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Thread: Just picked up a 85' 6.2 C code Suburban

  1. #1
    Join Date
    Sep 2014
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    Default Just picked up a 85' 6.2 C code Suburban

    Hello everybody!

    First diesel here so sorry ahead of time for any dumb questions.

    Couldn't Pass up the deal on this so I Bought it.

    Already been through a couple of the basics:

    New Batteries, Oil change, and Belts, replaced a couple fuses.


    Starts up and runs great When its cold. Once it warms up and I stop, it turns over for days, no start.

    Got it to start once by holding the gas open, doesn't work every time.

    Smokes a ton when you do that also.

    Thinking 33's or 35's for the new tires, looks like a lot of people run 3.08 gears, with the stock tranny.

    Im thinking a nv4500 sounds nice, but Im planning several trips and camping excursions so any reccomendations would be welcomed!


    Thanks,

    Garrett
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  2. #2
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    Panama City, FL
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    Default Huh . . .

    Not sure about the starting issue, I'm sure someone with a lot more knowledge than I will chime in soon.

    What tranny do you have now? If it's the 700R4 I wouldn't mess with it assuming it is perfectly functional. As for tires and gears, if you go with 35's you will probably need deeper gears, at least 3.42 (like mine) or possible 3.73, again others here will add their $0.02. Good luck and enjoy.
    1982 K5 Blazer 4wd w/ 6.2 turbodiesel (Banks Sidewinder) w/ rear disk brakes, more to come . . .

  3. #3
    AKMark is offline Building another 6.2L powered vehicle
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    I've had Suburbans with 3.42's and 31's as well as 3.73's with 31's. 3.73's were perfect for 31's. The 3.42's got better fuel mileage, but couldn't tow anything.

    For 33-35's, 4.10 or 4.56's. 6.2's don't use much more fuel revving it higher going down the road and work so much better when they are closer to 2000 rpms.

    I have 4.10's and 36's on my K-5, but it doesn't have an overdrive, so it equals out and moves along nicely.

    Check the glow plugs. Does the glow plug light come on at all when warm? I have put a manual relay on mine. I control them. When it's warm it needs less, but sometimes these beasts need a little glow even when warm.
    05 2500HD CC LB LLY, 4x4, 3.73s 235/85R16's, webasto cab heater, to keep it warm.
    03 Buick Rendezvous - When you average over 80 miles per day driving around, you need one of these.
    85 K-5, 6.2, SM465, Rockwell T221, 1 tons, 36's. More goodies to be installed as time and money allows.
    82 K20, 6.2, SM465, NP208, stock except for bed rack, snow plow, and glow plugs are on a toggle switch. It works great for plowing!
    72 Postal Jeep - Yet another project

  4. #4
    AKMark is offline Building another 6.2L powered vehicle
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    Especially if someone has used either on them without disabling the glow plugs.
    05 2500HD CC LB LLY, 4x4, 3.73s 235/85R16's, webasto cab heater, to keep it warm.
    03 Buick Rendezvous - When you average over 80 miles per day driving around, you need one of these.
    85 K-5, 6.2, SM465, Rockwell T221, 1 tons, 36's. More goodies to be installed as time and money allows.
    82 K20, 6.2, SM465, NP208, stock except for bed rack, snow plow, and glow plugs are on a toggle switch. It works great for plowing!
    72 Postal Jeep - Yet another project

  5. #5
    Join Date
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    Portland, OR
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    Thanks for the help so far everybody!

    I think the fuel source is the culprit but im going to go ahead and replace the glow plugs with some new 60g plugs.

    35's with 4.10 gears? Im not going to be towing much but i want to be able to get through the mountains and hills without slowing down all of traffic behind me.

    would 33's be a lot smarter for that?

    Ive got the room now for either

  6. #6
    AKMark is offline Building another 6.2L powered vehicle
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    33's would be a better option. I had 285/75R16's (33's) on my 99 6.5 K2500 Burb with 4.10's and it was a beast.

    The 6.2 is going to be a dog compared to almost anything else, but gearing will help. With a 700R4, if you are paying to regear, I'd go 4.56's. You'll like the pull it has versus 4.10's and you won't use much more if any fuel.

