5.2 Magnum Swap Part 13: Cutting and Rebuilding

by ThreeThirdsFab
September 22, 2015
In The Shop
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Welcome to part 13 of our 5.2 magnum swap, follow along as we swap a 5.2 magnum from a 1993 ZJ into our 2004 4.0 WJ. Sometimes you need to tear things down before you can build them up. That is the case this week as we cut into the front of the Jeep to remove the stock metal bumper, making room for some custom tube work and an oversized cooling system.

Read The Rest
Part 1: It’s Finally Happening
Part 2: Out With the Old
Part 3: The Last of the Stock Components
Part 4: All About Brakes
Part 5: Pulling the 5.2 (time lapse)
Part 6: The Test Fit
Part 7: Cutting and (not) Fitting
Part 8: Broken and Upgraded Parts
Part 9: Leaky Plenum Gasket
Part 10: Side Projects and Summer Fun
Part 11: Setting the Motor
Part 12: Custom Exhaust & Driveline
Part 13: Cutting and Rebuilding
Part 14: Giant Radiator in a Little Jeep
Part 15: Custom Tube Bumper
Part 16: Driveshafts
Part 17: A Real Firewall
Part 18: Starting Final Assembly
Part 19: Extending The Engine Cage
Part 20: Still Assembling
Part 21: It Lives!
Part 22: Brakes and Wiring

Cutting and Rebuilding

Since the motor is pushed so far back to clear the TTB crossmember we had concerns about how effective our clutch fan would be. The simple solution would be to use an extension from the clutch to push the fan forward and back into the radiator shroud. While this would work, we wanted something a little cleaner and more professional looking. We wanted to replace the clutch fan with a high output electric fan. This would ensure proper airflow over the radiator and would also give us a chance to remove the mechianl fan to free up a little power. While the fan doesn’t rob the motor of too much power, every little bit helps.

There are many options for fans out there and they all have their benefits and downfalls. By far, the most popular is the Ford Taurus Mark VIII. This single, two speed, fan can produce around 3,250 CFM, depending on what source you read. Also popular are the early 90’s Volvo fans. While we are usually in favor of junkyard finds and repurposing parts from other vehicles, when dealing with the cooling system we wanted something a little newer and more reliable.

For this application we are going with a Derale 16927. With dual 12” fans producing a combined 4,000 CFM we are confident this will keep the 5.2 cool in the desert heat. For extra cooling, we will be pairing the fans with a oversize radiator. At 26 x 19 x 2.25” it has 15% more surface area and is 80% thicker than the stock ZJ radiator.

The only downside to our massive cooling system is the considerable amount of unibody we need to remove to make it fit.

After removing the front half of the TTB WJ we started rebuilding. Crossmember first, to protect our swing steering. From there, we started to build up to form the lower half of the bumper.

With the radiator still in transit, this is just a rough start until we are able to set it in place and test the final fit. There is still a lot of fabrication to do, but we are very happy with how it is coming along.

A Day in The Junkyard

While Dan was spending his weekend with the plasma cutter, Andy took a tour of the local junkyards in search of a high output alternator. Some of the 2001-2003 Dodge Durangos with a 5.9 came with a 160 amp alternator. Even though this search could be compared to searching for a needle in a haystack, it is worth the time. Stock ZJs only produce 90 amps and remanufactured 160 amp alternators cost $120 more than junkyards alternators.

After 3 junkyards we finally found our needle in the haystack. While pulling the alternator we noticed how much larger the air hat on the Durango was. For another $15 we grabbed that too. It may be too tall to fit under the hood, but we couldn’t pass up the opportunity to try.

What’s Next

Next week we want to finish installing the fan and radiator. Our goal is to have it all set in place and be able to pull the motor Monday to start finish welding everything. From there it is all wiring and plumbing.

Don’t forget to check back next Tuesday for updates.