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Quadrasteer 8.1L Suburban tow rig

2003 Suburban 2500 Quadrasteer camper towing 8.1L 6.0L swap 4L80-E
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It was partly because of the GMT800 wide frame rail spacing and leaf springs mounted outside of the frame that it it ended up 3.5" wider (I won't use an automatic car wash). I've been told the added width made the extra side lights a legal requirement, but I couldn't tell you what the law says.
 
Removing main belt makes no difference. Seems to come from underneath - maybe inspection cover area. Starter dragging a little? Torque converter bolts hitting? Also wonder if there is an 8.1L-specific inspection cover because it bolts to the 6.0 oil pan, but leaves a gap with 8.1.
 
Blue85 said:
Removing main belt makes no difference. Seems to come from underneath - maybe inspection cover area. Starter dragging a little? Torque converter bolts hitting? Also wonder if there is an 8.1L-specific inspection cover because it bolts to the 6.0 oil pan, but leaves a gap with 8.1.
Click to expand...

Is the sound occurring at 1x crankshaft speed? Does changing the engine speed make a linear or nonlinear difference? :thinking:
 
It ran out of gas with cabinets blocking the fuel door, so I had to get it off jackstands and roll forward.

BTW, it was always kind of high in the back, but now the front is even lower. Trying to figure out how many turns to put on the torsion key bolts to account for about 200 extra pounds. I meant to measure height before I started, but forgot.
 
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Frequency scan app shows around 8-12Hz, so it's 1X engine speed. It's too fast to be valve train, but sounds more like a rattle than a tap, tap. Torque converter unbolted makes no difference. I can't find any signs of an exhaust leak or anything making contact.

I'm pulling the front diff to drop the oil pan.
 
So everyone knows that Craiglist "ran good when pulled" means "yanked because of rod knock" and "minor noise" means "rod ejected through block wall." But how could the oil have been clean when it came home, but some metal after 10 minutes of idling? Remember that broken oil pan? Looks like the windage tray was dented in the same event.

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The random marks in the middle are from me trying to bend the dent out with a screwdriver. Bearings all feel tight!

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Stick the oil pickup in a can of oil and start it for a few seconds!
 
The good news is that my "expert" hammer work on the windage tray has eliminated the noise.

It reminded me that when I did initial compression checks the engine didn't want to turn past a point. It seemed like the weak battery and jumper cables weren't enough to push compression on the one plugged cylinder. But it was actually digging #2 rod bolt into the windage tray. I thought upping the cables and 2nd battery did the trick, but it must have bent the tray just enough. Since the tray is springy, it never bent enough to have full clearance.

The bad news is that oil pressure is gone now. I removed the oil pump to get the windage tray out and just put it back again without thinking about it, but must have gotten something wrong. I don't find much info online, except to say the drive shaft or extension likes to break (and always use a new one!).
 
Looks like I just rushed through oil pump installation. I suspect the bolt felt tight because the drive rod was misaligned. Bolt was loose and 1/16" gap at the top of the pump. This time I gave it 4 ugga-duggas to be certain (kidding).


Started up with 50psi, went into closed loop and started adding fuel (it's still on stock LQ4 tune), all the sensor signals look good. Only fault message is for 4x4 (front actuator is out of vehicle). It's running oil cooler and tranny cooler in the rad, plus aux tranny cooler and power steering cooler out front and none of it seems to be leaking.

Got to put the front diff and steering back in*, hook up the torque converter, etc and get on to tuning. Oh yeah, and give it a couple of oil changes.

(*other than pull the engine, I only see 2 ways to get the front diff out. 1] remove DS motor mount and mount bracket. How fun will it be to get that aligned again? 2] disconnect the drag link from the steering box and idler arm and push it out of the way, then rotate the diff through a series of different moves.)
 
Pre-tuning, by just giving it time to set fuel trims, it idles smoother than the 6.0 ever did. This truck always did trim positive, maybe the MAF is a little off. It's at +25 right now. I do need to confirm fuel pressure is right for this motor.


Might as well take a drive around the yard to help burp the air out of the cooling system. With the big rad and dual heaters it seems like this thing needs 6 gallons of coolant now.

 
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+25 lol not surprised being 2.1 liters larger
I forget if the limit is either 25 or 30 before setting lean codes.
Are you doing the tuning or someone else?
 
Chevy305 said:
+25 lol not surprised being 2.1 liters larger
I forget if the limit is either 25 or 30 before setting lean codes.
Are you doing the tuning or someone else?
Click to expand...
I'm using HP tuners, which is a new tool for me. I just got it yesterday, actually. I segment swapped the 8.1L engine and trans fields from a 2003 8.1L Suburban file into my stock PCM file to preserve all VIN, VATS, dual fuel-tank, speedometer and other vehicle parameters. Plus, the PCM I got with the 8.1L was damaged - probably smashed during the engine extraction which was surely a chain around the engine tied to a crane piloted by a monkey. Maybe it could be repaired, but I would need some detailed drawings that don't seem available. Initially, this made the fuel trims worse, with the larger injector characteristics apparently overshadowing the >1L/cylinder number :saweet:. Same result on my spare MAF. As every shade-tree mechanic knows (and I did have a table with a laptop under a shade tree...) high positive fuel trims at idle point to a vacuum leak. A mechanical fan makes a stethoscope hard to use on vacuum leaks, but I did determine that the throttle body gasket was leaking. Local stores don't stock these for some reason, so I ended up cutting some PVC shower pan liner into a "temporary" gasket, which brought the fuel trims back down under 10 everywhere. So it seems like a valid configuration ready to start actual tuning (the only difference from stock so far is PE).

I can't progress much without plate and insurance, but with this engine and tighter torque converter it's ripping grass with every throttle blip around the property.:woot:
 
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