Trying to get it mostly right the first time: A 5.9 Magnum, 46RE swapped and tummy tucked daily driver TJ

The people who used the stock radiator used a combination of hoses and pipe to route the lower radiator hose.
But these were all people who were running the 5.2. As you said the 5.9 is supposed to be harder to cool and everyone I know used a aftermarket radiator.

The one recommended by the guy I met who does these swaps a lot is Alloy Works.
https://www.alloyworksplus.com/
The brass radiator I have was the one AA used to offer.
 
Last edited:
  • Like
Reactions: Dan_Goodwin
Spal’s new brushless fans are the thinnest, powerful fans I have found. Their 500 watt, 16” draws something over 40 amps. It cools my 392 Hemi which puts out a crazy amount of heat.

Also to reiterate what Rick said: if you trim the threaded part if the fan shaft it buys you a bit of room. I also did that to mine.
 
Last edited:
I have an 1.25" Rough Country body lift. What are your reservations with running a BL? I'm typically anti BL, but in this case I believe it solves far more issues than it creates.


On another note, I've learned a lot about motor mount placement and radiators / fan clutch clearance lately that I'll elaborate on in detail when I get time to write about it. In short, I'd strongly recommend moving the mounts at least 1" back of where AA recommends you place them regardless of your transmission choice.
I work nights that is why I have not responded until now. My wife and I are 5ft 8 inches tall, I have shorter legs. currently I have a 4 inch lift and I have the JCR sliders. It is maxed out for me to step into the jeep flat footed. If the sliders are dirty I get dirty. Its more for comfort than anything else basicly. I had the tube steps and when i took those off and went to the sliders my wife complained a bit lol.
 
  • Like
Reactions: Wildman
Interesting. I have a Black Magic electric fan on mine along with a brass radiator. When I started having the overheating issues I swapped it out for a aluminum radiator off Ebay that came with a Spall fan & shroud. But IMO it's a poor design and the mounts aren't correct either.
I cut the threaded snout off the water pump to clear this setup where with the brass radiator & Black Magic fan I didn't have any clearance issues.

As for the A/C causing clearance issues what upper hose are you running? Not mine but it shows the clearance.

View attachment 330897

This was mine but I took the compressor off since I didn't reinstall A/C. Still trying to decide if I want A/C.

View attachment 330898
The outlet on the Summit radiator is at least 1.5" more toward the center than yours. That's my issue with that radiator.
Spal’s new brushless fans are the thinnest, powerful fans I have found. Their 500 watt, 16” draws something over 40 amps. It cools my 392 Hemi which puts out a crazy amount of heat.

Also to reiterate what Rick said: if you trim the threaded part if the fan shaft it buys you a bit of room. I also did that to mine.
Good to know that's an option. I was worried I was cutting off all the material off that held the pulley on. My current Mishimoto fan is 3.5" deep and I only have 2.75". I found a Spal fan (30101516 ) that's under 2.5" deep that should fit the bill. Noted on the brushless unit.

I work nights that is why I have not responded until now. My wife and I are 5ft 8 inches tall, I have shorter legs. currently I have a 4 inch lift and I have the JCR sliders. It is maxed out for me to step into the jeep flat footed. If the sliders are dirty I get dirty. Its more for comfort than anything else basicly. I had the tube steps and when i took those off and went to the sliders my wife complained a bit lol.
Gotcha. After you swap in the V8 you'll likely need a spring change anyway - you could swap in shorter springs to make up the difference for the added body lift.
 
I am not sure if this helps but this is 3 and 7/8s from the face of the water pump pulley

20220517_110103.jpg


20220517_110033.jpg
 
Here's how I cut the threads off my water pump. And this is a FlowCooler pump.

20220517_112852.jpg


20220517_112859.jpg


This is the aluminum radiator.

20220517_113623.jpg


The side tank is really small IMO.

20220517_113645.jpg


And then the filler neck is below the top so you can't get it full. And I'd hate to admit what I'd paid for it.

20220517_113654.jpg


And then the brass radiator from AA. It cooled the 5.2 until I had the cracked head just fine. I'm going to try it first with the 6.7.

20220517_113634.jpg
 
I am writing this thread in Word and posting this thread across multiple forums, so some of the things below have been discussed prior.

Next up was to start installing the front clip to allow progress on the wiring and plumbing. The goal was to hear it run, so I installed the passenger fender and front grill, leaving the driver fender off to ease of access to that side of the engine bay if needed. The last 10% of a project takes 90% of the time and that has been no different here.

