Need mod suggestions for better towing

I own a 2000# pop up camper and haul gear for up to four people at a time and my 99 XJ is having a hard time of it. I'd like some bolt on mod suggestions to help the XJ work a little easier and cool off better, since it's overheated twice while towing (thread about it in OEM Tech). It has the towing package with tranny cooler already.

So far my current mods include:

-Air Lift suspension, which is incredible and I highly recommend.

-Hawk LTS pads and new NAPA rotors which helped stopping power significantly.

Planned mods include:

-Gauge cluster upgrade (SE gauge now)

-Tranny temp gauge (suggestions?)

-rear disc swap, possibly D44 axle w/discs

What I need help with is engine mods, to include the cooling system. I'll be camping in Florida during the summer so being able to keep everything cool under load is most important. The A/C will be running at all times. Also anything to help the power short of a blower or stroker kit, I remember reading that a more free flowing exhaust helps a lot, so:

-Suggestions for exhaust/intake? Ignition? Would a header help significantly?

-Cooling mods.....Aftermarket radiator? Better flowing water pumps, fans, etc?

-Trans cooler.....I have the stock cooler, but would like a bigger, better cooling unit. Suggestions?

Sorry if this is too much at once, but so far my XJ has been completely stock and I've never considered mods until now, so I have no clue where to look and what to look for. I also thought this thread would be great for people in similar situations, when I did a search for towing mods, most of the threads that turned up didn't have much info and were mostly about brakes.

All input is greatly appreciated, I plan on getting started soon and will document everything to help out others that tow with their XJ's.

Hi-flow t-stat housing, BIGGER Trans cooler, possible taurus e-fan swap, water wetter (local parts store), zj fan clutch,

radiator: alumarad, bekool, ffdynamics

FLUSH the COOLING SYSTEM.

Something that made my temps drop alittle is a higher flow muffler. I have yet to buy a high flow cat. But thats on the list.

lilredxj99 said:

Hi-flow t-stat housing, BIGGER Trans cooler, possible taurus e-fan swap, water wetter (local parts store), zj fan clutch,

radiator: alumarad, bekool, ffdynamics

FLUSH the COOLING SYSTEM.

Click to expand...

The taurus e fan sounds interesting....Now would that replace the belt driven fan or the stock e fan? Also how does a zj clutch make a difference?

This reminds me.....Are there electric water pumps available for XJ's? If so are they effective?

Crimzon316 said:

Something that made my temps drop alittle is a higher flow muffler. I have yet to buy a high flow cat. But thats on the list.

Click to expand...

Ok, are there any decent bolt on kits from a free flow cat all the way back? My stock exhaust probably needs to be replaced anyway, might as well go all out.

3 row radiator, Large tranny cooler, E-fan set up to delete your Mech fan, Free flowing Exhaust (Borla makes a complete kit but will still need a high flow cat), bore out your TB.

If your have major concerns a oil cooler may be nice to have.

Its not bolt on but I would re-gear to 4.10 on the stock size tires. Pulls great and mileage is not hurt that much. For a tranny temp gauge I recommend the B&M gauge/sender and a Autometer "A" pillar pod. All of the other stuff has been covered, a good cooler is a must.

I really like my Firepower ignition, I run it on 2 of my 5 XJ's and do feel some difference. I run a .045 gap and NGK V power plugs.

At 2000 lbs you should not need anything extra. The stock XJ is more then up to it. Maybe a fresh rad and your set.
Do change you trany fluid every 20k if you tow a LOT.
Do change engine oil every 3.5K when towing. I run 20W 50 when towing hot long and heavy.
A coolant temp gauge and not a just dummy light. Dummy lights were to supplement gauges not replace them.
Things that are nice.but not a must.
A trany fluid temp gauge. At 2000 lb and with a stock addon cooler I see no REAL need for it.
A larger trany cooler. same as above.
Fresh shocks. Always nice when need.
Having brakes up to spec. Also a good idea at any given time towing or not.
With 2K of trailer and stock tires I see of no real reason for brake mods. You got the good brake booster now. So just adjust the drums up to spec and your off.

Well 2000 lbs is just the camper dry weight. Add in four people and all the gear and it's substantially more. And like I said, I'll be hauling during the summer in FL and ambient temps are 90+ average. I know the XJ cooling system isn't the greatest so I'm just trying to help it along.....

But at the same time I don't want to do too much, I know it's not hard to get too much flow and cool the engine too much screwing things up efficiency wise. Any tips on how to avoid this?

xjtrailrider said:

Its not bolt on but I would re-gear to 4.10 on the stock size tires. Pulls great and mileage is not hurt that much. For a tranny temp gauge I recommend the B&M gauge/sender and a Autometer "A" pillar pod. All of the other stuff has been covered, a good cooler is a must.

I really like my Firepower ignition, I run it on 2 of my 5 XJ's and do feel some difference. I run a .045 gap and NGK V power plugs.

