factory cooling

[yardape]

I have heard good and bad about GDI. I have never heard anyone that was disatisfied with a Modine. Modine also was the recommended brand by a mechanic I know who's business thrives on satisfying customers. The number of rows makes one automatically deduce that more is better which is not the case from everything I've read. Tube and fin design are more important factors.

 

[Atl XJ]

It's a little thicker so qualify your motor mounts or else you may get a surprise from the fan clutch.

I agree 100% on this. I found out the hard way and ruined a brand new Modine. The factory motor mounts were worn at 100K miles and I accelerated hard and the metal tabs on my new fan clutch caught the metal strap on the radiator, wrapped it around it and put some serious holes in my radiator before I could pull over and figure out what all that clanging was. I was barely able to limp it the 20 miles home (interstate with no traffic thankfully) stopping to add more water several times along the way and then it pretty much exploded all of the coolant left in it immediately after I pulled into my garage and shut it off.

I went to the radiator shop where I got my Modine and told them that the strap broke on it (prepared to pay for another one) and they didnt ask me any questions and gave me a new one free of charge. The said they have so little problems with Modines they dont even have to send the defective ones in to Modine, they just replace them no questions asked.

 

[pauldo39]

If a shop replaces modine radiators without any questions then that sure says something about the company behind them. I agree, Modine seems to win in terms of the most people satisfied. And the whole thing about 2, 3 rows etc... one of the first threads I read on this site was about someone who actually replaced their factory 2 row with a 1 row with huge coolant passages and said it cooled like a charm. It's interesting to get such a huge variety of perspectives, as I'm sure each type works better for certain uses. My XJ has 112,000 on it, should I consider getting the motor mounts looked at before getting a new radiator as to avoid the whole fan clutch situation? Another thought, I don't know if any of you know the exact answer to this, but why would the jeep engineers set the cooling fan to kick in at 223 if that is considered by many to be too hot?

 

[RichP]

Mainly I suspect because it's not at the boiling point, at atmospheric pressure the coolant will boil at 212 but it's under about 15lbs of pressure which makes the boiling point much higher [don't remember the forumula but I think it takes it to the 285* range]. This is also one of the advantages of running synthetic oil, it's not nearly as effected by high temps as organic oils. The flip side is that the system components, hoses mostly, need to be in good condition to handle those pressures or things burst. Also remember that these sensors are not dead accurate either, so take that temp setting with a grain of salt..

 

[corbinafly]

Engine coolant "runs" all the time anyway. It is constantly circulating through the engine block and when the thermostat opens up, it will also circulate through the radiator. Which brings me to say; "So what if it runs all the time?"
Shade tree mechanics. I hear echoes of a quote from the Forrest Gump movie...

X2.
Your pump is always pumping. Actually, I'd say that the pump has to work harder when the t stat is closed, because then, the only place it can pump the coolant to is through the block and heater core. Now if the t stat were open, it could pump through the radiator as well which would lead me to believe that there would be less restriction that the pump would have to overcome.

K

 

[corbinafly]

Btw, after reading through this post there is a lot of praise for three row radiators. A three row does not cool any better than a good quality two row like Modine. You are actually worse off having one in the long run since the smaller coolant passages like to clog.

I totally agree.

But If you still want an all metal 3 row GDI, I have one that I replaced with a Modine. It was in for about 6 months. Still like new. I had 50/50 antifreeze, distilled water in it the whole time. Ill let it go for cheap!

K

 

[corbinafly]

http://www.alumrad.com/dblpass.html

Check this out. $198. Aluminum core looks sweet.

K

 

[viperbaron]

Humm, Interesting thought, but with the thermostat open, then there is a larger volume to circulate.

 

[XJXJ]

If a shop replaces modine radiators without any questions then that sure says something about the company behind them. I agree, Modine seems to win in terms of the most people satisfied. And the whole thing about 2, 3 rows etc... one of the first threads I read on this site was about someone who actually replaced their factory 2 row with a 1 row with huge coolant passages and said it cooled like a charm. It's interesting to get such a huge variety of perspectives, as I'm sure each type works better for certain uses. My XJ has 112,000 on it, should I consider getting the motor mounts looked at before getting a new radiator as to avoid the whole fan clutch situation? Another thought, I don't know if any of you know the exact answer to this, but why would the jeep engineers set the cooling fan to kick in at 223 if that is considered by many to be too hot?