An engine needs 3 things to run: fuel, air and spark. To get the spark, the wiring harness, PDC and battery were installed and plugged in for testing and all new 4GA marine grade wire was run to the starter, PDC, engine ground and chassis ground. I build all my battery cables with marine grade wire with tinned lugs that are crimped (not soldered) on, marine grade heat shrink on top of that, all protected with split loom and held on with heat shrink at either end. Additionally, all new spark plugs, plug wires, and coil were installed. The accessory drive was re-installed, as well as the throttle body to provide the air.

This left fuel delivery. I’d saved the fuel line from the Durango since I’d read that it was a plug and play – I found this to be incorrect for Durangos. Instead of trying to track down an OEM hose, I opted to purchase an Evil Energy AN-6 hose kit to plumb the fuel line (and will later use this for the transmission cooler). The kit has great reviews and is very well priced so I opted to give it a try.
The new fuel line was assembled and installed, so now we had fuel. And of course I had to see if this garbage ran. With the transmission in park, fresh oil in the motor and a few quarts of ATF I turned the key and was greeted with no gauges, but the starter did turn over. I pulled the harness and corrected a 5V supply wiring error. With the harness reinstalled, the gauges now worked and I cycled the key a few times to prime the fuel rails. As a note, the TJ only runs the fuel pump for 3 seconds until the engine is running. No leaks. I turned the key to start

And it fired right up.

It was alive, though only for a split second before shutting itself off. I’d read and assumed the Durango ECU would give me an issue, either from SKIM or triggering the security feature (yes, those are different features) from the lack of a BCM. I was greeted with a transmission code and an EVAP related code, so I had communication with the ECU… I’ll call that a win. Since I had another ECU from a 99 Ram that I’d hoped was SKIM free, I moved on to installing the cooling system and transmission cooler to allow the engine to run for a bit longer.

This is where this project starts to put up a fight.
 
  • Like
Reactions: CV04TJR and Wildman
I purchased 2 finishing clamps (LINK) and used the leftover AN hose to plumb the transmission cooler. The transmission has a ¼” NPT fitting that I needed to adapt to AN-6 – Summit Racing had the adapter I needed for this (LINK). I used 2 45 degree fittings from the kit to come off the transmission and routed the hoses along the driver side frame rail and up to the barbs on the cooler. I’ll try to get some pictures of this – it’s difficult to photograph once installed.

The power steering cooler was plumbed in using hose from the transmission cooler kit. This was as simple as removing the return hose and routing the new hose.

The AC condenser was re-installed and then the Summit Racing radiator. And here’s where the issues come up. I discussed my initial findings in Post #58. I have updated those findings here:

  • Motor mounts installed in the AA recommended location do allow the use of stock exhaust manifolds. This saves a lot of time and cost being able to re-use stock parts.
  • I have less than 2.5" from the threaded fan mount of the water pump pulley to the radiator - there's not a combination that I've found to be that narrow and I've looked at both electric and mechanical. Proform advertises a Slim Fit radiator and fan combo that would fit, but there is alarmingly little information and forum chatter about it and its $700. With a V6 Dakota fan clutch installed, I have 2.5” from it to the condenser, only slightly more room than a stock radiator
01ae90c408cd7fdbf3acd0d41cfc495e3494fd43fc.jpg

  • Very few V8 swap radiators on eBay have provisions to mount a shroud or electric fan. You'll have to pony up and pay for a quality radiator to get those mounts or run an upgraded stock replacement. These guys are local to me and have a great reputation: https://cgj.com/product-category/radiators/antique-performance-radiators/jeep-radiators
  • Additionally, many V8 swap radiators flip the inlet and outlet as compared to the stock TJ setup. In doing so, the radiator outlet is halfway covered by the AC compressor with little room to make the turn. This is not unique to Summit - any V8 swap radiator with horizontal tanks and a driver side outlet will have this issue. A radiator with either the stock orientation or an LS swap radiator (in/out on the passenger side) would fix this.
01a149d80b14dcd3e5b96393b86ef0e72d34cf1659.jpg


