Rebuilding the 5.3 in my 02 Yukon! Need advice/tips!

[Nozbich]

It's pretty late right now, but hello everyone! I am currently in the process of rebuilding the motor in my 2002 Yukon SLT 5.3l Flex Fuel DBW. It's my first time ever going this far into a rebuild and I wanted to give updates and pics as I went along. So far, I have torn the motor down to the heads and block and by tomorrow night I should be able to pull it out. The reason I decided to tear it down is because I had the dreaded 706 Castech heads that caused gradual then sudden coolant loss eventually causing the Yukon to overheat. As I tore into the block I saw my coolant and oil was mixed together.

My goals for this build isn't to make 750 hp or nothing crazy but I want to go beyond bolt-on stuff while I have it torn down. So far I have looked at the following on the rebuild:

Intake:
- TBSS or NNBS Intake Manifold (including the C5 filter, LS3 90mm TB, new bolts, X-Link, connectors, etc)
- Airaid MIT (keeping the stock airbox)

Cooling:
- E fan conversion

Fuel:
- Since I have the Flex Fuel with the bigger injectors, is there anything fuel related I need to change?

Top End:
- 706 (non-Castech) or 862 heads (Unsure of what supporting stuff I need for this)

Bottom End:
- Texas Speed Cam (212/218 .550/.550) (Also unsure of what supporting stuff I need for this)

Exhaust:
- Long tube headers to true duals with an X-pipe

Rear End:
- 4.56 or 4.88 still haven't decided yet

Also some other misc. things such as sensors, connectors, bushings, mounts, and other things that are almost 23 years old now.

Bare with me please and I am open to ANY suggestions, advice, and tips as I go along with this rebuild.

 

[Tonyrodz]

It's pretty late right now, but hello everyone! I am currently in the process of rebuilding the motor in my 2002 Yukon SLT 5.3l Flex Fuel DBW. It's my first time ever going this far into a rebuild and I wanted to give updates and pics as I went along. So far, I have torn the motor down to the heads and block and by tomorrow night I should be able to pull it out. The reason I decided to tear it down is because I had the dreaded 706 Castech heads that caused gradual then sudden coolant loss eventually causing the Yukon to overheat. As I tore into the block I saw my coolant and oil was mixed together.

My goals for this build isn't to make 750 hp or nothing crazy but I want to go beyond bolt-on stuff while I have it torn down. So far I have looked at the following on the rebuild:

Intake:
- TBSS or NNBS Intake Manifold (including the C5 filter, LS3 90mm TB, new bolts, X-Link, connectors, etc)
- Airaid MIT (keeping the stock airbox)

Cooling:
- E fan conversion

Fuel:
- Since I have the Flex Fuel with the bigger injectors, is there anything fuel related I need to change?

Top End:
- 706 (non-Castech) or 862 heads (Unsure of what supporting stuff I need for this)

Bottom End:
- Texas Speed Cam (212/218 .550/.550) (Also unsure of what supporting stuff I need for this)

Exhaust:
- Long tube headers to true duals with an X-pipe

Rear End:
- 4.56 or 4.88 still haven't decided yet

Also some other misc. things such as sensors, connectors, bushings, mounts, and other things that are almost 23 years old now.

Bare with me please and I am open to ANY suggestions, advice, and tips as I go along with this rebuild.

Careful with the 862 heads. They were prone to cracking too. Had them in my van and I also was experiencing coolant loss. Googled it and saw they also would crack.

 

[Marky Dissod]

As I tore into the block I saw my coolant and oil was mixed together.

This'd be enough for me to replace every single bearing and guide in the engine.
Everything that should've been lubed by oil has been contaminated by coolant.

Axle: 4.56 or 4.88, still haven't decided yet

If you don't drive any city / stop'n'go / metro urban miles, 4.56 or 4.88 might be a good idea.
The more highway miles your vehicle accrues in 4th gear with the TCC locked,
the more I recommend 4.10 or 4.30.

 

[justirv]

It's pretty late right now, but hello everyone! I am currently in the process of rebuilding the motor in my 2002 Yukon SLT 5.3l Flex Fuel DBW. It's my first time ever going this far into a rebuild and I wanted to give updates and pics as I went along. So far, I have torn the motor down to the heads and block and by tomorrow night I should be able to pull it out. The reason I decided to tear it down is because I had the dreaded 706 Castech heads that caused gradual then sudden coolant loss eventually causing the Yukon to overheat. As I tore into the block I saw my coolant and oil was mixed together.

