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Discussion Starter · #1 ·
Under the high flow water pump thread I have been posting about heater problems so back ground is there. Anyway, Alex got the new water pump, tried again to flush partially clogged heater core with store stuff then CLR- almost nothing came out. Also flushed hoses along fire wall- nothing there either. Put everything back together, ran truck for 20 minutes, revving to 2k as if driving. Still not enough heat to open t- stat. Turned car off, went in house. 3 hours later his son came in and said he thinks jeep is on fire. Alternator red hot, flames starting to lick out of housing. Doused repeatedly with water. What would make that happen?! In the other thread, I mentioned problems with my guages going out, so gonna do dielectric grease..moving along, while he was running the truck, he noticed red check guages light come on and voltage guage pegged at zero but he didn't think much of it since the cluster is acting up. Could have burned up my truck and burned down his house. No idea why this happened or what else is damaged. I know I bought the alternator at Auto Zone 2 years ago, I usually buy new with lifetime warranty but they said there's no record of it and call the manager tomorrow cuz he's better at finding that stuff. If I can get a refund instead of a replacement, should I go to Napa, do they have better stuff? I'm ready to lose my mind!! Thank you for any help, I'm dumbfounded at this development 🤦‍♂️🤯
 

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I always choose NAPA over the Zone, unless circumstances dictate otherwise. I am amazed the tstat is not opening. Did you install a reverse rotation pump. The serpentine system needs counter clockwise rotation
 
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Discussion Starter · #3 ·
A.Z exchanged it. At the time it went out 2 summers ago A. Z. was the only thing around, we replaced it on the side of the road cuz it threw the belt, which we replaced too. I don't know anything about reverse rotation pump. We just put the belt back on per the diagram. Where is this pump located and why wouldn't it already be in there stock if that's what it should have? 🤯 And as for it not getting up to temp, there's a ghost in my machine, not much left to check/replace. I sure do want to know why my alternator caught on fire tho...
 

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Dang that stinks. Sorry to here that. The voltage regulator is in the ECM. A fusible link is in the wire from the alt to the PDC. Which is just a 10 gauge wire with a piece of 12 gauge in it. It will burn out the 12 gauge like a fuse. If it caught on fire someone may have replaced it with just a straight piece of wire. Diodes inside the alt may have fried. Check the hot wire to the Alt and make sure it isn't shorted to ground.

When you say nothing came out of the heater core, do you mean crap, or no water will flow. How do you know the t-stat isn't opening? are both heater hoses getting hot, or neither one? A reverse flow water pump will have a smooth pulley and the back of the belt (non-ribbed side) will ride against it. pretty standard in these 4.0's PM Sent
 

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Discussion Starter · #5 ·
I'll look up all that stuff about the wiring and see if I can get a grip without asking too many more stupid questions. I just discovered the other guy meant the water pump itself. I ordered the new one from rock auto, they usually send the right thing. I don't remember if it said reverse or not but if that is required then, maybe wrongly, I assume that's what they sent. And I meant no crap from heater core, water came out fine. The t- stat isn't opening bc if my guages are to be trusted, it's only getting up to 190° and I still have no heat. Was just checking after flushing heater core again with CLR. The new water pump isn't even in yet. And now bc of the alt. fire, we're dealing with that instead. I'm gonna have to go into rock auto history to see what I got for a pump, good thing it's not installed yet.
 

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The reverse rotation is for a serpentine belt, since it runs off the back of the belt instead of the grooves
 

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Discussion Starter · #7 ·
Ok, but you're talkingvabout the water pump right? I'm not finding any good vids showing what you are trying to explain. Just that the water pump should be a reverse flow. Am I missing something here?
 

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I don't know of any vids for that. You just have to make sure you are getting one for a serp or V belt. The old 4.2L would have the clockwise rotation, but bolt up
 

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Discussion Starter · #9 ·
Just an update...replaced water pump, sanded surface rust off pully. Replaced idler pulley. I still have no heat! Someone mentioned quite a while back (I think in high flow water pump thread) that it could be the mechanical fan. So, everyrhing else has been replaced, checked, flushed and every other damn thing which only leaves that fan! I finally got over there (to Alex's)and on start up that fan spins full bore, no problem with e- fan- it's not coming on at all which is correct in this case. I ordered the new mech fan (which has been stuck in N.Y. for 3 days) and if that doesn't fix it then, lawn ornament? We'll see 🤨
 
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