01efaf88bbdb3a25bf3bd4629a2c2ba7440cfa92a1.jpg

  • I've not found hard evidence, but many say that the stock 4.0/2.5 radiator will cool a 5.2 but not a 5.9. A stock replacement upgraded radiator might be adequate to cool the 5.9. I purchased a stock replacement aluminum radiator and am hoping it will adequately cool my 5.9. An oil cooler and hood louvers are my Plan B. Plan C involves a grinder and a lot of re-work.
  • The ZJ fan clutch is the same height as a Durango fan clutch at 3.5" and contacts the lower tank of my aftermarket radiator when I install the radiator. This would make any water pump or radiator replacement a nightmare as the grill shell would have to be unbolted. It does clear a thinner stock (OReilly replacement) OEM radiator.
  • A 1997 Magnum V6 Dakota clutch is 2.97" and allows the lower radiator tank to clear on installation. It still doesn't allow the thicker Summit radiator to fit. This combination does allow a stock 4.0 TJ fan shroud to be attached, but since I have a tummy tuck the fan is no longer centered of the shroud. I could shim the motor if I wanted to make this work, but that will make future work on the accessory drive difficult. From left to right: 99 Durango, V8 ZJ, Dakota.
012538bc8d6b02d9ce2087f000a742431468d4bb29.jpg

  • This leads me back to electric fans and my final solution. My current Mishimoto fan is 3.5" deep and pulls around 1800 CFM. With the aftermarket TJ radiator installed, I only have 2.75" between the water pump pulley and radiator. I found a Spal fan (30101516 ) that's under 2.5" deep and is rated for 1600 CFM.
In short, the AA recommended placement does allow use of stock driveshafts, exhaust manifolds and fan/ radiator but can really limit your cooling system if you need more cooling capacity. You can build an exhaust to fit - you can't make a radiator and fan fit where the space doesn't exist.

With the radiator hoses back in the stock location, my final hose selection for the upper is from a 4.0 ZJ (Dayco PN#71659 ). The lower is a combination of FLEXIBLE HOSE, STOCK DURANGO HOSE, and an ADAPTER.

We're almost caught up!
 
FWIW, the radiator on the 1998 ZJ "Niner" (5.9L) is the same radiator as the 1998 4.0L ZJ, except for the location of the inlet and outlet (they are mirrors of each other). Same size, same thickness, etc. It's not much bigger - if anything - than a standard TJ radiator.

I have never seen any issues with Magnum-swapped TJs running the factory TJ radiator, other than having to get funky with coolant hose routing.
 
If you want to get good insight into the power of an electric cooling fan, pay attention to the current draw. You can get a 10 amp fan rated at 2700 cfm, but that is at zero static pressure. Place that same fan in front of a radiator and a condensor and it will pull nowhere near that. Find a quality fan that draws 40 amps regardless of its cfm rating, and it will be able to pull high cfm at high static pressure. Quality fans like Spal will publish performance graphs showing cfm against static pressure - cheaper fans will not - and that is the real tell.

I run a Spal brushless fan (which is rated at something like 41 amps) in front of my Hemi, which puts out a crazy amount of heat. But that is after going through two lower amp fans - both rated at similar cfm as I recall - which could not keep up.

Nice work, I’m enjoying your build.
 
FWIW, the radiator on the 1998 ZJ "Niner" (5.9L) is the same radiator as the 1998 4.0L ZJ, except for the location of the inlet and outlet (they are mirrors of each other). Same size, same thickness, etc. It's not much bigger - if anything - than a standard TJ radiator.

I have never seen any issues with Magnum-swapped TJs running the factory TJ radiator, other than having to get funky with coolant hose routing.

But it should be noted that the 98 ZJ ran a dual speed electric fan. And everything I've ever read about the 5.9 was that it was harder to cool than the 5.2. I'm curious to see what mine is like.
I didn't have clearance issues with my brass radiator and Black Magic fan but I'm also not sure if my motor mounts are in the AA recommended location. I sort of remember Evan saying something about moving them a bit.
 
I made a to-do list on cardboard to both keep organized and enjoy the satisfaction of crossing things off the list. I had several things started and almost complete, so I wanted to focus on finishing some items.

018e68a5c3d3df6b5a5113ee692915792616c872c6.jpg


One of the items I’d started and not finished was the exhaust, so I decided to get that knocked out. I’d need the O2 sensors for the engine to run properly anyway. I like to build my exhaust to be serviceable and adaptable over time if I choose to swap mufflers and my old design put the catalytic converter behind the crossmember, which would ultimately limit the length my muffler could be. I decided to move the cat in front of the crossmember to allow future changes to the muffler. Here’s an exhaust fab tip – keep your old O2 sensors around for welding in the new bungs. This will help ensure the threads aren’t distorted during welding.

01198c67f35e81815e5e587d1d13b664b198bcdc7d.jpg

Here was the final result:

01bbeebd37213e9b74936a2ccf971015e2ea355bdd.jpg


The muffler is attached with a band clamp on either side. Since my exhaust is 2.5”, I found a Dynomax tailpipe (PN# 54287) that bolted in to the stock locations. And here is a terrible quality picture of the whole system installed in the TJ:

0163d26fb9409b0c3c7c17eb8c7eb189c141c75a50.jpg


I promise to get some better pictures when I can get this on a rack or at least jack stands.

