6.2 Turbo with 6.5 Parts - Build and Questions Thread

[79Vette]

I got a bunch of 6.5 parts several years ago, and am finally getting around to installing them on my 1009. I have some questions about assessing engine condition and I am sure I will have more questions as I work through the swap, and will document everything here in the hopes it helps someone down the road. This has all been done before, so hopefully nobody is annoyed by seeing it again.

The truck has been a daily driver for 6 years and starts and runs great, but gets really terrible fuel economy. Like 11-13 mpg regardless of city/highway, and regardless of speed (60-80 mph does not seem to make a noticeable difference). I have new injectors and am working on sourcing a new IP (current one leaks badly), so hopefully that helps.

I just did a compression test following the procedure in -34 TM, but I didn't see anything in the TM about the engine needing to be hot. The truck had been sitting overnight so it was cold, and these were my results:
Cyl 1: 395 psi
Cyl 3: 380 psi
Cyl 5: 380 psi
Cyl 7: 405 psi
Cyl 2: 400 psi
Cyl 4: 420 psi
Cyl 6: 400 psi
Cyl 8: 405 psi

I saw some threads on here about how the engine should be hot, so I am going to go install the new glow plugs and drive it for a bit and try again and will post an update. But initially I am not too worried. It seems like everything is pretty much in the 380-400 psi range per the TM, with no more than 40 psi (10%) variation between cylinders.

I had previously posted a thread about oil pressure (here) where I was concerned about low hot oil pressure. I'm also hoping to double check that with a new manual gauge, and will post updates here instead of that thread.

Currently showing 30 psi idle / 40 psi driving when cold, and hot it drops down to 20-30 psi when driving 0-5 psi at idle. However the dash low oil light never comes on, so I don't think the 0-5 psi at idle is real. The light does come on at start up and goes out in a fraction of a second and sometimes stays up for up to a second on the first startup after an oil change, so I know the factory sender and light work. Engine has had clean oil changes (no visible metal) for 6 years and runs great, besides the poor fuel economy and suspect oil pressure gauge.

I have a big project on my Corvette going and am in the middle of starting a stressful new job, so I'm hoping to get a few more years of service out of this motor running ~8 psi of boost. Eventually I'll pull it to replace the bearings, do head gaskets/studs, inspect the timing set, and maybe send the block/heads off to the machine shop depending on how they look, but I don't want to do that today. Let me know if you think any of this sounds crazy of if you would do things differently.


EDIT: I am working on the injectors now and some of them are pretty tough to remove and the threads are pretty crusty. Is there any way to clean the threads in the block without a special tap? I am worried the new injectors wont thread in smoothly...

 

[adf5565]

Good luck! Hopefully the IP/injectors helps your mpg, the only time I got that bad of mileage was when I first got my m1008 but it got alot better after a few hundred miles of hard use. Especially since your compression is good it seems like the injection system is tired.

My only other suggestion when it comes time for your rebuild is to take a look at new promaxx 6.5 heads vs getting your existing ones rebuilt. They come ready to go and aren’t too expensive so it may be comparable $$ to getting yours rebuilt, plus they supposedly don’t have crack issues and will have the 6.5 injector angle which clears the turbo manifold better.

 

[87cr250r]

I always got 16-20+ mpg on my stock M1008. I recently put a 6.5 center mount turbo engine in it. My last tank averaged 16 mpg, all stop and go traffic and on 37 inch tire.

11-13 is too low. Something is wrong. Are you seeing any smoke? These engines are clean out the tail pipe under all conditions unless they're turned up. Do you have a fuel leak?

 

[79Vette]

I always got 16-20+ mpg on my stock M1008. I recently put a 6.5 center mount turbo engine in it. My last tank averaged 16 mpg, all stop and go traffic and on 37 inch tire.

11-13 is too low. Something is wrong. Are you seeing any smoke? These engines are clean out the tail pipe under all conditions unless they're turned up. Do you have a fuel leak?

Yeah I agree, its too low for this setup. I am in K5 on 33" tires, 3.73 axle gears, and a SM465 manual trans with Advanced Adapters "Ranger" overdrive. Cruise RPM is 1900 at 70 mph. I'm hoping for 18+ mpg with that setup, but we'll see what I can get.

No smoke visible in the daytime, and just a wisp visible at night in the headlights of the car behind me when accelerating from a stop light. There is a leak from the IP (it's getting replaced soon), but not nearly enough to make the difference between 20 mpg and 13. I think it would be pretty obvious if it was leaking 10+ gallons of fuel per tank, and this leak isn't that bad. All rubber fuel lines are new about 4 years ago and the hard lines are good. No fuel leaks besides the IP. I'm hoping the problem is a combination of badly worn injectors, worn IP, and maybe a worn out timing chain.

