JeffN Posted July 3, 2011 Share Posted July 3, 2011 When it get 85 degrees and hotter out the only way I can keep this 90 4.0 from overheating is to turn the heater on full blast, not at all comfortable to drive like that. Using the A/C is a no go when it's that hot out. I am beginning to believe most of it is due to the airflow thru the radiator getting jammed inside the engine bay by not having a real place to escape while driving. I see alot of people put vents in their hoods to let hot air escape, but mine is a 2wd vehicle, not an offroad vehicle. What I am really looking for is ideas, I have a new thermostat, radiator has been boiled out and flow checked, Aux fan has a temp switch that goes off at 200 degrees and works fine. Under 85 degrees it runs right in the middle, just anything above that it gets really hot. Link to comment Share on other sites More sharing options...
starkizer Posted July 3, 2011 Share Posted July 3, 2011 I'm guessing you have checked the coolant and exchanged it as needed? I know that the thought of someone else doing anything to your Comanche is horrible, but I know Sears offers Coolant Exchanges for about 85 bucks. Its a little more then what you can do in your drive way. Its a big pressurised machine they hook it up to and suck all the old out and put new in, no risk of getting air bubbles. I had mine done and it helped alot. I also had to take the aux fan off its auto switch thing as it was messed up and ran it to a switch in the dash so I could control it. I do plan on putting in hood Scoops to bring air into the engine thou. More for looks, but I want the functional. Good Luck. Link to comment Share on other sites More sharing options...
kyleag89 Posted July 3, 2011 Share Posted July 3, 2011 If your truck is running hot and both your fans are operating properly than you have a weak or faulty componant. The waterpump could be on its way out or your radiator could be clogged. Whats your coolant look like? Link to comment Share on other sites More sharing options...
ParadiseMJ Posted July 3, 2011 Share Posted July 3, 2011 If your truck is running hot and both your fans are operating properly than you have a weak or faulty componant. The waterpump could be on its way out or your radiator could be clogged. Whats your coolant look like? I don't know if the air gets "jammed up", I also think vents *help* but they won't solve your cooling problems. If any part of the whole cooling system is weak it'll play hell trying catch up. Running hot at highway speeds is a coolant circulation problem, Pump, Core or Radiator (or all). Running hot at slow speeds, idling, traffic, slow n' go is an air flow problem over/thru the radiator. Fan clutch (and you could upgrade thjat e-fan with a curved 10 blade from the JY. If you just can't figure it out and it gurgles or burps, you have air in the system With your Jeep at oper. temp. and engine off turn the mech fan with your hand, if it spins freely the fan clutch is toast. Other thing s to look at are t-stat, cap, pressure bottle. Sounds like your cooling system needs some attention. It's 100+ here today and mine is running at 200~210 with the A/C on, up and down hills, fast or slow. Link to comment Share on other sites More sharing options...
JeffN Posted July 3, 2011 Author Share Posted July 3, 2011 I am an auto tech and used the coolant flush machine we have at the shop, brand new water pump, not rebuilt. Did a block test to look for exhaust gas in antifreeze, antifreeze is brand new. Clutch fan works perfectly, as does the electric fan. Cap is brand new, fluid level is perfect. Took out the condenser and ran a fin guide over it, although the huge gap between the A/C condenser and radiator seems weird. One thing that bugs me is that there is no rubber "plate" for lack of a better word at the bottom of the radiator. It may be an air guide keeping air from going out the bottom of the radiator once it goes thru the condenser. Oh, i did pull the new pump off and made sure it had the right impeller blade on it for flow, my flow is excellent. I may go have a 4 core radiator made for it using my side tanks, this is driving me nuts Link to comment Share on other sites More sharing options...
Boots Posted July 4, 2011 Share Posted July 4, 2011 Not trying to be smart, but are you going by the factory gauge? are you sure it's accurate? Link to comment Share on other sites More sharing options...
ratrapp Posted July 4, 2011 Share Posted July 4, 2011 my mj used to get hot on hard pulls in hot weather as well.between a partially clogged radiator and crappy expansion tank it would get hot.i switched to a new all aluminum radiator off of ebay and done away with the expansion tank,it stays a consistent 195-200 degrees on the interstate now,even at 75-80 mph at 95 degrees just yesterday. Link to comment Share on other sites More sharing options...
Jerry Forrester Posted July 4, 2011 Share Posted July 4, 2011 I know you said you had the radiator cleaned, but I think you need a new radiator. That's what cured mine from running hot. later, Jerry Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now