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Bertha the Daily Driver/Weekend camper, 1991 V2500 GMC

Follow along as I continue to modify/improve my 1991 v2500 GMC Sub with a L96 and factory 4l80e for daily driver/weekend duties.

CriticalAction

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CriticalAction submitted a new Build:

Bertha the Daily Driver/Weekend camper, 1991 V2500 GMC

I had been wanting a 3/4 ton sub for a while now that I had a K5 and had owned a single cab. I figured the ample cargo space and 4 doors would come in handy as a near stock daily driver/weekend camper. Well long story short a friend of mine happened to post this 1991 V2500 GMC Sub from Idaho that I figured he was never going to sell as I knew he loved it. So a quick text and 1 weekend later and I had made a very big impulse decision. He assured me it ran and drove great so I hopped in and followed my dad the 75 miles home in it without a hiccup.

This vehicle is the newest I have owned for a few years and the fact that it came in the yard under its own power is another achievement of itself. At least that is what I keep telling people.

Plans for this include:
- Clean up the interior i.e. dash pad, headliner, shampoo the carpets, fix the broken gauge bezel
- ls swap
- new rims and tires
- rear locker
- All new fluids
- Tune up (cap, rotor, plugs, wires)
- Window motors
- New windshield
- All new body seals and window seals/scrapers

The point of this vehicle is to stay at or near stock height with a reliable drivetrain and nice enough inside that people do not mind riding with me. This is because my K5 is a little harder for people to swallow no matter how much I love it...

Let me know what you guys think!

Read more about this build here...
 

Justin V

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I'm assuming the tune up will come before the ls swap?

:whistle:

:popcorn:
 

CriticalAction

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Well the first thing I did when I got home was try to figure out what rims and tires I wanted to run. I knew I wanted to go bigger but had to search around. Ended up finding a set of 2007-2010 Silverado HD rims in excellent condition with hub caps for cheap enough. Then I went with some Falken Wildpeak AT3W in the 255/80r17 (33x10.50) variety after my dad had good luck with them on his 03' Tahoe.

Right away I also changed all the fluids, checked the brakes, gave it a quick tune up, and started driving it. I ordered a new windshield, door/cab seals, window motors, barn door seals, and new lock switches for the front doors. I didn't take any pictures of those because it wasn't much to document.

Over the past several months all I have been doing is driving it and tinkering on it here and there. Put a new passenger rear door window in it as it was cracked, fixed the rattling rear AC fan, and charged the AC system. The factory rear A/C and heat works great I am happy to report. I went back/forth between BBC/383/LS/350 until I came across a 2015 L96 with 21k miles close to me all complete. Well about two weeks ago I went and picked up. We brought it back and quickly stripped it of anything I wouldn't be using, built a little stand for it and set it in the shed until I collect enough parts to get it in Bertha.

Looks like I am ordering my harness this week from Lone Star Dyno out of Texas and I am already putting the list together for what else I might need to get it done. The LS swap page on facebook has been a big help along with asking a ton of questions to Terry at Lone Star and Scotty at Tejas.

I will be retaining the factory AC system, factory 4l80e, factory cluster, stock ls mech fan, and leaving everything in the stock location so I do not have to change driveshafts, shift linkage, or T case shift linkage. Some pictures below of what I am working with and the mess that was the shop after stripping it down. Also what Bertha looks like as of now(dirty I might add).

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CriticalAction

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Minor Update/Plan lay out:

Placed order for harness from Lone Star Dyno along with flashed ECM/TCM, 2010 camaro pedal, and throttle body (6 week lead time).
Ordered Gen 4 ECM mount and camaro pedal mount from Tejas Steel works (should be here next Wednesday).

Plans include:
- Retain stock cluster
- Retain stock AC system(it works perfectly)
- Retain 4l80E(swap internal harness to later 93+)
- Engine in stock position with ICT Billet plates
- EP381 fuel pump
- Russel fuel fittings
- PTFE braided fuel hose
- CU730 radiator (factory squarebody BBC rad)
- Utilize stock 5.3 mech fan(try and fit 2015 6.0l fan later on)
- Move battery to passenger side
- Energy suspension motor mount inserts
- Hooker LS swap manifolds
- LS brackets R4 AC compressor high mount bracket kit
- Much more that I still need to figure out...