I just replaced the injectors yesterday, probably should have done it when I got the truck years ago. I have the DSG gear timing set to put in, but that's a ton of work to get the front cover off and I'm hoping to wait a couple years to do it when I pull the motor to do the bearings.

My only other suggestion when it comes time for your rebuild is to take a look at new promaxx 6.5 heads vs getting your existing ones rebuilt. They come ready to go and aren’t too expensive so it may be comparable $$ to getting yours rebuilt, plus they supposedly don’t have crack issues and will have the 6.5 injector angle which clears the turbo manifold better.

Those heads look good. will definitely keep that in mind when it comes time for a rebuild (hopefully not for awhile though!)

 

[79Vette]

Does anyone have a good source for sheet metal for these trucks? My front inner fenders are a bit rusty, and the passenger side is cracked where the battery tray mounts.

I definitely want to replace the passenger side, and am trying to decide if there's any difference in fit or quality between the various vendors. Jegs lists theirs as 20 gauge (probably made by AMD?), but none of the other vendors I've looked at specify. Does anyone have a positive experience with any brand of replacement fender they can share?

 

[vanaisa]

They all (aftermarket) are TingTong made.
J

 

[87cr250r]

The CAPA certified fenders are worth the extra money. The non-certified are thinner metal and dent when you lean on them.

 

[adf5565]

I got the fender liners from LMC. Price with shipping wasn’t too bad. Quality seems comparable to OEM, they’re sturdy.

 

[79Vette]

Does anyone have advice for removing stuck exhaust manifold bolts? I've been spraying them with PB Blaster every day for a couple weeks, but when I tried to remove them this weekend they were still stuck pretty tight.

I usually just go straight to an oxy acetylene torch and get everything nice and hot, but there is not a ton of space to work around the injectors, injector lines, and glow plugs. If the engine was out of the truck I am sure an oxy acet rosebud and an impact would have them all out quick, but there just isn't much space to work with the engine in the truck and I am worried about roasting the injectors/lines with the torch. I guess I could pull the injectors and GPs and just b careful not to knock anything into the open holes while working on the exhaust bolts? I'd appreciate any tips or tricks you may have

 

[87cr250r]

You can pull the heads with the manifolds attached. It's probably a good time to do head gaskets anyways.

 

[79Vette]

You can pull the heads with the manifolds attached. It's probably a good time to do head gaskets anyways.

Do you need to take the hood off to lift the heads out? They look pretty heavy (60-80 lbs?) and I'm not sure how to set them back on without disturbing the hee head gaskwt

 

[87cr250r]

Hood can stay on. Batteries come out as well as fuel filter. Head weighs 65lbs, manifold is maybe another 10lbs. One bolt on driver's side head is challenging to get the torque wrench on because it is very close to brake booster supports.

 

[adf5565]

My only other suggestion would be to pull the 2 motor mount bolts and lift the front of the motor up a couple inches so you have better access to the manifold bolts. This could be a bit of a pain though so might be easier to just pull the injectors/glow plugs to apply heat. I'd advise removing the glow plugs anyways to install the turbo manifold.

 

[79Vette]

You can pull the heads with the manifolds attached. It's probably a good time to do head gaskets anyways.

Thinking about this a little more, is there any advantage to replacing a head gasket which is not leaking? I don't want to use studs, so I would be reinstalling with a new set of factory style torque to yield bolts. I'm worried if I take the heads off and the head and/or block surface is not perfectly flat then the new gasket may not seal.

I should have some time to work on it this weekend, and am going to start with lifting the motor a couple inches (need to do that anyway to put in new motor mounts) and removing injectors/plugs so I can get at the bolts with an acetylene torch. I will post back with an update once I give that a try

 

[87cr250r]

The head gaskets tear up the top deck of the block. Maybe replacing it will help prevent the damage. The newest head gaskets have some reinforcement near the water passages on the ends where they are most likely to let go.

Then again, you may open a can of worms.

 

[79Vette]

So, I got the 6.2 manifolds off over the weekend. It took an average of 30 min per manifold bolt, but I didn't break any of them in the block. So that was nice. I ended up pulling glow plugs, injectors, and moving all the engine wiring out of the way and made space to use the acetylene torch. It wasn't very hard, just time consuming.

