Need Help Diagnosing My Problem

[Winger98]

I've been having some temp/heater issues with my 07 Dodge Grand Caravan and wanted to run it by the folks here. first, if I just run the A/C I don't seem to have any issues. But if I turn the heater on, it blows cold for awhile. Then there is a temperature spike before it settles back down to normal and then it starts blowing heat consistently. If I turn the car off but come back before the car cools too much, the heater will still work. but if the car sits and cools too much, it does the same temp spike, settle, then works.

Now, I've been thinking the thermostat is going. And I like this because it's a pretty darn easy fix on my van. But there's something else. Of course.

There is a whining sound, like a pulley going, from the front driver's side. Which, of course, could be connected to the heating issues. Or it could not be connected to them at all.

I'm tempted to just take it to the mechanic because I don't feel like hassling with anything serious, or just replacing the thermostat and seeing what happens (it's a twenty dollar part and a thirty minute fix, so it's not a huge investment). Any takes on this?

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[HansonBro]

I've been having some temp/heater issues with my 07 Dodge Grand Caravan and wanted to run it by the folks here. first, if I just run the A/C I don't seem to have any issues. But if I turn the heater on, it blows cold for awhile. Then there is a temperature spike before it settles back down to normal and then it starts blowing heat consistently. If I turn the car off but come back before the car cools too much, the heater will still work. but if the car sits and cools too much, it does the same temp spike, settle, then works.

Now, I've been thinking the thermostat is going. And I like this because it's a pretty darn easy fix on my van. But there's something else. Of course.

There is a whining sound, like a pulley going, from the front driver's side. Which, of course, could be connected to the heating issues. Or it could not be connected to them at all.

I'm tempted to just take it to the mechanic because I don't feel like hassling with anything serious, or just replacing the thermostat and seeing what happens (it's a twenty dollar part and a thirty minute fix, so it's not a huge investment). Any takes on this?

Twas I...I'd replace the thermostat but save the old one. New thermos are notoriously crap.

You could try and bleed the coolant system by ramping up the front end as high as you can get it and idle the van well past operating temps with the coolant reservoir cap off. If its a pressurized system, the cap itself could be a problem. Air pockets are the bad guys

After that and concidering the whining noise you describe, it could be the water pump itself or the belt tensioner. You can manually adjust the belt tension by inserting just the socket wrench (blank) and turning but its not permanent

 

[HansonBro]

If it was the belt tensioner id expect battery issues as well so check the gauges for 12v

 

[Winger98]

sorry for not keeping track of this. Awhile later (2 weeks?) started getting a pool of coolant under the car. Radiator was leaking. Not sure if it was leaking the whole time but it took that long for the leak to get serious or if something finally gave, but dumped some of a leak stop in, topped the fluids back off, and it's been fine. Going to have to replace the radiator at some point, but this will put it off for a little while.

Still squeals, though. Thanks for the suggestions.

 

[ShelbyZ]

sorry for not keeping track of this. Awhile later (2 weeks?) started getting a pool of coolant under the car. Radiator was leaking. Not sure if it was leaking the whole time but it took that long for the leak to get serious or if something finally gave, but dumped some of a leak stop in, topped the fluids back off, and it's been fine. Going to have to replace the radiator at some point, but this will put it off for a little while.

Still squeals, though. Thanks for the suggestions.

Does it squeak like a loose belt or like a bad pulley/bearing? I would pull your serp. belt and check your waterpump pulley for any noise and/or play.

Your initial issues with temps/heat sounds consistent with an air pocket in the cooling system (IE from a leak, blown headgasket, not enough coolant, etc.), which likely came from the leak you found.

Did you verify that the leak was coming from the radiator and only the radiator? Reason I ask is because a squeak with the issues that you have usually means the water pump either has a blown seal or bearing, or is about to. Sometimes WP leaks are harder to detect because it's a small leak coming from the weep hole and/or it's leaking into some kind of timing cover, soaking into tens of thousands to hundreds of thousands of miles worth of dirt/grime, blown away by the radiator fan or dripping onto something hot enough to cause it to evaporate while you're driving like an exhaust manifold.

If you aren't exhibiting any other belt related issues like @HansonBro alluded to (IE battery not fully charging, power steering not working as well, etc.) then that makes a bad WP more likely.

I would check to make sure the leak isn't coming from the WP before spending the money on a radiator. Waterpump should be cheaper to replace, just not as much fun...

I bought a cheap car a few months ago that had the same symptoms yours did, but without a visible leak. Turned out to be a bad radiator cap and blown WP seal and bearing.

Whatever you do, make sure you thoroughly bleed the system of any air. I like using this specific funnel while the front of the car is raised to get the air out and see that the Tstat is working:
https://www.amazon.com/Lisle-24680-...argid=aud-801381245258:pla-436789109021&psc=1

Now that you've introduced "stop leak" to the system, make sure that you also thoroughly flush the system after you make repairs. I NEVER use that stuff, but when I deal with cars where it's been used, it always seems to work much better than intended and eventually cause more problems. The previous owner of the car I referred to above poured that stuff in that car and not only did it clog up the leak, it clogged the bottom corner of the radiator, the heater core and some steam lines between the cylinder heads. I ended up replacing the WP, radiator, radiator cap, tstat and all hoses, flushed the engine and heater core with the garden hose until the water was clear, drove the car around with 100% distilled water in the cooling system and re-flushed two times and now I STILL get glitter from that stop leak stuff under the radiator cap when I check it.

 

[Winger98]

Alright, since using the stop leak the leak has indeed stopped. But my heating went again. I ruined a thermostat and had the system flushed. worked fine for awhile, then the heat went again Monday. So, I backwashed the heater core today, let some CLR sit in the heater core for awhile, then backwashed the heater core a few more times with distilled water until nothing but water was coming out. And...there is heat again. A lot of heat. It's welcomed with all of the new fallen snow.

@ShelbyZ yeah, I'm very sure it was from the radiator. With the amount that was leaking and where it was leaking, I'm not sure there could have been another choice.

I'm mostly hoping to just get through winter and into warmer weather with it. Working in the cold sucks.