gas engine out, diesel going in...any suggestions?

Reply

  #1  
Old 07-16-03, 09:39 PM
cheese's Avatar
Forum Topic Moderator
Thread Starter
Join Date: Jul 2001
Location: USA
Posts: 16,575
gas engine out, diesel going in...any suggestions?

Hello!

I have just taken the plunge into a new project, lol. I am wondering/hoping that someone here has done a similar project and can give me some feedback about the procedure and results.

I am about to do a gas-to-diesel conversion. I have a '84 GMC sierra classic (suburban) 3/4 ton with the original 350ci engine and 700r4 tranny removed. I am buying a '86 custom deluxe 3/4 ton with a 6.2 diesel and 700r4 tranny. I plan on pulling the diesel and tranny out and installing it in the suburban. The truck with the diesel is complete with all controls, a vacuum pump, hydraulic brake booster, and the works. I will be installing all of this in the 'burban. I wonder if the wiring harness on the gas powered vehicles also includes the pigtails needed for the diesel components, or if I will have to swap harnesses, or fabricate parts of the harness. I'm also wondering what other little details there may be that would make this project a nightmare. Seems like it would be a fairly easy thing to do, just time consuming.

I think the diesel engine that I want to install has a problem with the injector pump too. What it is doing is cranking up fine, running great, until it gets warmed up. Then it stumbles and smokes pretty bad, like the fuel is turned way up. Any idea how to fix it, or do I need to have the injector pump rebuilt or replaced? Or is there anything else that could cause these symptoms?

Thanks in advance for any info!
 
Sponsored Links
  #2  
Old 07-16-03, 10:05 PM
Visiting Guest
Posts: n/a
i don't know many specifics on GM, but common sense says to make sure the front suspension, all around brakes, and rear axle are up to the added weight/power, bigger front springs come to mind too. as an example, i do know the '5.9' cummins six cylinder is much, much heavier than the '5.9' gas V8 in dodge trucks, requiring at least those parts i mentioned.

you're doing it the way i'd do it, with the 'complete' donor car making it as easy as it can be.

you didn't say what color the smoke is. usually on a diesel whitish/blue=lean, black=rich
 
  #3  
Old 07-16-03, 11:48 PM
cheese's Avatar
Forum Topic Moderator
Thread Starter
Join Date: Jul 2001
Location: USA
Posts: 16,575
Don't know for sure...didn't see the smoke myself, but the guy I'm buying the truck from said he thinks it was a bluish color. At first I was thinking oil burning, but the oil was full (although dark) and he said it didn't use oil, and I think if it was oil, it would do all the time, if not more when it was cold, rather than no smoke when cold and lots when hot. What do you think?
 
  #4  
Old 07-17-03, 12:53 AM
fatcatdj
Visiting Guest
Posts: n/a
CHEESE--you're not going to like my reply. I work at a television network which has 2 G30 satellite trucks. One is a gas and the other is a diesel. We here at the network(cant tell you which one) says the Diesel transplant will go as well as a heart donor with different blood type. Stay away from GM diesels! The only diesel worth its salt is the Volvo truck--we have many of those satellite trucks as well. ---no problems w/ Volvo, mucho problems w/ GM. Good luck
 
  #5  
Old 07-17-03, 04:00 AM
Joe_F
Visiting Guest
Posts: n/a
Arrow

I agree. This is a headache waiting to happen.


1) Brakes differ. Different RPO codes and parts between the two. Also, the boosters and other parts for the diesel application, when they go bad (not if) will be more money.

2) Wiring differs. Diesels don't have many of the solenoids, electrical items and such that a gas 350 has.

3) The 1986 6.2 liter vin code C or J diesel is a Detroit diesel. Back then they were crude. Today's Duramax is far superior and less of a "diesel" than the old ones in the sense of refinement. Bottom line: this thing will sound like a big, old clanking stinky NYC garbage truck.

