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6.5L Turbo Diesel 1992-00 6.5TD - Discussion forum for the 6.5L engine.

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  #1  
Old 07-14-2009, 07:14 PM
Busted Busted is offline
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Arrow 6.5 Diesel Block Identification (moved from navistar thread)

I have a block with GM in the lifter valley and on the main caps, the 1255506 casting number on the bell flange, and 506 on the back of the block, but no Navistar diamond and no 506 in dots in the valley. For those who see a lot of chinese/AMG blocks, what do I most likely have?

It's crack-free, looks beefier with the thicker taller main bearing caps etc., just want to be sure before I pour a lot of money into a buildup . . . .
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1982 GMC Sierra Grande Camper Special
6.5TD: ARP head studs, DSG girdle kit, DB2 turned up 1/8th, '97 Cummins intercooler, custom 3" downpipe to 4" straight exhaust, wastegate @12psi, boost and pyrometer, NV4500 with mech. clutch, twin-sticked NP205, D60 front/D70HD DRW with 4.10 gears, '93 serpentine belt setup
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1997 Chev Express G3500
6.5TD 15 passenger van
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  #2  
Old 07-15-2009, 08:09 AM
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Quote:
Originally Posted by Busted View Post
I have a block with GM in the lifter valley and on the main caps, the 1255506 casting number on the bell flange, and 506 on the back of the block, but no Navistar diamond and no 506 in dots in the valley. For those who see a lot of chinese/AMG blocks, what do I most likely have?

Sounds like an early 506 block. Look for the date code on the opposite mounting flange as you found the casting number. Post that and we can tell you what it is, if there isn't one, post a picture and I can tell if it's foreign.

J
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1982 C10 SCSWB 6.5TD, mods too extensive to list. (13.69 1/4 mile @94.6 MPH) RACE TRUCK
1982 C10 SCSWB 6.2NA, 2.73 700
1986 C10 SCLWB 6.2TD 3.73 700
1989 V20 SUB 6.2NA, 3.73 400
1994 G20 VAN 6.5NA, 3.42 60E
1994 K20LD ECSWB 6.5TD, 3.42 80E
1995 K20 SUB 6.5TD, Wrecked, ran into by stupid teen.
1995 C3500HD DRW 6.5TD, 12' Flatbed 5.13 80E
1995 C3500HD DRW 6.5TD, 18' Rollback Wrecker 4.63 80E
1994 C20HD ECLWB 6.5TD 3.73 80E Wifes Truck.
1995 C20LD ECSWB 6.5TD 3.73 80E
1995 K20LD SCLWB 6.5TD 3.73 80E
1996 K30 DRW 6.5TD 4.10 80E
1997 C10 Tahoe 2Door 2WD 5.7L to 6.5 Conversion Underway
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  #3  
Old 07-15-2009, 08:12 AM
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The date code is C221

I also can't find oil spray nozzles, but then I'm not completely sure what I'm looking for . . .
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1982 GMC Sierra Grande Camper Special
6.5TD: ARP head studs, DSG girdle kit, DB2 turned up 1/8th, '97 Cummins intercooler, custom 3" downpipe to 4" straight exhaust, wastegate @12psi, boost and pyrometer, NV4500 with mech. clutch, twin-sticked NP205, D60 front/D70HD DRW with 4.10 gears, '93 serpentine belt setup
in progress

1997 Chev Express G3500
6.5TD 15 passenger van
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  #4  
Old 07-15-2009, 08:22 AM
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Figured I'd post a couple pictures anyway for future reference/comparison.





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1982 GMC Sierra Grande Camper Special
6.5TD: ARP head studs, DSG girdle kit, DB2 turned up 1/8th, '97 Cummins intercooler, custom 3" downpipe to 4" straight exhaust, wastegate @12psi, boost and pyrometer, NV4500 with mech. clutch, twin-sticked NP205, D60 front/D70HD DRW with 4.10 gears, '93 serpentine belt setup
in progress

1997 Chev Express G3500
6.5TD 15 passenger van
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  #5  
Old 07-15-2009, 09:29 AM
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The early 506 blocks had large outer bolts (center mains) and no spray nozzles.

The spray nozzles are located in the main saddle of the block on both sides of center.

The center hole in the main saddle is the oil feed hole. The ones a little offset are the squirt holes.

The squirt holes have a little aluminum nozzle pressed into them and they aim up into the cylinder to help cool the piston crown.

The nozzles recieve oil all the time the engine is running.
The oil feed from the pump comes from the oil gallery to the mains via the cam and then feeds the goove in the upper main bearing. The groove has pressure oil all the time as does the squirt nozzles.

The 97 production 6.5's had the large outer bolts and the nozzles. These were one of the most failure prone blocks built.

In subsequent years the outer bolts were reduced to 10MM down from 12MM and the size of the oil squirt holes was reduced also.

The oil pump used on the squirt motors was of a larger displacement to handle the huge loss of oil volume from the squirts.

These pumps have a 1/2" (Approx) spacer in the middle of the pump between the pump body and the cover. The gears are longer too.

The squirt block pump can be used on a non squirt block but not the other way around.

