02 Caravan 3.3 Heating issue

Hey all, it's been so long since I was here I had to re-register to get on, holy. Anyways, just bought a 02 Caravan 3.3 auto, had an over heating issue so I checked and checked, did the obvious changed thermostat ( stant thermo, new ) and I find that the water pump impeller fins are sheared right off. The impeller was plastic if you can imagine, anyways I put a new pump on it and it all seemed good, for about a week. I'm scratching my head now, tear out the new stant thermo and it wont even open at 240 so I order another and stuff it in. No good. Now I'm no newbie here, I've been a tech for 25 years. First start of the day it warms up normal, slowly get heat, then the heat drops off ( im talking heat out of the heater, the gauge always reports correct ) blows cold, gauge spiks to max, stat opens, gauge falls to half the never leaves half but the dash heat comes and goes as the thermo opens and closes. So today I pulled the new pump back off because I'm thinking the impeller is off or even the wrong impeller. Now I look at the impeller and it is a counter clockwise impeller but the pulley is pulled clockwise, being an 02, the earlier models go counter. I know there is a newer rad in it because the bills the guy gave me tells me so, I pull the thermo out of it, top it up and yes the rad flows very very well. No over heat with stat out, I cant see a head gasket as the oxy's dont tell me there is an issue, the is no misfire code, and with the stat out ( other than no dash heat ) it performs well. Any input would be great, thanx.

edit:
So in short, Thermostat = good
Rad cap = new & tested to 17 lbs, good
System flush = clean & flows free, good
Rad = flows clean & clear, good
System pressure test = tested to 17 lbs hot & cold, leak free, good.
Scanner tested = no codes, no fault indicators,all systems report well within parameters, good.
Belt & tensioner = Clean,not slipping, good.
With thermostat removed system appears to flow only under high rpm which is why suspect the impeller is incorrect for this pump on this application. I drew a pic, rather crude but I tried,lol, to show the direction which the impeller turns. I think it's turning the wrong way myself but I could be lost in thought after beating my head against the wall on this one.

My crude drawing of the impeller.

I'm a new tech, while I've nvr experienced this b4 id say this theroy is spot on considering all you"ve tested and done.. would the temp sensor have anything to do with this issue. I'm talking about the sensor on the engine which tells the comp and gauge its hot or cold??

Thanx for the try but no..........when it does it's first over heat of the day there's no doubting it's hot and I mean hot to the eyes under the hood. I don't go by the gauges anymore, after 25 years theres just things you don't do,lol. I think the thing to do here is go to the dodge dealer and put my hands on a new dealer water pump and see which way the impeller viens lean.

So off to another supplier, NAPA, to look at 2 other pumps. Looked at a new and a rebuilt, bot of those were different bands than i bought and both of the ones I looked at where different brands. Well what do you know, both of the NAPA pumps were in fact the same as the one i have on the van, the impellers run in what seems to be reverse. I'm scratching my head on this one. I am starting to wonder if down lower in the rad some of the cores are plug. You can see the top few and the rad really does appear to flow well. i wish I could pull a tank to get a clear look. I have not been beat in 25 years of doing this. i have had cars towed in from other shops to my shop because they couldn't figure out the issues, I'm not gonna be beat from a caravan, geez.:banghead:

If I am not mistaken, the impeller pulls the coolant from the tube behind the housing and pumps it to the lower rad hose. This would mean that the impeller would need to be more efficient at pulling than pushing.

I am having the exact opposite problem you are with my van. Due to failures, I have replaced the rad, waterpump and thermostat and I cannot get my van to heat up enough , especially on cold days. Turning on the heat inside the van to high will cool down the engine as well.

Anyhow, I think you are not looking at the correct problem. I'd verify that the rad was not plugged, these rads were not a good design from that factory and chances are the previous owner of your van never maintained the cooling system properly (like 99% of the world out there). Flush and clean the entire system before condemning waterpumps.

The cooling system flows hot through the top hose into the rad, down through the rad and cold back into the bottom hose and back through the engine and exit again through the top hose back to the rad and so on. This van has been maintained be on belief. When we bought the van the guy us a huge binder with every receipt he ever got. The rad was replaced not long ago from a Chrysler dealer. One tank was slightly seeping so they changed it. I have been a self employed tech for 25 years and I haven't seen that many records keep and a vehicle maintained like this one very often. I am seriously thinking about yanking the rad and heading off to our local rad shop, they are a very reputable shop so I have no worries about what they have to say about it. I have to admit that this one has got a good bite on me but i will win, guarantee it.
As for your lack of heat issue, that's got an interesting ring to it. I have a coulpe of stupid questions, are the cooling fans running all the time?? Check your thermostat manually, boiling water and a thermometor and slow step up the temp of the boilg water to see where it actually opens. I put a new stat in our van and it wouldn't even open at 240 degrees.

So here's the new deal. I removed the check valve in the thermostat and drilled 2 other 1/8 in holes in the thermostat and put it back in. It did not over heat, not even close, it only got up to about the 1/4 mark on the gauge. It cinsistantly blew heat out of the dash but it was tough to get a good read because it was -21c today with a -30+ wind chill. So now I'm going to solider one of the hole up so that there is only 2 holes. When I get back to the shop I am also going to test this thermostat because I am really starting to think this stat may also be bad.

I believe the hole is supposed to be in the 12 o'clock position as well. Is this where you had it?

Yes I had it there. Those stats are indexed, meaning they will only go in one way. If you try to put them in any other way the stat wont seat into the housing and it will bend the housing all to hell.

Ok, I'm pretty much ruling out the water pump now. I was going to ask about the positioning of the t-stat, but you addressed it in your previous post. I'm leaning towards a clogged rad. In your original post you did say that the fins on the original pump wore off. They had to go somewhere, right? Maybe they clogged up the veins in the rad, or worse, the heater core? Yikes!

That could also explain why it was good for about a week or so. Depending on how much you drove it, it took some time for all the debris to pile up in one place and clog things up.

Ok then, so took the stat back out this aft and stuffed it into boiling water and the damn thing didn't open up for till round 2 of the boiling water bath. When it did it snapped open and it is binding on the shaft so it opens sideways and only about 1mm. I didn't have another stat as i was simply testing the stat today so I soldiered up 2 of the 3 holes ( leaving the factory hole with the valve removed ). The damn van ran just the needles width below half on the gauge and blew heat very well. I simply can't believe that I managed to get bad new Stant thermostats right out of the box. I am going to get a dodge stat next and if this turns out to be the entire story I think I had better start buying lotto tickets, and lots of them because that would be some kind of way out there odds. 2 new stats bought at 2 different stores.