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I finally found some time to get this all put together. This thread is going to have A LOT of pictures and information regarding the swap I did on 10/3.
Some background:
The old 3.5 2005 that was in my truck gave up at 206k. Through the swap we determined the cause was a failed thermostat that caused it to seize. I found a new motor that had 93k on it from a 2006 Chevy Colorado. The truck was setup to be pulled behind an RV, so the actual driven miles on this motor are unknown, which made it a GREAT motor to pull, because it was rarely driven and well taken care of.
Lets get started! Towed the truck from Rapid City to Pierre (where I am from) to the shop we rent north of our house.

We got to the shop at roughly 5:30PM and began tearing down. We drained all the fluids and pulled the radiator. There were no particles/chunks in the oil, so the seize was definitely top end related. Cylinder #3 was the culprit, as it was the only spark plug out of all brand new plugs that were fouled.

We unmounted the A/C compressor from the block, which is trickier if you are not planning on replacing the A/C compressor. The top bolt is hidden behind the pressure line, because normally if you are pulling the compressor, you are replacing it!

Power steering pump was next, three bolts hold it to the block and we used a metal wire to hold it off to the side for the engine pull later.
Soaked the exhaust manifold bolts in WD-40 and they came right out! The very back bolt was not original and wasn't tight at all. We discovered why later when we loaded the old engine in to the back of the truck. I will explain that later.

Next we took torque converter bolts out. We made a special tool using an old 12 point 18MM socket and a flat piece of metal. The rubber plug between our engine and transmission isn't big enough to fit a full sized ratchet in there and a wrench can't angle enough to reach the bolts.

Turning over the engine was a task easier said than done, as this motor was almost completely seized. The starter could bump the motor over, but even with this long of bar it was not an easy task to turn it over.

At this point we only have the bell housing bolts, fuel lines (didn't have the disconnect tool) and motor mounts before this engine was ready to pull.
This ends day one at roughly 8:30, which is about 2.5-3 hours of actual work time to get it thus far.


The next morning we woke up at 8 AM, had breakfast and went to town to buy some things we would need for the day. We picked up a fuel line disconnect tool (OTC wasn't actually that expensive, and I can reuse it someday) and 2 gallons of unmixed DexCool.

We got to the shop around 9:30 AM and started working on getting the new motor prepped, bell housing bolts out, motor mount bolts, and disconnect the fuel lines.
We removed the exhaust manifold completely, which made it much easier to access the bell housing bolts.

Disconnecting the heater core hoses is almost too easy. You just grab a pair of pliers, squeeze the clip, push the hose on farther and pull it right off.
I disconnected the fuel lines and finished unbolting the bell housing from the engine. The two dowel pins are located right above the starter motor and likewise on the other side. Mine were pretty stuck in there, but nothing a little pry bar cant fix. We hooked the motor on to the lift, and lifted slightly, to ease the tension on the motor mounts.
We used the front engine eye and stuck a transmission bell housing bolt in the opposite direction of the passenger side lower part of the block. We also used a block to protect the valve cover from getting damaged in the process.
**NOTE1 If I were to do this again, I would take out the 4 bolts holding the motor mounts to each side of the block, as well as taking out the single bolt holding it to the frame on each side. The motor mounts are very tall and getting the engine up high enough to clear them is tricky because the transmission hits the transmission tunnel before you can get that high.
**NOTE2 There is a pilot shaft that actually sticks about an inch in to the crankshaft, which makes NOTE1 more important as well.



Here you can see the pilot shaft on the end of the torque converter that will make it really difficult to get the engine far enough away when lifting.

Here she is! Free from the pickup!

I salvaged my SuperSparkz.

Installed the new temperature sensor in to the lower radiator hose.

Mounted the new SuperModulation eFan on to the radiator.

Used an easy out to get the bolt out of the head on the new engine (junkyard must have broken it off)


Used a puller to get the pulley of the old power steering pump. Installed on to new pump.


