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Quadrasteer 8.1L Suburban tow rig

2003 Suburban 2500 Quadrasteer camper towing 8.1L 6.0L swap 4L80-E
All the flexplate bolts were tight and there aren't any witness marks from it moving around. After removing the bolts, I pushed it back into the transmission and didn't notice anything weird. I didn't try sticking it back on the engine since the engine is still on a stand.
 
Built adapter harnesses for the knock sensors and the temp sensor.

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Temp sensors.jpg

The '01-'02 3-wire temp sensor is 2 thermistors, as my diagram shows above. In '03 they went to this same package, but only 2 wires. Fortunately all of these GM sensors have the same resistance curve. So I've just wired to the B-C thermistor and left pin A floating. Sensors in both engines were reading about 4.8K when I checked this, which is about 58 degrees.

chart.jpg

I've pulled the EGR wires from the 8.1L harness to add to the harness in the truck. There were two wires pulled loose, so I had to repair those with parts from a donor harness. Actually most of these wiring parts are from Buicks past. Side note: pull-to-seat connectors are stupid. Yeah, EGR is dumb. Whatever. Might as well wire it now while it's easy and then I have options.
 
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If the 6.0 didn't have egr, it's pretty easy to make the 8.1 not have it either. Make a block off plate out of some steel and bolt it to the back of the intake with an egr gasket. Make sure the tune for the 8.1 don't include the egr controls and delete the pipe off for the driver's side exhaust manifold. The later 8.1's didn't use egr anyway.
 
The decision to leave EGR in was just to keep everything stock. I know blocking it later is much harder than doing it now, but adding the wires was also much easier.

Lengthened CAM, re-routed Crank, added adapter harness for Coolant, Added adapter harness for knock sensors. Added EGR harness into PCM connectors. Here's everything before dressing.

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The milk crate is my seat.

Done this way, the harness is just a roll of electrical tape away from supporting a small block again, if the desire should ever arise.
 
Engine is all bolted in, but I'm held up by Amazon not shipping stuff. I decided to run an '03+ 8.1L oil pressure sensor (3-pin) because it threads right in and mates with my harness. Can get it in town for $90 but scored a warehouse deal for like $14. I'm a sucker for a deal, but didn't realize it would take them a month so I'm waiting to install the intake manifold.

I just figured out that I have to re-pin these sensor connectors. Another case where the online posts say "just lengthen the wires" or whatever with no details. Always do your own research.

Crank and CAM wiring differences.jpg
 
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Good news:
  • Radiator, condenser and core support installed
  • 03+ oil pressure sensor installed
  • Intake manifold installed.
  • Power steering cooler installed
  • Fuel system and EVAP complete
  • Transmission cooling complete (factory rad + aux setup)
Bad news:
  • Radiator oil cooler fittings don't match the new cooler lines
Seems the radiator is 03+ and they changed all the oil cooler fittings between 02 and 03. I'll have to detail it in another post.

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I think I've finally figured out the oil cooler lines and fittings. The fittings I need probably are available, they are just generally listed as transmission cooler lines for something else. These parts must all come from Oetiker.

oil cooler radiator fittings.jpg

oil line types.jpg
 
Even side by side these could easily be mistaken for the same part.

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But the good news it that they do fit my oil cooler lines.

So other than needing some more fluids I don't know of anything standing in my way.
 
Great work Luke!
I actually spotted a 3/4 4WS Burb yesterday, and thought about you. It looked in pretty nice condition as it drove by in the other direction on a two lane road...lol
 
How do you recognize the 4WS from a distance?

The rear fenders have a "bulge" to them is the best way to describe it. If you look at a normal one next a 4ws one, it's obvious. I think they have a marker light over the rear tire too (I know the trucks do). Out in the wild when you see one they look a little off if you don't know what they are.
 
Correct. The Q-steer rear has a wider track width. On pickups they had a fiberglass bedside that almost looked like a step side (that was actually the production bottleneck in early production). The SUVs got a fender flare wider than the standard flare, and with side marker lights on them. Most (not sure if all) also had the cab marker lights.
 
The rear fenders have a "bulge" to them is the best way to describe it. If you look at a normal one next a 4ws one, it's obvious. I think they have a marker light over the rear tire too (I know the trucks do). Out in the wild when you see one they look a little off if you don't know what they are.
I forgot about that, they need that because when you're steering the tire travels on a sweeping arch.
 

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