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Calling all 6.2/6.5 gurus

J

Jake907

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Hi folks, I’m looking for a few good gurus to help me with my project. I have an ‘89 GM diesel crew cab. She spent many years as a fleet vehicle for a pipeline service company, then went through half a dozen private owners before I rescued her.

I was told she had an 6.2L originally, and that later there was a crack in the block and they ordered a new block, and that at that time GM had discontinued the 6.2 and instead sent them a 6.5 block and were told that everything would bolt on and run just fine. So if all that is true then I have a 6.5L N/A all mechanical engine.

So the other day a guy at work sold me a mostly complete 6.5L from a mid 90’s truck, so that I could use it as a donor. I want to turbo charge my engine, and move over the serpentine setup.

My questions:
1. Can I use my original mechanical pump with the turbo? Why or why not?

2. I understand there is a difference in injector height, I believe I put the shorter ones in my truck already as I was wanting to do this mod back then like 5 years ago. Is that the only difference, or is there fuel volume/pattern/pressure/etc. difference as well?

3. What are the questions I should be asking that I’m not thinking of?

Thanks guys. I appreciate any and all feedback.

JakeD0225E6B-5A02-4AC4-BBBA-66D296EF0D64.jpeg
 
So turbo won't be a problem you'll just need to make or buy a turbomaster. Injectors won't be an issue since you already have short ones. But if you're using the turbo exhaust manifolds even the length won't matter. Biggest issue is AC if you have it. The stock manifolds and turbo won't clear your AC.
 
ak diesel driver said:
So turbo won't be a problem you'll just need to make or buy a turbomaster. Injectors won't be an issue since you already have short ones. But if you're using the turbo exhaust manifolds even the length won't matter. Biggest issue is AC if you have it. The stock manifolds and turbo won't clear your AC.
Click to expand...
Thank you. I don’t have A/C. But I’m planning to add an aftermarket. If I don’t have time for that then the serpentine will just have to run a dummy pulley in that spot.

Also I meant to say injection pump, can I run my mechanical injection pump with the turbo without changing injectors?

So, what is a turbo master? Can you send me to a thread or a link?
 
Welcome to the forum Jake

Question- are you thinking of adding the turbo from the donor engine to your current setup, or swapping in the complete donor engine?

I am no guru, but thought there was a difference between N/A pistons and turbo'd pistons. As in turbo had some sort of heat treating to account for higher boost and combustion temperatures. Do you know if the 6.5 block sent to replace the 6.2 was spec'd for a turbo or not? This detail may be important to whether you're doing an engine swap or just adding a turbo. Clear as mud?

You can use the mechanical pump and for many this is the preferable path. Fewer electronics = fewer headaches

Take some time to read through the stickies and whatnot, there's a wealth of information on here that goes over things like the turbo master and such. Depending on what you want to do with the truck there's way better options out there than stock

I'd also recommend upgrading the water pump as even your mid 90s donor engine probably doesn't have the high output water pump.
 
DieselAmateur said:
Welcome to the forum Jake

Question- are you thinking of adding the turbo from the donor engine to your current setup, or swapping in the complete donor engine?

I am no guru, but thought there was a difference between N/A pistons and turbo'd pistons. As in turbo had some sort of heat treating to account for higher boost and combustion temperatures. Do you know if the 6.5 block sent to replace the 6.2 was spec'd for a turbo or not? This detail may be important to whether you're doing an engine swap or just adding a turbo. Clear as mud?

You can use the mechanical pump and for many this is the preferable path. Fewer electronics = fewer headaches

Take some time to read through the stickies and whatnot, there's a wealth of information on here that goes over things like the turbo master and such. Depending on what you want to do with the truck there's way better options out there than stock

I'd also recommend upgrading the water pump as even your mid 90s donor engine probably doesn't have the high output water pump.
Click to expand...
Ah, that’s interesting, I haven’t heard anyone mention a difference in the pistons yet. I’ll have to look into that. Thank you.

