1999 Chevy K2500 Suburban 6.5 Diesel (Automatic)

[cRiPpLe_rOoStEr]

That's a nice rig. BTW one guy at 4BTswaps claimed to have had some good fuel-savings improvement by replacing the engine-driven cooling fan by a dual-fan setup out of some Chevy minivan with dual-zone air-conditioner.

[101Volts]

Originally Posted by Hersbird

here is a picture of where the hole will develop on the outside of the transfer case
(Photo removed for quote - 101Volts)
until it happens it's not worth worrying about. Like I said I fixed mine with $5 worth of JB weld but they do make a kit that can go inside and permanently fix it but it has to come out and apart for that.

Thanks, I'll have to keep an eye out for that.

Originally Posted by oil pan 4

Some times the GM coolant level detector just turns on for no reason.
Mine would always come on, I would check it and the radiator would be full.
The 600 watt block heater is a poor excuse for a coolant heater, this is a coolant heater:
http://ecomodder.com/forum/showthrea...mer-23893.html

Honestly, the coolant does seem to be low as it is now even hot. Maybe we'll have to call the previous owner and ask what coolant he was using. I read in the (mostly gasoline related) manual that it should use DexCool and an employee at AutoZone told me the same, but just in case...

Originally Posted by Ecky

^ What he said. I have a 400w on my 1.0L engine and it takes several hours to make an appreciable difference.

I'm not sure what kind of wattage the current heater is. I have to fix or get the cable fixed though, one of the wires in it just frayed. But I may change the heater and add more heaters to it, Diesel Dave style.

[101Volts]

Originally Posted by Big Dave

Congrats on the new diesel.

I had a 83 K2500 diesel pickup for 17 years and 305,000 miles, so have some insight into this vehicle.

Buying a used 6.5 my first advice is to have the engine, radiator, and heater professionally acid-cleaned and back-flushed. these engines are touchy about being over-heated. I'd still have that old 6.2 but the engine got hot and cracked the block at the No. 8 cylinder.

I completely agree with Post #8:
"The single best FE improvement I made to my gas 1991 K2500 was swapping the 4L60 Auto Transmission out for a NV4500 Manual Transmission. I know you may not want to do that right now, but it would be something to keep in mind."

That a minimum 2 MPG improvement just waiting to happen. Further, and maybe more importantly, you'll be ditching a transmission that was never intended to be used with a diesel. Even the 6.5 makes a lot of torque at low RPM. so much so that the torque converter cannot pump enough fluid to keep the transmission cool. A cooler does not help. Fluid flow is simply inadequate. My old 6.2 had a 700 R4 and later a TH400 and I trashed them seven times. Spectacular failures - scattering parts an fluid down the road. Lots of plastic parts obviously melted and ferrous metal parts turned blue. The stick completely eliminates this problem. The conversion is old hat in the Chevy pickup/Suburban community.

There are uncorroborated stories out of GM about a 6.2 suburban with 2.73 gears that could get 30 MPG. I don't see why you couldn't get 23-25 with some modest effort.

Here is your gold mine for 6.5 information.

The Diesel Page - for the 6.2L, 6.5L, and Duramax 6600 (6.6L) GM Chevrolet and GMC diesel engines.

They've been at this for nearly two decades.

Yeehaw, Thanks! (And while anyone else is reading who contributed, Thanks to you too.)

Where could I get the radiator, heater and engine acid-cleaned and back-flushed? Pittsburgh isn't too far of a drive for me.

I may change the transmission eventually, but for now the automatic one is staying.

Also, This vehicle is going to be towing things like a 4,700-5,400 pound car + trailer so I'm not going to change the gears in the rear. I'll be changing the differential fluid, though.

And so far, the vehicle has a roof-rack on it and I'm not sure if I can remove it or not.

[101Volts]

Originally Posted by cRiPpLe_rOoStEr

That's a nice rig. BTW one guy at 4BTswaps claimed to have had some good fuel-savings improvement by replacing the engine-driven cooling fan by a dual-fan setup out of some Chevy minivan with dual-zone air-conditioner.

Thanks, I may get an electrical fan though which I understand is supposed to get even higher MPG since it's not on all the time.

[101Volts]

On subject of fluids!

What full synthetic differential fluid could I use? And what full synthetic ATF could I use? I was looking at Mobil-1 for the Differential Fluid, and for a while I was thinking of some Mobil-1 for the ATF as well but I'm not sure it will work.

[aardvarcus]

The subject of fluids will get you a wide array of opinions. I would suggest determining the OEM specification, and sticking to a fluid of that specification (unless you have a good reason not to) from a reputable brand. There are many high quality fluids brands out there, and I don’t really think any of them are truly significantly better than the others, so long as you are using the correct spec.

Me personally, for the engine I run Mobil 1 engine oil with a Wix oil filter for convenience of local purchase. For everything else, (differentials, transmission, transfer case) that doesn’t get changed often I get Amsoil fluids. Two of the biggest reasons I run Amsoil are that I like that Amsoil’s website gives you the specifications and amounts for your vehicle and that they tell you the viscosities of their fluids at different temperatures.

If you don’t already, definitely get a hand held oil transfer pump for adding the fluid to the differentials and transfer case.

