A good deal gone wrong..my 1985 k10 diesel build.

[ol'blazer]

I bought this 1985 k10 as a work truck, i paid 800 for it and it ran nice and drove the day i looked.. but when i got home and started going through the truck that i found that the temperature quage was either running cool or over heating. when i checked the coolant i found that it kept blowing back through the rad. I have a blown head gasket, or cracked head.. i guess i should have gone through the truck a little better before buying it....
anyway i decided to make this truck into my winter project and fix the head gasket and/or head. add a 6.5 turbo with about 7-8 psi, and make it pretty!

[ol'blazer]

i started today by clearing some of the accessories out of the way.. not huge progress!

[bnoon]

You know we can't see your google email attachments right?

[Corts60]

I would never buy a GM diesel without being very, very thorough. Especially at a dirt cheap price. The old saying: if it sounds too good to be true, it usually is.

[ol'blazer]

Originally Posted by bnoon

You know we can't see your google email attachments right?

sorry guys!

Originally Posted by Corts60

I would never buy a GM diesel without being very, very thorough. Especially at a dirt cheap price. The old saying: if it sounds too good to be true, it usually is.

to be honest i really wanted to build a k10. and this one came up for an alright deal..if i couldn't fix he 6.2 i wouldn't hesitate to do a 350 or ls swap.

[ol'blazer]

I also picked up a gm3 turbo set up for a 6.5, i paid 150 for everything. doesnt have shaft play, seems like an okay deal!

[ol'blazer]

started the engine tear down.


someone really went to town tightening the injector lines.. a few of the injectors started to twist out before the line!


i bought all these shocks from the shop i work at. they have been laying around for years so my boss told me to take them all for 65$. i should be able to make a set work for my truck!



someone "re wired" my glow plugs.. and this is what i found under the loom lucky the truck didn't burn down!

[ol'blazer]

not huge progress.. got a boost gauge and pulled the exhaust manifolds

[bnoon]

I'm sure getting those manifolds off was a treat! Making good progress.

[ol'blazer]

Originally Posted by bnoon

I'm sure getting those manifolds off was a treat! Making good progress.

I was dreeding pulling them, but someone had them off at one point and anti seized the threads do they came out fairly easy!

[ol'blazer]

tonight i pulled off the valve covers, rockers and pushrods. everything looked really good and extremely clean!. zero sludge build up!




everything looked very good.... that was until i found this unpleasant surprise..




the tip of one of my pushrods broke off and stayed in the rocker. i see this as a good opportunity to change out my rods and rockers from a set from a 6.5.
i heard the 6.5 rockers where steel, not cast iron, and had better oil ports.

[ol'blazer]

got a bit done tonight, first i found a ton of old filters at the shop i work at and my boss told me to just take them all. out of all of them six will work on my truck.


also got the right head off.. i was looking forward to kicking back and tinkering with my truck tonight.. but pulling the head was a work out!



i am continuously surprised at how clean this engine is. i haven't found any carbon build up on any of the valves or pistons!

[93M6Formula]

Only the early 82-84ish got the cast iron rockers. I personally believe they are stronger and more durable and actually swapped them onto my first 6.5 after a stamped rocker got a hole warn into it. The stamped steel rockers from 85-02 6.2/6.5s are usually okay though but they have those plastic buttons that tend to give out. A good fix while you have it apart is to put a bolt and a lock nut in it's place so you don't have to worry about those plastic buttons breaking.

[ol'blazer]

pulled the left head off the truck tonight...found my problem..not exactly the ideal outcome...




i was hopping it was only a head gasket, but i know its a cracked head.. so now i guess its time to price out the cost of used, machining, or my other options..

[ol'blazer]

did some research and measurements tonight. turns out 82-83 6.2 diesels had larger exhaust valves that later models. these larger valves made the casting between them lighter, they were known for cracking between the valves just like mine. when i measured my valves they were the 1.93 large ones.

while i had the caliper out i measured my cylinders. turns out my cylinder bore is 0.020 over.

so here is my theory, at some point the engine in this truck was wrecked. so someone built an engine from a 82-83 and dropped it in my truck before the heads cracked.

[68Timber]

One vote here to fix it and add the 6.5 turbo.

[Oregoon]

Keep at it! The 6.5s were good motors, and the 6.2 can be built properly and will last a good long time.

Hey, you're this far, right?

[slotard]

What're your plans? Find a good head/heads? New engine? If so, gas or diesel? A 4BT swap might be a reasonable way to go if you're putting something else in there.

[ol'blazer]

Originally Posted by BRUISER

One vote here to fix it and add the 6.5 turbo.

I think I would be different from the standard small block or big block, nothing against them!

Originally Posted by Oregoon

Keep at it! The 6.5s were good motors, and the 6.2 can be built properly and will last a good long time.

Hey, you're this far, right?

I agree, now that I know what's wrong with the engine I would be kicking myself if I scrapped this engine

[Corts60]

Those cracks aren't necessarily your problem. There shouldn't be any coolant passages right there between the valves so it is unlikely you were getting water in from those cracks.

Oldsmobile diesels are known to crack between the valves as well but will continue to run forever. Both heads on my truck are cracked between damn near every valve. Doesn't give me one issue. Not sure if the 6.2/6.5 do the same thing or not.

[ol'blazer]

Originally Posted by Corts60

Those cracks aren't necessarily your problem. There shouldn't be any coolant passages right there between the valves so it is unlikely you were getting water in from those cracks.

Oldsmobile diesels are known to crack between the valves as well but will continue to run forever. Both heads on my truck are cracked between damn near every valve. Doesn't give me one issue. Not sure if the 6.2/6.5 do the same thing or not.

I've been doing some research for the last day. i have heard that majority of the time the cracks don't lead to any issues. the only way i will know for sure is to either put another set of heads on the engine and cross my fingers, or pay to get my heads pressure tested.

a part of me just wants to ditch the 6.2 and put in a 350 that i know is a strong runner.

[ol'blazer]

Doing some more research tonight, I found out that if the cracks start from the seat, they usually move towards the valve guide. There is a water jacket there and that would cause my problem.

[ol'blazer]

Originally Posted by slotard

What're your plans? Find a good head/heads? New engine? If so, gas or diesel? A 4BT swap might be a reasonable way to go if you're putting something else in there.

to be honest im just going to roll with it for now. I'm going to start with a set of good used heads. if that doesn't solve my issue i don't know if i want to stick with the 6.2. i was actually thinking about a 4bt, but other than the mpg, i would be better off going with the 6bt. i was thinking about building a small block for it, but i dont know if i want another small block truck. Im just going to start with the heads though.

[ol'blazer]

merry Christmas! my dad got me some parts for Christmas,
rockers and cab corner panels, head bolts, gasket set, and an electric fuel pump to bypass the diafram pump.

[MalibuSSwagon]

Look around your local area, check CL, etc. There was a guy selling NOS Military surplus heads for GM 6.2L, still wrapped in wax paper in the crate. I think he might have been selling them for $400 a set? Can't find his ads anymore but you may find a similar deal in your area.