5.3 Swap into YJ...what should I know?

[Asbjorn]

Well, of course my simple 4.2-4.0 swap has snowballed and it looks like I’m picking up a 5.3/4L60e this weekend. I’m grabbing the ECM and stock harness while I’m there.

So, what should I know before I go look at this thing? The story I’m told is it’s out of a wrecked 2002 Suburban with about 150k on it. Supposedly ran fine before being pulled.

Any problem areas to look at?

Also, I think I’ll probably buy a stand alone harness as the wiring aspect of this intimidates me. So, any preferred sources for a harness, or someone that will modify the stock harness and reprogram the ECM?

Any and all input is appreciated!

 

[UNSTUCK]

I have wired quite a few of these engines. I promise it's not as hard as it would appear. There are great resources online for finding out what wires you need to keep and what wires you can get rid of. Any company/person you would use to "thin" down a harness is just doing that. So you may as well pay yourself to do that. The plus side of doing it yourself is you can shape the harness to exactly fit your jeep and you can use your factory fuse box for the power your engine needs instead of using a second fuse box.
If you have to buy a harness, call John at Speartech. You can tell him exactly how you want the harness to run and he does a pretty good job of building it that way. He does start from scratch so it easier to do that. If you do go that route, dont buy the factory harness.

If you can't run the engine before purchasing, make sure all the front bolt-ons are there. If you have to buy them later on you could spend more on them than the engine cost. Make sure you at least turn the engine over by hand two full revolutions. Make sure it feels smooth. It will catch under compression, but that feels totally different than catching on metal. Find the easiest point in the rotation to turn the motor and move it back and forth several times as fast as you can. See if you can feel a knock. Look for damage. Broken block ears, broken wires, broken plastic, stripped out bolt holes.

Find someone locally willing to do a base tune on the ECM and then who is willing to either dyno tune or at least do a tune while he drives with you. At the minimum you need the base tune just to get it to start and to remove some of the emission and MIL codes.

 

[Anchor_Mtn]

Mounting. I really liked the Novak Adapters for the YJ. Easy to weld in and makes motor placement a breeze.
Wiring. If you have the matching harness and computer for that motor, ship it all to 150tunes.com. They have done great work for me on the swaps I have done.
Fuel. If you are trying to use the stock tank, the old style YJ fuel pumps dont put out enough pressure for the LS injectors. Buy/find a fuel pump out of a YJ with a H.O. 4.0(92-95). You will have to adapt your fuel line to the GM rail. Theres an adapter on Summit racing that makes it easy... Im pretty sure its this one..Russell Fuel Rail Fitting Adapters 640853
Cooling. The Advance Adapters Radiator... a little pricey but it makes it easy and it works.

 

[Asbjorn]

Thanks for all of the info and tips!

Looking around, there appears to be a variety of vendors/companies that sell harnesses or do modifications. I’ve been looking at one particular site that makes me think I can thin the harness myself. Maybe I’ll give it a shot and if all else fails, I’ll spring for one from the pros.

For fuel, I’ll be running an aftermarket cell, so probably an external pump and a Corvette filter/regulator. Any suggestions on pump options? It looks like the majority end up using a readily available pump made for Fords.

 

[UNSTUCK]

Your fuel rail will be a return type, so no go on the corvette filter. An internal pump is always best. Try this set up:

https://www.summitracing.com/parts/...MIlturu7H52gIV1rjACh3pvwDpEAQYAiABEgLJQfD_BwE

Add in the Walbro pump with all the 1's and 0's, 11000111 or something like that, and an inline filter. You'll be good to go.

On the harness, take your time and work through each individual wire. Shorten where needed by cutting a middle section out of the wire and soldering back together. Lengthen by adding a section of wire where needed. Be sure to solder any connection made. NO butt connectors anywhere. Otherwise you can purchase a crimper and super high dollar GM crimp on terminal ends, which I have, but I still add a bit of solder on each of those. I either have a lessor quality tool or something as I can never get them as good as the factory.

 

[Bart]

There is a lot of good advice here. Don't forget to grab the gas pedal and computer if it is a drive by wire.