    Also, I've broken 1/2 ton axles without a trailer on icy ground. I prefer the 3/4 or 1 ton axles to keep things from breaking so easily. I have a 3/4 front and rear from an 86 Suburban. If you were closer I would cut you a deal.
    05 2500HD CC LB LLY, 4x4, 3.73s 235/85R16's, webasto cab heater, to keep it warm.
    03 Buick Rendezvous - When you average over 80 miles per day driving around, you need one of these.
    85 K-5, 6.2, SM465, Rockwell T221, 1 tons, 36's. More goodies to be installed as time and money allows.
    82 K20, 6.2, SM465, NP208, stock except for bed rack, snow plow, and glow plugs are on a toggle switch. It works great for plowing!
    72 Postal Jeep - Yet another project

  7. #7
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    Default

    Quote Originally Posted by FalcortheRooster View Post
    Hello everybody!
    Starts up and runs great When its cold. Once it warms up and I stop, it turns over for days, no start.
    Garrett
    This sounds strange to me. My problems used to be the opposite. I'm also curious what would cause a "hot start" problem. Heard of it on gas engines, but not diesels. I would think it would be fuel system related.
    Another welcome to the forum Garrett. Nice looking Burb. Hope you enjoy it. Keep us posted on your progress.
    Old habits, die hard.

  8. #8
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    Howdy and welcome...
    On the hot start issue....Glow plug control. If your glow control is saying that the engine is warm enough to start without glow plugs then you don't get them. If your wait light is not coming on or you cant hear the glow relay cycle then you are not getting glows.

    My van(175,000), needs glows EVERY start. I have a bypass switch in the line that I can engage the glows any time I want. Works great, I used a momentary starter button.

    My 1986 blazer(60,000) sometimes will start COLD without glows and if it has been running at it pops fast. This is good since the glow control for this rig died a tragic death and has not been updated yet

    IMHO...the reason for this is compression and injection. An older engine with some miles on it has less compression and the4 injectors have a dribble instead of a spray. Both lead to hard starts.

    60g's are good update, I have had good luck with the quick heats from Kenneddy as well.

    Also make sure that your starting system is in good condition and that it spins over fast enough.
    Hope this helps!

    Good luck!
    1996 Chvy 3500 CCDWLB 6.5 Heathed, NO vac, marine injctrs, ARB bumper, BIG pipe, 3" lift, bright lights, bypass oil system.
    1986 Chvy 6.2 M1009 blazer RAM AIR, Headers, Custom interior
    2001 Chinook RV, V10 gas
    1974 John Deere 1530 diesel tractor
    1993 John Deere 455 Diesel lawn mower
    1967 GTO, 1989 Honda Transalp
    2009 VW Jetta TDI, flashed and piped, 6speed, fun car!
    1998 6.5 suburban, stock, daughter's
    1993 6.5 3500 CCSWLB GM8, Heathed, big exhaust, gauges, Son's

    1984 6.2 ATS turbo 3500, SCDWLB - Son's
    3 kids, 1 wife, 1 dog
    Gunsmith, Tactics Instructor, Fabricator USMC 87-93 Semper Fi!

  9. #9
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    Quote Originally Posted by AKMark View Post
    33's would be a better option. I had 285/75R16's (33's) on my 99 6.5 K2500 Burb with 4.10's and it was a beast.

    The 6.2 is going to be a dog compared to almost anything else, but gearing will help. With a 700R4, if you are paying to regear, I'd go 4.56's. You'll like the pull it has versus 4.10's and you won't use much more if any fuel.

    Also, I've broken 1/2 ton axles without a trailer on icy ground. I prefer the 3/4 or 1 ton axles to keep things from breaking so easily. I have a 3/4 front and rear from an 86 Suburban. If you were closer I would cut you a deal.
    such a FNG here, what parts do I all need to swap gears? just the axels and gears?

    I have room for 35's currently but not sure if I wont drop the lift a little to do a suspension upgrade.

