MIL 6.5 install questions

[Storm]

I'm pretty sure that I found the right place to ask some detailed questions. I have ended up completing the purchase of a MILSPEC 6.5 and 4 speed trans. to put in a 91' 2500 4x4 Sub. ( Just need to pick it up this wknd) I have offered the right amount of refreshments and finger foods to entice the technical, mechanical greats, and have secured a warm and dry location to do the swap.
I asked the general questions in the intro section and was wondering if anyone here knew that the motor/trans would match up to the motor mounts or if I need to do some cutting? The front distance should be covered because I ordered a dual 16" electric fan set-up and but i'm worried more about the bell housing because the set-up looks shorter and until I can do some measurements I was wondering if anyone has done it themselves? Back-up is have a new drive shift made. I also think I will have to fab some shift linkage?
I'm sure there will be a ton more questions but I plan to create a detailed log to submit for historical data or just something to point and laugh at. Thank you for any help in advance.

 

[WarWagon]

I would return the electric fan setup or cancel it. Even though you have the old body style the airflow requirements for a precup diesel are above what any electric fan set can provide. Get the 6.5 hotter than 210 and you start cracking heads. Electric fans are for light duty gas "toys". Clutch fans can pull over 10,000 CFM with the hood closed and radiators in place vs. the 5500 CFM "freestanding" of the electric fans. Freestanding is without a radiator or hood in the way.

Other than the oil pan clearance possibly being an issue the clutch fan should fit the stock shroud. The turbo may have issues with the AC box. The crossover pipe may have issues, but, with your lift maybe not.

What year of engine and trans? Is the trans electronic?

I would order a ring set and deglaze the boars. This will give you new engine performance and eliminate any blowby the used engine may have. Military engines don't always get the rings broken in well.

 

[OrionThade]

x2 on what WarWagon said.

 

[Storm]

CtChevy427; Thank you placing the post in a better spot.
WW; Thank you for the advice on the fan and the adequate amount of airflow needed to keep it cool. The motor is a from 99' and was rebuilt 05'. I cant answer specifically if its elect. trans, guess i'll know in a few days though. As for the military Soldiers and Marines not taking time to break in the motor by the Manufacture suggested recommendations, say it's not so. Rings are a good idea that I didn't think of. I did some research in LMC and motor mount for the 6.5 and 350 are the same so now I just need to figure out fore and aft space.

 

[WarWagon]

The two military engines I have, both 6.2's, the ring set wasn't seated very well. On teardown of one of the engines after 30K of severe WOT towing service the 2nd compression ring still had the break in coating on half of the ring. The initial 30K of military service did not seat them properly. I used total seal gapless rings and the engine oil is gas engine clean after 4K miles. Unheard of in a 6.2 with soot black oil always.

If the trans is electric then you need a seprate trans controller. I think Burning Oil sells them. I would also swap out the DS4 injection pump for a DB2 mechanical pump. This eliminates the PMD and the computer. Makes it simple. You will need the IP lines to do the swap. The 1999 4L80E was supposed to be the best although the trans is about as tough as it gets for all years.

 

[jmack91z28]

I always heard the first years of the 4l80e were the best. I've been told the GM bean counters got to it after a couple years and really weakend it up.

Never been able to prove that though, so i'm not totally sure.

Storm, is the turbo center mount or side mount?

 

[ak diesel driver]

the later years are supposed to have sturdier hard parts. ie the earlier years has a hollow input shaft and the later solid also supposed to be a gear cut change too. I have an 03 waiting to be built for mine

 

[DZZ71]

I have the dual for Taurus electric fans on my truck and have no complaints. With the H.O water pump and a clean rad I haven't over heated it once yet. Even Workin the piss out of it flooring it at every corner and doing 2 min burn outs havent overheated it yet. I have towed about 10,000 pound and had no problems eather. But I wasent working it that hard towing. I read over at the place they are rated for 3300 CFM on the highspeed for each fan?

 

[WarWagon]

When you reduce your cooling capacity you are fine until you need the 'extra' cooling you had before the electric fans. Recall we upgrade the 6 blade fan to the 9 blade fan. In any case, in the 1/4 mile you could remove the cooling fan as you have enough heatsink to go 1/4 mile without cooling fans. So with cool weather, no AC use, and taking it easy over the longer term you can get away with less cooling.

The OP has a lifted vehicle and the lift itself messes up under body airflow and pulls less air through the radiator. So there is a greater fan need with a lift.

I experimented with a 10 blade 21" fan out of a Trailblazer because I had one laying around. Pulling the grades while getting hot to Lake Havasu with the AC off, heater on, and windows down was a clear indication the blade pitch was not steep enough. It was only 80 degrees out at the time. The 21" Duramax fan solved this problem. Sadly the heating from the weak fan caused the outer head bolt hole to crack in the block. Later that summer a teardown of the engine for rebuild scrapped the block...

 

[DZZ71]

When I was working my truck like described in the last post it was all done with both fans on the low speed. I have never had to turn them both to full power. I don't know how
Much of the rad your 16 inch fans will cover but
The Taurus fans I got from the junk yard cover about 95 percent of the rad the way I made them
Fit. This same application dident work as well on my
Durmax. I smoked off a brand new set
Of tires and half way through the temp skyrocketed. BUT the 05 is the worst year for overheating issues

 

[jmack91z28]

Electric fans don't flow as much but you also aren't taxing the engine to make it cool itself. So shouldn't it kinda be 6 of 1, half a dozen of the other?

 

[Storm]

Great advice guys and thank you much.
Jmack; it is a N.A. motor, turbo will be one of the updates of the future.

Damit! Tornado warning gotta sign off, enjoy all.

 

[WarWagon]

Electric fans don't flow as much but you also aren't taxing the engine to make it cool itself. So shouldn't it kinda be 6 of 1, half a dozen of the other?

An alternator at 100 Amps pulls about 3 HP. Electric fans pull 40 Amps, not even 1.5 HP. A clutch fan although measured in torque for clutch holding power take around 5 HP or more. Not much of a 200 HP engine. But it would take 2+ alternators to get there powering electric fans.

I had electric fans in my 1995 Yukon for about two weeks. The fan motors kept burning up. The better solution was a new fan clutch and a small electric pusher fan for the AC. The best solution is a Duramax fan for cold AC as I learned after going to 6.5 diesels. In a 1993 4.3 gas 1/2 ton I tried electric fans. A fuse popped stopping the fans and resulting temp runaway bent the rods in the AC compressor and vented the system through the relief.

The 2005 Duramax adds the restriction of the intercooler to further reduce CFM through the radiator an electric fan can pull. The software over speed of the turbo, mouthpiece restriction, EGR cooler, overdriven fan and generally too small to do the job cooling system being standard GM issue on lots of things makes the perfect storm on the 2005 Duramax. I can get a 2008 Duramax really hot towing out here - jut not into overheat shutdown mode.

 

[DZZ71]

I deleted the AC condenser and I have dual alternators that's probley why the truck won't over heat for me since it's so free flowing with minimum restrictions. Also you you say the clutch fan uses 6 HP or more? Is that locked or just normal use. Also was that with a completly clean rad and AC condenser? Or did you factor in some truck have 10+ years of dirt grass and other junk clogged away. I did the LBZ mp mod on my 05 with 4 inch dual exhaust, CIA and EGR delete and still overheated. The problem with these trucks is the Rad is to small. Flexalite sells the new rad with the dual electric fans for the fix to the problem for good.