Sounds like u have a closed system with a open system rad cap. If that's the case, u probably are getting air in the system/engine when it cools. With an open system, u've got to have a bottom fill bottle plumbed to the base of the rad cap and the bottle must have coolant in it even when the motor is cold.

 

I'm new to Jeep's, so i dont know the oem thermostat temperature. Could you put a 180 Degree thermostat in it?

 

I could, and that would be good for city driving since its hot right now. It'd start open loop sooner, but my problem is when im at 210-250 degree's. At that temperature a 180 and a 195 tstat are both going to be open. My cooling problem is occuring at running temp.
And if you put a lower temp thermostat, I think, and correct me if im wrong, but it will force the engine into an open loop too soon compromising milage.

 

Ya, you are correct. Hmm. Well its a temporary fix to go to arizone and back. Did you try bleeding air out of the system? Sorry, i'm a rotory expert and i'm just now getting into pushrod engines.

 

I suggest when you get the time convert the coolant system to an open system.

 

I believe my 1992 is open no?

 

Mine (a '91, u do have open system i believe) was doing the same. Only at highway speeds. Would idle all day no prob. But 55-70 and higher it got hot. My problem was a clogged radiator. I replaced it with eom, new stat, cap, rad hoses, and water pump while i was at it. Under $200 and my system is all brand new. Easy to do as well. Cool as a cucumber.

 

Open loop/closed loop has nothing to do with the t-stat. When the engine is started cold, the system is in open loop. The engine is running off factory programming in the ECU. As the O2 sensor(s) in the exhaust reach operating temp +/-650F, they start sending AFR information to the ECU, thus closing the loop. Under steady/moderate cruise driving conditions, the loop remains closed. Under hard acceleration/deceleration, the loop opens, reverting back to factory programming and fuel maps.

 

Excellent, that's how u git 'er done and shes cool as a cucumber.

 

that's what i was thinking, but not sure. sounds like a trip to jy to grab an overflow, any suggestions? thanks

 

The bottle needs to be bottom fill (the hose from the rad cap) AND the bottle cap needs to be vented so that no pressure can build inside the bottle. Parts stores have nice clean new ones for cheap.

 

picked up a coolant overflow bottle from a 93 subaru impreza for $5 to finish off my cooling system "modification/upgrade":


here's a mock setup (still need to fab the bracket using part of the joist hanger in pic above):

this should work as long as the "new" bottle is mounted below the aluminum one that replaced the oem plastic one, right? don't worry, i've already washed, scrubbed, & rinsed the jy bottle thoroughly. i'll route the overflow from it down the fender well & replace the hosing where necessary. bracket tomorrow.
(btw: i bought the joist hanger bracket to use for my homebrew license plate relocation bracket)

 

Is there a tube under the cap that goes to the bottom of the bottle?

 

if you're talking about the jy bottle, then yes. cap has "in" that goes to the bottom of the bottle, & an overflow tube that is vented from the cap, so no worry of loss of pressure, as long as the bottle holds fluid. the diamond plate bottle has a 16lb rad cap, overflow from that will go into plastic bottle, & hopefully complete my homebrew "CLOPEN" (closed/open) cooling system. more pics when i get bracket finished.

 

Once installed, be sure to check that it's functioning correctly. As the engine/coolant heats up, coolant level should rise a little in the plastic bottle. As the engine/coolant cools (overnight) the coolant level in the plastic bottle should have dropped a little. The rad cap in an open system has 2 separate valves and both must function correctly to keep air OUT of the cooling system.

I'm somewhat concerned about that diamond plate tank possibly interfering (trapping air) with how the pressurized portion of an "open" system works. There should be zero, zip, nada air in the pressurized portion of an "open" system. Most people either splice into the top rad hose with a rad cap adapter or install a later model radiator that has a cap. That diamond plate tank has a rad cap but, it's not mounted directly in the top rad hose and that's what concerns me.