 

[crimsonride]

Oh man. I just finished my swap. Here's my advice.

Make sure you grab the computer, harness, both O2 sensors, MAF sensor and gas pedal. Also, keep your temp sensor and oil pressure sensor from the old engine before you chuck it.

Read the Novak guide, it it immensely helpful.

A few things that can help save some money.

I reworked the wiring harness myself. It's not at all as bad as you would think it would be. Jus sit down at your workbench and start at one end. I can give you some good resources. It'll only take a couple hours and that's to do really nice, if you wanted you could have it done in about twenty minutes if you weren't anal about pulling out all the unnecessary wires and junk.

I swapped the output shaft on my 4L60E myself. That was a little bit more complicated but still not the most difficult thing ever.

I can recommend a cheap radiator I got off of Amazon that has worked well with my engine. It was $150 vs $600 from some of the other guys. I would say you'll need to run an electric fan with this though. I'm not certain if the mechanical fan works as well.

Unlike Anchor_Mnt I have had good luck with my stock YJ fuel pump. It was a 95 with a 4cyl. Maybe the older YJ pumps are different.

 

[Asbjorn]

So, I ended up passing on the motor and trans I had my eye on. I was just too skeptical without hearing it run first and who was selling it.

With that said, I have my eye on another powertrain that is still in the vehicle. It's a 99, so drive by cable. Probably going to go look at it this evening and if it all checks out, I'll probably jump on it.

@crimsonride any and all resources you have would be greatly appreciated! Particularly the wiring stuff and the 4l60e output shaft swap. I'm assuming you swapped it to a 23 spline to work with the Jeep t-case? I'm planning to run a 4:1 D300 for now, but tossing around the idea of just springing for the Atlas if the output shaft swap will be difficult/expensive.

I think the fuel pumps were different, I'll probably grab a later model YJ pump.

 

[RockChucker]

I would be leery of a 99. I don't know about 5.3s, but I know some of the 6.0s were cast iron heads instead of aluminum. That is pretty close to the first year of the engine. Unless it is a smokin deal. Just my .02. Also, I would recommend getting a 6.0 out of the gate. I have a 5.3 that is going to be getting pulled in favor of a 6.0. My brother's jeep is built nearly identical to mine. Crazy how much more power his has. This wasn't my determining factor in doing it, but definitely solidified further my decision.

 

[mbryson]

......

@crimsonride any and all resources you have would be greatly appreciated! Particularly the wiring stuff and the 4l60e output shaft swap. I'm assuming you swapped it to a 23 spline to work with the Jeep t-case? I'm planning to run a 4:1 D300 for now, but tossing around the idea of just springing for the Atlas if the output shaft swap will be difficult/expensive.....

As the owner of a “polished” Dana 300, I'd go with the Atlas. Buy once, cry once.

 

[UNSTUCK]

My theory about transmissions goes like this: Buy a cheap junk transmission, knowing ahead of time that it needs to be rebuilt. Do not buy one that's "good". Knowing that it needs to be built anyways, it will cost nothing extra for the output shaft swap.

 

[Asbjorn]

As the owner of a “polished” Dana 300, I'd go with the Atlas. Buy once, cry once.

I agree. I already have the 4:1 D300, so that is why I was going to stick with it for the time being. If I didn't have either, I'd definitely just go Atlas. I still may just sell the D300 and put that towards the cost of the Atlas. I'm at the point that I need to buy coilovers too, so the budget is going to get tight.

 

[crimsonride]

I had a 4:1 Tera low in my 231 so I kept it but I'm starting to wish I had an Atlas. It's starting to whine and complain and I'm thinking my planetary gears are going out.

Anyway.... as MBryson stated.... now's the time if you're going to do one.

Hit me up when you get going and I'll get you all the info. The 99 would be a bit different from the motor I did though. I think it's a different generation.

 

[Asbjorn]

I passed on this 99 engine as well. We'll see if anything else pops up and how I proceed.

 

[UNSTUCK]

What was wrong with it?

 

[Asbjorn]

Nothing wrong, I was doing some looking around and found some numbers that made me believe the 99’s aren’t the most desirable as far as performance goes. I guess I sort of talked myself out of it.