Like:

What fittings did you guys use for adapting to the fuel rails? I have seen the push lock and other screw on ones.

What did you guys use for air intakes?
 

CriticalAction

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Well I got the TBI 350 and associated parts out a few weekends ago, just haven't updated the thread. After that I set the parts I would be reusing outside along with the suburban up on ramps so I could power wash everything. This thing has had a horrible ATF leak since I have owned it. Everything cleaned up pretty nicely and I was able to confirm that the previous owner was right about the tranny being rebuilt. Supposedly only has 7k on it since the rebuild so I think it will be fine behind the 6.0l LS.

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CriticalAction

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I ordered the first box from Summit for everything I thought I would need to set the whole combo back in the vehicle the next weekend. First parts to go on were the Holley LS R4 AC bracket as I had gotten mixed feedback from all companies that make brackets like this on whether or not it would fit. The clearance issue occurs differently for each company but it could be anything from the water pump casting not working due to the VVT bulge or the water neck hitting/being too close to the bracket itself. Well after Holley's tech line confirmed they would fit the water pump but were not sure whether or not I would have spacing to the filler neck I decided to take the chance. Well as you can tell it paid off and I have plenty of clearance for the hose and clamp.

Next since this is the first generation 4l80e they are a bit different than the later 93+ ones and you have to swap out the internal harness for the later style to get the correct plug. Everything plugs right in and no modifying required. I bought it for $50 on Amazon from Pheonix Transmission Parts.

I also threw the ICT billet swap plates on and the upper clams so I was 1 step closer to dropping it in. Also got my oil pressure senders hooked up. The 2015 is for the ecm and the big pot on will drive the 91 gauge inside. Vibrant performance 16790 for the trick little banjo fitting. /

Well I was reading through Larry's Polar bear build again when I got to the part of him stripping the harness he stated that getting a factory wiring diagram was very helpful in doing swaps like this. Well a quick search on Ebay showed me two very nice original manuals for R/V and P models. It showed up in time for me to strip the factory harness down over the weekend as well. Unfortunately I see that I did not take a picture of the finished harness but I have an in progress pic.

We all know about the different spacing LS cranks have vs the older SBCs so once we had the older engine out and could use a straight edge to compare the flex plates/TC snout holes it was looking like this was a factory dished flex plate on the L96. After checking and rechecking it was looking like I would just need the TC snout extender piece (ICT Billet 551165) to mate the two together. The only other difference between the two flexplates is that the L96 is a 3 bolt and the sbc is a 6 bolt with a slightly wider bolt pattern. With some research and talking to several people it is ok to drill 3 new holes/die grinder out the original 3 to make it fit with no loss of strength. Keep in mind here that the L96 flexplate did have 6 landing pads that appeared to be for bolts but only 3 were drilled. Picture shown below is of the L96 flexplate bolted up after modification. You can also see the factory dish of it in the picture.

Question for anybody who follows this thread. I have seen it all the time where people will write for a bit and then have a picture, then write for a bit and another picture. How do I stagger them into the post like that?

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Justin V

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After you have uploaded the image, but before you hit post, there will be a button next to the queued image that says image.


Click your cursor where you want the image to appear and then hit that button.
 

CriticalAction

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After you have uploaded the image, but before you hit post, there will be a button next to the queued image that says image.


Click your cursor where you want the image to appear and then hit that button.
Sweet progress too.
Awesome thank you. Now I can better explain my stuff along with the pictures.

I also am further along then the thread shows right now. The engine/trans/tcase is all set in place. I just ordered a bunch more stuff to work on it again this weekend. Expect a more exciting update tonight about my progress over the 4 day weekend we just had.
 

CriticalAction

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Over the 4 day weekend it was a thrash to get as much done as possible. So right as I got home we started finishing up the engine bay, painting, undercoating, removing the old battery tray for POR15, straightened the fins on my condenser, etc.

This took us all of Wednesday night and into Thursday day. Then we tried to quick stab it in the engine bay before the party for the 4th... Well quick and doing something you have never done don't go hand in hand... Every SBC I have done basically just installed themselves but there is something to be said for an engine that was designed to fit in that engine bay. After 3 tries we gave it up and enjoyed the fireworks/family. Started again on it bright and early Friday morning by pulling the frame side mounts off of the Burb and bolting them onto the engine. This gave us just enough extra clearance that we were able to get it in.

