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Hi guys (and gals, if there are any). I have an unusual cooling problem, not the usual overheating one. I can't get my engine in my Willys up to operating temperature. I know the usual one is overheating, mine is the opposite. Here's the specs: 355 Chevy Vortec, CCW waterpump and 16" Flexilite fan with shroud, 2 Row aluminum radiator, 195 degree thermostat (and I tried two different ones), two temperature sensors; (1 mechanical one hooked to a gauge in the engine compartment, 1 electrical one in the dash) 50/50 water/antifreeze mix, 16# radiator cap. It acts as though the thermostat is stuck open, but I had some doubt after trying 2 new 195 degree ones. When running down the road, the dash gauge will barely get over 130, usually less, if I stop and look at the underhood mechanical gauge, is usually about the same. I do feel heat coming from the heater though. Even idling in the driveway, it won't get above 150, and thats after idling for 30 minutes or more. My mechanical temp sensor is mounted in the intake manifold (Edelbrock RPM-AirGap) next to the thermostat. My electrical sensor is mounted in the left head between cylinder 1 and 3.
Anybody got any ideas on what else I can try to get it up to temperature?
Thanks.
 

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When you first fire the engine, does the upper hose stay cool until the engine is fairly warm? If you remove the radiator cap when it's cold do you see the coolant flowing? Have you tried blocking off the air flow to a portion of the radiator? Removing the shroud?
 

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too cool

You may want to try a water restrictor and see if that helps any. You can usually get them from circle track suppliers.
 

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In cases like that, sometimes there is too much flow through the bypass. If you take the water pump off you can see it. Plug it with a freeze plug and then drill a 3/8" hole in it to make a restrictor.

That would just be a crutch fix, though... Not fixing the problem. That engine shouldn't be underheating. Its odd that both temp gauges would be off and read the same, and it would also be odd that both stats were bad, but I would be tempted to try another stat, or test the one you have.
 

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possibly its the temp sender location in the air gap. Unless the thermostat is sticking open the coolant in the block has got to get hot. I think curtis' idea is probably right. Too much through the bypass. Take the cap off the radiator and stick a thermometer in the coolant after it sits at 130 for a few minutes to eliminate any sender issues.
 

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another thing your heater core will act as a small radiator, try blockign off the flow into your heater core and see if the temp goes up, not that that will sove anything but it will tell you if thats one of your issues,,,,,,,,,,put a big piece of card board in front of your radiator that will restrict airflow and thus hender its cooling capabilitys............idk just a few idea's
 

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Somehow water is circulating through your engine with the thermostat closed. You could as a test, remove the thermostat and replace it with a solid piece of gasket material and see if the engine heats up. My guess is it wont. Is the heater connected in the proper manor. Also you did not somehow end up with a reverse flow pump on a standard engine or vice versa. Bottom line is if the thermostat is working and there is no other path for the water to circulate the engine should heat up.
 

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underheats

Try taking guts out of stat,flow will still be slowed down.If it still runs cooler or the same then I would cover rad.partley to see if you can get to temp.What temp is your area when you test? Odd problem to have!!!
 

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strange problem is right

I'm with T-bucket23 on this one. The coolant has to be circulating through somehow. If you start the engine up the top rad hose shouldn't start getting hot until the stat opens. If it starts to get hot before that then the stat has to be opening. Take it out and boil it in a pot with a thermometer in beside it. See what temp it opens at. Let us know what you find.
 

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If this is a new engine,, maybe there is a air lock in the block,, sometimes air will get trapped in the upper portion of the block and dosen't allow proper circulation of the coolant,, and since there is no coolant around the sending units , it will give a false reading,, but this usually results in a steam pocket,,
and boilover, the gage in the head should give a higher reading than the one in the manifold,,
You might try a 7 # cap,, altho the newer engines require the higher pressure caps because the temp should run around 195 *for this engine,

Interesting problem,,,, be sure to let us know what you find,,,, :confused: Bill
 

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sender

This is pretty far out there but, did you use teflon tape on both of your sender units. This could mess with resistance reading of the guage. Kind of a leap but just a thought. Try teflon paste instead of tape.
 

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Actually you should NOT use any tape or sealant on the sender threads.. because they will not ground to the block properly, and the gage not work, :D :D ;)
 

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Bad Rat said:
Actually you should NOT use any tape or sealant on the sender threads.. because they will not ground to the block properly, and the gage not work, :D :D ;)
The odds of any sealant totally insulating the threads is slim to none.
 
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