    I have the 4 speed, so i was thinking of switching to a nv4500 since it sounds like it has the most cost/benefit worthiness.

    Ive read some people get marine fuel injectors, is it worth it?

  10. #10
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    IMHO...stay with good factory injectors. The 6.2 in NON turbo trim does not need the high pop marine injectors. They can also cause other potential problems.
    If you are looking for more power...
    -save your pennies and buy a banks turbo kit.
    or
    -go the non-turbo route and improve all the little things.
    I have experience with doing both and the turbo route is by far the best, diesels were meant to be turbo-ed.
    1996 Chvy 3500 CCDWLB 6.5 Heathed, NO vac, marine injctrs, ARB bumper, BIG pipe, 3" lift, bright lights, bypass oil system.
    1986 Chvy 6.2 M1009 blazer RAM AIR, Headers, Custom interior
    2001 Chinook RV, V10 gas
    1974 John Deere 1530 diesel tractor
    1993 John Deere 455 Diesel lawn mower
    1967 GTO, 1989 Honda Transalp
    2009 VW Jetta TDI, flashed and piped, 6speed, fun car!
    1998 6.5 suburban, stock, daughter's
    1993 6.5 3500 CCSWLB GM8, Heathed, big exhaust, gauges, Son's

    1984 6.2 ATS turbo 3500, SCDWLB - Son's
    3 kids, 1 wife, 1 dog
    Gunsmith, Tactics Instructor, Fabricator USMC 87-93 Semper Fi!

  11. #11
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    Apr 2001
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    Default

    Hot start issue.
    Likely the rotor/head in the Injection pump is tired and can't build enough pressure at cranking speed when hot

    Dump in a couple quarts of motor oil (in fuel tank) and see if hot start is better, if so then new IP is in order.

    Stay away from high pop injectors,
    Factory standard spec squirts are the ticket.

    A fresh IP and a new set of squirts and the rig should run sweet.

    60G plugs are the ticket

    3.42 gears were a common ratio with these rigs in the 1/2 ton models
    Great mileage, but not a real rocket.

    I have had 33 inch rubber on with 3.42 gears, but it kills the power.
    3.73 or 4.10 with the big rubber is far better
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  12. #12
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    Quote Originally Posted by FalcortheRooster View Post
    such a FNG here, what parts do I all need to swap gears? just the axels and gears?

    I have room for 35's currently but not sure if I wont drop the lift a little to do a suspension upgrade.

    I have the 4 speed, so i was thinking of switching to a nv4500 since it sounds like it has the most cost/benefit worthiness.
    My advice would be to slow down a bit on the proposed changes and research a bit more. Start with what you're trying to accomplish.

    Are the tire size upgrades mostly for looks or for actual off-road use? If you're going to be daily driving the truck, towing, and mostly seeing highway miles I'd recommend a more mild size increase to improve mileage and towing over bigger meats.

    With a tire size selected, then start looking at gearing. The two options are either changing the existing ring and pinion in the differential - which is something for a professional to do, not a first timer - or swap the entire axles out for ones with the gear ratio you want - which is more of a "bolt on" change for someone without a lot of experience.

    Same with the transmission swap. I'm going to guess you have the 700R4 with an overdrive of 0.70. Or do you have the Muncie 4-speed manual? The manual doesn't have an overdrive. The NV4500 has an overdrive of 0.73. So you're actually losing a little bit there if you currently have the automatic or gaining overdrive if you have the manual. If you currently have an automatic, you're going to have to swap in everything for the clutch. Even if you already have the Muncie, swapping transmissions isn't something I'd recommend for someone just starting out.

    As others have said, stock injectors are going to be a better bet for you than marine or other "bling" versions. Better to do some exhaust upgrades to get things flowing better.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  13. #13
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    Aug 2014
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    Panama City, FL
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    Default Ditto . . .

