GMT400 6.5 Swap Help

[adventr]

Welcome.
Question your sanity- not needed. You are as nuts as the rest of the group! Haha

All the posts makes this thread flow perfectly. Don’t apologize.

Make sure you are legal with your dmv to convert gas into diesel and that you can use older engine in newer truck.- many places made it illegal to do either one.

Decide what you are gonna do about the dash gauges because the two won’t interchange.

Rip optimizer down. It is not a new engine and the stories they all get changed by mileage is flat out wrong. Too many guys were the wrench turners that can disprove that. That looks like it was opened up- that is not from GEP. So could be that hack outfit in NY had their hands on that one! I know 2 guys, 1 Army & 1 USMC that were up in the chain dealing with hmmwv fleets- they had a certain amount of the NY specials sent to them automatically snd the failure rate was so high they just set them aside and paper whipped that the install was done- then send the reman to auction. they slap in 1 set of bearings and don’t use the select fit or nothing on 2 that I opened up. Your lucky to get 5,000 miles when that happens and the block/rods/crank can all be junk afterwards. Not opening them up is a HUGE MISTAKE!

Inspect for main webs cracked #7 or #8 cracked cylinders, etc. Then all New bearings, gapless rings, balance the lower rotating assembly. GEP is horrible for cast flashing- do that work and flush the oil journals. Throw away that hummer thermostat crossover. Replace the hmmwv 2 wire cps with truck 3 wire. Save that sensor with the db2- folks want that stuff.

Leroy rents a primer tool, or buy a moroso unit that you can prime before every start.
I would get p400 heads over promax for sure! Not that much more expensive.

Getting the lower assembly balanced is worth the cost of shipping it to a shop- that balance makes a huge difference in longevity of the engine. Where are you at and maybe someone here can Recomend a machine shop not too far away from ya.

If you are 100% you are never going to go for big power- rethink the head studs. I have put together hundreds of 6.5s using NEW factory bolts and had no failures so long as boost was kept under 14psi. If you stick with the head studs- make sure you read up on options for sealing them from leaking- to many people learned the hard way the arp sealant tube goes in the trash.

Will, I appreciate all of that info. Kinda bummed about part of it, but at least I know. My main goal was to stay away from that business out of NY.

I'll get it pulled apart and then take some pics and post up for review on here. Hopefully we can make a diagnosis either way. Was hoping to be able to just run this short block as-is and keep the project moving forward at a good pace.
I'm located in Arkansas, so if anyone has a recommendation for a machine shop within driving distance, I'm all ears.

News to me on that part about the head studs, I'll be sure to research that and figure out the proper way to seal them up.

Dash gauges - I was really thinking that I could use the gauge cluster from the blue truck. I'm curious about the reason it won't work, and if there is any way to make it work!

Thanks

 

[adventr]

Ok, gonna be lots of pics from here on out. Haven't been inside of an engine in a number of years. Hoping you guys can take a look at these pics and help me out.

I'll just say that I have pretty low hopes for this engine now. Least I didn't pay $7500 for it. Lol





Got it home and unloaded and on the engine stand. My shop truck is actually a 98 model 6.5 truck. Was fitting to haul it home with it.
2000lb engine stand from HF actually works pretty good. It's beefy and doesn't flex with the 6.5 on it.












Immediately started tear down. Gotta know what's inside so I'll be able to sleep peacefully tonight..

 

[adventr]

Engine date code is "09 11 M". I believe that means 2005.

Lots of parts on the exterior of the engine had random loose bolts. Injector line nut was cracked. So far, everything inside appears to have been torqued. Well, it wasn't loose anyway.

 

[adventr]

Gonna get the other head pulled off, and then flip it and pull the pan tonight. Gonna know one way or another.

 

[DieselAmateur]

Welcome to the loony bin you're fitting right in!

Sounds like you have a good grasp of engines and electronics. If your mind is set on electronic injection I won't try to dissuade you, just know that the electronic DS4 IP is one of the more problematic elements of this engine and with Stanadyne ending production in 2020 parts will become rare/ obsolete.

If you're looking for genuine GEP parts source them from Chris @Twisted Steel Performance or John @uniquediesel. If you want ANY reputable machine work done I recommend Chris without hesitation. It cost me $230 to ship a crate P400 to him, cheaper than sending individual heads when it was all said and done. Even if you don't want any upgrades/ mods done it would be worth the piece of mind (in my opinion) to send a used engine to someone like him to check bores, bearings, tolerances etc to make sure everything is within spec.

If you want the best guarantee against crack- free heads, P400 heads are the way to go

also not sure where @Burning oil is at with the latest batch of timing gear sets, but consider a set too so you don't have to deal with timing chain slop ever again

 

[Will L.]