My goals for this build isn't to make 750 hp or nothing crazy but I want to go beyond bolt-on stuff while I have it torn down. So far I have looked at the following on the rebuild:

Intake:
- TBSS or NNBS Intake Manifold (including the C5 filter, LS3 90mm TB, new bolts, X-Link, connectors, etc)
- Airaid MIT (keeping the stock airbox)

Cooling:
- E fan conversion

Fuel:
- Since I have the Flex Fuel with the bigger injectors, is there anything fuel related I need to change?

Top End:
- 706 (non-Castech) or 862 heads (Unsure of what supporting stuff I need for this)

Bottom End:
- Texas Speed Cam (212/218 .550/.550) (Also unsure of what supporting stuff I need for this)

Exhaust:
- Long tube headers to true duals with an X-pipe

Rear End:
- 4.56 or 4.88 still haven't decided yet

Also some other misc. things such as sensors, connectors, bushings, mounts, and other things that are almost 23 years old now.

Bare with me please and I am open to ANY suggestions, advice, and tips as I go along with this rebuild.

I'm not sure of your budget or ultimate HP goal. I plan to bore and stroke my 5.3 when the time comes. Some may say (for me) to just do a 6.0L upgrade, but being in CA engine swaps can leave you at the mercy of a CARB referee. If you bore, get your block sonic tested if planning to out out 3.902 (or .903). I like your cam choice. For that I recommend checking TSP for thier cam packages, which may include things like newer style lifters, trunnion kit, beehive or dual-coil springs, and maybe thicker pushrods.
I'm assuming you also have the 4L60e, that will need attention maybe sooner than later after this build. I plan on going from 3.73's to 4.10's as my destinations are usually a few hundred miles away. Following!

 

[Nozbich]

Careful with the 862 heads. They were prone to cracking too. Had them in my van and I also was experiencing coolant loss. Googled it and saw they also would crack.

I had no idea this issue was prevalent with the 862 heads too. Thank you for the tips, I’ll be sure to bring my new heads and block in for testing.

 

[Tonyrodz]

I had no idea this issue was prevalent with the 862 heads too. Thank you for the tips, I’ll be sure to bring my new heads and block in for testing.

I also read--iirc--it was only the castech heads, so if you're looking for a set make sure they're not castech heads.

 

[Nozbich]

I’m finishing up unbolting the converter and some lines underneath and it will be ready to pull and mount on the stand!

I'm not sure of your budget or ultimate HP goal. I plan to bore and stroke my 5.3 when the time comes. Some may say (for me) to just do a 6.0L upgrade, but being in CA engine swaps can leave you at the mercy of a CARB referee. If you bore, get your block sonic tested if planning to out out 3.902 (or .903). I like your cam choice. For that I recommend checking TSP for thier cam packages, which may include things like newer style lifters, trunnion kit, beehive or dual-coil springs, and maybe thicker pushrods.
I'm assuming you also have the 4L60e, that will need attention maybe sooner than later after this build. I plan on going from 3.73's to 4.10's as my destinations are usually a few hundred miles away. Following!

The machine shop I’m using is backed up for about a month so this is good. I was checking those kits out and actually found a BTR kit that comes with Stage 2 v2 cam, beehive springs, 1 piece push rods, and valve seals for a good deal. I do have the 4l60e but I was thinking about just finding a low mileage junker 4l60e while I have the motor out.

 

[justirv]

I’m finishing up unbolting the converter and some lines underneath and it will be ready to pull and mount on the stand!



The machine shop I’m using is backed up for about a month so this is good. I was checking those kits out and actually found a BTR kit that comes with Stage 2 v2 cam, beehive springs, 1 piece push rods, and valve seals for a good deal. I do have the 4l60e but I was thinking about just finding a low mileage junker 4l60e while I have the motor out.

Looks like your having fun and making progress. As far as trans, recommend perhaps '05-'06 for updates (4L65e). Might be a challenge locating "low mileage", but I've seen a few under 100k miles. My experience with the 4L60's life expectancy, even when well maintained is in the 150k-175k range. Adding fresh, additional HP will shorten that duration.

 

[rockola1971]

You can have the 4l60e built to 4l65e specs. The major difference is the planetary 4 vs 5 element. Doesnt add much cost to the bill for the 4L65e build. The kevlar 2-4 band, Beast or equivalent sunshell and the latest and greatest steel and clutch kit then all valve body updates and you will be golden.

