1990 YJ 4.2L overcharging

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Drillerguy

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Joined
Aug 26, 2021
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Spokane
I have a 1990 YJ with the 4.2L inline 6 cylinder engine. I installed a shiny new 3 row aluminum radiator with electric fan, the fan burned up in about 15 minutes. The company that i got the electric fan from replaced it. This one also burned up in the same time frame.

After checking around, the alternator is putting out 15.3 volts. Thinking the internal regulator was bad, I replaced the alternator with a "new" rebuilt one, this one also is putting out over 15 volts.

No other electrical issues. What am I missing?

Thanks
 
What brand of radiator and fan did you get?
I did the same thing, bought a Champion radiator/fan combo from Amazon for about $400.
It's been working fine, though after buying it I have seen some negative reviews.
Keeping my fingers crossed...

As far as the voltage, are you looking at the gauge or a meter?
The gauges tend to read a bit high.
Why the fans would burn out is very odd, DC stuff usually has about a +/-5V Tolerance.
...Unless it's Chinese crap.
 
Last edited:
The radiator, electric fan and shroud came from Radiator Express, love the radiator, seems like it is high quality.

The fan is a Champion Stage 2, wired through a relay, temperature sending unit supplied by radiator express.

The voltage gauge in the jeep reads high but I don't trust it. Measured the voltage at the battery with a meter, before starting it was 12.5v and after starting and at a higher RPM it is 15.2v.

I have burned up 3 electric fans now, seems odd to me too that they burn up. there is not room with the new radiator for the stock fan clutch, so I am going to put a flex fan on until I can figure out the voltage issue.

Is your fan a puller or pusher?
 
Damn, 3 fans?
Mine also came from Radiator Express.
Like your's, the radiator Rocks! Hot air at the top, ambient air at the bottom
Mine's a puller, and I selected it specifically for that reason.
Actually got a call from RE warning me that it might not clear the water pump.
I knew that it would because I only have a 4 banger, and half the engine bay is fan shroud.
I just wanted to get rid of the propeller and that ridiculous shroud, and the OEM rad had a Bad case of the crusteeze...

Had a 16" pusher on my last Jeep, seems to me it was a Hayden or something like that, anyway I paid a LOT of money for it.
Only problem I ever had with it was the relay.
It worked great for years, I just didn't like looking at it.

I am concerned about this new fan having a "Made in China" sticker on it, but so far, so good.
Your voltage is a little high, but that shouldn't be killing fans.
That's definitely weird...
 
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