I am mighty concerned about the rust in there. Clean that up before spinning engine.
Is that an exhaust valve mark on the #1 piston?

Did you note which way the rocker push rods were facing? There is supposed to be a ring of paint on the upper end. It is important they go back in that way.

You can just throw away the old head bolts, They are one time use.

On the ip (injection pump) there is a blue id tag. Can you post a picture of that please?

Take note boys and girls, 2005 optimizer and diamond precups. This is GEP adding a turbo to previously non turbo hmmwv engines because they needed power.

 

[adventr]

I am mighty concerned about the rust in there. Clean that up before spinning engine.
Is that an exhaust valve mark on the #1 piston?

Did you note which way the rocker push rods were facing? There is supposed to be a ring of paint on the upper end. It is important they go back in that way.

You can just throw away the old head bolts, They are one time use.

On the ip (injection pump) there is a blue id tag. Can you post a picture of that please?

Take note boys and girls, 2005 optimizer and diamond precups. This is GEP adding a turbo to previously non turbo hmmwv engines because they needed power.

The amount of rust concerns me as well. Pretty obvious this thing has been sitting for a WHILE. I did pull the crank pulley and put a socket on the balancer bolt to see if it wanted to turn over at all. Granted I didn't put a lot of effort into it, but it sure didn't feel like it wanted to budge...

What you're seeing on the #1 piston was some kind of white residue (maybe calcium?) that wiped away with my glove. I noticed that after the pic and double checked it.

Yes sir, push rods have a gold colored ball on the end that was under the rocker arm. I made sure and place each push rod with it's corresponding rocker arm.

I'll snag a pic of that IP tag for you. Actually going to pull that thing off of there soon.


Just for my reference, when you say "diamond precups" are you referring to the diamond shaped International logo?





Here's a pic of the passenger side pistons after removing the head. Used some better lighting.

 

[adventr]

The valve covers and the oil pan were a bear to get off of there. Pretty sure I tweaked the valve covers in a few different spots trying to pry up so that I could get my razor blade in there. Hopefully the valve covers on the blue truck aren't glued on like these things were.

But, I managed to pull it apart. Here's what I'm looking at. To me, there does appear to be a lot of rust. Most seems to be surface, but I have no idea if that crap on the cylinder walls would clean up.
I'm sure this thing is gonna need pulled apart and at least re-honed and re-ringed.

I've taken pics of everything I could see with the engine in it's current rotation. I *think* i'm looking at the correct areas that are prone to cracking. Please tell me if I'm wrong.
I haven't seen anything that looks like cracking so far, but of course I can't see everything without being able to spin the engine.

Picture dump:

 

[adventr]

Rest of the pics:

 

[adventr]

What do you think should be my next step here? Calling it a night, but will get back at it tomorrow. I appreciate the help.

 

[MrMarty51]

Soak them pistons. Remove rod caps, see about shoving the pistons to the top of the bores then with the rods mostly out of the way, protect the rods so that the rods or bolts dont scar or mar the cranking shaft. Lift the crank then get a real good visual of the main bearing webs.
Looking at the highly visible webs, those look like they have not cracked. If the rest of them are that clean then I would say You have a block You might be able to work with.
Check that number 8 cylinder bore.
I dont know, of it is cracked or blowed through, it might be possible to sleeve that hole. Others with more knowledge on such matters should say yay or nay on that fix.
If You are planning on using those pistons, then, be sure to ream the ridge from the top of the cylinders before removing the pistons.
Ridges should be reamed before fitting pistons and rings back in.
I use a long feeler gauge and check the fit of the piston to the bore.
Then I decide if I will just rering the pistons or do a bore job.
I do not have a set of inside mics to measure bores with so the feeler gauge method seems to have worked well for me for a lot of years.
I also will use like a 0.010 over size rings on stock pistons, that too works well if the clearance of the piston to cylinder is to the outsr limits.

 

[ak diesel driver]

The diamond Will is referring to is the one stamped on the face of the precup

 

[Will L.]

Block looks good.
You have so much rust everywhere- just wow.
Take a salt shaker, shake it one time on the table and look how much salt is there. That same amount of rust is enough to ruin every bearing in four v8 engines. Now figure out how much rust would have run through that engine.
if you don’t do a complete tear down, clean and flush- that new engine would be toast. Think of why an oil filter has to be so perfect.

Removing valve covers and oil pan is best with a full metal tang 2” puddy knife. Use a hammer and drive it through and chase it all the around. They are only a couple bucks new and cheaper than buying a new set of covers.

Good to hear on the calcium on piston and push rods.

here is the precup with diamond identification.

 

[adventr]

Good to know on the precup! Have stumbled across that term in my research on these engines but never knew exactly what they were referring to.

