young_boomer None
1/11/20 5:14 p.m.

I got this K5 Blazer in early Spring of 2015 and wheeled it around with my friends for a few months at the end of high school.  It had a tired old Goodwrench 350 crate block in it so I figured that was a good place to start on improving it.  Unfortunately college got in the way for 5 years, which brings me to right now.  I joined Wreck Racing, and the E28 LS swap and a couple other guys convinced me that instead of botching a fourth intake gasket job on the old 350, I ought to just swap to an LS.

Here's the Blazer in 2015:

Blazer Background:

When I bought it, I was informed that somewhere along the way, someone had taken the old stock Detroit Diesel and swapped in the 350--so the dash gauges aren't hooked up at all (there's a loose mechanical oil pressure and mechanical coolant temp gauge), there's somehow even less electronics on board than either one would have stock, and it retained all the Diesel hardware--from hard fuel lines, to a 31 gallon tank, to the hydroboost brakes (big cam?).  Also its name was Mary Beth, and changing the name of a truck twice as old as I am just felt wrong, so Mary Beth it still is.


Back to the LS Swap:

I had been watching local Pull-a-parts for trucks and SUV's, and black Friday an email came in with a 2004 Yukon and a 2003 Tahoe.  I went down to the yard, and the Tahoe was in great shape, so I started working on pulling the Yukon motor.  For those of you that haven't had the privilege of meeting the local crowd at the South Atlanta junkyards.... Well, you can imagine.

I pulled the complete intact harness, minus an O2 sensor, and the engine plus some extra hoses, relays, and the fuse box.

While we were there we also pulled an Acura J32 for the WR $2020 challenge X T R E M E

2 motors in 5 hours wasn't too bad.

This thing was gnarly, so I sprayed it down with a pressure washer, and it came totally clean.

I swapped plugs before putting the engine in the Blazer.  Check out the gap on the old plugs.


We also had to rework the harness and ECU for a standalone setup.  Thanks to we had the complete pinout of what turned out to be a 2003 Yukon, not a 2004, ECU.  This was important because I decided that I was going to retain my 700r4 transmission, so I needed to run drive by cable.  The newer P59 ECU's don't have the driver for the Idle Air Control valve necessary for DBC--except a few 2003 ECU's.  In the future I might swap this ECU for the challenge E28's ECU if we run it in exhibition, since my P59 has 3 bar capability while the older P01 in the E28 doesn't.  The Blazer needs a 4l80e before it needs a turbo.  Both of which might be in the future.

What a rat's nest.


For those that don't know, the motor mounts on an LS are in a different place than the small block, and the block is a bit shorter.  To keep the trans/transfer case/driveshaft in the same positions, the engine needs to be set back 1" from where it wants to sit naturally.  I was trying my hardest to keep this swap on a tight budget.  I'm still doing pretty well, but not as well as I had hoped.  That led me to design an adapter plate myself.  Here's the drawing of it:

It didn't work right , so I ordered billet adapters from a reputable company on Amazon.  That one hurt.

The last piece of the puzzle was getting a DBC throttle body, which was really easy to do at the junkyard.  The one I got came off of a truck with EGR, so it was disgusting when I pulled it.  Here it is half clean, I used a screwdriver and a can of brake clean.  I hope I didn't scratch up the inside too much.

That's the end of all of my prep work, next comes the actual swap.

Stampie GRM+ Memberand UltimaDork
1/11/20 5:23 p.m.

What year is the K5? I converted my 88 square body from diesel to had and was able to keep all the dash stuff. 

young_boomer New Reader
1/11/20 5:58 p.m.

It's an 83.  Don't know why nothing worked, didn't ask, didn't really care.  Right now I might try to integrate everything into the old dash, or I might go with a tablet gauge setup.  Haven't decided yet, but I'm just monitoring things on my bluetooth OBD II phone reader right now.

young_boomer New Reader
1/11/20 6:15 p.m.

I set a personal record for engine removal.  3 hours and 10 minutes from start to finish, all done solo.

The engine bay is gigantic:


There's a few things that need to happen before I can sit the engine in and fire it up.  We needed to clean up the wiring, which I left to my resident electron expert from Wreck.  We were both shocked this thing hadn't caught fire.  I'm convinced the only reason it isn't burnt down is because it had been a lawn ornament for 3 years with the battery disconnected.


I pressure washed the engine bay and took out some extraneous things we wouldn't need with the LS. 

