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Old 03-05-2013, 06:56 AM
MOPWR2U MOPWR2U is offline
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Default Do the Hemi Conversions have an overheating problem?

I've read several places that the Hemi conversions have overheating problems. Is this the case, or not?
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Old 03-05-2013, 07:04 AM
Panhead5 Panhead5 is offline
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Good question !! I'm thinking of doing one and ran into a Gentleman in Ouray Co. in August of 2011 with an AEV 5.7 conversion .He said he loved the conversion but did have overheating problems.I'm definetly not into that.

Donjku chime in here !!
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Old 03-05-2013, 08:04 AM
scubatech scubatech is offline
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Originally Posted by MOPWR2U View Post
I've read several places that the Hemi conversions have overheating problems. Is this the case, or not?
The conversion kit has a larger radiator included within. I would think that issue would have been taken care of a long time ago?
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Old 03-05-2013, 09:50 AM
MOPWR2U MOPWR2U is offline
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Well thats what I was thinking, that any overheating problems were from the first few conversions, and the problems, if any, were sorted out by now. Thats what I'm trying to determine.

Although, I have to ask myself ... "self, why does AEV sell a heat reduction hood?"
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Old 03-05-2013, 09:55 AM
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Originally Posted by MOPWR2U View Post
Well thats what I was thinking, that any overheating problems were from the first few conversions, and the problems, if any, were sorted out by now. Thats what I'm trying to determine.

Although, I have to ask myself ... "self, why does AEV sell a heat reduction hood?"
Because it gets hot under the hood, especially when moving very slowly with lots of RPMs.

I firmly believe that most "problems" you hear about on the intrawebz have been exaggerated 100x, if not more.
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Old 03-05-2013, 01:56 PM
donjku donjku is offline
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Ah yes, the dreaded overheating issue with hemi conversions..........

For the record, my hemi conversion NEVER overheated. Never saw the gauge even move beyond what it always ran at. But here is what I learned in reading about this, talking to hemi conversion owners and even some discussion with AEV.

I would agree that it has been extremely overblown on the web. From those I have talked to that have had the issue, it is a combination of altitude, grade, speed and vehicle mass. Heavy JKs, maintaining sustained high speed at altitude ascending long fairly steep grades. A common place for seeing the coolant temps climb - I-70 approaching the Eisenhower tunnel, either from the east or the west, but probably from the west is worse because the grade is steeper and the prevailing wind is behind you (less airflow thru the radiator). Some hemi owners will hold 75 MPH up this grade. I can tell you that is a very hard pull on any cooling system. I know of one 6.1 conversion that slowed down to 55 and saw the temps come back to normal. There are other locations where this can happen to be sure, but the I-70 approach to the tunnel is a good acid test. Some hemi owners who have experienced the problem have tried removing the fender liners, putting on hood louvers and other band aids with little to no success.

Keep in mind, from my reading and talking to hemi owners, this seems to be a "rocky mountain" problem. But I am not certain of that. I do think there was a guy in Texas who had overheating issues, but I think he had other issues as well. I think once you get away from a "stock tune" and try to drive more HP thru tune changes, you run the risk of overheating - but that is just my theory.

I am not sure why I never had overheating issues. Perhaps it was because I ran dual trans coolers and thus kept my trans temps about 50 degrees below what others where running. This put less heat load into my radiator allowing it to do a better job of cooling the coolant. I also ran my JK lighter than most, with AL bumpers and sliders.

I recall talking with someone from AEV (may have been at SEMA in 2011 or 2010) that the 3.6 uses a much higher flow rated fan set up than the 3.8 did. They theorized that people having overheating issues with the old 3.8 stock fans might want to try the new 3.6 fans. But I have never heard of anyone doing that. It will be interesting to see as the 2012 and 2013 conversions start coming out, if the overheating stories resurface.

For those contemplating a hemi conversion, it is something that should be noted, but I don't think it should be a deterent. When you read about these situations, try and find out - how heavy of a JK? How fast were they going and how steep was the grade? And at what altitude? (air is thinner - does not conduct heat as effectively???) The Eisenhower tunnel is at 9 or 10,000 feet above sea level - that is pretty high. And you will have the 3.6 fan set up, which I think pulls something like 40% more air? I will be surprised to see AEV 2012 and 2013 conversions having over heating issues as AEV runs a stock tune. Now other conversion shops that mess with the tune - all bets are off.
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Old 03-05-2013, 02:05 PM
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MoparNorm MoparNorm is offline
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I helped install a Hemi last year, with the upgraded radiator kit. We didn't use the heat reduction hood. The Jeep lives at 7,000 ft. And recently is on loan to a customer in Bishop, CA. That's, several highway hours away from the Big Bear Shop. At the base of Mt. Whitney.
It runs a tad warmer than the 3.8, but I wouldn't call it overheating. The Jeep has run both 35's and 37's and has had both 5.13 and 5.38 gears, with no visible difference, in temps.
In short, the conversion is great!
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Old 03-05-2013, 04:47 PM
MOPWR2U MOPWR2U is offline
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donjku,
That doesn't sound too good. I live in the rocky mountains, and I planned on using the Jeep for a daily driver and for towing an 18' auto transport trailer, loaded with ATVs, that would weigh up to 4500 lbs, depending on the load. I drive across a 10,000 foot tall mountain pass every week in the summer time. If these Hemi Jeeps are overheating with no load, then adding a trailer might be just asking for a problem. I need to call AEV and ask them if their recent conversions are doing any better in this regard.
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Old 03-05-2013, 05:12 PM
Panhead5 Panhead5 is offline
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I wouldn't worry too much about it .I mean you asked if they overheat and now you're worried that they do overheat.I guess don't do the hemi .

I just remember that gentleman with the killer AEV rig volunteer that he had some overheating concerns .He also lived in the Denver area.
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Old 03-05-2013, 05:43 PM
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djb_rh djb_rh is offline
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Quote:
Originally Posted by MOPWR2U View Post
donjku,
That doesn't sound too good. I live in the rocky mountains, and I planned on using the Jeep for a daily driver and for towing an 18' auto transport trailer, loaded with ATVs, that would weigh up to 4500 lbs, depending on the load. I drive across a 10,000 foot tall mountain pass every week in the summer time. If these Hemi Jeeps are overheating with no load, then adding a trailer might be just asking for a problem. I need to call AEV and ask them if their recent conversions are doing any better in this regard.
Where did you get a Jeep with a frame rated to tow 4500 pounds?

Just because you add "enough" HP for it doesn't mean it's a safe towing situation, and AFAIK the highest tow rating for any late model Jeep is a JKU at 3500 pounds. Exceeding that is asking for trouble, IMHO, no matter what you've done to the drivetrain. And it's certainly illegal.


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