1991 Diesel (conversion) Suburban

[jjosu]

Relatively slow going the last few days. The overriding lesson learned is this: if anyone ever tells you a GM gasser to diesel conversion is "plug-n-play," they are wrong. Well, if it's a pre-88 model Burb or truck, it might be close. The '91 has a bunch of damn wires, computers, fuel lines don't match up nicely, torque converters are different, etc.

That being said, the fuel tank is close to being reinstalled and the lift pump is in. Wiring harnesses semi-sorted out. Engine install *should* begin some time this week, depending on the shop's schedule. I'm nothing more than an extra hand once the actual swap starts.

 

[warwgn]

keep at it man, just takes time, dont get to discouraged.

 

[jjosu]

Slow go, waiting for the shop to slow down to put the engine in. The good news? It's in! (sorta)



Bad news? Motor mounts are being a little difficult. And the AC box flat-*** will not work. Right now, it's removed from the truck. Did some research, and it looks like the answer is to find a s-10 80's model AC box and frankenstein it to the blower housing. The S10 is smaller generally and points toward the passenger front fender. The stock one is big and points directly at the turbo.

 

[chilliwak]

I am happy to see the motor on the way into your rig. If the AC is the only thing slowing you down, then install it later on. The main thing is to get the motor in and the necessary parts mounted so that the truck becomes drivable. Please keep us updated with the progress. Its always nice to see pics of a cool:Wow1roject like yours come together.

 

[jjosu]

Major milestone today - the 6.5 fired and ran. Surprising considering the glow plugs weren't even connected (no harness). Ran pretty strong for the few seconds we let 'er go. Power steering and ATF squirting everywhere kind of ruined the fun.

Testing it without everything hooked up was necessary since I'd never actually seen the engine run. Knew it would turn over, but had not seen it run. Tranny cooler is hooked up now, hydraboost will arrive tomorrow.

 

[jjosu]

Also, the exhaust is going to be, err, interesting. Turbo dumps directly into the frame and shock mount. There is maybe 5" of clearance. Buddy at Outlaw Diesel has a spare Holset HX35 on hand, and that may help since it can pivot for the downpipe angle. Either way, exhaust is going to have to be outside the frame rail.

 

[redthies]

I was planning a 12 valve swap into my F350, but I keep reading about "easy" swaps going sideways... Looks like you are getting close though. It will be worth it in the end!

 

[ExpoMike]

redthies - There is no such thing as an "easy" swap, even within the same manufacturer. Start changing that (i.e. Cummins into Ford) and it can be a very furstrating, money and time consuming conversion.

IIRC, this frame body/frame style only offered the 6.2 non turbo and it wasn't until the '88 newer body style (truck, '92 burb) that the offered the 6'5 TD. I know the HVAC system was completely different to allow it to fit. Good luck on getting it all sorted out and contrags on getting it at least running.

 

[jjosu]

Build is close to being completely ground to a halt over a $20 part...that is unavailable anywhere any more.

Seriously, the pushrod/spring assembly that goes between the master cylinder and hydroboost is kicking my ***. Bought the new hydroboost and assumed all was good. Note in the new assy says "save and re-use the rod/spring assembly and re-use." Well, I don't have one, and neither do GM dealers. So far, local salvage yards have been worthless.

 

[jjosu]

It lives! Drove her home tonight for the first time in 2 months. Not exactly road-worthy. EZ-TCU is not set up right, and the accelerator cable is too long. Tranny only shifted out of first once on the six mile drive home. I figured it would be an adventure, so my wife followed in the Volvo with hazards on. Got over 35 once I think. Turbo howled the whole way.

I found the pushrod on craigslist. Turns out it was on the same truck the engine came from.

An accelerator cable specific to a '91 6.2 is due to arrive at some point next week. My shade tree project for the weekend is continuing to sort out wiring so I can get some gauges working. Right now, all I have is volts.

Interesting possible solution to the turbo dumping directly onto the frame...considering a stack venting directly through the hood. Not technically legal, which is an issue. I threw out the idea of venting through the quarter-panel, re-purposing a snorkel for the job. Not sure what we'll do on exhaust just yet. Right now, there is no downpipe and it's just blowing out of the turbo. Of course, the hood is not currently on.

Stack through the hood would require: unbolt turbo exhaust plate, invert it. Attach short pipe, cut hole in hood. Thoughts?

 

[jjosu]

Almost forgot pics.

Already leaking oil on the driveway.


That rats nest in the lower right is the bane of my existence at this point in time.

 

[bftank]

good to see this so close to being done!

regarding the hood stack. what the worse that could happen? cops tell you to fix it? doubt it would affect visibility much noise would probalby just go over the windshield. i say try it out with out the hood on for a while and see what you think.

 

[FellowTraveler]

Exhaust issue

Using 6.2 exhaust manifolds w/properly sized dual turbos and dual exhaust, or banks setup w/y pipe and one turbo would solve the exhaust routing problem, however, as you know it will be a pain in the ___s and labor intensive. Some might argue the dual exhaust manifolds are restrictive the Banks setup dis-spells that notion.

4L80e control have a TPS on injection pump or? How about rpm signal?

When 4L80e rebuild comes due a Trans Go full manual shift kit will eliminate need for trans controller.

 

[jjosu]

Yes, the EZ-TCU has a TPS sensor. Also has in and out for RPM's, though I don't currently have either connected as I haven't gotten to replacing gauges in the build yet.

Installing a moderate body lift is another possibility for the exhaust issue. Not a big fan of body lifts, but it would give 1-3" extra room to route the down pipe. After all the suspension work, the truck does sit maybe 1" lower at the front, so a 1" body lift up front might be in the works soon anyway. The 35's have already chewed the stainless fender wheel well bling off of the passenger side too.

 

[bftank]

offroad design sells a 1" aluminum puck body lift.