Just picked up a 85' 6.2 C code Suburban

[FalcortheRooster]

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

[MajMike]

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.

[AKMark]

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.

[AKMark]

Especially if someone has used either on them without disabling the glow plugs.

[FalcortheRooster]

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

[AKMark]

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.

[joeq]

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.

[Dvldog8793]

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!

[FalcortheRooster]

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?

[Dvldog8793]

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.

[Robyn]

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

[trbankii]

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.

[MajMike]

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.

[AKMark]

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.

[Dvldog8793]

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....

[FalcortheRooster]

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