I didn't get any pictures of this part.
The 2006 is a return-less style fuel injection system, so the rails had to be swapped to make this all work. I ended up stealing all the 2006 injectors and installing them in to my 2005 rail, which worked perfect since they are exactly the same.
I also robbed my old intake manifold off my 2005, because I had already installed all new gaskets in it one week ago and already removed the ugly cover that goes over the manifold. Here is the engine almost ready to be put in!

**NOTE3 Don't be dumb like I was and think you are going to be able to use the harness off your new motor! Save yourself the time and swap the harnesses now while you have the engine out. Every single connector between the 2005 and 2006 harness is the same except for...wait for it....ONE. One connector is different. It just happened to be the LAST connection I was going to make before we were going to start it. Don't waste your life swapping harnesses when the engine is already in, it ISN'T fun.
Now that you have your old harness swapped over to the new engine you are ready to drop it in! I changed the filter before putting the engine in, but didn't fill it with oil until we put it in.

If you take my NOTE1 from above and leave the motor mounts off the motor when putting the motor in the drop will go very very quickly.


Filled it with 5 quarts of Castrol full synthetic and 1 quart of Lucas oil stabilizer.

Everything was installed in the reverse order from above, and I don't have many pictures other than this dreaded moment:

Near the middle of that harness you will see the fuse box block. Next to that is a small oval connector. THAT connector is the only one that is different in this ENTIRE harness from a 2005 harness. The 2005 harness has around 8 pins, the 2006 has way more than that. Don't do what I did, obey NOTE3.
Here she is almost fully installed!

Filled it up with coolant and topped off the power steering reservoir.
First startup!
https://www.youtube.com/watch?v=LtHNde55y5E
I had a fouled plug in cylinder 5 and I forgot to hook up the brake booster vacuum line.
Got a new spark plug in and let it idle until warm up. eFans kicked in at exactly the right time and everything was running as good as it can on the wrong tune. The 05 and 06 motor is just different enough where the idle target gets messed up and it will idle at 400 RPM. It still ran butter smooth even that low.
Now it was about 7:00 PM and we were ready to head home, and clean up the next day...or so we though!
Got about 1/2 mile from the shop when the gauges freaked out. My speed went to 0 and my low fuel light, abs, all that jazz. They flashed back on and I kept going. I hit some washboards on the gravel road and this time the gauges freaked out and the engine shut off. I stopped and we hooked up a chain and towed it back to the house, where it would be easier to diagnose.
Once in the garage I started diagnosing the electrical issue. I found a blown fuse in IGN at the bottom left corner of the fuse box when standing on the driver side. I put a smaller fuse in, turned the key, POP. It also was trying to run the starter when I would be in accessory or run continuously. Shut it off, unhooked the computer and plugged the computer back in one connector at a time until the fuse popped.
It would pop when the center connector was plugged in which is mostly transmission related. I got under the truck and started inspecting all of the transmission connections, which all looked good. I found a wiring pinout for that connector here on the nation and discovered there was A LOT of grounds for the computer in that harness. Grounds cause lots of problems.
I got back underneath the truck and discovered that I had forgotten to tighten the bolts that hold the three computer grounds to the engine block :ugh:. Tightened them up, threw a new fuse in IGN and BAM. Fired right up and hasn't had a problem since.
The road was extremely muddy and the tow home absolutely caked my front end in mud from the recent rain. I snapped this picture when we fixed the problem and I was out on a second maiden voyage.

I put a 2A trickle charger on it over night, as the next day I was going to be driving 200 miles to Rapid City on this fresh swap.

That's all folks! I am falling back in love with this truck again and put in a bunch more parts the next day that will be located in my build thread, so check it out! I also got a special surprise out of the truck that donated its heart for my truck to live again!
Kenan, my brother, used the forklift to load the old engine in to the back of my truck for the 200 miles journey back to Rapid.


Here she is in all of her glory!

Now I said I would explain the exhaust manifold bolt not being the right bolt, so here is what we found that was QUITE interesting if you ask me.
On the backside of the old 3.5 you can see this tag. This tag has the date stamped on it that signifies when the recall was performed to fix the head problem! The date says 9/10/2007! I thought it was cool. Whoever did the recall work didn't install the correct exhaust manifold bolt back in!

