienced the burp issue on this car. BRB with any results.
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Old 03-13-2011, 06:41 PM   #12
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Even though the stock sensor is indicating temp rise, the top radiator hose doesn't seem that hot. It is as if it is not full of water. The hose seems to be hotter along the bottom edge. Top of same hose not warm. Hose does not seem to be pressurizing much, although it is at a higher pressure than when cold.

Classic burping problem?
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Old 03-13-2011, 09:28 PM   #13
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If you want to know if the pump is working pull the upper radiator hose off the rad and run the car and see if you get any flow. If it is flowing though you can normally see it in the rad, the inlet is right next to the cap.
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Old 03-13-2011, 10:47 PM   #14
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When I started the car up without the rad cap, I saw no evidence of coolant flow, only a little subtle circulation. Then the water expanded, still no evidence of flow. Capped it before it overflowed. I ran it a bit on ramps, massaged/squeezed the radiator inlet pipe, let it cool off, then off the ramps. I'll check it in the morning.

Any chance the rear narrow diameter metal pipe (return from heater core and rear of head) is blocked? As in partially cooked due to excess turbine heat? Or just a clogged heater core? Guess I need to bypass the core for diagnostics.

I'd flush everything backwards and forwards with water but I don't have a heated area to do this, and it is still too early in the season in NH to leave it with pure water.

In the mean time, I've ordered the Lisle mega coolant funnel burp gizmo. Figure I'll be using it a couple of times, just figuring WTF is going on.
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Old 03-15-2011, 04:16 PM   #15
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why not try to do a flush on the cooling system? pop open the drain plug and stand out there with a hose, make sure the heat is on high inside the car. Also a good tick is once all the anti-freeze is out, close the drain plug, add some vinegar to the radiator and top it off. Let the car run till the fans kick on and then reflush the system.

The vinegar will eat up all the calcium build up. Also be sure to use only distilled water to prevent build up.
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Old 03-15-2011, 06:18 PM   #16
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First: +1 on full flush of the cooling system.

Next:
With car not running, enough coolant drained to be below the upper radiator hose.

1. Remove upper radiator hose from radiator.
2. Press mouth firmly against radiator hose opening.
3. Blow.
4. Wash off mouth with clean water.

If you cant blow through the cooling system, you've got a block. It may not be "free flowing" because you've got a thermostat in the way, but air should be going through the little hole in the thermostat without a ton of trouble.

To test if your water pump is working, button the cooling system back up. Remove one of the small coolant feeder lines (such as the lines that pass through your throttle body or oil cooler). Start car.

If you get a stong squirt squirt, your water pump is working. If there is little to no squirt squirt, it dun been broke.
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Old 03-15-2011, 07:02 PM   #17
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Heater hose further from engine, is coolant coming FROM the heater, e.g. when it's cold and your heater is on full blast, the coolant in there is being cooled... ???

If the heater hose is stone cold then there's a blockage somewhere between the pickup in the bakc of the head, and the pipe that runs under the exhaust mani.
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Old 03-16-2011, 12:06 AM   #18
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Originally Posted by JasonC SBB View Post
Heater hose further from engine, is coolant coming FROM the heater, e.g. when it's cold and your heater is on full blast, the coolant in there is being cooled... ???

If the heater hose is stone cold then there's a blockage somewhere between the pickup in the bakc of the head, and the pipe that runs under the exhaust mani.
Since I have not cracked the hoses off the heater core, I do not know if there is coolant flow. But I do know the heater hose furthest from the back of the head is cold, even when the stock temp sensor is very hot.

Vent air when in heat mode is cold, and TEC3 ECU says the temp in that hose is cold. The heater hose IS cold, I touched it. This indicate blockage of some sort OR dead pump.

The real answer is to flush everything out and then sort stuff though. With a pure water system, I can try experiments. With coolant I need a way to mitigate the mess. I will have to flush the area with water afterwards. Too many pets/animals in the area to leave coolant puddles. Really have to dilute the stuff. Damn it, I'm pushing the season here. Too cold still to go all water, even for a night.
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Old 03-16-2011, 12:18 AM   #19
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Originally Posted by fooger03 View Post
To test if your water pump is working, button the cooling system back up. Remove one of the small coolant feeder lines (such as the lines that pass through your throttle body or oil cooler). Start car.

If you get a stong squirt squirt, your water pump is working. If there is little to no squirt squirt, it dun been broke.
Thanks for the idea on checking the flow with a small coolant feeder line. I hate dealing with coolant, minimizing the mess is a plus.
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