Thinking about an 85 GMC 6.2 Diesel Surbaban... - PeachParts Mercedes-Benz Forum

Graplr · #1 08-04-2009, 05:26 PM

I know it is not a Mercedes...but it is a diesel.

It has 49-some thousand original miles on it. The original transmission went bad and the original owners just let it sit for a long time. A mechanic bought it from them and put a new tranny in it along with some other parts. A high school/college kid bought it from the mechanic a few months ago, but he decided he didn't want to take it with him to college 5 states away so he is trying to sell it.

AC is inoperable (which is okay as I have a r12 charging and vac station with ALOT of recycled r12) but other than that everything supposedly works. A few spots of surface rust.

My dad had one of these when I was a kid but a 2wd version. This is a 4x4. He doesn't know much about cars but he tried to tell me they weren't good pullers. I'm not buying it to pull with it as much to have a 4x4 vehicle/family hauler.

I have been looking at late 90s diesel trucks as well (Powerstrokes and Cummins mainly).

Anyone know anything more about these vehicles?

Thanks!
Ryan

Doktor Bert · #2 08-04-2009, 05:46 PM

I have a 1985 Suburban that my parents bought from a family friend. It is a 350 gas engine and has a tag in the window that reads "GM-FACTORY SPECIAL VEHICLE." I rebuilt the 350 and used gapless rings, a UD camshaft with .450"/.462" - 207°/211° - 110° LSA specifications, ported polished 305 HO heads with a 6 angle valve job. It is a premium fuel only motor with 9.50:1 compression, but with the 700-4R transmission and 3.42:1 axle, it gets 18-19 mpg on trips using cruise control.

Bottom line is, my folks also have a 1985 Sub with a 6.2 Litre engine. It runs and pulls very well. Keep in mind the 6.2's and 6.5's do have their share of problems as with any vehicle of that vintage....Robert

Ian White · #3 08-04-2009, 05:52 PM

Yes the 6.2 and 6.5 L GM were known for breaking the cranks through the rod journals of # 5 and 6.CYLS I had a 6.5L (turbocharged) in a pickup decent mileage, but underpowered. They had extemely high cylinder pressures ( 21.5 to 1) so that is something that isnt too good for performance options. Heath Diesel in Ellensburg, Washington is a great place to look for 6.2 and 6.5 performance, but it is limited in what you can do, with the high compression and also the fact that it is electonically injected, and that it is Indirect inj like our benzes. Hope this helps!

Graplr · #4 08-04-2009, 06:40 PM

I knew the engines weren't comparable to our Benz's, I guess my main concern is everything else like 4x4, trans, etc. Honestly, power doesn't mean much to me. As long as it will cruise on the freeway at 70mph and get me up to speed faster than a 240D, I'll be okay.

He is asking $2500, which is exactly what I sold my back up car for with the intention of using it for buying a 4x4 diesel vehicle.

Think $2000 is about the right amount for this??

I haven't seen it in person yet so obvisouly I am assuming everything stated and shown in pics is correct. He lives about 1.5 hours away and I'll have to find someone to go with me so they can drive the benz back, so I don't know when I'll get around to it...maybe tommorrow if the SO gets of off work early enough.

Thanks for the input.
Ryan

a2t · #5 08-04-2009, 06:57 PM

sounds really good and these are very hard to find. Ive been looking for a diesel burban for about 9 months now, nothing has come up. Im looking more for the 6.5 but the 6.2 is very good too from what ive read. Parts are cheap, and about the only engine complaint Ive heard is you gotta slap new heads on around 150k, but even that is autozone cheap and easy. i'd say look it over, and for $2k its a no brainer if its decent

bigblockchev · #6 08-04-2009, 07:56 PM

I have a 95 burb with a 6.5 turbo in it. The PO replaced the engine to the tune of $10K but the later engines (599) blocks are more reliable. That said I have seen many mid 90s Gm diesel burbs and trucks with new engines around 250K , after which I think they are fine for quite a while. The 6.2s are more reliable but they are quite under powered. I had an 85 chev 3/4T 4x4 which was slow but really cheap to run, I regularly got in the 25 Mpg (imperial gallon) range. with that. Pretty close to 1100Km range in town more on the highway. My 85 was a standard but the autos 700R4s were prone to failure but not as expensive to fix as the more modern 4L80E . Some had Turbo 400s behind them which were terrible for mileage but never broke. Long and short with 49K on it if it isn't too rusty it is worth considering.

t walgamuth · #7 08-04-2009, 08:14 PM

I had several subs with 6.2 power. all were 2wd and all had 373 rear ends (at least after I changed them or before) all had positraction. all had the turbo 400 tranny. one of them was used by a travel trailer mfgr to deliver tt with and had 150K when I bought it. I had a 24' wilderness that I towed with it. it would run 65 flat out towing with the air on and did about 12 mpg iirc.