Since I'm using a 700r4 and a 4.8 (I don't think I mentioned that yet), I have a dished flexplate that needs a spacer and bolt holes in a different place, since the old torque converter had American spacing and the new flexplate has Imperial spacing.  What I did was take a die grinder and elongate the holes about an eighth of an inch inward to clear the old bolt holes.  Time will tell if that was a good idea.  The spacer I used was an ebay spacer that just makes the nose of the 700r4 converter a little longer to fit into the crank. Here's a picture of it bolted to the torque converter as a test fit:

I also learned that the exhaust manifold on the passenger side had a bung cast into it for the old style EGR even though there was no EGR on the truck I pulled it from.  That means that it wouldn't clear the frame rail of the squrebody, so I had to go hunting for a manifold that didn't have the EGR bung.  Forums said Trailblazer SS, Camaro, etc, but I found a manifold without it on... a... 2003 Yukon?  I took both manifolds since we had mangled the flange on the drivers manifold we pulled from the original Yukon.  Pull-a-part tried to charge me for the heat shield, which was another $10.  Ridiculous.  I also picked up an intake duct to see if I could make it fit anywhere in my engine bay.


Of course, that was after we had accomplished putting the engine in, and bolting up the flexplate.  It worked like a charm, but I could only get to 4/5 bellhousing bolts.  I hope I don't die driving this thing.


My biggest concern this whole time was the exhaust.  Since it was a diesel, it never had catalytic converters from the factory in '83, but no one would work on it anyway.  So I enlisted @papamilad, our resident exhaust expert at WR.  We both convinced each other to do side dump exhaust.  Here it is in the process of being mocked up.  This truck had true duals when I got it, and I plan to keep them.  Neither of us really liked how this ended up, so we're going back to the drawing board tomorrow and doing it over again.


In the meantime I kept working with another WR guy (I'm not sure if he's on here) and we plumbed up the fuel system.  I kept my stock carb tank with no baffling.  Time will tell if this will haunt me, but for now I'm going to keep on trucking and not let it go below a quarter tank.  We used an old Mercedes inline pump pulled a long time ago from a junkyard, mounted on the frame rail, and a new Ford Motorcraft fuel filter sitting in the engine bay behind the engine.  I forgot to take pictures of that, but here's a pump:


And finally we were ready.  It was Sunday before school started again, and we wanted this thing to run so we could come back this weekend and do cleanup on the rest of things.  I turned the key aaaand.... The pump was seized.  What a terrible night.

Luckily we came back the next morning, plumbed in a replacement pump we had lying around, primed the fuel system, and it fired up after it turned over twice.


That was so gratifying after this thing sat for 3 years.  Tomorrow we plan on finishing power steering, plumbing the radiator and steam tube, and mounting a working TV bracket for the 700r4.

GoLucky Reader
1/12/20 12:01 p.m.

Nice truck! How did you handle the VATS? 

young_boomer New Reader
1/12/20 3:50 p.m.

In reply to GoLucky :

I have a friend with access to HPTuners, so it was easy to delete after I got a couple GM credits.

young_boomer New Reader
1/12/20 8:17 p.m.

Didn't get as much done today as I wanted to, but it's almost ready to go.

First priority was finishing up the radiator plumbing.

I assume this is the diesel radiator.  Both radiator ports were 1.75" which was impossible to find a stepdown for.  I finally found one on or something like that.

The other side is mostly the same.

Next up was to finish the power steering.  I wanted to keep my hydroboost because I didn't see a need to spend any money to change it.  I picked up a new hose from Autozone since it was tough to find heavy duty trucks at the junkards around here.  This hose was made for a Yukon Denali.  I guess the 6.0's came with hydroboost.  This hose just dropped right in.  It was tight to make it fit, but once it was in it had a bit more slack in it.  It took like 2 hours just to get it seated in the pump side since the motor mounts butt up right next to the pump.  I wound up having to unbolt the junction block from the alternator support to get into it, then tightened it from underneath, with the wrench going between the diff breather and the crossmember.

Do you like how I plugged the brake booster vacuum line for a test start?


Finally I put in my TV cable bracket--I'm pretty proud of this one.

Somehow I didn't take a picture of how it mounts, but I attached it to the fuel rail.  I didn't have a chance to make a piece for the throttle body plate yet, so I haven't been able to drive it.


Went out once I measured the steam tube port to grab some adapters for plumbing the steam tube.  I think on the stock truck plumbing they splice in to one of the hoses, but I had an unused port on my radiator from where the heater hose originally went in the small block.

That silly fitting is 3 fittings: 3/4" barbed female stepdown screwed into a stepdown screwed into a 1/4" stepdown.  Turns out nobody makes fittings to step directly from 3/4" to 1/4".