I'm having the expected interference with the passenger side exhaust manifold, but there's plenty of threads on that and I think I can figure it out. I also need to figure out an oil feed and return, but that seems pretty easy too.

What are you guys doing for battery relocation to clear the turbo? I don't have the military batteries, but my Group 31s are still pretty big. Once I get the passenger manifold and turbo installed I'll start looking at battery options, but I'm afraid I'll need to buy smaller ones... I have AC and an air compressor on the driver's side, so there's no space there for batteries. They need to go on the passenger side if they stay in the engine bay.

I've seen a post on here using Optimas in a custom tray, which I could do. But it's $500-600 in new batteries. Does anybody ever relocate them to the cargo area, or under the bed floor in a custom box? My fender liner keeps breaking where the battery trays bolt in from all the rough forest service roads and desert trails so it would be great to have a more robust solution...

 

[adf5565]

So, I got the 6.2 manifolds off over the weekend. It took an average of 30 min per manifold bolt, but I didn't break any of them in the block. So that was nice. I ended up pulling glow plugs, injectors, and moving all the engine wiring out of the way and made space to use the acetylene torch. It wasn't very hard, just time consuming.

I'm having the expected interference with the passenger side exhaust manifold, but there's plenty of threads on that and I think I can figure it out. I also need to figure out an oil feed and return, but that seems pretty easy too.

What are you guys doing for battery relocation to clear the turbo? I don't have the military batteries, but my Group 31s are still pretty big. Once I get the passenger manifold and turbo installed I'll start looking at battery options, but I'm afraid I'll need to buy smaller ones... I have AC and an air compressor on the driver's side, so there's no space there for batteries. They need to go on the passenger side if they stay in the engine bay.

I've seen a post on here using Optimas in a custom tray, which I could do. But it's $500-600 in new batteries. Does anybody ever relocate them to the cargo area, or under the bed floor in a custom box? My fender liner keeps breaking where the battery trays bolt in from all the rough forest service roads and desert trails so it would be great to have a more robust solution...

I fit 2 group size 65 batteries on the front tray. With a new fender liner I haven’t had issues, I’ve even stood on the battery tray and it didn’t seem to move.

CUCV M1008 Build

As part of the change in motors I went with a DB2-4911 IP. I purchased this from Diesel Care. There seems to be a lot of bad reviews on them, however they have one of the best prices and I've seen on here that cucvrus recommended them so figured I'd take a chance. It took 2.5 months for the...

www.steelsoldiers.com

 

[Finnegan1008]

Good luck! Hopefully the IP/injectors helps your mpg, the only time I got that bad of mileage was when I first got my m1008 but it got alot better after a few hundred miles of hard use. Especially since your compression is good it seems like the injection system is tired.

My only other suggestion when it comes time for your rebuild is to take a look at new promaxx 6.5 heads vs getting your existing ones rebuilt. They come ready to go and aren’t too expensive so it may be comparable $$ to getting yours rebuilt, plus they supposedly don’t have crack issues and will have the 6.5 injector angle which clears the turbo manifold better.

The harder I run my truck the better the engine does. I’ve never had another engine that needed this treatment quite like my 6.2

 

[79Vette]

I fit 2 group size 65 batteries on the front tray. With a new fender liner I haven’t had issues, I’ve even stood on the battery tray and it didn’t seem to move.

CUCV M1008 Build

As part of the change in motors I went with a DB2-4911 IP. I purchased this from Diesel Care. There seems to be a lot of bad reviews on them, however they have one of the best prices and I've seen on here that cucvrus recommended them so figured I'd take a chance. It took 2.5 months for the...

www.steelsoldiers.com

Thanks. I'll take a look at group 65 batteries if I can't get my 31s to fit. They're less than 60% of the weight which should definitely help with the fender breaking.

They have about half the capacity of the group 31 though, so I'll probably need to add another battery for my refrigerator and other camping gear. It all works great with the group 31s, but I'm a bit worried about getting stranded with a dead battery... At least that extra battery could go under the floor or something


Edit: does anyone have input on sizing for the oil supply line, and if a restrictor is needed? I don't want to send all the oil to the turbo and spin a bearing in the engine.

I'm thinking a restrictor around 0.07"-0.09" and either AN6 or AN4 lines would work, but would love to hear what you all are using successfully

 

[nyoffroad]

As far as the battery goes, be on the lookout for the left hand battery tray from a civilian Blazer, Suburban or truck, and mount one on each side, or have two on the right side and one on the left that powers the hotel load.