The OEM factory engine temperature range is fine with my Renix. Hard to argue with 270k miles and the head never been off yet. I'm still never a quart low between changes. It's probably a fairly efficient temperature for best metering mixture and ensuring complete combustion which I'll take any day for maximum engine life. Rich (slobbering) mixtures only wash/dilute your lube oil.

Your mounts are probably worse than you think. Hard to visual those damn things until they're off but 112K (how many years?) is probably enough to show some slop. They're cheap and you should do the tranny mount at the same time. If you go with a new rad, do all the rubber at the same time and then you'll be good for 5-8 years with few engine cooling worries. Cross your fingers for the water pump or just be highly anal and do that at the same time too.

Also, insist on distilled water for the coolant mixture. That will help keep everything clean and exchanging heat properly.

 

[corbinafly]

Humm, Interesting thought, but with the thermostat open, then there is a larger volume to circulate.

I doesn't matter how much volume it has to circulate. It all passes through the same holes at the t stat housing. Think of a sump pump, for example. It doesn't matter how much water you're pumping out. When it's pumping, it's always pushing the same amount of water through the pipes or hoses. Now if you increased the sizes of the pipes or hoses the pump would not have to work as hard to push the same amount of water through due to less friction.
It's the same idea with the water pump. But with the t stat open, it has a larger opening that it can pump through so there is less restriction in the "lines" so to speak.

K

 

[pauldo39]

Thanks for all the input, RichP what you said does make sense about where the fan is set. Now towards the beginning of this post a lot of people talked about their successes with 3 row but then I read the article about the design of the XJ and how there is little room at the front of the engine bay to fit a more conventionally designed radiator, which is why there seems to be overheating problems. Squeezing another row in there has to make things even tighter, I guess that's what a lot of you are saying and it makes sense, and I could be all wrong but if the jeep engineers felt a 3 row would be more efficient I'm guessing they would have changed it? Also, can anyone attest that a waterpump has a longer effective life if a lower temp tstat is used? I've gone through so many waterpumps in the 3 years I've been driving it's ridiculous, and does anyone have a brand of w/p they highly recommend? btw that aluminum radiator does look pretty awesome

 

[pauldo39]

XJXJ, May I ask what mileage you swapped out your motor and tranny mounts? I guess that's been an issue I've paid literally no attention to but the last thing in the world I want is a brand new radiator getting eaten alive by the mech. fan getting too close, as apparently this has happened more often than I would have guessed! As long as I've gotten stuff taken apart, might as well check everything. This is great, i think I've learned more in the past few days on this forum than I have from everywhere else combined!

 

[corbinafly]

If your going to replace your motor mounts with some of the OEM variety, I would strongely suggest that you get factory mounts from the dealership. Many, including myself, have had new oem mounts from autozone, kragen, etc., fail in a very short period of time. Mine failed in less than a year and others have had much worse luck. I haven't heard anyone complain of premature failures with original mounts from the dealership.
Do a search on oem mounts and you'll seeeeeee.

K

 

[yardape]

Water pump afficanados use flokooler water pumps which can be found at www.flowkooler.com and elsewhere. I don't have any experience with these but they are brand new rather than your typical rebuilt variety and supposed to increase low RPM circulation. Never heard any complaints about premature failure on these. A friend and I replaced my shot motormounts and tranny mounts at 130K with the NAPA variety and they've held up for at least a year so far.

At some point you will make a decision as to what you are going to do. While you are getting alot of questions answered, no one is giving you a definitive answer about why your engine is overheating,... and you won't get one. Unfortunately you are involved in the "XJ cooling system crapshoot." Be prepared that what ever you do, if anything, that it may not "fix" your problem but you will at least start the process of elimination which is what diagnosis is all about. If I were you and going to open the cooling system and replace 1 part, I'd replace as many as I can. That means radiator, hoses (lower one with spring coil) thermostat, don't forget the cap, possibly water pump but yours sounds relatively new,.... so that when you're done you have no weak links in the system and if the problem persists you can look elsewhere. Replacing worn motor and tranny mounts first can only improve your ride.

I'm not going to assume what your circumstances are with respect to expertise level, what tools you have available and if this Jeep is your daily driver. From your questions however, you sound eager but a bit new to this. If that's true, the prospect of doing these repairs and upgrades can seem overwhelming. The last thing you need to do is be in the middle of a job like this and find a surprise that you need to go to the parts store for and have no transportation. Plan carefully, have a plan "B," and have fun. For the most part, while diagnosis can burn brain cells, R&Ring parts is not rocket science.