So today I finished all the liquid plumbing.  Hopefully this week I can finish the exhaust plumbing and the TV cable throttle body mount.

young_boomer New Reader
1/14/20 8:10 a.m.

Filled the radiator yesterday and pulled it into the garage to work in the rain.  The TV cable still wasn't hooked up, but the 700r4 goes into a failsafe mode when the cable is fully retracted, which means that you can go into gear and idle around.  This was the first time it had moved in 3 years:

I also rinsed off some of the nice plant growth from sitting.  I had to really clean the windows since it was literally undriveable even to get into the garage, you couldn't see a thing.

We spent the rest of the day tying up a couple loose ends.  We tacked up the exhaust on the driver's side and finished wiring in an O2 sensor plug that I cut in the junkyard.

The last major obstacle was the TV cable bracket.  I tucked the cable under the fuel rail, because it was completely taut sitting on top of it.  That gave me the extra couple ratchets I needed to get the correct geometry on the cable.  It sits 23 degrees counterclockwise from idle, about 1-1/8" from centerline.  I used an augmented reality protractor app on my phone to measure the angle, then we cut off the cruise control nipple and rewelded it in the correct place for the TV cable to connect to.  The connectors aren't exactly the same size, but it slipped on and it's completely stable on it.

The cable automatically adjusts.  You depress the plunger on the top, and push the extender all the way in.  Then you open to WOT and the cable ratchets out to fully extended.  The initial adjustment tends to be a little tight, which means that the shift points are high, but line pressure is also high.  This is less dangerous to the transmission, but it would only shift when it had essentially no load on it.  I need to dial it in a little better before the next drive, probably one or two more ratchet points out.  The line pressure controls shift points and clutch slipping in the transmission, so it's more dangerous to have it loose, but you can generate more heat with higher line pressure.  The heat wasn't a concern for me since I have an integral trans cooler in my radiator and I was only going around the block.


We took it for a drive, and it was exactly like I expected, shifting too high.  When I got back from the drive, I checked the coolant level and it had sucked down everything I put in, so I need to refill before the next drive.  I guess the thermostat hadn't opened and the heater core probably sucked a lot of water into it as well.

I got made fun of for my all natural environmentally friendly seals.  The top needs to be hit with bleach and a pressure washer when I get a chance.


Gearheadotaku GRM+ Memberand UltimaDork
1/14/20 11:25 a.m.

Great job! I really need to learn more about LS swaps. The whole ECU programming worries me more than anything. 

young_boomer New Reader
1/14/20 12:35 p.m.

In reply to Gearheadotaku :

That was honestly one of the easiest parts of it all.  Just unchecked VATS and all the codes I didn't want it to throw.  Of course that's with HP Tuners, I'm sure it's tougher to do without it.  I've heard of LS Droid being a good option for deleting VATS too, and it's free, but you do need to know a bit more in depth about the ECU's, and you might need a bench harness? I'm not sure since I didn't have to do it that way, but I'm sure it can't be too bad.

young_boomer New Reader
1/29/20 1:59 p.m.

A week and a half ago I drove it down to campus.  Fixed the majority of the transmission issues with shiftpoints, but it still has a little long-spring-syndrome.  Like I said before, it's better for the transmission to shift high and hard rather than low and soft, especially since I can't control the engine output during shifts with the ECU like I could if I had an electronically controlled transmission.


My OBD2 reader came in so I can read all of my computer data.  My oil pressure gauge is not hooked up in any way, so I found a way to add it in the Torque app with a custom PID, if you want to log oil pressure digitally, here's the code for Torque (case sensitive):

PID: 22115c

Short name: Oil Pressure

Minimum value: 0.0

Maximum value: 100

Unit type: psi

Equation: (A*0.65)-17.5

OBD Header: Auto

Anything else is default.


When I drove to campus, I had my exhaust hung from zipties:


We finished the exhaust and I was honestly disappointed with how quiet it got.  I don't have a video, but my neighbors probably don't hate me anymore.  It's going to take me time to adjust.


Getting the exhaust off to weld it was almost impossible.  I hit it with PB blaster for 2 days and then a MAP gas torch to loosen them up.  I almost rounded a bolt with a crescent wrench becuase my deep wells were too deep and my standard sockets couldn't fit over the stud.


Next order of business is to fix my shifter since it hits my new exhaust.  This is probably going to be me flap-disking down the big cast bulge here.


I don't have a picture of my hangars, but they're really dumb.  I wound up going with a turn down after the muffler instead of side dump, at least for now.

rico750sxi_2 Reader
1/29/20 7:01 p.m.

Nice job and cool project. 

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