The ECU was swapped out, radiator full of coolant and I was ready to hear the Jeep run – or so I thought. When I went to crank the engine, the starter struggled to spin it over like it was hydro locked. Weird. I pulled the spark plugs and was greeted with coolant pouring out of multiple cylinders.

Yep, curse words were spoken.

Now is when I started to connect the dots from things I noticed during the disassembly of the donor – no thermostat and little to no coolant (can’t remember if it was dry or low). I’m having serious doubts about this motor as a whole at this point.

In a bit of, well, desperation, I pulled the intake and changed gaskets hoping I might have messed up when installing the Hughes plenum kit. Nope. No change. It still leaked live a sieve. I pulled out my inspection camera (which if you don’t have one in your toolbox, I highly recommend it.) to try to verify where the leak was coming from. Here is what I found:

012ea47f19a37d016371f303de21e1a301b43d311e.jpg


Coming from the top of the cylinder either means I have a head gasket that failed spectacularly or a severely cracked head, which these Magnums are known for. Due to other obligations and a pending family vacation to Las Vegas, the TJ was put on hold for a few weeks while I figured out a path forward.
 
But it should be noted that the 98 ZJ ran a dual speed electric fan. And everything I've ever read about the 5.9 was that it was harder to cool than the 5.2. I'm curious to see what mine is like.
I didn't have clearance issues with my brass radiator and Black Magic fan but I'm also not sure if my motor mounts are in the AA recommended location. I sort of remember Evan saying something about moving them a bit.

Well don't all XJ's run a combo mechanical/electric fan setup too? I know my 99 did and I'm 95% sure that my mom's 97 did too... I think it's more a problem of airflow and heat soak due to the tight engine compartment, rather than a radiator limitation - still good to note though!
 
Ouch man!! Those Magnums are reliable, even with cracked heads, and over the years I've built and torn apart a handful and even on abused motors, I rarely see catastrophic head or head gasket failures...

Fingers crossed for you!
 
Ouch man!! Those Magnums are reliable, even with cracked heads, and over the years I've built and torn apart a handful and even on abused motors, I rarely see catastrophic head or head gasket failures...

Fingers crossed for you!

Well I'm one of those lucky guys who had a severe crack on my exhaust valve. I didn't have coolant leaking into the cylinder but it would pressurize the radiator enough to blow coolant out.
 
  • Like
Reactions: pc1p
Well I'm one of those lucky guys who had a severe crack on my exhaust valve. I didn't have coolant leaking into the cylinder but it would pressurize the radiator enough to blow coolant out.

Yup, it does happen - in my 20 years of Magnum stuff, I've had one do the same (got it for free too, owner thought it was junk!). End up being used for a 390 stroker for a First Gen Dakota street/strip truck.
 
Ouch man!! Those Magnums are reliable, even with cracked heads, and over the years I've built and torn apart a handful and even on abused motors, I rarely see catastrophic head or head gasket failures...

Fingers crossed for you!

I'll preface by saying I haven't taken it apart yet. I am far from an expert, but I like to think I have a clue when it comes to engines - this one has me a little stumped. The donor Durango ran fine and had well used but clean oil when I got it but now with the spark plugs out, I can fill the radiator with coolant and it be pouring out of the #3 cylinder within an hour and pooling up in others. The shear volume of coolant leaking into the cylinder has me scratching my head.
 
I’d thought through several different scenarios and fixes, from remanufactured heads to a brand new crate motor – I was all over the place. My preference was the new motor (at $2300), I just had a hard time stomaching that right now. I kept a watch on FB Marketplace just in case and happened up on a deal I couldn’t pass up – a 2wd 99 Ram 1500 with a 90k mile 5.2L and rebuilt transmission. The best part is I got it delivered to work for not much more than the cost of reman’d heads, so in the off chance my 5.9L is an easy fix I can get my money back out of this truck. Nope, its not a 5.9, but at this point I’m not being picky. I won’t know the difference anyway.

019053cb138fc825bd132982ba24df63149a1be821.jpg


01f12fe3d100d63d39c5cd7c2171f18f884c4cc293.jpg


This is the kind of clean you can't fake - it's obvious this truck has been cared for.

0152b5b0131f16e2db83fb2b2a3e2238967e3972f2.jpg


The truck runs flawless (it actually starts with a key!) and gives me confidence this will be a good donor. I’m taking this week to re-organize parts and tool and slam a Wave Runner back together before the holiday weekend for a test drive at the lake. After the 4th, its full bore back on the TJ.