454 TBI is eating thermostats... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

wyattglock · 02-01-2013, 10:01 AM

My 89 R3500 is eating thermostats. In the last 12 months, it has melted 4 of them. I have tried Stant, Mr Gasket, and Fail Safe. Is it possible that the heater core or radiator has sediment in that is breaking loose and clogging the thermostat? The radiator was brand new when I bought the truck, but the heater core has not been replaced yet. I have flushed the system 2 times since I rebuilt the engine. The truck did this before the rebuild, and hasn't stopped yet.
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INSIDIOUS '86 · 02-01-2013, 10:15 AM

Melted them? Or clogging them? If your engine is scaling inside then there not really much to do other than pulling the engine and taking heads off and turning the block upside down for pressure washing scale out
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wyattglock · 02-01-2013, 10:34 AM

They are melted when I pull them out. I have run the stock 195 and then 180 t-stats, but get the same result. It just makes me wonder if there isn't build up in the core that is breking loose and clogging it long enough to cause overheating.
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INSIDIOUS '86 · 02-01-2013, 01:15 PM

I have never heard of a thermostat melting. These are metal right? You sure ther are not corroding really fast? If so you may have a ground issue that's making issues with the cooling system.
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wyattglock · 02-01-2013, 01:28 PM

My friend that was borrowing the truck is looking at it with me, it feels like the water pump is not working right. No pressure. The tstat is opening fine, so I am going to change the pump.
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wyattglock · 02-05-2013, 02:49 PM

Changed the water pump, and put a 195 degree thermostat back in it. I will see if that takes care of the problem. Thanks for the help, sorry for the panic. It was a very bad day when all this happened. All good now, hopefully it stays that way.

02-01-2013, 10:01 AM	#1
wyattglock Registered User Join Date: Jul 2010 Location: Lafayette, IN Posts: 622	454 TBI is eating thermostats... My 89 R3500 is eating thermostats. In the last 12 months, it has melted 4 of them. I have tried Stant, Mr Gasket, and Fail Safe. Is it possible that the heater core or radiator has sediment in that is breaking loose and clogging the thermostat? The radiator was brand new when I bought the truck, but the heater core has not been replaced yet. I have flushed the system 2 times since I rebuilt the engine. The truck did this before the rebuild, and hasn't stopped yet. Posted via Mobile Device

02-01-2013, 10:15 AM	#2
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: 454 TBI is eating thermostats... Melted them? Or clogging them? If your engine is scaling inside then there not really much to do other than pulling the engine and taking heads off and turning the block upside down for pressure washing scale out Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

02-01-2013, 10:34 AM	#3
wyattglock Registered User Join Date: Jul 2010 Location: Lafayette, IN Posts: 622	Re: 454 TBI is eating thermostats... They are melted when I pull them out. I have run the stock 195 and then 180 t-stats, but get the same result. It just makes me wonder if there isn't build up in the core that is breking loose and clogging it long enough to cause overheating. Posted via Mobile Device

02-01-2013, 01:15 PM	#4
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: 454 TBI is eating thermostats... I have never heard of a thermostat melting. These are metal right? You sure ther are not corroding really fast? If so you may have a ground issue that's making issues with the cooling system. Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

02-01-2013, 01:28 PM	#5
wyattglock Registered User Join Date: Jul 2010 Location: Lafayette, IN Posts: 622	Re: 454 TBI is eating thermostats... My friend that was borrowing the truck is looking at it with me, it feels like the water pump is not working right. No pressure. The tstat is opening fine, so I am going to change the pump. Posted via Mobile Device

02-05-2013, 02:49 PM	#6
wyattglock Registered User Join Date: Jul 2010 Location: Lafayette, IN Posts: 622	Re: 454 TBI is eating thermostats... Changed the water pump, and put a 195 degree thermostat back in it. I will see if that takes care of the problem. Thanks for the help, sorry for the panic. It was a very bad day when all this happened. All good now, hopefully it stays that way.



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