I'm running a new amc 401 in my cj. Becool alum rad, elec fan. Won't stay cool. I've tried everything. I know there are guys out there running 401's in cj's. What are they doing?

Please...Somebody!

uh oh another thread like this. You should do a search for heating issues. Check your timing get the air out and use a couple of bottle of super coolant and she should run cool. If its overbored too much use a little block filler half way up and you should be able to run it like that.

Is super coolant the brand name? I used some kind of water additive, but it was a different name.

What's a block filler?

Thanks

first.. thing i would do is.. ditch that electric fan for a mechanical one... but if you really want to keep it.. do you have a fan shroud for it? how much of the radiator does it cover? with the correct fan and shroud.. this should stay cool.... also use a good quality anti-freeze with the correct mixture and make sure you get all the air out of the system... air in it.. will make it run hot..

i ran a stock 401 in mine with the stock 3 core cj radiator for years.. no problemos.... unless i took it up around 85... :D

My elec fan is a 2500 cfm, but it has no shroud. It's 16" in diameter. I was looking at an elec fan with a shroud that covered the entire rad. Do you think it would inprove my situation?

under what conditions does it over heat or does it run hot no matter what? Obviously there are the easy things like if it doesnt over heat at highway speeds you need a better fan. Also Have you tried running it without the hood on to see if you arent getting enough airflow out of the engine compartment?

edit: also sounds like your electric fan is pretty weak I would jsut put a quality mechanical fan on there.

My 401 is bored .040 over. I run a conversion radiator from Mepco (believe it is a 4 core). Taurus fan wouldn't keep it cool. I went back to a mechanical clutch fan, a 160 Tstat, and a full fan shroud. Also changed my coolant mix to about 80% water, 20% anti-freeze. It stays cool under most conditions now, though will still get a little warm under slow crawling speeds on a hot day.

My elec fan is a 2500 cfm, but it has no shroud. It's 16" in diameter. I was looking at an elec fan with a shroud that covered the entire rad. Do you think it would inprove my situation?
It could, if it's a powerful enough fan.
Not having a shroud is definitely a mistake. That alone will greatly improve your cooling efficiency. I'd personally go with a stock seven blade clutch fan from a CJ w/ HD cooling and a stock shroud. Get the air out of the system; run a 16lb cap w/ an overflow bottle; don't go over 50/50 antifreeze/water (and an even higher proportion of water, if you're not where it'll freeze.) .....And be sure the system holds pressure.

I know flex-a-lite rates there 2800 CFM fan to cool 300hp so I would say too small of a fan with no shroud at least isnt helping anything.