6.5 to 6.2 swap-info needed!

[bubble-city]

It has been a few years since I owned a GM diesel, and I'm ready for another one. I can get a great deal on a 1995 Crew Cab dually, 6.5 turbo, with a broken crankshaft, and 205k miles. I am looking for some suggestions/options for repair. I have a 1982 6.2 that I saved from my previous truck that had a cracked head. I also have a 1984 6.2 in a G30 van, with only 108k and a bad injector pump. I assume that the crankshaft from the 1982 engine will not work due to the one piece rear main on the newer engines? Is it possible to replace the 6.5 long block with the 6.2 from the 1984 van? If not, what about using the 6.2 shortblock and 6.5 heads? The 1995 truck has not been abused, but it has seen many miles pulling trailers. I am a little leary of spending the money replacing the crankshaft since the engine has 200k on it already. The 1984 van was my daily driver until the pump went out, and at 108k should outlast the truck. I am trying to do this as economically as possible. What would you do?

[redbird2]

First off you can out the heads from a 6.5 on a 6.2 block, as you stated and you are correct you can not switch the cranks due to the rear seal change. The 6.2 heads could be differant on the van motor you need to check the end bolts that hold the intake on to the heads look at the angle they are drilled to see if they are the same, the other thing could be the thread pitch of the injectors where they screw into the head the older heads (dont remimber the year break) had coarse threads new heads fine threads.

I have purchased remained cranks from napa in the past for some wherfe in the 250.00 range came with new bearings just idea. good luck

[bubble-city]

Thanks. Prices on cranks are about the same here, plus another $50-80 if the old one is broken. I didn't want to spend the money on a different crank, though, unless it was my only option. The 1984 van is worthless, except for the good engine, so I'd like to go that route if I can. If I have to use the 6.5 heads on the 6.2 block, that would be o/k. They are probably designed a little better, since they are 11 years newer. Any other differences you can think of?

[dalpil]

I just went through this with my 94 gmc 3500 dually. I had a cracked 6.5 and got a "great" deal on a rebuilt '82 6.2. I was told everything would bolt up and it's true. I don't know what heads I have but the 6.2 came with a factory turbo setup on it. Here's what I learned the very hard and expensive way: you have to switch everything over for the serpentine setup including the timing set cover and water pump. It turns the opposite direction from the original. You have to switch over the crank position sensor, the vacuum pump, the electronic fuel injection pump. After everythings installed you have to do a tdc relearn to set your injection timing. It has to be done with a gm scan tool - either yourself or a dealership. After it's timed and running right, you have to get the boost and pyrometer guage set, because the pistons will melt if you run a stock 6.2 over 1100 deg. f. You can get to 1100 deg. empty not pulling anything with the stock 2 3/4" exhaust. Have to go to at least a 4" free flow just to perform nearly like the orig. 6.5. If anyone would have told me all of this before I started I would have realized that you will spend the same amount for a rebuilt 6.5 block. I have been working out these kinks since thanksgiving last year. So yes, you can run a 6.2 in a 6.5 truck, but it's no cheap date. I'm hoping the 6.2 will hold up better than the 6.5, I think they have less of a tendency to crack - at least that's what I've told myself since I've spent money like a drunken sailor since I turned the first wrench. Have fun!

[dalpil]

Oh yeah, I almost forgot, on a hard pull up a long hill, if your rpm's stay at 2800 + for more than a few seconds you get a ses light - which is a wastegate fault. I haven't even started to resolve this yet, it wasn't the actuator and I have enough vacuum. Might need a manual boost control, haven't taught myself enough about that yet.

[jeffscarstrucks]

Is it a good idea to try to install the 92-93 non electronic pump set-up in this situation? Jeff

[Bnave95]

Oh yeah, I almost forgot, on a hard pull up a long hill, if your rpm's stay at 2800 + for more than a few seconds you get a ses light - which is a wastegate fault. I haven't even started to resolve this yet, it wasn't the actuator and I have enough vacuum. Might need a manual boost control, haven't taught myself enough about that yet.
When this happen does it smoke?
This could just be a small vaccum leak in the hose system. If you have boost but loose it,look at the rubber parts that come from the Vac. pump. Check the boot at the waste gate for cracks,splits.

[bubble-city]

dalpil, Thanks for the info. I had already figured on switching everything external over from the 6.5, using just the long or short block. My main concern, other than exchangability, was if the older 6.2 would hold up with the turbo. Based on your experience, it sounds like it may, but I will have to be more carefull than I would like to not melt it! Looks like I will be fixing or replacing the 6.5, and will have a spare 6.2 in the garage.
Thanks, Mike.
p.s. When does the "newbie" disappear? I have visited this site many times, and was a paid subscriber when I had my last diesel truck. Just curious!

[DmaxMaverick]

......p.s. When does the "newbie" disappear? I have visited this site many times, and was a paid subscriber when I had my last diesel truck. Just curious!
Once you have 10 posts, it'll change to "Contributor", not that you haven't been contributing. We have members that have been around for over 5 years, never having made a post, or very few, and they are still "Newbies". Don't sweat it. Doesn't mean a thing. If you don't like it, change it. The user titles can be changed in your user profile settings.

[dalpil]

Thanks Bnave95,
I don't get any more or less smoke when the wastegate fault occurs. Before I got the bigger exhaust it actually seemed like the computer "disabled" the turbo. When it would happen and I was backing off the throttle to stay under 1100 deg., after the fault occurred the exhaust gas temps would automatically drop to 8 or 900 and not build any higher. I lost power and I'd be running with my flashers on 'cause I was getting passed by nuns in station wagons. If I turn the ignition to off and restart the engine the light is gone and my temps will rise like before. After the 4" exhaust things got alot better, but I still can set that code if I really work at it.

[4348rd]

Is it a good idea to try to install the 92-93 non electronic pump set-up in this situation? Jeff
that's the truth , stop all the stalling