Click to expand...

GEARS... I would think that would be your best performance per dollar spent. I agree 4:10's with the stock AW-4, and the 4.0L would be the ticket with stock size tires...

xWhatever on gears.
The XJ is rated to tow 5k with the factory tow package and no other mods. If you are having problems at aroudn 2K trailer - call it 3.5 fully loaded - you are probably looking at the improper function of stock equiptment. Like a plugged radiator, failing tstat, a leak somewhere, etc.
If you are sure that all that stuff is fine and want to mod, I would go for a bigger radiator & tranny cooler + trans temp guage. Use the current trans cooler as an oil cooler (you'll have to relocate the oil filter. kits are at napa) and call it a day. In Florida and the surrounding territories it is flat & low altitude enough that you shouldn't need more power from the 4.0

Regearing made a huge difference on how my XJ towed. When I had 31" tires and 4.56 gears, I hardly ever had to use OD on the hills. Now I have 33" tires and its a dog again while towing. So 4.10 gears on stock tires should be plenty for towing that kind of weight.

I'm not running stock size tires, 235/75/15 on 10" wheels.....Not sure if the relatively small increase would make a difference.

I'm thinking about getting this radiator since it also has a bigger trans cooler built in.

http://www.quadratec.com/products/51210_7002_07.htm

Leica99XJ said:

I'm not running stock size tires, 235/75/15 on 10" wheels.....Not sure if the relatively small increase would make a difference.

Click to expand...

Thats too wide a wheel for a 75, should be on 7" or 8" max, I'm surprissed you are keeping a bead on hard corners. I consider the 235 a stock size tire, 30" is almost stock.

xjtrailrider said:

Thats too wide a wheel for a 75, should be on 7" or 8" max, I'm surprissed you are keeping a bead on hard corners. I consider the 235 a stock size tire, 30" is almost stock.

Click to expand...

Everyone here said it would be fine, I actually started a thread about it. If I had to do it again I would have ordered 8" but the 10" are doing fine.

I'm actually thinking about replacing them with used stock wheels once i get to FL. The used wheels available up here in NY are trashed from winters.

Leica99XJ said:

Everyone here said it would be fine, I actually started a thread about it. If I had to do it again I would have ordered 8" but the 10" are doing fine.

I'm actually thinking about replacing them with used stock wheels once i get to FL. The used wheels available up here in NY are trashed from winters.

Click to expand...

Really? I just went back and looked at your threads, and while you did start a few threads about rim size, you are concerned about 8" rims, and ask if people think 8" rims are too wide. You don't even mention 10" rims, no one actually does. Everyone was telling you to go with a 7" wide rim, so I would take this as not everyone told you that you would be fine with a 10" rim.

"Anyone running 235's on 8 inch wheels?"
"Need wheel size help"

The fact is the 235/75R15 tire is 9.3", and you are using it on a 10" wide rim. The rim is too wide for the tire, not the smartest decision.

Start with a 3 core radiator. Add a separate transmission cooler in front of it, plumbed into the stock setup. Speedway sells a kit to manually set the temp for your fan so you can dial it down when needed without constantly watching the heat gauge. If that doesn't control the overheating, Taurus E-fans or a GC clutch probably won't either. You simply can't get more airflow through the radiator than going over 45mph. Do check your mech fan clutch is operating properly.

Gearing is the biggest help, also the more expensive. Changing out two ring and pinions gets expensive from a labor standpoint. The 2.5 drivetrain comes with 4.10 gears stock, and it may be cheaper to swap axles out complete.

A 99 should have the rainbow manifold, hi port head, and split cast iron exhaust. That's about the best the factory did offer. Boring the throttle body and installing a freer flowing cat and cat-back exhaust would help. More than that, a cam change. A supercharger just means you really need a diesel tow rig.

Smaller highway tires and lowering the height could help, but since that's counterproductive, is there a possibility to reduce the towed weight? 2K seems like a lot for a pop up. I've towed a pop up with 03 Caravan with 3.3 and 4 up in the Ozarks. It handled exactly as expected, plan ahead and don't expect lift off speeds.

Most of what you can do will also help offroading, it's hard to go very wrong in that regard.

Begster said:

Really?

Click to expand...

My bad, you're right. I have 8" wheels, got confused there......I know I went bigger than stock and I thought for some reason stock was 8".

I'll be ok......I think.

TiRod said:

You simply can't get more airflow through the radiator than going over 45mph. Do check your mech fan clutch is operating properly.

Click to expand...

Well I'm thinking then a fan is not the problem because it overheated at speed on the interstate, and when I pulled over and just let it idle it cooled off, so it must be the fan is pulling enough air, correct? What could be causing it to overheat at 65mph?

A supercharger just means you really need a diesel tow rig.

Click to expand...

Haha, I've considered both adding an S/C or just buying a damn pickup