can a 6.2 replace a 6.5t? how practical?

[sak778]

Greetings Friends,
I have a 94 gmc 2500 with a 6.5T 4l80e 4x4. Can i put a 6.2 out of an 80's suburban into it? What will I have to reuse? I know i need to keep the electronic injection pump with the pmd, shorter injectors and lines and manifolds and intake.
Will the 6.2 work with the turbo? will all my accessories bolt on? My 6.5 block is broke/missing around the starter bolts. Thats how I got it. Yes a have got the bolt on brace.
Any other options I should look at? I'm new to the 6.2's and 6.5t's but i've had a 7.3 powerstroke and a 6.9 idi ford.
What are the differences between an 83 and an 87 6.2na? these are my choices to replace my 94 6.5t. The 6.5t in my truck is also doing the dissappearing coolant trick. Soooo I'm thinking thad one or both of my heads are cracked.
Soooo is using the 6.2 heads out of the question? I just got laid off so money is tight. But I also bought a used tested pmd and a new extension cabel so I can get it off the intake manifold. So I will spend money where it's needed. suggestions, reccomendations? Thanks, Sean

YMMV

[Robyn]

Hi there

What you want to do is quite easily accomplished, and in fact I am doing the same thing for my 1995 GMC Dually CC 4x4

The 6.2 is essentially the same as the 6.5 with the exception of the bore.

To install the 6.2 (early engine of say 1982-1988 production) into your 1994 truck, here is what you need to do.

The later 6.5 heads must be used.
If the 6.2 is an early one with the two piece rear main seal, then you must use an oil pan from the 1988 to 1990 vintage 6.2 engine that was installed in the GMT 400 style trucks ( 88 and later pickups)

***Note***
These pans have the same sump configuration that will clear the IFS differential but have the slightly different rear arch over the rear main to fi the older style two piece rear main seal main cap.

OK
Now the timing cover along with the crank sensor off the 6.5 must be used and the crank sprocket that has the reluctor.

You must also use the 6.5 dampener too.

The entire accessories package will bolt right onto the 6.2

Use the 6.5 water pump (Must use this)

Before you remove the IP from the timing cover, mark the IP and the cover so the IP can be put back precisely where it came off. (makes life easier)

The intake, fuel lines and injectors are all usuable as are the Valve covers and other tid bits.

You will need to relocate the oil feed for the turbo as the 6.2 does not have an oil passage on the RH front of the block.

You can either T off the oil pressure switch fitting or use the port thats between the two oil cooler lines.

The 94 6.5 used 3/8 bolts for the bell housing as do the older 6.2 engines.

All the rest of the goodies will bolt right onto the 6.2

Keep in mind that the pistons in the 6.2 do not have a coated top, so its a grand idea to keep the exhaust temps no higher than a max of 1000F pre turbo (at the ports)

The older 6.2 engines were routinely fitted with the Banks turbo system and had the Hell ran out of them and lived just fine.

You will likely not even notice the difference in the loss of the few cubes between the 379 (6.2) and the 395 (6.5) (16 cubic inches)

Now if your loosing coolant, I would get your old engine out and yank the heads off, as its very likely that its just a head gasket issue thats causing the troubles.

200K miles or so is sort of a magic threshold that the gaskets start going away at.

Dont toss the old girl out yet.


Once the heads are off, clean the decks really well and examine the area around the number one and two cylinders.. (two front ones)

It is common to see erossion in the deck around the fire rings. More than just some discoloration ( an actual groove) must see the decks machined .010" and the thicker gaskets used.

Head gasket issues is likely the issue me thinks.

The heads can crack on these. Any cracks onto the fire deck of the head renders it JUNK the precups can crack around the ports. As long as the cracks are not longer than 3/16 and or do not cross the fire ring they are fine.

Cracks between the valves is normal but can go into water at times.

If in doubt, have the heads pressure tested.


Good luck and keep us posted.


Missy