4) Suspension is different. Any GM parts books show different spring rates, RPO codes and the like between gas and diesel.

In essence, you'll have to swap everything to effect a proper swap.

My opinion: Either fix the 86 as it stands now keeping it original, or put the right gas 350 in the one that's "Missing it".
 
  #6  
Old 07-17-03, 10:57 PM
cheese's Avatar
Forum Topic Moderator
Thread Starter
Join Date: Jul 2001
Location: USA
Posts: 16,575
LOL...I knew I was going to get these responses about the differences in components, and I gave it a lot of thought before deciding to do the swap. I figured since the suburban is a 3/4 ton with towing option, it would have sufficient brakes for the added weight. I agree that the springs may need to be changed (can do that, ball joints, Aframe bushings and shocks all at one lick). The donor truck has the hydraulic booster and all controls and is basically driveable. It is not a show winner by any means though, and my wife loves the 'burb. (It has the bells and whistles and looks nice). If I stick a 350 back in it, I'll be putting my life's savings into the fuel tank, lol. The diesel gets good fuel mileage, and I kinda like diesels anyway.

So...basically this is the predicament I'm in: Wife wants the suburban. I will not fix it with a gas burner because of poor economy. BUT...wife wants the burb. hmmm... then a freind of mine offers me his old truck for $400.00 with the diesel. He gets really good mileage with it. Tranny was rebuilt about 6 mo before he parked it. And...wife wants the burb. So I have a short circuit in my head for a moment, and buy the diesel. Now I'm committed, lol. Did I mention wife wants the burb? (I like it too, as long as I can pass up a gas station once in a while). I guess if I have to change everything, I will.

It is a cheap project, so I can afford to spend time on it. I think the only wiring I will have to deal with will be the glow-plug control and light circuit.

I have a friend who is Hyster's top diesel mechanic in the region, and he is willing to help me with it (I'm not well versed on diesels).

Thanks for the input, any other info is appreciated as well!
 
  #7  
Old 07-18-03, 04:11 AM
knuckles
Visiting Guest
Posts: n/a
Cheese:

The much maligned 6.2L isn't that bad of an engine...if you know what to do to make it last.

1. While you have it out, open it up & replace the head gaskets. While the heads are off, install ARP head studs & nuts in place of the original head bolts.

2. Remove the oil pan & remove the main caps one at a time. Inspect the bearings for wear & replace the main bolts with ARP main STUDS & nuts.

3. The Stanadyne injection pump used on these things was, as Joe_F likes to say, lackluster at best. It has been updated about a zillion times. Remove yours & have it professionally rebuilt. This can cost anywhere from $180-$400. It's well worth it.

Haynes sells a Diesel Engines Manual that covers most domestic diesels including yours. It costs about $20 and covers common maintenance / repair items. Well worth it.

The swap should be pretty straightforward since you have both trucks at your disposal. You may need to swap the entire underdash & underhood wiring harness from the donor truck into your Suburban, but even that isn't much of a challenge. It's just time consuming.

Remember (especially since your wife will be driving this thing) that diesel trucks were equipped from the factory with lots of extra sound deadening panels. Try to swap these in from the donor truck. If they're too beat up or disintegrated, get new ones from GM or use Dynamat (check your local stereo shop) instead.

I like the 6.2 like Joe_F likes his beloved 301 Pontiac. Properly maintained & upgraded, they can provide years of fuel efficient service.
 

Last edited by knuckles; 07-18-03 at 09:22 AM.
  #8  
Old 07-18-03, 05:41 AM
Joe_F
Visiting Guest
Posts: n/a
Cheese:

The guy who used to live in the house of the guy who gave me the 1979 Craftsman snowblower we're chatting on in your forum was a diesel truck GM man.

He was ALWAYS under the hood of that thing when I would pass by on my nightly walks. LOL.

I would agree with Knuckles---you're going to have to be EXTRA anal with the maintenance on this one!