They tended to crack the block if they had 410 rear ends as they revved too high on the highway.

decent vehicles if in good condition.

rust prone.

don't open the vent windows as they will break the latches off.

replace the door hinge bushings with brass.

Graplr · #8 08-04-2009, 08:29 PM

Thanks for the input guys. If I can find someone to go with me I'm going in the next day or two. If all is as stated I'll probably by it.

I know they are rust prone. I grew up with gas suburbans mostly so I have always liked them. I have kept my eye on them and have seen plenty of rust buckets.

a2t, you should check up here. Diesel Suburbans are actually somewhat common. There always seems to be one or two for sale.

Doktor Bert · #9 08-04-2009, 08:32 PM

They are surprisingly fast when fitted with a proper engine...Robert

biopete · #10 08-16-2009, 12:06 PM

I have an 84 6.2 Suburban. Great trucks. Mine is not 4x4 and is just the half ton but came with tow package. It runs great. Injectors need replaced now at 277,000. Are you sure yours does not have 145,000 or 245,000 rather than 45,000? You can tell by the rest of the body being pretty well used

I paid 2000 for mine.

Still, i just did a 1700 mile road trip in mine in 5 days . Ran like a top 50% veg, 50% biodiesel. It got 20 mpg average and i cruised at mostly 65 and 70 and got as high as 90 on a couple occasions. Plenty of room for cargo and still sleepin in the back at rest areas

BobT · #11 08-16-2009, 06:20 PM

6.2 is known to be a solid, albeit low power engine. I had a 6.5 turbo Burb that was fine once I took all the measures to make it better but with no intercooler it was limited. Now i have a ram 3500 with the formidable Cummins but its apples to oranges comparing it to the sweet mercedes diesels - that only propel car chassis and not 12000 lb trailers behind 7500 lb pickups.

I would get the 6.2 and use it as a family hauler/towing truck

Cervan · #12 08-17-2009, 01:30 AM

the 6.2 and 6.5 diesel engine that came in those trucks are detroit diesel v8 engines. They were notorious for good and bad things. For one they parts are pretty cheap to come by, and the engine does get pretty dang good fuel milage for a huge truck. One of the drawbacks were the durability of the parts and the design was just ok. its a pre-combustion chamber design so it still burns relitively clean but the blocks were prone to cracking, the cranks were weak, they had overheating problems on a few cylinders. just multiple block/crank issues. a company however did start making there own blocks (kind of like DARTON blocks for hondas and toyotas) They started making revised and strengthened blocks that really withstood the test of time but you do pay the price...

marybeth · #13 08-17-2009, 10:09 AM

Helped a local High School convert a 1985 GMC 6.2L to run on Veggie (two tank system)

Even after two decades+ of constant use and abuse by everyone from students/teachers/maintenance workers-the GMC and its 6.2 held up really well and took to veggie well also.

The fuel filter was a funky basket-type arrangement, which we replaced quickly as well as installing an electric fuel pump.

$1.5-$2K seems reasonable for one

mobetta · #14 08-17-2009, 02:41 PM

Hey graplr- did you get this one? dont you have enough projects going right now, w/ a wedding and a new home?

I did a veggy conversion on an 84 RV with a 6.2 in it, so if your going that route, I may be able to help a bit there. I reckon the first thing one should buy is a back up IP for these engines- which are mechanical on this app.

I am actually thinking about a burb, too- but I think I want to put my cummins 4B in there. I like the fact that you can get up to 9 peeps in there, depending on the seats. w/ another one coming in august, we need to upsize a bit from our wagons w/ third row. I've seen a few nice deals this summer on newer trucks w/ bad engines or transmissions. like a 98 for $800. but we arent quiet ready for another project to begin.

t walgamuth · #15 08-17-2009, 08:14 PM

Quote:

Originally Posted by mobetta

Hey graplr- did you get this one? dont you have enough projects going right now, w/ a wedding and a new home?

I did a veggy conversion on an 84 RV with a 6.2 in it, so if your going that route, I may be able to help a bit there. I reckon the first thing one should buy is a back up IP for these engines- which are mechanical on this app.

I am actually thinking about a burb, too- but I think I want to put my cummins 4B in there. I like the fact that you can get up to 9 peeps in there, depending on the seats. w/ another one coming in august, we need to upsize a bit from our wagons w/ third row. I've seen a few nice deals this summer on newer trucks w/ bad engines or transmissions. like a 98 for $800. but we arent quiet ready for another project to begin.

A 5.9 will fit.