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Amc 360 cant keep cool

3K views 35 replies 18 participants last post by  OldTexas 
#1 ·
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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#2 ·
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.
 
#3 ·
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
 
#8 ·
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!
 
#9 ·
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...:rolleyes:
 
#10 ·
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.
 
#13 ·
PARRISH200 said:
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.
 
#20 ·
I have a tendency to agree. Even if it were not getting hot, I would not want to run at 3300-3400 all the time, especially if only going 65mph.

Also, by experience, I would caution you about removing the thermostat and testing. I recently added A/C to my 304 and in the process added a "high flow" racing thermostat. Mistake. The water needs to flow across the radiator slower to give it time to cool. No thermostat may let the water go through too quickly. When I put a standard thermostat back in, I got a lot better cooling. When you think it through, it makes sense. CJ radiators dont have a lot of surface area anyway.

With that in mind, check to see if the builders put in a high flow water pump, that could be making the water flow too quick and not allowing the water to cool.

Another thing would be a fixed fan, no clutch, and also see if you have better air movement by moving your fan closer (or farther) from the radiator to see if you get better air flow in relation to the fan shroud. The spacer kits for that are not expensive. Also look at the diameter of your fan in relation to the diameter of your fan shroud.

You might try this too:
http://www.radiatorexpress.com/prod...MC+and+Ford+V8&part_id=218256&aaia_id=1309621

I recently put one in. It is a good quality radiator and did a lot to cool my engine with its 4 row core.

Good luck, keep us informed.
 
#14 ·
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/product_info.php?cPath=21_35&products_id=147
http://www.flowkoolerwaterpumps.com....html?osCsid=95041102d4a5c2a5f578ef143befb04d
WOW, both are about $100
http://shop.advanceautoparts.com/we...one-or-gmb_5421322-p?searchTerm=waterpump=$32
 
#15 ·
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.
 
#17 ·
Those posting about the tstat is right. It could be closed even brand new I've seen cheap ones fail. I am sure it can't be a gear ratio thing. That jeep shop doesn't know what they are talking about. They seriously are trying to take you. 4.56's isn't even that low. Low is above 5's. A radiator shop can check your cores out and make sure nothing inside is collapsed. A 3 core radiator as you stated having should be enough to cool it too. I'd start with thermostat as its cheapest and then move to radiator. What else is their to cooling other than that stuff a fan and pump?
 
#19 ·
another quick one. may sound dumb but...
are you sure the fan is rotating the proper direction? if a belt gets put on wrong around the pulleys you can reverse the rotation of the fan or the pump or both.

i am not familiar with the engine and if it has the old v-belt acc system this may not be a possibility. i wouldn't have mentioned it if i hadn't seen it happen however.
if however the fan had been swapped from something else the rotation may have been reversed on the setup it came from. just trying to throw out another idea that can be checked in 10 seconds.
 
#21 ·
Yeah Mike, it did sound dumb...at first glance...but after thinking about it for a minute I recalled that they made 360's up till 91'(I think) well into the serpentine days so who knows what direction the pump or fan for that matter is turning. while I doubt the OP would miss the fan pushing air out of the front of the radiator, in a puzzling situation like this all ideas should be checked out....probably no dumber than running around with the hood off...lol...ocg:laugh:
 
#22 ·
Have to throw a flag guys.

Water running thru a radiator slower will not make it run cooler. Thermodynamics applies here.

The way water gets cooler is by each water molecule transferring heat to something else. To do this each water molecule must either touch the cooler radiator walls or touch another cooler water molecule. To do this, water must be moving. The faster it moves, the more molecule interactions with the inside surface of the radiator and other cool water molecules, and the passages in the engine. This will make it transfer heat better.

Your water pump will only move water so fast, and your radiator is only rated for reducing fluid temperature by about 25 degrees.

The only reason they make bigger or smaller radiators is that engines are different sizes and have different water volumes. Your passages must not be fouled or they will insulate the inside of the radiator and prevent transfer of heat.