:salute: I hope you enjoyed my not so formal write up on 2005 to 2006 3.5 swap.
Some background:
The old 3.5 2005 that was in my truck gave up at 206k. Through the swap we determined the cause was a failed thermostat that caused it to seize. I found a new motor that had 93k on it from a 2006 Chevy Colorado. The truck was setup to be pulled behind an RV, so the actual driven miles on this motor are unknown, which made it a GREAT motor to pull, because it was rarely driven and well taken care of.
Lets get started! Towed the truck from Rapid City to Pierre (where I am from) to the shop we rent north of our house.

We got to the shop at roughly 5:30PM and began tearing down. We drained all the fluids and pulled the radiator. There were no particles/chunks in the oil, so the seize was definitely top end related. Cylinder #3 was the culprit, as it was the only spark plug out of all brand new plugs that were fouled.

We unmounted the A/C compressor from the block, which is trickier if you are not planning on replacing the A/C compressor. The top bolt is hidden behind the pressure line, because normally if you are pulling the compressor, you are replacing it!

Power steering pump was next, three bolts hold it to the block and we used a metal wire to hold it off to the side for the engine pull later.
Soaked the exhaust manifold bolts in WD-40 and they came right out! The very back bolt was not original and wasn't tight at all. We discovered why later when we loaded the old engine in to the back of the truck. I will explain that later.

Next we took torque converter bolts out. We made a special tool using an old 12 point 18MM socket and a flat piece of metal. The rubber plug between our engine and transmission isn't big enough to fit a full sized ratchet in there and a wrench can't angle enough to reach the bolts.

Turning over the engine was a task easier said than done, as this motor was almost completely seized. The starter could bump the motor over, but even with this long of bar it was not an easy task to turn it over.

At this point we only have the bell housing bolts, fuel lines (didn't have the disconnect tool) and motor mounts before this engine was ready to pull.
This ends day one at roughly 8:30, which is about 2.5-3 hours of actual work time to get it thus far.


The next morning we woke up at 8 AM, had breakfast and went to town to buy some things we would need for the day. We picked up a fuel line disconnect tool (OTC wasn't actually that expensive, and I can reuse it someday) and 2 gallons of unmixed DexCool.

We got to the shop around 9:30 AM and started working on getting the new motor prepped, bell housing bolts out, motor mount bolts, and disconnect the fuel lines.
We removed the exhaust manifold completely, which made it much easier to access the bell housing bolts.

Disconnecting the heater core hoses is almost too easy. You just grab a pair of pliers, squeeze the clip, push the hose on farther and pull it right off.
I disconnected the fuel lines and finished unbolting the bell housing from the engine. The two dowel pins are located right above the starter motor and likewise on the other side. Mine were pretty stuck in there, but nothing a little pry bar cant fix. We hooked the motor on to the lift, and lifted slightly, to ease the tension on the motor mounts.
We used the front engine eye and stuck a transmission bell housing bolt in the opposite direction of the passenger side lower part of the block. We also used a block to protect the valve cover from getting damaged in the process.
**NOTE1 If I were to do this again, I would take out the 4 bolts holding the motor mounts to each side of the block, as well as taking out the single bolt holding it to the frame on each side. The motor mounts are very tall and getting the engine up high enough to clear them is tricky because the transmission hits the transmission tunnel before you can get that high.
**NOTE2 There is a pilot shaft that actually sticks about an inch in to the crankshaft, which makes NOTE1 more important as well.



Here you can see the pilot shaft on the end of the torque converter that will make it really difficult to get the engine far enough away when lifting.

Here she is! Free from the pickup!

I salvaged my SuperSparkz.

Installed the new temperature sensor in to the lower radiator hose.

Mounted the new SuperModulation eFan on to the radiator.

Used an easy out to get the bolt out of the head on the new engine (junkyard must have broken it off)


Used a puller to get the pulley of the old power steering pump. Installed on to new pump.


I didn't get any pictures of this part.
The 2006 is a return-less style fuel injection system, so the rails had to be swapped to make this all work. I ended up stealing all the 2006 injectors and installing them in to my 2005 rail, which worked perfect since they are exactly the same.
I also robbed my old intake manifold off my 2005, because I had already installed all new gaskets in it one week ago and already removed the ugly cover that goes over the manifold. Here is the engine almost ready to be put in!

