Is there any cooling system upgrade that really helps?

[foggybottombob]

I added some water wetter to the coolant today but I'm not sure if it helped or not. I plan to drive in stop and go traffic at midday tomorrow. That should tell the tale.

[foggybottombob]

I had a Taurus 2 speed fan installed over the weekend. I drove through downtown stopping at countless red lights with the A/C on max and the temp stayed below the 210 mark. I did not even have to switch on the high speed side of the fan. But I still got up to about 225 degrees indicated driving about 75mph on the highway. So I think I'm going to need the hood vents too.

At least I think my low forward speed overheat problem is fixed.

[SilverXJ]

I think you have a water flow issue if you are overheating at highway speeds.

[foggybottombob]

I'm wondering if the mechanic put a water pump in that is meant to turn the other direction.

[foggybottombob]

I can't tell that the water wetter made any difference at all.

I installed a Taurus high speed fan and that has fixed the slow speed overheating. I can sit at a red light now with the AC on and the 4500cfm fan keeps the temp around 210 degrees F.

I still get some overheating at speed on the road when climbing hills. I bought a FlowKooler waterpump and will be installing that next week.

[cruiser54]

I'm wondering if the mechanic put a water pump in that is meant to turn the other direction.

I experienced that at the Jeep dealership years ago on a 258 in a CJ. It overheated quickly and massively. I doubt that's the problem.

[92tank]

here is a thought:

what if you knew that it was just a lack of rad area. if you dont use the a/c you could flush the front cooler and hook up the heater core line to it. if you still use the heat you just run it though the heater core first then the cooler. OR it you still use the a/c get one from the jy and ad it up front or even a large size trans cooler.

i know its able to be done i saw something simular over the weekend on a trans-am w/ 383 (about 425 hp at the crank) and it stays at about 160-180

[foggybottombob]

The radiator area is definitely the main issue. I had a FlowKooler water pump put in and drove it in the mountains all day last Saturday. I can say that the flowKooler water pump had zero effect as far as reducing the coolant temps. I had to turn on the heater once in a while to keep from overheating going up long hills offroad in the mountains. Most of the trip was between 9000ft and 12,000 ft. I finally just left the taurus fan on high all the time. When I turned the fan down on low speed the temp would start to creep up.

I'm going down to a shop today to get a quote on the hood vent install. One of the guys I was wheeling with Sat had hood vents in his XJ and he said it made a lot of difference for him. His XJ was overheating and he does not even have a stroker in it. I think the high altitude less dense air makes overheating easier to attain too.

[92tank]

i have a few more ideas for you to check out:

1. are your fans blowing in the right directions?
2. have you extended the rubber mat under the engine and its not letting the air flow out like it should?
3. does the lower rad hose have the spring in it?

hope this helps

[Sharp Rock]

One more idea. Have you checked to make sure your radiator cap is "holding" the pressure that it's supposed to? I've had this one bite me before (girlfriend's XJ). And it wasn't the cap's fault. Someone had dented the sealing surface where the cap mated to. Radiator shop spotted it, repairs done (read cheap!) Fixed it's frequent overheating. They could have sold me another radiator and I would have never known. Over the years, the caps can go weak too.

Good luck with it.

[foggybottombob]

The fans blow in the right direction, the water pump turns the right direction and the radiator cap holds pressure.
I added hood vents and now I think I have helped cooling at speeds over 50 mph. The taurus fan on high speed takes care of overheating from 0 mph up to about 35 mph. Now I am left with a little over heating from about 35 mph to 50 mph. I plan to swap my 3 row radiator back to a 2 row radiator and see what that does. I have read that a 3 row radiator has two problems, it slows down the coolant flow and the 3rd row from the front receives the heated air from the front two rows and thereby does not do much heat exchange.

[double_T]

Definitely going to go with some hood louvers down the road, but do they have issues with letting in rain? If so, what are some solutions? It only rains maybe 20 times a year here in Colorado, but it will really come down when it does!

[foggybottombob]

Rain is the reason I went with the scoops instead of louvers. I think that these will not let in nearly as much rain as the ones with slots all the way down.

At any rate, I have not heard of anyone having problems with rain even when they had a hole in the hood with expanded metal under it.

[Missourian]

I have experienced the impeller coming loose on the shaft of the water pump. The engine will run a little hot at idle but overheats on the highway.

I would look at this impeller... that is what I would do and it's not that much work to pull it out.


Before you ever modify your ventilation, radiator or water pump you have got to look a what has changed. Based upon what everyone is saying STROKING your 4.0L to a 4.6L does not create the issue (a .060 over 4.7L is said to slightly increase temperature). So, looking at water flow, then water heat exchange (radiator) and open system (leak) [our cooling systems are a closed system] for the source of the over heating.


One other issue is "burping" your system. I have experienced trapped air in the cooling system resulting in overheating after replacement of the water pump. The trick is parking on an incline, running to temperature, opening the radiator and waiting for the gulping or scavaging to take place and having a gallon of 50/50 mix water/anti-freeze on hand to quickly fill the radiator as the engine pulls water and expells the trapped air.

[TAnderson22]

Part of what is here is in the fix (if it is a fix - its just knowing the 4.0l cooling system requirements at it's basic levels). A lot of this site and others of the like, regardless of the make, model, or vocation of topic, is the conglomeration of years of hearsay and conjecture presented as fact, by the blind leading the blind. Much of what is spoken is laughable when taken in by the ears of an experienced technician, though it can lead to hours of entertainment for them.

I'm sorry I cannot give you my "fixes", I spent years in the shop learning the proper way, the hard way, and I do not give away secrets of the trade. Experience is earned, not given away on the internet. There are no shortcuts if you want to play technician.

Part of the statement below is true; but cooling systems 101 (Save opening the cooling system at operating temp! Holy Jesus Dude! Especially with trapped hot air!) . The other part is the problem as to why every 4.0l has heat transfer problems, but is only multiplied by the new BTU's the extra displacment is creating. And products on the "shelf" are the cuprit because we got too lazy as a society to "do it ourselves" and make things "right".

Get a Jeep factory service manual, read it, especially the cooling section, and you may be able to piece together the mystery; perhaps just stumble upon it and get a sense of accomplishment by solving the puzzle; For me; No one ever told me; I found out for myself.

I think you can do it too. It's all in the "chemistry" here...................

The trick is parking on an incline, running to temperature, opening the radiator and waiting for the gulping or scavaging to take place and having a gallon of 50/50 mix water/anti-freeze on hand to quickly fill the radiator as the engine pulls water and expells the trapped air.