    Quote Originally Posted by Dvldog8793 View Post
    IMHO...stay with good factory injectors. The 6.2 in NON turbo trim does not need the high pop marine injectors. They can also cause other potential problems.
    If you are looking for more power...
    -save your pennies and buy a banks turbo kit.
    or
    -go the non-turbo route and improve all the little things.
    I have experience with doing both and the turbo route is by far the best, diesels were meant to be turbo-ed.
    Ditto on the Banks Turbo, my K5 has one and a friends 6.2 Burb doesn't, the difference is night and day. Per the tires, unless you're dead set on 35's consider the cost differential too, 35's are steep.
    1982 K5 Blazer 4wd w/ 6.2 turbodiesel (Banks Sidewinder) w/ rear disk brakes, more to come . . .

  14. #14
    AKMark is offline Building another 6.2L powered vehicle
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    Swapping gears is not something you do by yourself the first time. Do it wrong and things break badly and leave you stranded.

    To swap gears you would need at least the following parts
    1. Ring and pinion gear for the ratio you want (for both front and rear)
    2. Master install kit (for both front and rear)

    The list of tools you need is longer and expensive.

    You might find axles with the gears you want in a junkyard in good shape, then just swap axles which is easy.

    I know it's about 5-7 hours of shop time to swap gears per axle.

    A NV4500 is a great transmission, but spendy.
    05 2500HD CC LB LLY, 4x4, 3.73s 235/85R16's, webasto cab heater, to keep it warm.
    03 Buick Rendezvous - When you average over 80 miles per day driving around, you need one of these.
    85 K-5, 6.2, SM465, Rockwell T221, 1 tons, 36's. More goodies to be installed as time and money allows.
    82 K20, 6.2, SM465, NP208, stock except for bed rack, snow plow, and glow plugs are on a toggle switch. It works great for plowing!
    72 Postal Jeep - Yet another project

  15. #15
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    Grand Rapids MN 55744
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    On the gear swap....
    We just had a front end rebuilt with new gears for my sons DIESEL jeep project. There is a local guy that does all the race cars around here...I know him so he gave us a deal. New gears, install kit, new bearings seals ect...labor= $550. that was with my son doing the tear down.
    Most of the time if you ask around you will find out how the "gear guy" is in your area as it seems to be a specialist program. I have done two and they held together but I didn't want to be on the whipping post if my kid was stuck out in the woods with a blown diff!

    Story of my K5 M1009:
    stock engine, 31.5 tires with t400 and 3.08 gears = Pretty doggy
    Opened exhaust and increased intake airflow, 33.5 tires = Better power
    Headers, open intake, ram air, pump turned up tiny bit = MUCH better power

    My neighbor with pretty much same setup truck wise, all he did was add the banks and it about the same difference that I saw in my truck before any mods.

    IMHO....do the things that are FREE first and see if it makes you happy then start throwing money ta it....
    1996 Chvy 3500 CCDWLB 6.5 Heathed, NO vac, marine injctrs, ARB bumper, BIG pipe, 3" lift, bright lights, bypass oil system.
    1986 Chvy 6.2 M1009 blazer RAM AIR, Headers, Custom interior
    2001 Chinook RV, V10 gas
    1974 John Deere 1530 diesel tractor
    1993 John Deere 455 Diesel lawn mower
    1967 GTO, 1989 Honda Transalp
    2009 VW Jetta TDI, flashed and piped, 6speed, fun car!
    1998 6.5 suburban, stock, daughter's
    1993 6.5 3500 CCSWLB GM8, Heathed, big exhaust, gauges, Son's

    1984 6.2 ATS turbo 3500, SCDWLB - Son's
    3 kids, 1 wife, 1 dog
    Gunsmith, Tactics Instructor, Fabricator USMC 87-93 Semper Fi!

  16. #16
    Join Date
    Sep 2014
    Location
    Portland, OR
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    thanks everybody for your help. So far I have taken care of most the electrical problems. It now rarely doesn't start, but sometimes it has the same symptoms so More repairs are on the way.

    This vehicles primary function will be for camping and hopefully if the MPG can get where I want it/convert to veggie oil/combo set-up.

    I figure if im planning on keeping bigger tires (like the 35's i just got) then i should plan on getting 3/4 ton axles too.

    i found a good shop relatively nearby that is very familiar with 6.2's

    hes got one in his jeep with a turbo

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