I’m not sure exactly what I’m doing yet, I like the old engine because it’s shown me to be reliable and I don’t know the history of the new one.

One thought I had was I could pull the old old one, rebuild it, add the stuff I want from the new engine and stuff it back in. Scrap the donor and move on with life.

I’ll look into the hi volume water pump thank you.
 
The pistons are fine. They are just slightly larger diameter. Newer blocks have the oil cooler ports to help cool the pistons and you might have that depending which 6.5 you got. You need to keep the boost at 11 and keep engine temp under control and all will be happy.


Yes mechanical ip (injection pump) is great with the turbo. Many of us (ME included) only will run a mechanical ip. And I added a turbo to my original n/a truck and hummer many times. Because it comes with the gm turbo- run it. Later consider a better turbo because the gm is a pos.

The v belt system is annoying for a couple issue like finding belts sometimes. Other than that and annoying to adjust the belts, it is better. You could keep the waterpump you have because the v belt pumps are balanced flow. Then you could add the Hmmwv fanclutch if you want for even better cooling easy.

My best suggestion is add the turbo and leave the rest. Turn up the fuel screw in the ip to feed the turbo. Drive it and see how ya like that. Later rebuilding the injectors to the higher pop pressure can help but isn’t a requirement.

It helps us all if you add the truck details and the donor parts in your Signature. Look below where everyone is typing and you will see the truck details- we don’t type that each time it is there automatically in the signature line :
 
Will L. said:
The pistons are fine. They are just slightly larger diameter. Newer blocks have the oil cooler ports to help cool the pistons and you might have that depending which 6.5 you got. You need to keep the boost at 11 and keep engine temp under control and all will be happy.


Yes mechanical ip (injection pump) is great with the turbo. Many of us (ME included) only will run a mechanical ip. And I added a turbo to my original n/a truck and hummer many times. Because it comes with the gm turbo- run it. Later consider a better turbo because the gm is a pos.

The v belt system is annoying for a couple issue like finding belts sometimes. Other than that and annoying to adjust the belts, it is better. You could keep the waterpump you have because the v belt pumps are balanced flow. Then you could add the Hmmwv fanclutch if you want for even better cooling easy.

My best suggestion is add the turbo and leave the rest. Turn up the fuel screw in the ip to feed the turbo. Drive it and see how ya like that. Later rebuilding the injectors to the higher pop pressure can help but isn’t a requirement.

It helps us all if you add the truck details and the donor parts in your Signature. Look below where everyone is typing and you will see the truck details- we don’t type that each time it is there automatically in the signature line :
Click to expand...
Thank you for all the info sir. I like the idea of just putting the turbo on there and call it a day.

Do you have a link for that hummer fan clutch, I like the sound of that. I don’t like how high the temp gets before the fan engages.

Also, thank you for the link to the turbo master.
 
Before doing a roadtrip with this unit, check out the fluid dampener on the leroy diesel website. He is one of the sponsors of this forum.
The fluid dampener just might save You from a busted crankshaft.
If a fluid dampener is not affordable, check Your current harmonic balancer and if it appears to be at all questionable, replace it with another Delco balancer. The front pulley too. The pulley is rubber mounted too and can come apart and cause vibration issues thats tough on crank shafts too.
 
There is a thread on here of a guy with a suburban that put it on diy.
Buying parts from ebay. I am bad at searches- can someone post a link please for him?

What you should do imo is first post a picture of your thermostat crossover. If it is not a block off style- that has to be corrected. Then put in a 180 stat. Keep your 190 for living in AK.

Get an aftermarket temperature gauge installed in the rear passenger side head. That is your engine saver. 200 is ok, 210 watch the gauge more than the road, 220 pull over immediately and let it idle to cool off. You will hear higher numbers are ok, but not from people who get 300,000 miles from these. The military says 230 & 240 is ok, but they put in new engines at 25,000 miles all the time.

