TJ Needs some cooling help..

[alosix]

Living in a relatively flat area most of my life, I've never had to deal with climbing long grades and the Jeep as been fine.

This weekend we took Rt 4 up to barney riley, with the trailer on the back of the Jeep the temp gauge starting moving up a good bit. I'd be able to keep it in check by running about 30mph.

Looking for some ideas for making this better. Looking at an aluminum rad, tranny (I've been real lucky using the redline high temp in the AW4 ), higher pressure cap and possibly rethinking the use of the 50/50 coolant mix year round here.

Any other ideas? Would really like to hear from those that had similar issues, swapped the parts and got results.

I'm not really looking to be able to pull these grades like a speed demon, it is just a little Jeep. But I'd like to be able to do it without having to constantly watch the temp gauge.

Thanks,
Jason

 

[dirty Bakers]

Water does the cooling better than coolant. Was your fan turning on/cycling? Maybe the increased rpm's to go faster then 30mph with no fan pushed it over. Any belt sqeeking? How is your belt tension?

 

[robert j. yates]

I am going to start off with a recent post I made on another forum:

I have been chasing a running warm issue for years.... practically since the Jeep was new. I originally started with a Radiators.com 3 row brass radiator when the OEM crapped out, a 7 blade fan swap followed and a Novack aluminum 2 row replaced the 3 row brass radiator. My hood is vented, there is a Hesco high volume water pump installed and I have also added a fan driven engine oil cooler. I was finally able to stabilize freeway operating temps at 220* with all of this and was of the opinion that I could do no better and 220* on the freeway (at 65mph) was where the Jeep wanted to be.

Now a note on the 7 blade fan swap....I used the Jeep TSB fan but since I have an early model 4 stud waterpump configuration on my 98, I used a heavy duty Hayden fan clutch instead of the TSB specified Mopar version.

That turns out to have been a mistake. A few days ago I swapped the stock 5 blade fan back into the Jeep along with a new Hayden fan clutch and the difference has been quite noticable. My rig now runs at 207* on the freeway at 65mph without use of the fan driven engine oil cooler enabled. I have tested this on various freeways with various grades over the past few days and the swap back to the 5 blade fan seems to have returned the Jeep to the 210* operating range.

I suspect that originally, a bad radiator was the culprit and I magnified that situation with a poor decision to install the late model TSB 7 blade fan when I went to the new radiator. It seems that the Hayden fan clutch is not able to drive the 7 blade fan as I can now hear the fan clutch kick in which was something that was not descernable with the 7 blade fan.

I now seem to have a huge amount of cooling reserve built in which while it cost me money, is not an issue for me as I use the Jeep to tow an off road trailer. That will be the real test of course but that will have to wait until I can find the time and money to actually get out on the trail.

At this point, I cannot recommend the 7 blade swap on the early model rigs and suggest to folks that you make sure you have addressed everything with your stock cooling system before you resort to the swap. HTH.

Read between the lines of my post and you will see that what you really need to do is attend to the current condition of your cooling system to make sure you know exactly, the condition of each componant. If everything checks out including the OEM radiator, then you can start applying modifications to build in reserve. What I would not do is change coolant ratios' or cap specifications.

For what its worth, you really do not say what hot is. I know for a fact that TJ's run OK at 235*....mine would do it regularly towing my Horizon over the Cajon Pass or up the Grapevine during the summer. It still may, I won't know that until I take it out and that might be another month in the making.

Anyways....if you are not exceeding 235* on a regular basis and only hitting that when towing on grades, I would say that you really do not have a serious problem. There is nothing wrong with building in reserve and particularly so when towing a trailer but take heed....once you start down that road, it might take you a while and a bit of cash to get you back to where you want to be. BTDT.

 

[alosix]

Water does the cooling better than coolant. Was your fan turning on/cycling? Maybe the increased rpm's to go faster then 30mph with no fan pushed it over. Any belt sqeeking? How is your belt tension?

Belt is good, the fan clutch is old. I think the balancing act I needed to pull was getting the tranny converter to lockup. It runs a lot cooler that way.

 

[alosix]

I am going to start off with a recent post I made on another forum:



Read between the lines of my post and you will see that what you really need to do is attend to the current condition of your cooling system to make sure you know exactly, the condition of each componant. If everything checks out including the OEM radiator, then you can start applying modifications to build in reserve. What I would not do is change coolant ratios' or cap specifications.

For what its worth, you really do not say what hot is. I know for a fact that TJ's run OK at 235*....mine would do it regularly towing my Horizon over the Cajon Pass or up the Grapevine during the summer. It still may, I won't know that until I take it out and that might be another month in the making.

Anyways....if you are not exceeding 235* on a regular basis and only hitting that when towing on grades, I would say that you really do not have a serious problem. There is nothing wrong with building in reserve and particularly so when towing a trailer but take heed....once you start down that road, it might take you a while and a bit of cash to get you back to where you want to be. BTDT.

Ah, yeah, define hot. Hot, on the stock gauge was getting right in the middle of the 210 and the 260 tick. I noticed when pulling the trailer across 40 last year on the climbs there that if I let it get past 235 it just wouldn't recover. It would go right into the 'red' and I'd have to stop and let it cool down.

