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Unread 09-01-2012, 01:59 PM   #1
PARRISH200
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Amc 360 cant keep cool

Thanks in advance for your advise and direction. I have an 83 cj-7. I bought this jeep recently, and have been servicing from top to bottum. The problem I am having is the cooling system. I have had the jeep at several shops, and have tinkered myself. So here is the meat of it. This is a late 70's amc 360, recently rebuilt by my local jeep show, high rise intake, 4bbl carb, rv cam. All previous owner work has been done in the last yr.. According to my local jeep shop it is running a 4.56 gear, also a less than 1 yr old 3 core radiator, and mech fan with heavy duty fan clutch, and v8 fan cowl
I have flushed, replaced the 180 t stat, replaced hose with spring, had timing checked, and lost more hair. on a side note the jeep still has the factory t-4.which i know is gonna be an issue of its own in the near future.
Anyhow the jeep is fine around town, and at idle. Havent been offroad much due to the overheating on the highway. any driving over 50mph for more than a few min jumps the temp from a @190 to 220 in min. if I pull over and let it idle it will drop back down in a few min. Also important jeep has after market bumper and winch.
So my jeep guys are telling me the only fix is to lower the gears, they recommend 3.54's, and also want a $1000/axle to do the job. My problem with this is that I feel like the real issue isnt being addressed. Any recommendations appreciated. several posts I have read recommend the electric fans and 4 core rad. and flokooler. However my jeep shop said it wont help, only lowering the rpms on hwy driving will remedy the issue.
I thought trying to convert over to the ax15, but they told me over $4000 to do that conversion.I would like to keep the 4.56 gears and run the 4spd and fix the overheating issue. Any help or recommendations appreciated.Also, where to buy need products would be a huge help. thanks again

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Unread 09-01-2012, 02:30 PM   #2
nshefbuch
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You can have a collapse on the inside of the radiator and it would be very hard to tell. A simple replacement or getting a new core could fix the problem. I run aluminum 2 core for mine and have absolutely no cooling issues. I even kept the stock clutch fan too. Stock water pump as well.

Other advice is I wouldn't go back to that "jeep shop" whatever that is. Find a engine builder who's reputation is decent and try them if you can't do the work yourself. Replacing a radiator is pretty easy and straight forward and only takes a few hand tools and catch pan to do so. Good luck on fixing it.
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Unread 09-01-2012, 03:00 PM   #3
Oldcraneguy
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What kinda revs are we talking? I would bet theres hundreds of jeeps running your same combo and making it work. I would give up my "jeep guys" before Id give up my gears! Im assuming your not running stock tires and trying to cruise @ 80 right?
One question, have you checked to make sure your lower hose isnt collapsing at high rpms when hot?...ocg
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Unread 09-01-2012, 03:13 PM   #4
Oldcraneguy
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Actually I got a cpl more questions, does it lose any coolant when it gets that hot?
Have you verified the temp with another gauge or one of those infra-red thingy's?
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Unread 09-01-2012, 03:38 PM   #5
PARRISH200
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i AM RUNNING 33' TIRES AND AROUND 3300-3400 RPM AT 62-64. I HAVE ADDED A SEPERATE GUAGE AND CHECKED WITH INFRARED, AND YOU CAN FEEL AND SMELL IT.
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Unread 09-01-2012, 03:39 PM   #6
PARRISH200
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I have replaced lower hose with one with spring inside, and no coolant loss that i can see, have not had to add any to reserve tank
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Unread 09-01-2012, 03:40 PM   #7
PARRISH200
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I agree with all posts so far. I really dont want to get rid of 4.56 and doing the 5 speed cost to much.
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Unread 09-01-2012, 03:42 PM   #8
hutch1200
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Good advice above, but man, what a head scratcher. For me at least! Could the pump be cavitating at high speed? How would you even test for this? Maybe pull it, and compare it to a HD job from a flaps? Might be worth a $40-60+ shot?
BTW nshefbuch, buy ya a cold one in our jeeps next year at Bloomsburg? My treat!
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Unread 09-01-2012, 04:18 PM   #9
Oldcraneguy
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I think if it were me Id pull the T-stat out and run it with the cap off just to check flow and if it flows well at high rpms with no signs air/cavitation, cap it off and try goin down the road with it and see how it reacts. with the stat out it should flow like a fire hydrant, if it doesnt youve got a restriction somewhere, if it does it would seem you need more radiator..
you could always do like my buddy and hang a second one from the roll bar braces...
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Unread 09-01-2012, 05:51 PM   #10
roadhog304
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have you checked the radiator to make sure it does not have buildup inside restricting the flow? A good radiator shop could do a flow test with to see if it has any internal restrictions.
I do not think your tachometer is right. On a gear calculator site your rpm with a 31" tire, 4.56 gears and manual non overdrive shows 3213 rpm at 65mph. 33"tires are 3018 rpm. That is not that fast but i try not to push my 360 over 2500 rpm. for you to drop to 2500 rpm you would need to run 55.
I have a 4 core copper rad. and a flow cooler water pump. I can run 195 to 200 degrees at an air temp of 95 degrees at 2500 rpm. I have a 195 t-stat. If the ambient temp goes up or the rpms go up my temp will go up also.
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Unread 09-01-2012, 07:24 PM   #11
PARRISH200
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It is likely my speedo guess is off. I figured the speedo is 12-15mph off
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Unread 09-01-2012, 07:26 PM   #12
PARRISH200
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What kind of pump do you recommend
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Unread 09-01-2012, 08:25 PM   #13
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Quote:
Originally Posted by PARRISH200
i AM RUNNING 33' TIRES AND AROUND 3300-3400 RPM AT 62-64. I HAVE ADDED A SEPERATE GUAGE AND CHECKED WITH INFRARED, AND YOU CAN FEEL AND SMELL IT.
If you are running 3300-3400 rpm's and driving 62-64 mph then I would say the jeep guy are right about regearing being the fix. That's a lot of rpm's for sustained driving.
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Unread 09-01-2012, 09:05 PM   #14
hutch1200
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I guess the question now is what are your plans for it. Is this a second Jeep to your TJ? What I'm getting at is this your MOSTLY off road jeep, DD or a % in between? I like roadhog304s idea of a flow cooler water pump FIRST. Do the cheapest stuff 1st! Then a rad test. As far as gears, that goes back to its' use.
http://www.bulltear.com/catalog/prod...roducts_id=147
http://www.flowkoolerwaterpumps.com/...78ef143befb04d
WOW, both are about $100
http://shop.advanceautoparts.com/web...=waterpump=$32
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Unread 09-01-2012, 09:17 PM   #15
davbytrace
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If you are going down that road that fast, with that amount of air moving across the radiator, the only issue is that you are not removing heat fast enough. You are not moving water or you have enough clogging to prevent heat exchange. Take out the T-stat and test it, or just remove it. Change to a flowkooler water pump. Clean out the radiator. Other than possible timing issues or an internal combustion chamber leak into the water jacket (via the head gasket), there is not much else it can be.
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