Good luck!

My vote would be to install a fuel injected 350 out of a newer Suburban. If you got crafty, a Vortec .
 
  #9  
Old 07-18-03, 10:42 AM
Member
Join Date: May 2001
Posts: 516
Funny, I have a friend who has a 85/6 Surburban and he had a 6.2 diesel in it. He absoloutely hated it, At 80,000 miles he junked the engine and did a 454 conversion. He's much happier now. Spends more in gas but he is not under the hood every other day. Says he's way ahead. For whatever it's worth.
 
  #10  
Old 07-19-03, 01:06 AM
cheese's Avatar
Forum Topic Moderator
Thread Starter
Join Date: Jul 2001
Location: USA
Posts: 16,575
Knuckles:

Thanks for the info! I will do those things mentioned. Where are these studs available? What happens to make the studs necessary? Do the bolts stretch, or are they weak and prone to break?

I planned on having the pump rebuilt, and probably the injectors tested. Seems like the pump should be fairly simple, and I have rebuild procedure for it...is there any reason I should not attempt to rebuild it myself? Apparently the pump cannot be installed out-of-time, since it has a line-up pin and can only go in one way. Is this correct?

The sound deadening panels is something I hadn't thought of. Thanks for bringing it up. I have very little invested in this, but I plan to do a first class job. I like the older trucks vs the newer ones because they are real trucks. If I have to spend a bit to make this one like new again, it will still probably be less than buying a used late model, and look better too IMO. I plan to replace most wear items for the suspension and drivetrain, and then move towards the body and replace window seals, headliner, maybe carpet, and all that stuff.
 
  #11  
Old 07-19-03, 08:39 AM
knuckles
Visiting Guest
Posts: n/a
cheese:

The 6.2L was known for blowing head gaskets & cracking main webs. Main studs & head studs stress the block less & provide better clamping force per lb/ft. of torque applied.

You are less likely to have head gasket and/or main bearing/engine block problems if you use studs instead of bolts.

You can buy ARP products from any decent speed shop. Their website is www.arp-bolts.com .

I checked their catalog & found the head stud/nut/washer set. Their catalog doesn't list a main stud kit for the 6.2L engine. I thought for sure they did, but perhaps they've been discontinued. Either that, or I mistakenly confused the 5.7L diesel main stud kit w/ the 6.2L kit. You may want to call or e-mail them & check to be sure.

ARP's catalog is available online in .pdf format. It explains the benefits of studs vs. bolts & also gives detailed installation instructions.

ARP head studs w/ nuts & washers PN 130-462

As for the pump:

Rebuilding the pump requires special tools & a VERY clean work area. I tried rebuilding a few 5.7L pumps years ago & never had any success. IMHO, this is a job best left to a diesel shop that has the tools to do the job right, has quick access to all parts, specs, upgrades, etc. and has a test bench to confirm their work once it is done.

Having the injectors professionally cleaned & tested at this time is a great idea.

It's been a couple of years since I replaced a 6.2L pump, but as I recall the job was actually easier than it seemed in the book.

Four Wheeler magazine did a 6.2L Blazer buildup a few years ago. Several issues dealt with pump/injector rebuilds, upgrades, modifications & timing adjustments. They were able to increase both fuel economy & HP as I recall. You may want to visit their website & see if back-issues are available.

I like these old trucks too. They're simple, durable & WAY cheaper than the late model IFS trucks. Parts are cheap & readily available from GM and aftermarket sources.

We recently installed new door seals, window seals, hinge pins & bushings, door strikers, carpet & headliner in my friend's '88 Blazer. It now looks nearly new inside and it's MUCH quieter when driving down the highway.

Good luck w/ your project & keep us posted.
 
  #12  
Old 07-19-03, 08:57 AM
knuckles
Visiting Guest
Posts: n/a
I checked the Four Wheeler website. The final part of the Blazer diesel series is available for free online. This article deals with the installation of a Gale Banks turbo kit. Nice, but very expensive. The turbo kit increased rear wheel HP from 134 to 172. Nearly 40 HP, but EXPENSIVE.