Just in case you run into this, on my old truck the fluid I took out of the rear differential was nasty. It must have gotten water in it. If I put my good fluid right in, there would have been a lot of that mess in my new fluid. I wiped out as much as I could, but then to help “clean” the differential out, I filled it up with some engine oil (cheaper and I had it) and drove it around like that for a bit. Then when I re-drained the fluid the second time, it got most all the junk out so my good fluid wouldn’t be full of junk.

[101Volts]

Originally Posted by aardvarcus

The subject of fluids will get you a wide array of opinions. I would suggest determining the OEM specification, and sticking to a fluid of that specification (unless you have a good reason not to) from a reputable brand. There are many high quality fluids brands out there, and I don’t really think any of them are truly significantly better than the others, so long as you are using the correct spec.

Me personally, for the engine I run Mobil 1 engine oil with a Wix oil filter for convenience of local purchase. For everything else, (differentials, transmission, transfer case) that doesn’t get changed often I get Amsoil fluids. Two of the biggest reasons I run Amsoil are that I like that Amsoil’s website gives you the specifications and amounts for your vehicle and that they tell you the viscosities of their fluids at different temperatures.

If you don’t already, definitely get a hand held oil transfer pump for adding the fluid to the differentials and transfer case.

Just in case you run into this, on my old truck the fluid I took out of the rear differential was nasty. It must have gotten water in it. If I put my good fluid right in, there would have been a lot of that mess in my new fluid. I wiped out as much as I could, but then to help “clean” the differential out, I filled it up with some engine oil (cheaper and I had it) and drove it around like that for a bit. Then when I re-drained the fluid the second time, it got most all the junk out so my good fluid wouldn’t be full of junk.

Makes sense. Though I do recall there's a thread on here where someone said "I think the instruction manual for this car states too thick of a differential fluid for this car" I'll just stick with 80w90 for now, differential wise.

The oil pump is a good idea, thanks. I didn't think of it.

I can understand about flushing out a system... My father used to do that with oil changes in the 1970s, but that was before oil got to be a lot thinner (to my knowledge.)

[Big Dave]

Re: Post #13

“Where could I get the radiator, heater and engine acid-cleaned and back-flushed? Pittsburgh isn't too far of a drive for me.”

Big Dave says;
I’m sure there is someone in Pittsburgh that can do it. I found a local radiator shop in suburban Naptown to do the job. Pittsburgh should be no different.

Depending on how long you can live with the truck down, pull the water pump off and give it a good looking-over. The water pumps on these trucks are integral to the block and are pricey. Ask me how I know. You really don’t want to run acid through the water pump if you can help it. Delime it by hand if you can.

Borescope your radiator. If it is badly limed up or corroded, think about a replacement. These are volume-built radiators and in the scheme of things, not all that expensive. Your water pump probably costs twice what a radiator costs.

If the radiator is merely corroded, a regular acid back-flush will add years to the service life, but if it is limed up you need to get drastic. If the radiator is limed up you can bet the farm that the block and heads are limed up and lime isn’t easy to remove. Citric acid won’t touch it. Rig up a pump setup and pump muriatic acid (swimming pool concentration – the stuff used for cleaning masonry is too strong) through it. Let it run a minimum of three days. A week is better. Lime is that tough. Then neutralize it with a solution of baking soda and distilled water. Back flush again with tap water, then with distilled water. At that point you’ve done all you can.

Just to show the extremes: My Ford uses an International 444E engine. Very tough engine still in wide use for school buses (which is savage duty for an engine.) It uses a very powerful (and expensive) water pump. So powerful that the high flow through the block would cavitate and pit through the first two water jackets. Seems amazing but I have seen such damaged engines myself. Ford pickup used to have to add an additive every three months or so to suppress the cavitiation. To fight this I switched tio waterless coolant. But I had to back flush and then completely dry the engine. That is major operation when you have a big engine in a tight engine compartment. And the waterless coolant is $40 a gallon. But it is the last stuff I ever have to put in it. Best of all: after six years of complete neglect I have zero cavitation pitting, zero corrosion, and zero lime. Bright metal looking back at me. You probably don’t want to get that radical. I drive a lot and expect at least 600,000 miles out of my engine and transmission. At least it won’t die from heat.



“I may change the transmission eventually, but for now the automatic one is staying.”

Big Dave says:
It’ll let you know when it’s time to change. Pieces scattered down the road are a cogent argument. Make a plan to convert and execute it when the automatic grenades itself.

[101Volts]

Oh say, can you see a brown or black dump that was in the tranny?



Yeah, that was in the transmission pan. I replaced the filter and fluid but will need to change the fluid at least two more times before it's clean enough for me. On the first of two fluid changes I may put some Seafoam Trans-Tune in.

The fluid went without being changed so long that even the plastic on the dipstick stinks. At least the lever shifts easier now.

[deejaaa]

I suggest going here and do some reading:
6.2 and 6.5 Diesel Engines | The Truck Stop
I am a member there also.
I have a 96 and 93 6.5 diesel. am fixing the 96 up for sale but will be keeping the 93.
I installed a Gearvendors OD unit, have the auto and 4.10 gears. at 65 I am at 2000 rpm, which is the ideal rpm for these engines.
I plan on putting a short bed and to shorten the frame and I want to put in a 5 speed and 12 valve Cummins.