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After that it was the rest of the weekend of solving problems and hooking up anything we knew that we could. 1st problem occurred with the power steering pump sticking out and hitting the frame rail... Well after some thought and a severe want to not cut the frame rail we just bent it down slightly with the idea that if it ever needed to go back we could do it. I am not a fan of it but it is what it is... I haven't seen many late model LS swaps into squares so I assume that would be why I did not see this coming.

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After moving on from that fiasco we bolted on the AC compressor and 4 belts later we had the correct sized one. We used the string like everybody says but the string measures in the bottom of the groove not the top like belts are measured. So we ended up increasing the size of what we measured instead of taking away like we thought we needed to do for the tensioner.

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We also figured out a way to use the stock PS pressure hose from the 2015. We just straightened out a few of the bends and put a 180 in it with our brake line bender (just about broke it) and it came out looking pretty nicely. It threads directly into the steering box! This must be what people meant with LS swaps being easy?

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Next problem: If you look back we had installed the factory GM vacuum brake booster adapter to the intake manifold. Well once the engine was in it was very apparent that there was no way to put the vacuum hose on for the brake booster without a severe kink in the hose or a 90. So we ran to Menards and bought a 1/2" pipe nipple a few inches long and a 90. My dad made short work of turning it down in the lathe and now the hoses lay nicely. (No pics but I can get some later if people need)

Transmission and transfer case were just the reverse of taking them out except for the dust cover... I had installed the engine clam mounts with the old brace rod plates underneath with the belief that I was going to reuse the brace rods that go to the dust cover of the 80e. I thought this would be a good idea because the LS engine loses 2 bellhousing bolts compared to the SBC and I wanted it as strong as I could get it. For a while there it looked like we could still make it work and we were cutting the factory dust cover in several places to hopefully make it bolt up. Well then I tried the starter and realized the LS 4l80e casting hole for the starters are way different and we gave up on using it. I just added the GM performance P/N to my next Summit order and now it will be a factory piece.

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We also ran the engine oil cooler lines underneath the engine crossmember because clearance was at a premium in the old routing location. Are these lines needed? No, but in 91' and 2015' they still felt it was in an HD application so I figured WTH some hose clamps, p-clips, and a few minutes with the flare tool produced this.

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All in all I will have to admit it sits in the engine bay pretty nicely once you address a few problems and throw the plastic cover on and fan shroud in. The fan looks like it ended up about in the right place even. This is just a stock 5.3 fan the body shop gave me with the L96 cuz they reused the 2015 one. They are fairly inexpensive so I think it would be cool to throw the HD one on later. According to rock auto it is 1 inch bigger and looks like a way more serious fan as far as blade design goes. It looks like I will have clearance in the fan shroud for it as well. What do you guys think?

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Placed my order Sunday night for fuel system, Hooker exhaust manifolds, radiator, hoses, and some other small things. My dad stopped by the local exhaust shop today to have them bend up some exhaust pipes for me. The hope is that I can have as much of this swap done before the ECM/TCM/harness get here in a few weeks. The less time I spend fiddling with it then the more time I get to drive it and get back to the K5. BB2019 is fast approaching!
 

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Just a quick update because I was a dummy and didn't snap any pictures of the radiator, shroud, fuel pump install, hoses, etc. I will get them this weekend, but here are the pictures of the finished fuel system. Had a slight leak at the union of the pressure hose to the regulator but I tightened it a bit more and it seemed to hold. If it ends up leaking then I have enough hose left over I will just buy new fittings and build another one. (We ran the fuel pump for a few minutes to check for leaks by putting power to pump plug). I think it came out looking somewhat nice. Honest opinions?

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CriticalAction

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Finally got pics of my progress from a few weekends ago when I got the fuel system done. Stock 2004 2500HD w/ 6.0l Radiator hoses worked perfectly.

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Also ran the steam port line to the closed off port on the CU730 radiator.