Radiators cannot remove the amount of heat that may come from a head gasket leak because they are not designed to do that.

There are lots of articles on the net about this subject.
 
#23 ·
I have replaced the tstat. And flushed the radiator after I bought it.the previous owner was running distiller water and water wetter.he only drove it around town and said it never overheated on the way home i saw that is running a little over 210 so I flushed it replaced hoses and tstat. When I flushed it I didn't know he was running water and while draining the water was rust colored. Anyhow, if I understand everybodies advise take radiator to shop, replace water pump with flokooler and run w/o a clutch on fan.thanks I will give it a try,and repost what I find. P.s. the fan is in correct direction,but not sure on size or the brand or kind of fan. I was told that the shroud is the v8 shroud,but does have gaps around it.i thought about using some hvac tape to close gaps. My brother in law is running the Taurus fan on his yj and has good luck with it,but I don't think I have room for it in cj
 
#24 ·
PARRISH200 said:
I have replaced the tstat. And flushed the radiator after I bought it.the previous owner was running distiller water and water wetter.he only drove it around town and said it never overheated on the way home i saw that is running a little over 210 so I flushed it replaced hoses and tstat. When I flushed it I didn't know he was running water and while draining the water was rust colored. Anyhow, if I understand everybodies advise take radiator to shop, replace water pump with flokooler and run w/o a clutch on fan.thanks I will give it a try,and repost what I find. P.s. the fan is in correct direction,but not sure on size or the brand or kind of fan. I was told that the shroud is the v8 shroud,but does have gaps around it.i thought about using some hvac tape to close gaps. My brother in law is running the Taurus fan on his yj and has good luck with it,but I don't think I have room for it in cj
Next time you take the tstat out or to test a new one boil water on a stove and out in new tstat to watch when it opens up.

Clutch fan or direct fan it won't matter enough to cause heating issues. Taking tstat out and running engine simple flows more water through the engine is all. I always drill a hole in my tstats before installing them to allow a little more water to get through. Been doing so for 14 years now.

The next thing we need to check is the size of your radiator. I know you said 3 core but what dimensions? I would change water pump if you take out the radiator as its not much more work to do so.

Post up once you get this figured out for our future readers to use this thread
 
#25 ·
~Subscribed~ I've got a '78 with similar issues. My work so far has been new 3 core radiator w/tanks, Flowkooler w/p, springs in lower and upper radiator hoses, full cooling system burp (with heater fully on), fan shroud, new controller for e-fan (takes reading from upper radiator hose now) 50/50 water/coolant mix. Now I haven't drilled a hole in my thermostat yet but after solving an oil leak I'm performing the Contour fan upgrade. There's likely going to be more than a few folks that'll remark 220 is just fine but I'm finding that they're driving XJ's and YJ's that by design have higher operating temperatures than these '70's V8's to meet emission standards.
 
#26 ·
gunk in the block

Both of my 360`s run hot. One of them i recently replaced a freeze out plug between number 6 and 8 cylinder. Behind the plug thru the coolant passage was solid matter. A lot of out to. I used a hammer and chisel to try and remove as much as possible. Who knows how much more it's lurking in the rest of the block?! This issue could certainly be found in other engines and prohibit proper coolant flow. Does anyone have a good flush additive they recommend? Someone told me liquid Lysol cleaner. But wtfk?

My Commando ran 230 degrees on highway for 15/20 minutes and thankfully there wasn't a problem. But all suggestions provided are great ideas. Our should i say COOL ideas! Happy Labor Day. May you have time to labor some love into your Jeep :cheers2:
 
#27 ·
Thanks again everybody for suggestions. I have heard about drilling hole in tstat,but not sure how big and does it matter where you drill it? Also the full system burp sounds like a good idea how do perform this as well?i will measure radiator dimensions tomorrow. I agree 220 plus is to hot for old motors, or in my case new old motors. Please let me know how the contour fan mod works out. I hope everybody has a safe and happy holiday full of jeeping
 
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