**NOTE3 Don't be dumb like I was and think you are going to be able to use the harness off your new motor! Save yourself the time and swap the harnesses now while you have the engine out. Every single connector between the 2005 and 2006 harness is the same except for...wait for it....ONE. One connector is different. It just happened to be the LAST connection I was going to make before we were going to start it. Don't waste your life swapping harnesses when the engine is already in, it ISN'T fun.
Now that you have your old harness swapped over to the new engine you are ready to drop it in! I changed the filter before putting the engine in, but didn't fill it with oil until we put it in.

If you take my NOTE1 from above and leave the motor mounts off the motor when putting the motor in the drop will go very very quickly.


Filled it with 5 quarts of Castrol full synthetic and 1 quart of Lucas oil stabilizer.

Everything was installed in the reverse order from above, and I don't have many pictures other than this dreaded moment:

Near the middle of that harness you will see the fuse box block. Next to that is a small oval connector. THAT connector is the only one that is different in this ENTIRE harness from a 2005 harness. The 2005 harness has around 8 pins, the 2006 has way more than that. Don't do what I did, obey NOTE3.
Here she is almost fully installed!

Filled it up with coolant and topped off the power steering reservoir.
First startup!
https://www.youtube.com/watch?v=LtHNde55y5E
I had a fouled plug in cylinder 5 and I forgot to hook up the brake booster vacuum line.
Got a new spark plug in and let it idle until warm up. eFans kicked in at exactly the right time and everything was running as good as it can on the wrong tune. The 05 and 06 motor is just different enough where the idle target gets messed up and it will idle at 400 RPM. It still ran butter smooth even that low.
Now it was about 7:00 PM and we were ready to head home, and clean up the next day...or so we though!
Got about 1/2 mile from the shop when the gauges freaked out. My speed went to 0 and my low fuel light, abs, all that jazz. They flashed back on and I kept going. I hit some washboards on the gravel road and this time the gauges freaked out and the engine shut off. I stopped and we hooked up a chain and towed it back to the house, where it would be easier to diagnose.
Once in the garage I started diagnosing the electrical issue. I found a blown fuse in IGN at the bottom left corner of the fuse box when standing on the driver side. I put a smaller fuse in, turned the key, POP. It also was trying to run the starter when I would be in accessory or run continuously. Shut it off, unhooked the computer and plugged the computer back in one connector at a time until the fuse popped.
It would pop when the center connector was plugged in which is mostly transmission related. I got under the truck and started inspecting all of the transmission connections, which all looked good. I found a wiring pinout for that connector here on the nation and discovered there was A LOT of grounds for the computer in that harness. Grounds cause lots of problems.
I got back underneath the truck and discovered that I had forgotten to tighten the bolts that hold the three computer grounds to the engine block :ugh:. Tightened them up, threw a new fuse in IGN and BAM. Fired right up and hasn't had a problem since.
The road was extremely muddy and the tow home absolutely caked my front end in mud from the recent rain. I snapped this picture when we fixed the problem and I was out on a second maiden voyage.

I put a 2A trickle charger on it over night, as the next day I was going to be driving 200 miles to Rapid City on this fresh swap.

That's all folks! I am falling back in love with this truck again and put in a bunch more parts the next day that will be located in my build thread, so check it out! I also got a special surprise out of the truck that donated its heart for my truck to live again!
Kenan, my brother, used the forklift to load the old engine in to the back of my truck for the 200 miles journey back to Rapid.


Here she is in all of her glory!

Now I said I would explain the exhaust manifold bolt not being the right bolt, so here is what we found that was QUITE interesting if you ask me.
On the backside of the old 3.5 you can see this tag. This tag has the date stamped on it that signifies when the recall was performed to fix the head problem! The date says 9/10/2007! I thought it was cool. Whoever did the recall work didn't install the correct exhaust manifold bolt back in!

:salute: I hope you enjoyed my not so formal write up on 2005 to 2006 3.5 swap.