Temp/Heat fluctuation problem

[Todd R]

Hello, I just replaced my water pump and ever since my temperature climbs and drops sometimes it will run normal for a little while but then it will do it again. It never overheats however. Now that it is getting cold I've noticed that the heat is only coming out warm. The heat has always worked great, I hardly every have it on anywhere near to high other than defrosting or warming up on a very cold day.

If it was not for the fact this started immediately after the water pump I would assume it is a thermostat and I am still leaning that way but I was wondering if anyone else has had a similar situation. I have parked it on an incline with the radiator cap (another suspect) off and let it run but I still have the problem.

Thanks for any input, Todd.

 

[drdoom]

Did the replacement pump come from China?

 

[deweyville65]

I assume you have plenty of coolant, and you "burped" the radiator, and there is no air in the system. If so, my money would be on the thermostat. Are the heater hoses warm/hot both going to and coming from the heater?

 

[Todd R]

Did the replacement pump come from China?

No, it came from Oreilly's.

I did not notice the country of origin but it could have been china.

 

[Todd R]

I assume you have plenty of coolant, and you "burped" the radiator, and there is no air in the system. If so, my money would be on the thermostat. Are the heater hoses warm/hot both going to and coming from the heater?

Yes everything is full and I did try to burp the radiator but it is possible i did not do that correctly.

One other thing that comes to mind its the over flow has not worked in a couple years I did replace the radiator cap last year and it did not help and when I changed the water pump I blew the line clean (it was heavily plugged) but it still does seem to work.

 

[deweyville65]

Todd, with the newer systems, you really need to have the overflow operable. I think the radiator is not full. You may need to change the overflow hose, be sure there is no air leak any where between the radiator and reservoir. Good luck finding the problem.

 

[Todd R]

Todd, with the newer systems, you really need to have the overflow operable. I think the radiator is not full. You may need to change the overflow hose, be sure there is no air leak any where between the radiator and reservoir. Good luck finding the problem.

It ran for at least 25,000 miles with the overflow not working. I just never bothered with it because it was running fine. But I will look for an air leak, thank you.

When I parked it on an incline today the radiator was full and after i let it warm up with the cap off for twenty minuets and let some fluid burp out I refilled it and drove it and it did not change.

 

[koda2000]

sounds more like the thermostat is sticking to me.

 

[Todd R]

Koda thanks for the reply, I keep leaning that way as well but it just seems odd that it would happen as I drive it for the first time after the water pump change.

 

[koda2000]

Koda thanks for the reply, I keep leaning that way as well but it just seems odd that it would happen as I drive it for the first time after the water pump change.

from my experience with "burping" the air out of the cooling system, it can be a little tricky, but you'll know when you haven't because your temp gauge won't register at first and will suddenly shoot from "C" to "H" because you don't have enough coolant in the engine. from what you described i don't think that's your problem. maybe some crap got into the cooling system during your w/p change and is causing the t-stat to stick, or more likely it's just a bad t-stat.

 

[Todd R]

from my experience with "burping" the air out of the cooling system, it can be a little tricky, but you'll know when you haven't because your temp gauge won't register at first and will suddenly shoot from "C" to "H" because you don't have enough coolant in the engine. from what you described i don't think that's your problem. maybe some crap got into the cooling system during your w/p change and is causing the t-stat to stick, or more likely it's just a bad t-stat.

When I had the old one in I did use some of that copper based stop leak. Could that have fouled and/or plugged something maybe the heater core as well?

 

[gonenuke]

Anything you put into the radaitor as a stop leak can plug up the heater core. This happened on a S10 I had. Had to pull the core and use compressed air to blow it all out TWICE.

 

[koda2000]

When I had the old one in I did use some of that copper based stop leak. Could that have fouled and/or plugged something maybe the heater core as well?

if that sealant was clogging the heater core you'd never get any heat, not just sometimes. you can always back-flush the heater core to be sure, but i'm still thinking t-stat. my neighbor just fixed his no-heat problem by back-flushing his heater core. he had NO heat, but engine temp was okay and constant. he had tried changing his t-stat (ended up costing him $ as he broke a bolt off and had to take it to a shop to get fixed).

 

[SoNic67]

When the water pump is replaced, usually means that the engine overheated at some point because a non-functional pump. Therefore the thermostat might have being overheated too, which lead to wax coming out of it and malfunction.
That's why it is always smart to replace the thermostat with the water pump.

And yes, all the 'stop-leak' products can clog up radiators and heater cores, because they are almost always used in too higher quantity... I use oil additives and oil-leak fixes, but not the coolant ones.

 

[Todd R]

When the water pump is replaced, usually means that the engine overheated at some point because a non-functional pump. Therefore the thermostat might have being overheated too, which lead to wax coming out of it and malfunction.
That's why it is always smart to replace the thermostat with the water pump.

And yes, all the 'stop-leak' products can clog up radiators and heater cores, because they are almost always used in too higher quantity... I use oil additives and oil-leak fixes, but not the coolant ones.

No it never overheated, I just had a leak and kept putting in water but with winter coming I needed to start running antifreeze I figured as long as I was in there I would replace the pump as I could not tell if the old had a very small crack or it was just the gasket.

Thanks everyone it seems the consensus is the thermostat, I will replace that and see what happens.

Again, thanks, Todd.

 

[SoNic67]

Let us know how it went.