LeftHandRubi

I don't think it is programming. I've used both AEV and BOR. Still have the issue. I think it is weight and capacity. The hemi's, I think, run near the envelop anyway. I have more of an issue because I have more weight. I like to drive fast going up to eisenhower tunnel. I do not like having to slow down and turn my heater on to dump heat.

Summer gasoline burns hotter too. That doesn't help either. The fundamental issue is radiator capacity, though. The just aren't big enough for all uses.

I'm not putting a hemi into my other JK until I know for a fact this can be solved.

You Jeep

I hear you. I am going to wait it out until these issues are resolved as well. Thank you for the input, very helpful!

AndyM

This issue is somewhat disconcerting to me. I have everything ready to go for my 5.7 swap, but the primary reason for the swap is for extra towing power. Overheating would defeat the whole purpose. I'm interested to see what the ultimate solution will be.

You Jeep

As am I, this is why I am waiting. No way am I going to drop the coin if it will not be reliable. Granted, I'm in so cal and would probably be fine but if I travel I want to be reassured that there will not be an overheating issue!

eDiveBuddy

Have you tried running it without the powerplant? I can see that blocking most of the radiator. I know you said you were going to relocate it. Just wondering if you actually pulled it out to see what temps it ran at.

Might want to try the TMD hood as well. It will vent more heat than the AEV hood and has cool air induction.

Were is the cooler for the PSC at?

Is the radiator too low? The fluid when you open the cap should be higher than the engine.

No kinks in the hoses. Water pump? Blockage in the plumbing?

I sure you've checked all these. It just boggles my mind you're having this issue when I just drove Reno to Chicago in a Jeep loaded to the gills and had no heating issues. I did not drive more than 200 miles though without a break. But that was to let the loaner Atlas cool down. I did see the transmission temps get hot. But 225 was the highest the water got with the A/C on through the mountains.

I hope you figure it out. It has to suck to know you have to worry about something.

LeftHandRubi

Thanks. We'll get it eventually.

So yep, took off the powerplant. Didn't matter. I did order a TMD hood, it should be here in a few weeks. No kinks, seems to be circulating ok.

Radiator is where the stock one was.

One thing we haven't checked is the water pump. It works, but maybe not well enough.

For 6 months, I had no issues. Why did they suddenly start? Could be the change over to summer gasoline put me over the edge. Or maybe the water pump impellers are worn. Or maybe the AEV radiator was partially plugged. (It sure seemed like it when we took it out and tested it).

The PSC Stinger presents quite the air dam too. Alone it didn't matter to much. I think now with all the other changes to radiator capacity etc, it will.

Its an irritation for sure.

JKDinker

Do the guys that do not have heat problems have skid plates? My inner liners are out and I also have the TMD hood. 180 thermostat. Seems to be working on the heat issue. JSS is working on a aftermarket water pump for the Hemi's. I think the stock one has plastic impellers. Mine has only got hot pulling a long hill in the mountains. On the trail or around town is no problem. But on a hot day the heat just pours out of it. Weird.

therza

I think you could be in for a very long wait. I don't think the kit manufacturers are agressively pursuing this issue, at least that is my impression. This has been an issue here in CO for SOME hemi jeep owners who: 1. Have added weight through upgrades or towing trailers AND 2. Like to keep the hammer down even when going up long steep grades. I live in CO and drive the same grades. I did not do axle upgrades to D60's, but I do run after market front and rear bumpers, sliders and full armor underneath, with 37s.. I have a 5.7 hemi and I don't overheat. I have conducted some "tests" at the Eisenhower tunnel. Running hard up the hill, 65 mph I will see some temp rise just as I reach the tunnel, maybe 20 degrees. It drops as soon as I enter the tunnel (no more uphill grade). If I keep my speed at 55 mph going up the grade, no temp rise at all.

I would not let this issue deter you from a hemi conversion. Just keep in mind that extra weight can be an issue when running long steep grades at high speed. These vehicles are clearly near the envelope when it comes to cooling capability. Just plan for that. If I were doing it over, I would focus on weight reduction where I could. There are some great new aluminum bumpers and sliders on the market now. A hemi conversion would be a good home for these! My 2 cents.

PS doing a hemi conversion for towing is probably not a good idea given the heating issues.

eDiveBuddy

I can't believe weight is the real issue with over heating. It may hasten the onset, but WK's rated at 12,200 lbs combined weight with the 5.7L . Maybe check to see if WK's are having the same types of problems and see what helps there.

I also don't know how a 180 degree thermostat is going to help overheating. Open at 180 versus open at 195 they should both be fully open long before it overheats. You're not trying to keep the engine cool, you're trying to keep it between 195 and 215. I would check to see that the thermostat is working though. And if needed I'd put in a new 195 degree thermostat.

When it overheats, is the coolant boiling off? If yes, have you tried a new radiator cap. Heck they're cheap enough, I just go ahead and put a new cap on anyway.

Are you using a 50/50 mix of coolant to antifreeze?

Have you bled the air out of the cooling system? Was the heater turned on when you did this?

What kind of exhaust are you running? If it's too restrictive, it can cause heat buildup.

Check the brakes? Seems stupid, but maybe the e-brake is sticking. Maybe, like me, there's a rock between the caliper and pad. (How mine got in there I'll never know)

Have you checked the hoses? Rev the engine to like 3000 rpms. If one of the radiator hoses collapse you have a bad hose.

Is the fan running at high? Mine stays on constantly.

Shouldn't be a problem, but is the belt slipping anyplace?

I do know the Hemi is a big engine being crammed into a little space. Airflow around the engine could be an issue. TMD hood or a Cop4X4 hood. (I wouldn't mess with the AEV hood but it has to vent better than the stock one). Try wrapping the headers.

Again

Fluid in the radiator should be higher than the engine.

Nothing blocking the radiator up front.

Nothing clogging the radiator or cooling system.

Water pump working ok?

That's everything I can think of. There has to be something different between the HEMI's with heating issues and those without. Could be just the driver, but I doubt that. You'd have to be insane to push a HEMI to it's limits in a JK (Though I guess there are those here who would )

I just can't stop thinking about this. It's a lot of coin to have this issue. I'd be pissed.

Also normal operating temps for a Hemi are 195 to 215. Max operating temp is 260.

therza

Basic laws of physics - more weight requires more HP to move it. More HP requires more fuel. More fuel burned means more heat generated. There is no "magic bullet" that just fixes it. It is complex and multi-faceted.

I do remember that the Service Manual procedure for bleeding the air from the motor is quite complex. I just did it the old fashioned way and it "seemed" to work. But who knows - maybe there is still air in the system?? Could it stay in the engine after 1,000's of miles?? I don't think so, but who knows!