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Then mounted up the Derale tranny filter in what was the most convenient spot I could find that was close to the cooler lines yet still able to get the filter off. I will just have to put a diaper underneath whenever I change filters. I wasn't too enthused about putting it down next to the transmission on the framerail because there is enough stuff that already want to occupy that space (driveshaft, fuel line, exhaust, T case brace rod, etc.)

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Also mounted up the Hooker LS swap manifolds. Compared to installing headers on a sbc I love them. I used ARP bolts with a little antiseize torqued to 18 ft lbs in the GM sequence. I assume with a few heat cycles I will have to re tighten.

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Also gotta love swapping a Suburban because you always have a storage unit for the parts yet to go on!

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Got the exhaust finished up this past weekend but unfortunately not without a little blood. We had not been working for more than 20 minutes when my dad was cutting the first head pipe down and the saw kicked the pipe out. The blade missed his fingers because his leather gloves have no marks but the pipe hit his finger so hard it busted the "cap" open. I didn't think it was too bad until he was running it under water and I saw him able to peel the "cap" of his finger way further then it should be able to. I said ER, we can't deal with that here. So 3 hours, 6 stitches, and a wasted night later we decided to hit it hard the next morning. He was pretty annoyed.

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I did something different for this exhaust system than I normally do and that is my dad stopped by the local National Muffler. The manager stated he had bend sheets going back into the 50s for factory exhaust systems... Skeptical as we were he found that a 91' burb with a diesel had factory dual exhaust. I had never heard of this but I took a chance and had him bend everything up. Factory 91' diesel exhaust was 2.25" from manifold to muffler and 2.5" from then on. He just bent everything out of 2.5" for me.

Obviously with any kit that isn't big bucks we still had to cut/massage some things to get them how I liked them. However, in the grand scheme of things we didn't mess with much. Obviously the LS swap forced some head pipe modification, and we extended the rear pipes past the shackle hanger so I could tuck them up higher. Overall I am happy with how it turned out. The entire system is 6 pieces with 2 mufflers and will come apart easy with stepped band clamps as opposed to the stupid horse shoe ones that crush the pipe. I have done a few exhausts with those and always hated how I could never remove the pipes again to work on stuff. I decided to fix that with this system.

No in progress pics but here is the finished system. The only thing that might get added is an H-pipe ahead of the mufflers because I have heard these LS engines do not sound very good without one and duals.

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CriticalAction

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Update:

Intake, different radiator hose, relocated steamport, all wiring I am able to perform have been completed. Pictures of how it looks sitting in there: (Still some loose wires that will be attached to ECM/other components, more on that later)

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Now the real update:

Good news and bad news. ECM, gas pedal, throttle body, harness, and TCM arrived from Lone Star Dyno. Took me a few days to find some time but was able to get everything installed, wired, and bolted in. After checking all fluids, verifying connections, lots of thinking, etc we went to do the intial fire up and could tell right away we didn't have fuel pump prime.

We didn't even bother to try to start it. Checked out the connector at the back where we had connected the Lone Star power supply wire to the stock connector. Instructions from Lone Star indicated that the purple wire was typically fuel pump supply and other smaller wire was sending unit connection. Apparently 91' is different because we assumed those directions would be correct and found out later that purple is actually sending unit and gray wire is power supply. We switched the pins and tried again. Fuel pump prime is good now. Turn the key to ignition... Crank and crank and crank but no fire. Doesn't even try.

Back to the drawing board we start thinking how to diagnose whats going on. This is my first LS swap so we start searching the interwebs to look for what could be wrong. Came up with several results like grounds, cam/crank sensors, injector pink wire + test, coil pink wire + test, etc. We checked everything power everywhere, grounds everywhere, scanner indicated that cam/crank sensors are reading so what do we do now? Well we did the old school check for spark with plug in wire, threads grounded, close to metal object. No go, so we do not have spark at spark plugs. Well no wonder it won't fire... Interweb search again and everything we had already checked would be the physical culprit. So I texted Terry at Lone Star (props to him for answering on a Saturday), and went through the same thing again. Check everything we had already checked 2,3,4 times, then we thought to check if a pin had gotten bent over on the ECM? Nope all straight and pointy.

So long story short Terry thinks he might have uploaded the wrong file to the ECM (happened once before) so I pulled it off and shipped it back for analysis. It should be getting to him today so hopefully I have an answer soon because if its not ECM related I have no idea what it would be in the harness. At this point I just want it to run. But I will be patient.
 