New AC Delco harmonic balancer and pulley every 100,000 miles- never use the cheap ones they fail in 30,000 miles. Or spend more money and get the fluidampr and it works better and lasts forever.
Upgrade your oil cooler lines- they fail and engine is trash. Leroy and others sell a kit- hmmwvs use regular hydraulic hoses that outlast the engine but you need a different cooler for that.

Check starter for front bracket- missing it will cause broken block.

These are the most critical items to do for long life of the engine.
 
You do need to add a boost gauge with the turbo, and an egt gauge.

Keep your boost at 11-12 psi and you should never have a problem. But keep in mind if you set the adjustment to that when the truck is empty on flat ground, it will build kore boost when the truck is loaded heavy and pulling a hill. Easy to adjust, no worries.
 
Will L. said:
There is a thread on here of a guy with a suburban that put it on diy.
Buying parts from ebay. I am bad at searches- can someone post a link please for him?

What you should do imo is first post a picture of your thermostat crossover. If it is not a block off style- that has to be corrected. Then put in a 180 stat. Keep your 190 for living in AK.

Get an aftermarket temperature gauge installed in the rear passenger side head. That is your engine saver. 200 is ok, 210 watch the gauge more than the road, 220 pull over immediately and let it idle to cool off. You will hear higher numbers are ok, but not from people who get 300,000 miles from these. The military says 230 & 240 is ok, but they put in new engines at 25,000 miles all the time.

New AC Delco harmonic balancer and pulley every 100,000 miles- never use the cheap ones they fail in 30,000 miles. Or spend more money and get the fluidampr and it works better and lasts forever.
Upgrade your oil cooler lines- they fail and engine is trash. Leroy and others sell a kit- hmmwvs use regular hydraulic hoses that outlast the engine but you need a different cooler for that.

Check starter for front bracket- missing it will cause broken block.

These are the most critical items to do for long life of the engine.
Click to expand...

I did that with the original cooler, the hyd. lines had compression fittings that went on the oil cooler lines which I cut the ends off. There is a reference to it in the Reference Library.

I can't bring anything up there anymore.


DIY Oil Cooler Lines (Small Lines)

I got the hose and fittings at our local Bumper to Bumper/ tire shop/ farm supply place. Castor is a small town so one store supplies many things. The hose is 1/2" double braid hyd. hose. The block 90* fittings have 3/8" male npt. on one end and 1/2" JIC. on the other end(part # JCM06-NPM08)...
www.thetruckstop.us
 
Last edited:
ak diesel driver said:
So turbo won't be a problem you'll just need to make or buy a turbomaster. Injectors won't be an issue since you already have short ones. But if you're using the turbo exhaust manifolds even the length won't matter. Biggest issue is AC if you have it. The stock manifolds and turbo won't clear your AC.
Click to expand...
Is that true on a 1989?

My 1989 C2500 was GMT400.

Adding AC and cruise control were the first things done to it. In about 1990.

I never added a turbo. The 6.2 lasted around 300,000 miles and was replaced with a GM crate 6.5.
It seems all we had to change was the injection lines. - would that be correct?
 
Guys, little update. I got looking at the donor engine, and it has several of the upgrades y’all have mentioned that I should do. It has the red turbo controller from Leroy’s, the fluid dampener from Leroy’s, and I think it has the hummer fan/clutch. I definitely need to dig in and see what else it has to offer. Might end up putting this beast in my truck instead of swapping parts.

If you had to take an unknown engine that showed up in a ball of dust and oil and try to determine if it’s reliable. What would you check?
 
Be a terrible lot of work to install the engine not knowing its condition to find it has cracked heads, blowed head gaskets or some other unforseeable catastrophic failure.
With it out of chassis, pop the rocker covers and see what the rocker spacer buttons look like. Cant tell much else from up there though.
One of those small bore camera scopes would maybe show if there is anything unusual in the cylinder walls.
But yeah, first get the engine solid and crankable. Do that compression test.
 
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