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Discussion Starter #1
Local seller has a 1994 ck2500 4x4 manual with the 6.5 swapped out for a 6.2, turbo brought over with. He says he tried to port the heads, screwed up and now they're shot.

I was going to call the seller today to get more information, first though I wanted to run a few questions by the crowd here.

First, are the 6.5 and 6.2 heads compatible? The local wrecker had a few diesels there although I think they were probably 6.5's. I realized when I got there and saw them that I have no idea how to differentiate them.

On that note, where are the engine and head codes located? Or is there a better way to differentiate a 6.5/6.2...

My understanding here is that I need to find out the block codes and head codes to make sure I get compatible replacements?

Lastly as I'm entirely new to these engines, is there anything i should be looking out for in particular with a swapped in 6.2? ( or on a 94 2500 4x4 for that matter ).
 

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R.I.P. Sam
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32,078 Posts
:welcome: colt

Here is a thread on what to look for in buying a truck. http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/345148-faq-purchasing-6-5l-diesel.html#post3615531

Honestly, the seller needs a better explanation on how his porting made the heads go bad, that's pretty hard to do.
The 6.2 and 6.5 heads are interchangeable, the ones from the early 90's were the same heads for both. Most 6.2 heads have a slightly different injector angle than the later ones and 6.5 ones. It allows the injector lines to clear the turbo manifold better. The injector lines can be carefully moved a bit to reach if the angle is wrong.
The only difference with 6.5 heads, is the precups installed in the heads usually have a larger opening for more fuelling for a turbo. 6.2 ones are smaller for better mileage, but none of this is really a concern.
 

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Mad (Sean) Max
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^^what he said^^
 

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What he said. But make sure the head type matches, ie. 6.2 heads or 6.5 heads and that the precups match from side to side. That's the important stuff.
 

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Let's take the Truck!
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:welcome: Being its a manual trans they may have went mechanical injection but if they kept the DS4 pump keep in mind for 94 obd1 you will need to purchase GMTD Scantech software to relearn the tdco. $160 investment but necessary unless you know someone with a Tech 2 scanner. Interchangeabilty of the heads these guys have you covered. The block id is on the leaf rear upper where the bellhousing bolts up. Will end with 141 or 660 maybe. 599?
 

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respect the DB4 5722....
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:welcome: colt

Here is a thread on what to look for in buying a truck. http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/345148-faq-purchasing-6-5l-diesel.html#post3615531

Honestly, the seller needs a better explanation on how his porting made the heads go bad, that's pretty hard to do.
The 6.2 and 6.5 heads are interchangeable, the ones from the early 90's were the same heads for both. Most 6.2 heads have a slightly different injector angle than the later ones and 6.5 ones. It allows the injector lines to clear the turbo manifold better. The injector lines can be carefully moved a bit to reach if the angle is wrong.
The only difference with 6.5 heads, is the precups installed in the heads usually have a larger opening for more fuelling for a turbo. 6.2 ones are smaller for better mileage, but none of this is really a concern.
really the only way to ruin porting heads would be if too much was removed, and now coolant is getting into the engine, or boost is pressurizing the cooling system, if it was the latter, could be just a blown, or poorly installed head gasket...:confuzeld
 

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Discussion Starter #7
Hey Everyone, thanks for the replies!

I'm not too worried about scan tools, a friend of mine inhereted the brand new never used OBD1 setup from the high school we both went too when they shut down their automotive classes to expand band class. I recall him saying it had cartridge inserts for most any make, should be something in there for GM.

This does give me all the info I need to proceed, I'll definitely try and get more info out of the seller about how he borked some iron heads...
 
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