Past Contemplation, Bought a Full Size Expo rig. GMT400 Tahoe - ideas welcome

[justcuz]

4.10's would be the tallest gear I would run with 35's.
If it needs tires just put 285/75x16's on it while you are gathering parts and use it.
If you blow up the rear end, GMT400 pickup and Suburban 4x4 rear axles are a bolt in swap and are cheap and plentiful in 3.73 ratios.
Use it and enjoy it while gathering parts for your SAS. You still have the Sammy for more challenging stuff.

 

[tommyp]

4.10's would be the tallest gear I would run with 35's.
If it needs tires just put 285/75x16's on it while you are gathering parts and use it.
If you blow up the rear end, GMT400 pickup and Suburban 4x4 rear axles are a bolt in swap and are cheap and plentiful in 3.73 ratios.
Use it and enjoy it while gathering parts for your SAS. You still have the Sammy for more challenging stuff.

Cool yeah sounds like a plan. Got a little work done this weekend.

Couldn't find a door pin that would work. But I straightened the pins I had and used them again. I think they will be ok I just would have liked to put in new ones. one broke off at the c clip and the other was bent pretty good but they will work.

Got that side all patched up for now

sloppily Painted with SEM Rust Shield. Everything is mostly hidden so I am not putting the finest effort into looks here. With welding or paint.

Tailgate went back on pretty perfectly and everything lines up good. New bumper came but none of the holes lined up with the plastic step cover that I have so I am going to have to figure out what I need to buy.

Parking brake seems jammed up. I am going to have to address that as well. Got it up on ramps and stands to start dealing with the Tcase.

 

[tommyp]

Got a little done tonight. Picked up an impact wrench to try to get the crossmember bolts off. Going to give them another go tomorrow.

Got the oldest to finish prepping the cargo area for paint

ugly

painted it up with some of the SEM Rust Shield. Should work ok.

 

[Solid94]

Coming along nice! If you are looking for strength I'd consider a SAS. It's what I have under my gmt400 and I love it. Keep up the good work!

 

[tommyp]

Its out. Not too much of a pain. Heavy but I just let it drop on the floor.

Hopefully I will get the replacement tomorrow. Guy with the parts truck still needs to pull the drivetrain.

Parking brake seems like it is stuck. Bought new shoes for the back. I will tear into them once the t case is back in.

 

[tommyp]

Donor truck just up the road and crazy owner excited about how easy it is to get to the case.

Lost a few of my 9 lives pulling that case.

out with the new in with the old.

In

Front driveshaft out of the donor. Fits like a glove.

vss plug for the 246. Had to splice in the connector from the donor truck vss plug to match the case.

making the cut for the shifter

got a little out of control with the sawsall. Not a great cut.

testing the shifter. I painted it later with the sem rust shield.

and done. Like it was meant to be there.

 

[tommyp]

Started working on the electrical today. Pulled out the automatic car starter after i figured out what it was.

On to the hvac disaster. I guess there was some issue with it so the previous owner cut off the plug and hot wired the fan to run on high with a toggle switch. Going to see if i can bring it back to factory. Will try to pull the panel from the tcase donor truck. Need the pigtal and the blower switch since those are long gone.

No clue what is going on here. Looks like the reminants of a switch then a resistor? He also was tapped into the rear defroster plug with another wire.

Fan switch rigged to the high speed blower switch wire.

Figured out that my backing plate where the parking brake attaches is toast so will have to replace the backing plate if i want a parking brake.

Also found a wierd wire running from the drivers door to a relay up front then to wires under the front bumper. No clue what that was about. Maybe fogs or something but why run to the door instead of somewhere easier.

 

[tommyp]

Did a bit more work on the Tahukon. Mostly fixing problems. Replaced the cap and rotor. This helped with a rough idle problem it was having.

Got a ball for the hitch and made a dump run.

went to work on this

Previous owner had hot wired the fan to just blow on high. Also had soldered into the hvac control panel for some reason. But luckily he had a spare one that he gave me with the car.

I had to buy a new high low switch but also the pigtail to go with it which wasn't so cheap. Got all the wiring going to the right spots and....

the fan still blew only on high. So bought the blower motor resistor and that did the trick. PITA to install but now it seems like everything works except AC which is missing the lines.

Tried to swap out the fuel filter but I am afraid I am just going to break the lines putting wrenches to them. They are about $200 to replace them all so I might leave it for now until I can figure something out.

Texted the previous owner with some questions. He told me the fix to the non functional gas gauge was to hit the dash above the cluster. Who new. He said this was for fog lights that were no longer on the car.

Oh and the 4wd system is having some issues. Luckily those buttons don't do much anymore with the manual case. I need to work on getting the 4wd actuator to function now.

Oh and hand calced some mileage. 10.5mpgs around town and light towing. not so good. I wonder if my cold start issues have something to do with it. I replaced the coolant sensor for the ecu to see if that did anything but it doesn't seem to have helped. But overall its doing well and getting back in shape

 

[justcuz]

Check the plug wires with an ohmmeter and also spark plug gap. You should be getting between 13-15 mpg around town. Run some injector cleaner through your next tank of gas.