CriticalAction

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It runs, and it runs good!

Terry checked the tune file and found that he had mistakenly loaded the stock tune back onto the ECM. He quickly fixed the problem and expedited the ECM back to me so I could try it on the weekend. After getting the ECM back from Terry I quickly plugged it in and Bertha started right up just like it should.

After some minor celebrating we pulled it around to the shop and started checking everything for leaks. After screwing the dash in a little more securely we hit the road for the first road test. Made it about a mile away from the house before the check engine light came on and the throttle was dead completely. Engine would start and idle but throttle was completely unresponsive.

So my sister came out to pull us back but while we were waiting we figured well lets try it again. Started it back up and the CEL is still on but the throttle was responding now. Quickly I limped it back home so we could pull the codes on it. Error code P0606 ECM fault code is what I found. Having no idea what to do I searched the internet for possible causes and everything was something that is either replaced new or would require a brand new ECM.

I decided to clear it and see if it came back again just to see if I was that lucky. Yes and no as I have gotten the code twice more since the first time but very sporadically. I have contacted Terry to see what his thoughts are and he said the same thing I had been finding online. That we would have to do some major diagnosis or just start replacing component$$$$$.

Currently Bertha is my daily driver and I am just carrying a cheap code reader in case I get the code again but I have been driving it for a few weeks now and it hasn't come up. So I don't know what to think.

Even though she works great I still have some stuff to clean up and that is adding the 4wd ground trigger for the 4low shift tables. I also need to take it to the local tuner to get the speedometer calibrated as Terry took a guess to what reluctor wheel was in my transfer case but there are several different ones through the years. So currently at about 3 mph my speedo is pegged. I just suction cupped a GPS to the windshield and am using it as a speedometer right now.

Beyond that I have just been driving it and enjoying it. I have probably 750 miles on it already including a trip to a buddies to deliver some square parts about 100 miles away. Cruise set on 82, AC on, and 1 finger on the steering wheel I cruised my whole way there without issue. Calculating with the GPS and filling at the same spot I got 12.5 mpg for my first tank of gas. Over all I don't think that is too bad considering that was 80-85 mph the whole way and a whole lot of playing around in between.

Anyways here is what the finished ECM mount, electrical setup looks like:

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CriticalAction

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Been a while!

Bertha as reported before was running excellently until after about 500 miles I had an interesting thing happen... Went out to drive to the gym and when I put it in drive she didn't move a bit. Figured I just missed the detent with the shifter and tried again and then she moved. I thought nothing of it but over the next few days it happened a few times and I started to think the transmission was starting to slip. Well in about 1 day of barely any driving it went from just happening in 1st to not having any holding power in any gear except 3rd and 4th.

Needless to say we dumped the fluid and yeah she was cooked. Parked it and started calling trying to figure out as far as getting it rebuilt soon. After a moderate amount of research and phone calls I have come to the conclusion that I screwed up by only changing the internal harness in the 91' 4l80e. I have gotten several conflicting opinions of whether changing the additional required solenoids would have saved it. However, it doesn't really matter as the transmission was toast.

Made a call to a builder in MN that my dad had gone through for his 4l60e in his Tahoe and commented that they understood hot rodding. I bought a good 2001 4l80e core from my buddy and sent it down. They set it up for 500+ HP with a 1800 rpm RV stall converter, trans go shift kit, beefier bands, higher line pressure, etc. Basically I wanted it to be beefy enough for towing, daily driving, and ready for a cam swap if I decided to go that route later.

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Installed it and so far after several thousand miles it has been flawless with zero issues. Bertha has been at full strength and I have only changed a few things since then. One of which being going to the 2015 2500HD fan and clutch. I had noticed on a friends 2015 HD that the clutch was extended to bring out the fan away from the engine. I figured it would work perfectly for extending further into my fan shroud. Additionally, the 2015 HD fan is larger in diameter than the 5.3 fan and would fill out the shroud better than the 5.3 fan which I always thought was a bit small for my shroud. Over all I am very very happy with the outcome and am posting it here for anyone that wants a beefier fan that fits better than the common 5.3 fan.

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