Diesel Question

[4cruzer]

Hey,
My brother and I are heading down to Panama if not further down this winter. I've decided that my 1985 4runner is too small to hold 2 fishing kayaks, a bunch of surfboards and ~8 months worth of gear for two dudes and a dog. Also, it's the perfect trail / expo rig and I wanna keep it that way.
So I bought a 1989 diesel suburban. It has the 6.2 motor. I've researched, and I know this motor has a bad rep, especially for towing, but this truck has been maintained and has low miles, so we're rolling with it...
This truck, for me at least, just needs to last through this trip, after which I'll be back in my trusty crawler. That said, please spare the countless bad experiences you may have had with the motor, I've heard tons!
Anyway, this truck has been fairly well equipped and has a 12,500lb winch already. It has two new red tops under the hood. These two batteries are connected without any sort of isolating switch like I have in the other truck. My question is this: Does that truck, because of a diesel motor's higher compression, need the two batteries just to crank the motor, or might the second battery have been installed to help the winch? I was planning on 'borrowing' the yellow top and the Engel from my 4runner for this trip. Should I run the yellow top as a THIRD battery or just replace one of the red tops with it and run an isolator? And will one battery be enough to crank that motor? I hope this all makes sense. I know there are some diesel gurus on here that might have some insight.
Sorry for the essay, any help is appreciated.
Cheers
Garen

 

[spencyg]

Many larger diesels have two cranking batteries due to the huge demands placed on them by the high compression of the engine. If it were me I'd add the 3rd battery with an isolator. The two existing batteries will definitely be an asset if you're winching, but they are there (in their plural) solely for the purpose of getting that 6.2L pig started....

Sounds like a good trip. I hope you have all the paperwork lined up for your dog.

Spence

 

[ntsqd]

Have a look at the battery negative cables. If they do not both go to the same bolt, rearrange things so that they do.

It is important that batteries wired directly in parallel have the least amount of resistance between them. Experience with a '91 gasser Sub has taught me that just the difference in the resistance of the engine block vs. a battery cable is enough to cause problems over a couple months time span.

 

[4cruzer]

thank you both for the input. I'll check those cables tomorrow.
Dog goes in for second round of vaccinations and paperwork next week... Just gave notice at work.. Getting pretty excited..
Anyone else have ideas regarding that battery question? Thanks!
Garen

 

[cruiser guy]

My BJ60 also has dual batteries and a 12v system from the factory. Not uncommon in diesels.

I wish you luck with the 'burb (you may need it)!!

 

[madizell]

Since you are traveling into dark territory, I would replace both of the main batteries at the same time, before you go, so that you start with, hopefully, two batteries of exactly the same potential. If you want to add a third, I would isolate that one.

 

[cruiser guy]

You can get batteries in Central America quite easily. I would keep what you have unless you are assured that you will be getting a "warm weather" battery. There ARE differences.

I ran my BJ60 on a single battery for the last year because the other batteries went bad. Chances are since itis not cold you won't need two batteries though I'd still start out that way.

 

[Overdrive]

I don't know how Chevy wired theirs, but Dodge has a common positive cable between the two batteries, with the ground cables being separate (going to each side of the block.)

I got along fine with one battery in my early Dodge/Cummins (first gens came with only 1 battery) but I live in a warm climate.

To be safe, use the two battery system as designed, with a third for your fridge.
Scott

 

[cruiser guy]

I don't know how Chevy wired theirs, but Dodge has a common positive cable between the two batteries, with the ground cables being separate (going to each side of the block.)

I got along fine with one battery in my early Dodge/Cummins (first gens came with only 1 battery) but I live in a warm climate.

To be safe, use the two battery system as designed, with a third for your fridge.
Scott

My Toyota diesel is the same, common positive and separate negatives.

 

[buldyourown]

I have owned an '88 6.2 for almost 10 years now. My dad has it now as his farm truck. Great truck, great motor. It has a bad rep because GM put it in 1 ton trucks. People tried to tow 5th wheels and 10k# horse trailers with it and blew them up. They are very reliable if treated nicely. They are also simple to diagnose and repair. No computer, no OBD, no carb. If that motor has compression and fuel, it will run.

The dual batteries are factory. You need them to crank the motor. The starter requires a LOT of juice. If the batteries are low, the motor will not start and you will drain the batteries and then you will really stuck. Have backup plan to charge you batteries. And no, you can't bump start it.

Spares I would bring: Starter solenoid, belt, fuel pump (small, inline type)
Change the glowplugs and fuel filter before you leave, though, you probably won't need the plugs in Panama. I barely needed them in Seattle.
Double check the coolant system. If it's not sound, it will give you problems.
Have fun. A diesel Sub or K5 chalet is on my dream truck list.

 

[cruiser guy]

The lack of a turbo will cause a significant power loss at altitude. Be kind to the engine when up high and live with the lower power or you could easily be F.O.R.D.
I would not add a turbo to that engine because of the other potential problems it has.

 

[Chas Stricker]

Sounds like a good rig and a great trip/adventure. I put a 6.2 in my old FJ55 and a Banks turbo. I would echo the fuel pump thought and spare fuel filters. I put dual pumps on mine (just in case) and used the mechanical location for the oil return line on the turbo. GM got bad press from the 350 they converted to diesel. The 6.2 is a fine motor and turbos well. Power on a "normal" is ok just realize you need to pace yourself. What tranny is it running? If it is the 700r4 I'd check it out more so than the 6.2. That's the tranny I put behind mine and loved it. It did go bang and I had to build it for what I was doing. Keep us informed.
Chas

 

[ntsqd]

My Toyota diesel is the same, common positive and separate negatives.

That is how GM did it and it cost me a set of new Exide spiral cell batteries in about 3 years. If the vehicle sat for more than a couple of days, as it frequently did and does, the batteries would be too low to start a gas engine. The current set, with a common ground (only one cable actually changed) are going on 2 years without any trouble. I brought both grounds to a marine battery combiner switch, so that I can separate them if need be, and then ran the engine block ground from the common lug of the switch.

I believe this modification falls into the Severe Service prep category, not the Enough to Function category.

 

[Freezer]

I'm running 2 Optima redtops in my rig and have no need for a third battery just for winching.

Unless you're going to use a lot of electric devices with the motor turned off, i'd say you'll be fine with just the two batts.