Hello, Overheating problem

Hey again,
Thought I'd take this jeep on a hundred mile long trial run before my big Minnesota trip. Had to turn back after about an hour into it cuz it ever so slowly overheated. Running it at 70 mph, it just slowly kept creeping up. I don't have a shroud and I had upgraded the motor from the 304 to the 360 (rebuilt). Or should I simply try taking the thermostat out? Strange huh? Thanks for any suggestions.
CH

 

First check the usual stuff. Is the radiator clogged? Is the lower radiator hose collapsing? Does your thermostat open fully? Do you have an air bubble in the system? Fan clutch working? Check for too much spark advance and/or lean air/fuel mixture. If you are running the standard 2-row radiator from an I6 Jeep it may not be enough capacity for the 360.

 

^ What he said. A 2 row radiator would not be sufficent to cool the engine. If the temps are slowly creaping up then it would seem that you do not have enough cooling capacity in the radiator. Also at 70 MPH it would not matter if you even had a fan on the engine much less a shroud. You are forcing sufficent air through the radiator simply by driving.

 

I had a 78 Cherokee for years with the 360 motor. It was the first of the smogged engines and never ran right. It pinged, and ran hot. I changed everything including putting in an RV cam. Never could get it to run cooler. Premium gas helped. I know that is not much help but I would think in a lighter vehicle it should be easier to get the temp down.

 

Hmm okay,
Good analysis... you know where to find an applicable radiator for a 74' CJ5 but with a 360 motor?
CH
Ps: noticed how after I put a 3" body lift that my radiator is sitting higher in relation to the motor/fan. But as you said, at 70 mph it would'nt even matter if the fan was on the thing.

 

I put a 3 row in my CJ. Any good raditor shop should be able to get you one. I have had it sitting in my drivway in 100* temps idling for over an hour without it over-heating. Of course the engine is a 6 and not an 8.

 

I have a 75 CJ5 with a 304. I had the same problem too. I upgraded to a 4 core radiator & added a stock shroud. Now it doesn't overheat. I wouldn't take the thermostat out.

 

I don't think it'll help much to take out the thermostat. I have found that some vehicles even jeeps won't run cool withot a shroud of some kind to direct flow. What kind of fan are you running? If your heating up at that speed I'd suspect that you may need a shroud new fan clutch or fan as well as a radiator suited to your needs. You'll need a radiator with a cooling capacity that matches the capacity of the engine. That is if you are running a 304 you'll need a radiator with at least 304 cu in of cooling area. Now we know that the jeep has a lot of frontal area but unless you can draw air through the radiator to cool the coolant it's all for naught. So be sure you have a shroud or electric fan or fan on the engine thats causing a flow through the radiator. You can't just assume it is. I once had this problem because I added a what I thought was a large enough themostatically controlled electric fan and it wouldn't cool until made sure I directed the flow directly through the radiator.

 

Taking out the thermostat may make things WORSE. Here in FL where it can get mighty hot you hear this idea all the time. The truth is when your thermostat is fully open it has a certain size opening in it. This openeing allows the water to flow thru the radiator at a slow enough rate to allow it to be properly cooled. If you pull the tstat out the water will flow thru the rad way too fast to be properly cooled. So it will actually run hotter. The proper way to do this is to pull the guts out of the tstate and put just the plate back in. This way the water will flow at the proper rate.

I have a 3-core rad on my 258 and it stays at 185 no matter how hot it is. So I would assume it would be not quite enough for a 360.

 

Got my 3 row fom Carquest. Around $250, if I remember rightly. Solved my problem on the '78 304.

 

Okay dokie fellas,
I got this old man that sells just jeep parts out of his pull barn and he happens to have a radiator for a 360 that will fit in my CJ 5. Pretty cool huh? But tonight my buddy and I are placing one of those flush/fill kits in the system and seeing if it happens to be clogged. But I suspect that , yea, my cooling system isn't up to snuff with my size motor. I'll let you in on what happened tomorrow... thanks a bunch.
I have been informed to take out the thermostat but from your advice, I understand how it works now... so I won't.
CH