Using the lower volume pump on a squirt block will cause a very low oil pressure condition at low speeds.

Cracks can't generally be seen well until the block is bare and clean.

Some cracks will start at the register fit where the caps sit in the block. Most though start on the inside of the outer bolts holes (center mains only) and progress outward and then down the web along the length of the hole.

Many of the cracks can't be seen easily even after the block is cleaned up.

The trick to finding these little animals is to heat the web around the outer holes with a propane torch.

You dont have to fry the thing but just get the web Hot to the touch in that area. Let sit a bit and any cracks will see any oily band show up as the oil cooks out.
As long as any cracks dont go beyond the depth of the hole, they can be repaired with the Lock and Stitch full torque inserts.

A crack that starts in the area of the register corner and progresses down the web pretty much dooms the block to becoming a door stop.

Also have a look see at the cylinder deck area especially in the area of cyl's 1 and 2

errosion around the fire ring contact area is common. If its not too bad it can be fixed handily by machining the deck .010" and using a OS Felpro gasket.

Before you rip the sucker all apart. Make sure how far above the deck the pistons come (both sides) stock is flush to.002" above.

If you find that the pistons are above the deck more than this Oh say .010 or ??? the block has been decked prior to you owning it.

Now Felpro makes a .010 thicker gasket. Cometic will make a thicker one if you need it.

If you find that you need to take .020 or so off the block, Cometic will custom make gaskets for you.

Ask me how I know this.

Always replace the cam bearings on these engines any time there is machine work done.
The cam bores have a groove behind them and there is a nice Hidding place for sahvings to get stuck. Then when you run the thing there is an issue. Game over.

Remove cam bearings, machine block, hot tank or wash, resinstall bearings.

Make sure the cam bearings are installed just like the originals with the oil delivery holes oriented the same.

The front bearing has a notch, it goes to the front.

Hope this stuff is useful

Have fun
Missy
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Last edited by Robyn; 07-15-2009 at 09:50 AM. Reason: addition
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  #6  
Old 07-15-2009, 10:31 AM
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You've got a 2001 block, just prior to the Navistar casting, in appearance.

It's has the later caps on it, with the slants from the top bolts down to the lower outer main bolts.

It's a GM block.

Proceed with tear down.
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1982 C10 SCSWB 6.5TD, mods too extensive to list. (13.69 1/4 mile @94.6 MPH) RACE TRUCK
1982 C10 SCSWB 6.2NA, 2.73 700
1986 C10 SCLWB 6.2TD 3.73 700
1989 V20 SUB 6.2NA, 3.73 400
1994 G20 VAN 6.5NA, 3.42 60E
1994 K20LD ECSWB 6.5TD, 3.42 80E
1995 K20 SUB 6.5TD, Wrecked, ran into by stupid teen.
1995 C3500HD DRW 6.5TD, 12' Flatbed 5.13 80E
1995 C3500HD DRW 6.5TD, 18' Rollback Wrecker 4.63 80E
1994 C20HD ECLWB 6.5TD 3.73 80E Wifes Truck.
1995 C20LD ECSWB 6.5TD 3.73 80E
1995 K20LD SCLWB 6.5TD 3.73 80E
1996 K30 DRW 6.5TD 4.10 80E
1997 C10 Tahoe 2Door 2WD 5.7L to 6.5 Conversion Underway
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  #7  
Old 07-15-2009, 01:19 PM
Busted Busted is offline
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Cool, thanks for the input!! When I looked in the valley and saw no Navistar diamond I was worried that I got a foreign block . . .
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1982 GMC Sierra Grande Camper Special
6.5TD: ARP head studs, DSG girdle kit, DB2 turned up 1/8th, '97 Cummins intercooler, custom 3" downpipe to 4" straight exhaust, wastegate @12psi, boost and pyrometer, NV4500 with mech. clutch, twin-sticked NP205, D60 front/D70HD DRW with 4.10 gears, '93 serpentine belt setup
in progress

1997 Chev Express G3500
6.5TD 15 passenger van
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  #8  
Old 07-15-2009, 01:32 PM
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Arrow

Quote:
The date code is C221
This is likely one of the last GM produced blocks. AM General's first re-designed (with Navistar's help) blocks appeared sometime in November of 2001, and had the new date code numbering system.

I'd be curious what cylinder heads this block had on it - i.e. whether small or large port pre-cups.

Jim
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  #9  
Old 07-15-2009, 05:59 PM
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The heads have the small port pre-cups, with one square stamped into them.
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1982 GMC Sierra Grande Camper Special
6.5TD: ARP head studs, DSG girdle kit, DB2 turned up 1/8th, '97 Cummins intercooler, custom 3" downpipe to 4" straight exhaust, wastegate @12psi, boost and pyrometer, NV4500 with mech. clutch, twin-sticked NP205, D60 front/D70HD DRW with 4.10 gears, '93 serpentine belt setup
in progress

1997 Chev Express G3500
6.5TD 15 passenger van
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  #10  
Old 07-15-2009, 07:05 PM
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Thats interesting. The later engines usually have the diamond stamped cups which has a large (largest) port.

Unless the engine was an N/A model.

Robyn
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