 

[justcuz]

Cold start issues could be pressure regulator or dirty fuel filter. You can check fuel pump pressure at the Schroeder valve. If pressure is good the it may be the regulator which lets fuel drain back and does not keep the system primed.
The 4wd syst em needs a connection to run the front axle engagement. It was part of the old system with the electronic shift. Follow the wires from the front axle and there is a connection that goes from the manual shift to engage the front.
Another thing you can do is find an AWD Denali and use the passenger side axle tube. There is no disconnect and will turn your front axle all the time. The outer axles and CV joints turn all the time anyway so it is not much difference.

 

[tommyp]

Cold start issues could be pressure regulator or dirty fuel filter. You can check fuel pump pressure at the Schroeder valve. If pressure is good the it may be the regulator which lets fuel drain back and does not keep the system primed.
The 4wd syst em needs a connection to run the front axle engagement. It was part of the old system with the electronic shift. Follow the wires from the front axle and there is a connection that goes from the manual shift to engage the front.
Another thing you can do is find an AWD Denali and use the passenger side axle tube. There is no disconnect and will turn your front axle all the time. The outer axles and CV joints turn all the time anyway so it is not much difference.

Huh interesting. May try to track down a Denali. I know there is something that you can put in the actuator to permanently switch on the front axle. I will probably do that in the winter when I am going to be in 4h most of the time anyway.

The cold start issue was I believe a bad body ground. I ran a new one and cleaned it up a bit and so far it starts on first go. I really need to redo all the grounds but I have been working on my garage build so not much time to mess with the rig. In the sammy I welded studs to the body and the frame and ran welding cable grounds. I will do that this winter on this rig.

I need to replace the fuel filter but there is now way it is coming out without trashing the lines. I am going to put a lot of the fixes on hold for a bit until my new garage is up so probably won't be till Dec or so before I can really tear into it. I am putting up a 30x38 addition to my house which will be mostly garage with some living space in back. Doing a lot of the work myself so it is a huge undertaking. But will have a kickass space for working on cars when it is done. Doing site prep now and need to demo my current detached garage.

Filled it up today and got 14mpg for around town. I figure that is what I am going to get anyway so I think I got that fixed as well. A lot better than the 10 last fill. Seems to be running a lot better a little bit of a stumble when cold but nothing like it used to be. I will have to go at the plug gaps etc when I find time. Right now just happy to have a working vehicle. Going to tow pretty heavy tomorrow so hopefully it will be uneventful. Thanks for the help and ideas.

 

[justcuz]

The stumble can also come from the distributor cap or wires grounding. Check inside the cap, they get a little bit of condensation inside and corrode the metal inside the cap causing a slight miss. Be careful tightening the cap though, it has a plastic inset that the screws thread into and can be easily stripped.
The homemade rust buster, I think it is acetone and ATF mix is more effective than any commercial product, maybe that on your lines will allow you to bust the fuel lines loose from the filter.

 

[tommyp]

So I towed a small tractor with it for about 150 miles. It wasnt too happy but not terrible. Considering it was probably about 5k pounds of load with trailer. Halfway through the tow started to get a lot of vibrations when stopped in drive. Not sure if Something is wrong with the 4l60 or if i did in the motor mounts. There was definately alot of powertrain movement as the tow progressed.

Weird thing was the mpgs. Got 9mpg during the tow which was expected. But after i took off the trailer I drove 4 hrs highway and only got 10 mpg. As i was starting this run the cap that was on the intake silencer popped off and the truck died. I figured out what was wrong quickly and got it back on. After the trip I rtved it on to eliminate any leaks.

I then drove it back the 150 miles home. I havent filled it since so not sure where the mpgs are now. When i got it home it started doing its no start BS. I went through the grounds again. I cleaned the battery to engine ground and ran a new ground from the battery to the frame. The no/hard start went away again.

Radiator looks like it has a leak so going to order up a 454ss one soon and replace it.

Still has the after start stumbles. Need to get new wires and gap the plugs next.

Have to tow the tractor again this weekend hopefully I dont do any serious damage. I dont need to tow this heavy often but need the family tractor/hoe for my addition.

 

[justcuz]

Don't forget to check that distributor cap inside.

Do you think the engine computer was in relearn mode when you got the 10 MPG. I wonder if a short drive and a shut down and restart may have changed things? I sometimes notice the same issue after I drive my 1993 Suburban in headwinds. It seems to take a couple on/off engine cycles to get the computer to re adjust to the driving conditions.

Did you tow in drive or OD? I would think at around 5000 lbs you were pretty much at the maximum tow rating of the Tahoe, maybe checking the engine and transmission mounts may be a good idea. I would look in the wrecking yards for an air to air factory trans cooler. They are on trucks, Tahoes and Suburbans. When I got mine I took the entire setup including the hard lines that go to the transmission. That and the larger radiator will help keep your trans alive.

Stock ground straps go from the firewall under the heater hoses to the back of the engine (usually the transmission bolt) and from the engine to the chassis. Many times they are greasy, loose or broken, causing a bad ground. Luckily the braided straps are also easy to find in the wrecking yards.

 

[tommyp]

I can check it but it is a new ac delco cap and rotor 2 weeks old.

I did tow in od wasnt thinking. Will tow in 3 next time.

I think you are right on the computer relearn. I dont think it is very fast to adapt. I just want to get engine stuff straightened then go to the 411 PCM. Hopefully that will be a bit more adaptive.

My grounds i think are non factory. One goes to the front of engine and the one in the back goes to the body. The one to the tranny I think is gone. Going to run another when i get a chance.

I think i have the factory trans cooler on mine. It is infront of the radiator.