Navistar NA 6.5 swap in 96 6.5 td

[jaydee1445]

Would like some input on this swap.

116k mile 6.5 TD in a 96 GMC 2500 Suburban vin S was hamfisted doing lifter change by PO’s shade tree and was never finished. I bought it as a basket. Somehow shadetree changed lifters without pulling drivers exhaust manifold and crossover pipe because the bolts and flange is rusted to the point of replacement. Not surprisingly motor is down on compression and #1 is a head hole. This block will be set aside for inspection tear-down and possible rebuild sometime later.

Plan is to swap a running low mile HMMWV GEP Navistar casting Naturally Aspirated 6.5 motor into her using the OE 6.5 turbo parts. The turbo and NA block are same casting and the NA and side mount heads are both 90 degree manifold bolts so turbo should bolt right up.

I think it would be wise to pull the heads, check prechambers, cyl for wear, stud the block, install new roller lifters, and a high compression head gasket. Obviously, the pan needs to be swapped so a high flow pump is a no brainier. I’m resisting pulling the bearing caps to plastic-gauge clearances but not checking while the pan is off is just stupid, right??
Am I getting carried away on a strong low mileage engine? The lazy side of me says just swap the pan and oil pump.....

Thought about reworking the 24 v DB2 pump for turbo application but it would be a $400 rebuild and $300 core to convert it to 12V and still need a Quickshift 4 to control OE 4L80e. The more I think about it, using the DS2 pump isn't worth the effort and cost to get trans and cruise control to play nice. PMD relocation seems to solve most the DS4 pump issues, correct??

Other than swapping the DS4 pump and 96 TD timing cover for the CKP sensor is there anything else to change on the NA motor to run the DS4 pump? AFAICT the NA and TD injectors are the same other than possibilly a slightlly higher popoff pressure on the turbo.

Is a gear-to-gear timing set worth the investment or should I do just do a new chain set?

What have I not thought about?


This is a family hauler not a Zombie Apocalypse Road Warrior; that will be a 6BT in one of the other Burbs we have collected.

 

[smdk2500]

Since you talked about pulling the heads and doing gaskets put in studs instead of bolts. The 6.5 bolts are TTY so you have to buy new ones anyway and studs are said to be much better at keeping the head gaskets alive.

 

[jaydee1445]

Since you talked about pulling the heads and doing gaskets put in studs instead of bolts. The 6.5 bolts are TTY so you have to buy new ones anyway and studs are said to be much better at keeping the head gaskets alive.

Yes you are right. That’s what I meant about studding the block. The improved GEP block does’t benefit from main girdle studs.
Used head bolt stretch might be part of the problem Shadetree reused the old bolts.

 

[smdk2500]

That’s what I meant about studding the block.

I didn't see you saying this the first time I read your post i had to read it again. Where have you found a gear drive timing set for a ds4 pump. Last I checked they where no longer available. I've only seen the chain drives. Are the Humvee oil pumps not the high flow? I know next to nothing about those engines. I thought when they went to having the oil squirters they all got the high flow.

 

[Frank Enstein]

I would do timing chain & gears, freeze plugs, Glow plugs https://www.summitracing.com/parts/drx-drx00050 these are the best I have found, rear main seal, oil pump/pickup, and the obvious gaskets required.

All of these can be a real mother hubbard to do in the truck.

Moving the PMD is a good idea as is some lubricity additive for today's fuel.

Check the clearance on the #1 rod bearing. It's the last stop on the oiling railroad.

Do rapid oil filter changes to clean out any sludge buildup in the engine.
I do not recommend any oil flush products.

The Diesel Place forum had lots of great advice. Most of what I know about Diesels I learned there. They seem to be gone though.

Using 6.2 heads/pre-cups will improve fuel economy at the loss of power.

I have a Frybrid conversion if you are interested as well as a 6.5 TD less the hair dryer and a small pile of parts.

 

[jaydee1445]

have you found a gear drive timing set for a ds4 pump. Are the Humvee oil pumps not the high flow?

Leroy shows a DS4. Decided gear-dive is a bad idea. The chain buffers engine harmonics.
HMMWV pick-up is different, not sure on the HI flow; your are probably right.

 

[smdk2500]

Leroy shows a DS4. Decided gear-dive is a bad idea. The chain buffers engine harmonics.
HMMWV pick-up is different, not sure on the HI flow; your are probably right.

I didn't know he had them back in stock. Been a while since I've had to buy anything from him.

 

[jaydee1445]

After messing with 3 compression gauges/ adapters I finally confirmed Shady screwed the original 6.5 up and sent wire transfer for the GEP engine. Probably looking at 5 weeks before it gets shipped.