If I go out again towing I'll take the logger with me to get the 'real' numbers out of the computer and chart them. Actually, that might not be a bad idea to go run to the grade to santa cruz from here with a heavy trailer and get an idea of how everything is going.

I'll take note on that 7 blade/fan clutch matchup and see if I can find anything that works good there.

It just needs a little 'headroom' for me to be comfortable.

At least it behaves on the trail crawling around, so I'd guess the current fan setup isn't all that bad.

Jason

Its a 1997 with 140k on the clock. Stock radiator, fan, and clutch.

 

[robert j. yates]

Its a 1997 with 140k on the clock. Stock radiator, fan, and clutch.

So OK, your rig will sweep the guage....thats not good so you ought to start looking into maintenance/modification.

Your fan clutch is probably tired along with your stock radiator. My stock radiator wasn't worth 5 cents as I repaired it twice (top tank gasket and crimp) right after the Jeep went out of warranty. That started me on the chasing my tail path but you already know that story from my first post.

Now if I were you knowing what I now know, I would first swap in a new fan clutch (re-using the stock 5 blade fan) and flush the radiator to see what happens. The fan clutch will serve you well even if you swap radiators and a can of flush is not all that expensive. If that works, great and you are only out $50-60 bux. If it doesn't work.... I would think about swapping in a nice 2 core aluminum radiator. They aren't cheap but they are better than stock and do not even think about the 2 or 3 row brass from radiaotrs.com or some such place. Those are in fact worse than stock and their reliability is questionable from my experience. I am using a Novack aluminum and it has served me well for the past 3 years along being a direct swap.

If that still does not work, then you will have to dig deeper into the problem. With the exception of the radiator, I do think that you should try and stay close to stock wherever possible, ie water pumps, fans, cap spec ect.

I assume gearing and all of that is correct since you mention an AW4 swap so that should not be bogging your motor or tranny and causing additional load which creates heat. And a word on tranny cooling, I have mine separated out of the radiator and on a separate circuit using a fan driven cooler mounted under the tub on the drivers side. Works well and I know a few others who are using this technique as well. HTH.

 

[alosix]

Its geared 4.10 on 35s. (was originally setup for 33s).

I'm still debating on 4.56s, but it tows very nice on flatter areas in 3rd gear with the 4.10 ratio doing about 2500 rpm @ 65mph. I'd hate to mess with that as it seems to work well. Its only real issues are steeper grades and passes when it comes to heat.

I'm in agreement on the fan clutch now. Would you still recommend the hayes one?

Water pump is new (well a year old) and its been flushed pretty regularly. Wouldn't hurt to do it again though.

I do like that Novak Rad, pricey but nice.

I've been trying to figure a way to 'duct' a tranny cooler in somewhere so its not in from of the fan. Got a few ideas so I'll see how that works out.

 

[robert j. yates]

Its geared 4.10 on 35s. (was originally setup for 33s).

I'm still debating on 4.56s, but it tows very nice on flatter areas in 3rd gear with the 4.10 ratio doing about 2500 rpm @ 65mph. I'd hate to mess with that as it seems to work well. Its only real issues are steeper grades and passes when it comes to heat.

I'm in agreement on the fan clutch now. Would you still recommend the hayes one?

Water pump is new (well a year old) and its been flushed pretty regularly. Wouldn't hurt to do it again though.

I do like that Novak Rad, pricey but nice.

I've been trying to figure a way to 'duct' a tranny cooler in somewhere so its not in from of the fan. Got a few ideas so I'll see how that works out.

4:10's are a little weak for the 4 speed auto on 35's so that is probably adding a bit to your situation.

I used a Heavy Duty Hayden that I got from Kragen for about $45. I'm happy with it.

Look under your tub on the drivers side opposite the muffler...that is a perfect place to mount a fan driven tranny cooler.

 

[alosix]

4:10's are a little weak for the 4 speed auto on 35's so that is probably adding a bit to your situation.

Possibly, though for whatever reason this engine just doesn't like to seem to cruise in the 3k to 3.2k range. It EATS fuel like crazy. Its very happy between 2500 and 2700. I normally won't tow with OD on anyway, so in the current setup the Jeep still has pretty decent power when loaded.

But its up for a rear locker and if I'm putting that in I'll just swap the gears. I lack the tools in the new place though . Maybe a trip to the Tech Shop with the Jeep is in order . 1/2 temped to see if I can hunt down a set of 4.27s.

I suspect that the clutch/radiator, and tranny cooler will take care of this issue. Especially the tranny cooler since there is a real difference between 3rd gear and TC locked and 2nd gear with TC unlocked.

It might also get a switch to keep the TC locked in 2nd for these sorts of things. I've been meaning to create another controller for the AW-4 anyway

 

[robert j. yates]

I think you are on the right track by keeping your problem solving simple. One last note...I don't think 4:27's are available for the D30 so you are out of luck unless you have a 44 swapped up there

 

[alosix]

I think you are on the right track by keeping your problem solving simple. One last note...I don't think 4:27's are available for the D30 so you are out of luck unless you have a 44 swapped up there

44 and a 8.8. pretty sure I've seen them for the 44, the 8.8 might be another story

Jason