BTW, they dyno'ed the truck before they did any pump or injector work. Their baseline was a whopping 94 HP at the rear wheels. They got that up to 134 HP with a rebuilt pump, cleaned injectors, advanced pump timing and free flowing exhaust.
 
  #13  
Old 07-19-03, 11:37 PM
cheese's Avatar
Forum Topic Moderator
Thread Starter
Join Date: Jul 2001
Location: USA
Posts: 16,575
Great! I'll look up that article. 40hp increase just by working on the pump, injectors, and exhaust sounds like it's definitely worth doing.

I'll be in with more questions from time to time, I'm sure, but it will be a leisure project. I'm not in a real big hurry, so it may run over the course of 6 months, depending on my schedule. Thanks a lot for the info, and any other advice is appreciated!
 
  #14  
Old 07-20-03, 08:13 AM
Joe_F
Visiting Guest
Posts: n/a
ZZ3/ZZ Series GM crate motor with all the goodies. Emission compliant, fast, reliable, AND has a warranty .

You'll find that GM drops very little for these vehicles. Need a door for a 1979 GM pickup? Yup still available. Door seals? Have 'em in three days. Whatever GM drops, reproduction companies pick up in a heartbeat.

It's like this with the Corvette, trucks, and to a lesser extent the Camaro and Firebird line for me. However, the reproduction companies in many cases may be selling the part to GM Restoration .
 
  #15  
Old 07-22-03, 10:44 AM
knuckles
Visiting Guest
Posts: n/a
Joe:

1. A 'ZZ' series crate engine is not emission compliant. Nor is the Fast Burn 385. No luck with the 350 H.O. either.

2. The price of these crate engines would probably exceed the entire cost of the diesel swap, including the cost of the Suburban!

3. The ZZ series engines are great...if you're installing them in a Camaro/Nova/Chevelle, etc. They're less than ideal for 3 ton pigs like a Suburban. Peak torque doesn't occur until 4000 RPM--not very useful in a big, heavy vehicle, especially if fuel economy is the goal.
 
  #16  
Old 07-22-03, 11:29 AM
Joe_F
Visiting Guest
Posts: n/a
I believe they DO have performance models for the trucks---I forget the part #s. Might not be ZZ series. But it's a GM/Goodwrench engine.

A ZZ series engine would exceed the value of MOST projects they are going in! .

I do believe there are emission compliant versions .

If cost/time/money were a factor, you could buy a clean Surburban with the diesel installed from the factory ready to go!

In the end, engine swaps like these always inevitably cost more than buying one already factory equipped (even if that one is a project) as there are the little odds and ends that nickel and dime you in the end.

It's like buying a V6 F-body to swap it for a V8. Even though they are both F cars and both "Chevy" engines perhaps, buying one with an 8 in it already puts you MILES ahead in cost in the end.
 
  #17  
Old 07-22-03, 11:52 AM
cheese's Avatar
Forum Topic Moderator
Thread Starter
Join Date: Jul 2001
Location: USA
Posts: 16,575
Joe, How is it going to cost me more than I can buy one for pre equipped with a diesel? I have a grand total of $400.00 invested in both the suburban AND the donor truck, which is complete, so I shouldn't have to buy anything to make the conversion. I got a great deal on the suburban...didn't pay a dime for it, and it is nice. Time spent on the project is not an issue. It is more like a hobby/project that I enjoy, so there's no loss there. A performance crate engine is as far as you can get from what I want, as you can tell from my initial posts. I dont want gas, and I do want economy (as much as can be had from a large vehicle like this). A suburban of comparable condition pre-equipped with a 6.2 diesel would cost me $3500 at the least.
 
