Crazy temps......

[lsittingbull]

This is driving me nuts. But here go..my temp will rise from cold to normal(midway) when driving then drop back down to cold..Sometimes it never leave the cold mark..and sometimes it works perfect..my heat follows suit. Now i`ve added coolant and changed thermostats..I wouldn`t expect my belt to be loose as that will cause the truck to over heat and kill my battery charging..So come on guys throw some ides my way, it`s cold down here in the carolinas.. woops almost forgot this is a 2.5 automatic..

 

[TimR]

This is driving me nuts. But here go..my temp will rise from cold to normal(midway) when driving then drop back down to cold..Sometimes it never leave the cold mark..and sometimes it works perfect..my heat follows suit. Now i`ve added coolant and changed thermostats..I wouldn`t expect my belt to be loose as that will cause the truck to over heat and kill my battery charging..So come on guys throw some ides my way, it`s cold down here in the carolinas.. woops almost forgot this is a 2.5 automatic..

how old is the water pump? Might it have a damaged/loose impeller?

 

[lsittingbull]

how old is the water pump? Might it have a damaged/loose impeller?

Factory pump. I do have over 200k miles on her though, I was told it could be my heater coil? Any suggestions...

 

[greenbean93]

Heater coil? Try thermostat. Also check your radiator, could be clogged which leads to a faulty thermostat.

 

[lsittingbull]

yea heater core, to many of these->..Im going to try and take the hoses of the the heater core and run water into the core in reverse and try and flush the deposits out...hopefully I can do this tuesday

 

[greenbean93]

Did you get it figured out?

 

[tomw]

You can get a "reverse flusing tee" made by the anti-freeze company, Prestone, I think. You put it into the heater core hose and then can connect a garden hose to reverse flush the system. You have to pick the correct heater core hose... for it to work properly.
That said, I think you are low on coolant and have an air bubble in the system. Try burping air bubbles out of the heater core lines by loosening the clamp at the heater core, and removing the hose to where it almost is disconnected. Start the warmed up engine at idle, and see if you can let air out of the hose by removing it slightly from the heater core pipe. If you get air, you can manipulate the hose to allow the bubbles to rise to the top by lowering the hose back towards the engine so 'up' will be at the core.
The temperature gauge needs to be in contact with the coolant to register, and the heater core needs to be full of coolant to provide heat. I think neither condition is met at times.
tom