 

[RichP]

Also keep in mind that when you buy parts from AZ, NAPA, etc they sell varoius lines, some make more profit than others and as a result are 'preferred' and 'recommended' by the part store. Water pumps for example, they come in two broad types, new and rebuilt, they make more money on the rebuilts and as a result they push them more. Car Quest sells like three levels, rebuilt, new cheap and a more expensive model that is also new. When I put my new carquest in there was NO difference in the pump that was visible, had all the same stampings and other than being shiny could not see any differences. If in doubt get it from the dealer, you can't go wrong there. As a fact I do only use mopar and Jeep parts on alot of my jeeps, they fit, they work and they last at least as long as what was in there. Plugs, caps, rotors, wires, belt, idlers I only use OEM dealer supplied ever since I saw a difference between dealer supplied champion spark plugs and auto store supplied champion plugs, the auto store champions were visibly lighter construction with thinner components, looked like a totally different plug.

 

[krakhedd]

Krak did not state anything to support his assessment of overkill for a 160 deg thermostat. Obviously, it was not overkill as it is working fine.
Engine coolant "runs" all the time anyway. It is constantly circulating through the engine block and when the thermostat opens up, it will also circulate through the radiator. Which brings me to say; "So what if it runs all the time?"
Shade tree mechanics. I hear echoes of a quote from the Forrest Gump movie...

Actually, I did. I said that there's no way the coolant system can get the motor down to 160*.

Mine DOES FREQUENTLY manitain 180*, so it DOES cycle off, to a certain point.

Think about it like this. Until the coolant reaches the temp of the thermostat, it is closed, and the water pump is only circulating coolant through the engine block. Once it opens, it adds considerable volume to the system, as well as backpressure. This is NOT free energy.

That said, I also forget what the other reasons behind it are, but you want the motor to maintain a certain level of heat in order for it to function properly. Somebody else who knows exactly what it is, please comment on it.

 

[corbinafly]

Think about it like this. Until the coolant reaches the temp of the thermostat, it is closed, and the water pump is only circulating coolant through the engine block. Once it opens, it adds considerable volume to the system, as well as backpressure. This is NOT free energy.

Actually, wouldn't the open t stat reduce the amount of backpressure the pump has to work against? Think about it like this... When the t stat is closed, the pump has to push the coolant through a much smaller opening and pull through the same opening. Now when the t stat is open, the collective openings through which the pump has to push the coolant through are much larger (think smaller versus larger exhaust for example). Sure it's pumping more volume for a given amount of time, but it's not working any harder to do it. Remember that the coolant that it pumps out it being pumped right back into the inlet of the pump. It actually requires less work for the impeller to maintain the same rpm with t stat open than it does with it closed.
What happens when you cover your radiator with a large piece of paper? The fan blades are under more stress as they try to pull air through. Now when you remove the obstruction, even though the fan pulls much more air, the blades are under much less stress because they're not fighting as hard to pull the air through...

Sorry about the long post.

K

 

[langer1]

Actually, wouldn't the open t stat reduce the amount of backpressure the pump has to work against? Think about it like this... When the t stat is closed, the pump has to push the coolant through a much smaller opening and pull through the same opening. Now when the t stat is open, the collective openings through which the pump has to push the coolant through are much larger (think smaller versus larger exhaust for example). Sure it's pumping more volume for a given amount of time, but it's not working any harder to do it. Remember that the coolant that it pumps out it being pumped right back into the inlet of the pump. It actually requires less work for the impeller to maintain the same rpm with t stat open than it does with it closed.
What happens when you cover your radiator with a large piece of paper? The fan blades are under more stress as they try to pull air through. Now when you remove the obstruction, even though the fan pulls much more air, the blades are under much less stress because they're not fighting as hard to pull the air through...

Sorry about the long post.

K

Actually it's just the opposite.

 

[corbinafly]

Actually it's just the opposite.

Oh really? Hmmmmm..
Please make me understand. Maybe I'm not thinking this through correctly.

K

 

[jeepsrock]

Hey guys i have the same problem as the initial poster...the temps in the valley here in CA are above 100+F a lot and even with no AC if i stop at a stop light or in trafic the temp climbs past the half mark (halfway between the 210 and the next mark). In the past i have had changed-
1. New Water Pump
2. New 3 core GDI ( purchased a while back)
3. New gatorback belt (belt tentioned properly)
4. New hoses
5. New Fan clutch (carquest brand)

What else can i do...?? I just flushed the system and nothing has changed ?

pete