  #18  
Old 07-22-03, 12:19 PM
knuckles
Visiting Guest
Posts: n/a
Well...the HT502 is emissions compliant for FI trucks originally equipped w/a 454. Lots of low end torque too. But talk about a budget buster!

The HT383 ( 12497317)is designed for truck applications, but it's not emissions compliant.

Same with the 350HO (12496968).

The Fast Burn 385 is available with an EGR equipped intake manifold, but it's technically not emissions compliant and is not advertised as such.

Generall speaking, I agree that conversions usually end up costing more in the long run. I've said so in this forum many times. The V-6 to V-8 F-Body is a great example. It's just not worth it because V-8 F-Bodies are a dime a dozen. Diesel Suburbans, even old ones like Cheese is working on, still bring a decent buck around here, especially if the body is in 1/2 decent condition.

To me, this swap makes sense. Cheese already owns both trucks, so all the little parts are at his disposal. Time spent on the project seems to be much less of an issue than money.

With a few hundred dollars in pump work, studs & gaskets, the 6.2 can be reliable & perform well enough to meet his expectations (reasonable torque/power & good fuel economy).
 
  #19  
Old 07-22-03, 01:25 PM
Joe_F
Visiting Guest
Posts: n/a
Cheese:

Count on needing more than a couple of hundred bucks in parts . Assuming the other parts are good, you'll still need a lot that will nickel and dime you .

A good pump rebuild is going to cost you. The ARP studs you need will cost you. Everything for a diesel application tends to be more money when parts break (and they will). In the long haul, a diesel will cost you more, but again, if it's your choice and you like it, go ahead. .

Diesels have unique parts for the braking system and cooling system and go by RPO code in the GM book. Some of the parts are outsourced on the engine side and carry the markup accordingly.

Around here all of those trucks are a dime a dozen. You can fetch them anywhere around here in the Northeast. Generally speaking the Vortec equipped and 1988 and up style C/K trucks fetch more.

My friend paid under 3000 for a 4.3 equipped 1990 GMC pickup which has been flawless for a couple of years (he's had it at least 3 years now). Not to mention the thing is CLEAN! I'm sure if I were at the bargaining table, I would have gotten it cheaper.

Talk about thrifty on fuel .

Maybe it our area here in NYC. I can trip over those trucks .
 
  #20  
Old 07-23-03, 11:45 PM
cheese's Avatar
Forum Topic Moderator
Thread Starter
Join Date: Jul 2001
Location: USA
Posts: 16,575
I can trip over them here too, but nobody will sell you one. They are high demand vehicles around here. Even the plain jane pickups of this vintage bring $2500 or more if they are half decent. I picked up the diesel truck kind of accidentally. The guy didn't want to sell it, but needed $$ by that friday, so he told me if I could give him $400.00 by that friday, I could take the truck, otherwise, it was not for sale....and I did. (It is not pretty, and has no options to speak of, and is not roadworthy because it has been sitting up for a long time, but will run). I also expect to have some expenses doing this. That was always a given. The diesel will last longer and be more efficient, that is why I want it.

I just got through putting a tranny together for my 85 truck, and swapping it in, because my old one went out since my last post here. That pretty much completes the drivetrain rebuild of that truck, lol. I built the engine about 2 years ago, the rearend about 1 year ago, and now the tranny. It only had about 250,000 miles on it, lol. It didn't owe me a thing. Great truck.
 
  #21  
Old 07-24-03, 05:45 AM
redneck
Visiting Guest
Posts: n/a
The 6.2 is a good motor, my buddy has one in a van, 200k pulling trailers and boats. It is still in good shape and runs fine, he just doesn't need/drive it anymore, but will not sell it--says he has owned it nearly half of his life! LOL! Never had the engine apart, but he did rebuild the tranny twice--those diesels are hard on trannys--second rebuild was at 160k and he installed tranny cooler then--very good investment on any automatic tranny.
 
Reply


Thread Tools
Search this Thread
Display Modes
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 05:31 PM.