Went back out in the garage and flipped the engine right side up. Sprayed a bunch of wd40 in the cylinders to soak overnight. Maybe that will help tomorrow during disassembly.

Speaking of, do you think I should disassemble the short block, or leave it together until I find a reputable machine shop and have them disassemble it? Not sure which is typically the preferred method.


Oh, and heres that pic of the injector pump tag for you :

 

[Will L.]

You should note the color by each main and rod bearing. The color indicates bearing size. But I still verify with a measurement of coarse.

I suspect the cylinder walls will be fine, but need checking. Start with a rag and some CLR cleaner. Get the rust out of the cylinders before rotating.
I tear it all apart. There is a lot you can do before it goes to machine shop.

Rust removal with evapo-rust or electrolysis- your choice. Then remove all the flashing is an easy diy item to be done before machine shop.

I meant to mention- I don’t see the point of the arp starter bolts. Get the gm ones. They work great and less money. Because you already have 2 starters on the trucks, you can run them and the brackets from them.

That db2 has potential to be rebuilt to a desirable unit. It might be good as it- but the amount of rust they let into the engine- and didn’t plug the fuel line so it’s a coin flip. Worthless or worth a hundred and a half (guessing at current value) as a rebuildable unit.
Right now all the 24volt stuff means only a hmmwv owner could use it.

your injectors should be tested before you use them, but should be set up at proper pressure for your use.

 

[ak diesel driver]

I'd disassemble it rather than pay a shop who won't care about parts. Get yourself a small log and carve on it until it's a pretty good fit to the top of the pistons. Then take a 2 or 3 pound hammer and start tapping on the top of the pistons, it will become evident pretty quickly which pistons are hanging up. Then concentrate more on those than the others but do continue to tap on them all. I've used diesel as a penetrant too. I've broke some loose that looked worse than that

 

[Will L.]

Yeah- AK DD nailed it- the money is a huge reason to do as much as possible yourself.

 

[WarWagon]

Found the cleanest 2000 Z71 model tahoe that I could.

Welcome from the end room down the hall at the asylum.

You see there is one thing to smite the 6.5L Diesel Gods ... Say by scrapping a somewhat rare for the day crew cab 6.5TD pickup. Then Murphy is going to have his way with you about the unreliable PMD/DS4 and no new head and rotors made for the DS4 anymore. They wore the tooling completely out I hear. Because there was never a "4 door Diesel factory option Tahoe/Yukon" you have discretion as to what you use.

The Ultimate Misery, Self Torture, S&M, is to inflict the DS4 PMD electronics on your project and constantly wonder "Did the damn thing ever work properly?" while it randomly fishbites just to test the sensors. and make you wonder if it was testing the sensors or is about to quit.

Then to pull a fairly reliable Gas engine out of the Tahoe for a 6.5TD.

Did the engine you got have anything more than "auction: Good Luck" as far as condition implied or paid for? It's been said that these engines make good Boat Anchors, however, the one you got has actually been used as a boat anchor! The 6.5 Gods are already onto you and your plans.

I would suggest you:
1) Get a good pair of walking shoes for getting the problems worked out of the swap.
2) Fix up the blue crew cab pickup with the 6.5TD as they are rare. (This may appease the 6.5L Gods so other crazy projects may continue.)
3) Just drive and enjoy the Tahoe: after all you need a parts runner vehicle

No really: anyone could just trip over the common as dirt Tahoes of this era as GM couldn't build them as fast as they were selling. Now how many of the Crew Cab pickups of this era do you see with any engine?

The DB2 Injection pump becomes 12V by removing the top cover with the 24V solenoids and dropping a 12V solenoid cover on it. Little trick to get the fuel metering valve not pinned WOT for a runaway condition is by bringing the cover down toward (the front of the engine) and then sliding the IP pump top cover back during install. Test with 12V for a "click". No Click means it ain't installed properly do not attempt to start or even rotate the engine by hand.

 

[MrMarty51]

And that CC truck looks to be in so much better condition than the rattle can that I have.
I bet that thing does not even have a squeak in it.
If it were closer, I would yank the engine and transmixer from My rattle can and bring the hull over for You to use up any way that You would like and haul away that wonderful looking truck that You have.
Does that have the bucket seats and center console or is it the 60/40 sort of a bencher like Mine.
I was really wanting the buckets and console but I had searched the CL adds and any other wehicle adds looking for the LB CC auto trans with a 6.5 for about four years and then this one appeared about 300 miles away so I went for it.
Dangnabbit, why does Arkansas have to be so far from Eastern Montana ?

 

[MrMarty51]

And yes, after having this LB truck, I now think that the SB would be easier to find parking spots for, so, I would even accept it with tje SB.