 

[strutaeng]

Hopefully block is okay and only needs bearings and a ball hone on the cylinders. Plan on replacing the cam bearings. Summit Racing makes a dedicated LS cam bearing installer for around $100, or have your machine shop install them. The cylinders hardly ever wear on these engines. A ball hone on a drill will bring back ideal crosshatch if the walls are polished.

Tear down everything, making sure you keep rod caps in the correct orientation. Don't pay much attention on inspecting things like bearings while you are dissembling; focus on keeping things in order. Empty cardboard boxes with holes cut out works well. Mark things like "Front" with a sharpie so you know which bank is which. Hopefully you have a large table ready to keep everything. A 6' folding table will probably be good.

Once everything is torn down, do a very thorough clean and inspection of wear items, such as bearings and journals. You may have to do a few passes, and realized you hadn't seen something on the previous pass. Attention to details is super important. Have GOOD lighting. Maybe even consider a magnifying glass if your vision is not the best. Once everything is inspected, you can determine what work is needed and what needs replacement.

Please keep us posted and good luck!

 

[Nozbich]

I finally got the motor out of ol girl tonight. I can’t tell you how many times I cussed at this thing not coming loose… it ended up being 1 final stud in the top back of the bell housing I missed.

 

[Nozbich]

Welp after a day of working on the motor on and off, I finally got it tore down and ready to go to the machine shop!

 

[Nozbich]

I finally found a set of remanned 862 heads that I will be replacing the valve springs, seats, retainers, rocker arms, rocker arm stands, etc.

My question is, what do I need to be able to fit 2” intake valves in those bad boys?

 

[Nozbich]

It’s been a minute since I updated this but I finally got my block and rotating assembly back from the machine shop. Here are some pictures of the work!

 

[justirv]

It’s been a minute since I updated this but I finally got my block and rotating assembly back from the machine shop. Here are some pictures of the work!

I recommend you get some plasti-gauge and an accurate torque wrench, take your time on test fitting of your rotating assembly, a quality ring compressor and rod bolt (rubber/silicon) caps for piston installation, and make sure you breathe and limit caffeine for when you're sliding that camshaft in . For me assembly has always been the fun part.

 

[Nozbich]

I recommend you get some plasti-gauge and an accurate torque wrench, take your time on test fitting of your rotating assembly, a quality ring compressor and rod bolt (rubber/silicon) caps for piston installation, and make sure you breathe and limit caffeine for when you're sliding that camshaft in . For me assembly has always been the fun part.

Oh yeah. The assembly is definitely going to be a blast! I actually just got my torque wrenches calibrated, bought a speedway adjustable ring compressor, valve spring compressor, feeler gauges, and some plasti-gauge. I'm still in the process of buying other misc. things while the engine is still out.

 

[Mudsport96]

I finally found a set of remanned 862 heads that I will be replacing the valve springs, seats, retainers, rocker arms, rocker arm stands, etc.

My question is, what do I need to be able to fit 2” intake valves in those bad boys?

Sorry I missed this post. Unless you are going to put some manual work into the heads to unshrowd the valves after installing larger ones, don't. A larger valve gets pretty close to the chamber wall, and can actually flow less then stock valves. And the small bore of the 5.3 block doesn't help matters. Plus, opening the chamber drops compression, even by a minute amount. Look up the stock LS heads comparison test. A 5.3 with a BTR cam and all the stock cathedral port heads. The 706/862 did better than all the others with the bigger valves. Including the 241 with the 2.00 inch intake valves. The best stock head for a sub 400 hp 4.8/5.3 is the 706/862.

 

[Nozbich]

Sorry I missed this post. Unless you are going to put some manual work into the heads to unshrowd the valves after installing larger ones, don't. A larger valve gets pretty close to the chamber wall, and can actually flow less then stock valves. And the small bore of the 5.3 block doesn't help matters. Plus, opening the chamber drops compression, even by a minute amount. Look up the stock LS heads comparison test. A 5.3 with a BTR cam and all the stock cathedral port heads. The 706/862 did better than all the others with the bigger valves. Including the 241 with the 2.00 inch intake valves. The best stock head for a sub 400 hp 4.8/5.3 is the 706/862.

Thank you for the advice! I actually decided against doing the valves and just doing springs/seals/and CHE trunnions.

 

[Nozbich]

Here is yet another update, I finally got around to putting the rotating assembly and cam together. Next up is the timing set, just waiting on a tool to get the crank timing sprocket off.

 

[Nozbich]

Update to the update. I got the timing set on!