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Rings and bearings while I have the engine out?

M

mjmmjm

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Hi, all. I've got combustion gases in my coolant, so I'm pulling the engine (in my sig) to replace the gaskets and get the heads checked. This stock engine has about 260k miles on it - a GM-installed replacement after the factory engine blew at 90k. I'm the third owner and would be surprised if the rings and bearings weren't factory. I'm wondering whether I should brave it myself - never done that work before. There's some rod knock or maybe piston slap. While I have it out on the stand, would it be worth it for a newb to check the rod bearings? Is it even possible to check them without having to replace them after removing the caps? If yes, I'd like to re-ring it too. I've heard both cautionary tales and encouragement to dig into it. This is not my daily driver but only a snow vehicle and short-distance materials hauler. Opinions? Tell me if I'm not including enough info. Thanks in advance.
 
On the 6.5 there is multiple issues that can occur. When together & running it’s almost always a case of leave the inside alone unless you do it all.

In this situation- pull the engine and inspect everything very well before you spend a single dollar.
Heads crack between valves. cylinder walls crack mostly #8 then #7. Block main webs crack into the main cap bolts. These are the big fears and can be fixed but more often are simply replacing the block. The heads depending the situation- but adding the brass tube inserts has become my vote of just do it before the problem comes up.

It is possible to find descent take outs from hmmwvs at auction but in that case understand they probably been overheated already so tear down from day one is still recommended.

When you find a good 6.2/6.5 or when you modify one into a great one with the he corrections-they become a really good engine with acceptable cost and power output. But random finding one is a coin flip.

Tear it all down, post tons of pics as you go.
I like to do a couple things before tear down when possible.
Water mist into intake to clean out the carbon then do a compression check.
These carbon thing is mostly a time saver.
The compression is just to know so when you look at things later and see problems you learn what is what.

Figure your budget before you begin.
 
@mjmmjm
After getting the engine out of My truck, finding the heads was cracked beyond what I was comfortable doing the lock&Stitch crack repair, then, the price of new heads, pistons, bearings, gaskets, machine shop charges for boring, it was getting mighty close to the price of the new Optimizer GEP engine from Quadstar tuning or Leroy Diesel.
The next thing to look out for, is Your current block cracked at the main bearing webs.
If so then the new engine, or a military take out, is the best two options.
 
Is your rig in good enough shape to justify the cost of a new engine? Do you need it enough? It’s an uninsurable risk of new engine cash sunk into it after a short time if the rig burns down or gets stolen.

Used military engines are, well the good ones, are scarce now. Most are scrap metal burnt out hulks of GM’s Disposable Diesel 6.2/6.5 engine. Look for a Military Blazer 6.2 engine perhaps still in one. I had luck with a couple 6.2’s with the 6.5 stuff bolted on. I also got a Iraq Dessert Sand filed scrap engine and one that needed a rebuild with a cracked cam bearing (low oil pressure).

Other budget options are dropping a 454 in it.

Some of us have pushed a main web cracked block as far as it would go.
 
WarWagon said:
Some of us have pushed a main web cracked block as far as it would go.
Click to expand...
This was my plan with that 6.2 I picked up for almost nothing. it runs but the main webs are cracked pretty bad. I might still consider doing it but I don't trust the IP that's on it. at idle it lops and throws black smoke out the exhaust. throttling it up and it clears up only to go back to idling doing the same thing.

what I don't know is if the IP that's on the 6.5 which has already been monkeyed with and turned up would work on it or I would need to get another that was setup for a 6.2. I need some contacts that could get their hands on a cheap good but used db2 and I would probably get this 6.2 ready to drop into the 93.
 
dbrannon79 said:
what I don't know is if the IP that's on the 6.5 which has already been monkeyed with and turned up would work on it
Click to expand...

A 6.5 is a punched out 6.2, period. With the same turbo setup off a 6.5 slapped on it should run the same. The precups do make a difference. But as long as it’s not the delivery van econo NA cups it’s fine.

You can turn down the 6.5 pump easily enough.

I would keep looking for a better engine block or consider a gasoline engine conversion. It’s a lot of labor and expendable parts like gaskets to drop a known bad block in.

The one I ran wasn’t cracked more than two webs on one side and not far if I remember correctly. The overspeed during an emissions Snap test is likely to blame for further cracking if not just the normal progression of main web cracks.
 
I did run across a 6.5 on the car-part.com site listed for $2300 but I think it was out of state. That site is a collection of JY’s that list their inventory online. It was out of a 2002 or some such iirc. That might be a viable option but I doubt they will drop the pan for me. Most of those listed offer a 6 month or 1 year warranty but you can’t open the engine up. I will keep my eyes pealed while I save up some funds. I’m sure I could possibly get away with a quick hone and replacement pistons in the one I have and make it better than it is now. I had a plan for just a re-ring job till I realized it ate a GP on at least two cylinders. I’m fairly certain those pistons have pinched and stuck rings causing all the blow by and low compression.

It will last me another year like this I’m sure, I only put 4k miles on it this past year so it’s not like it works very hard LOL
 
Yes, that is why Rocker arms will move more than others, because of the tension from the camshaft in the springs.

However, I would replace those plastic pushpins at a minimum. Better yet is doing the modification of replacing them with a bolt and a mechanical lock nut. Best option if you can afford it is to install the Harland Sharp robber arms.

DO NOT LEAVE YOUR EXISTING PLASTIC RETAINERS. I can see movement in a few of them and when they break, you will do some internal damage. Sometimes loose the entire engine.
 
I got the pistons out. All the upper bearings show copper like the one in the photo. I also have a few nicks on the crank - I know I did two of them. Am I looking at getting the crank polished, or can I gently smooth them out? I don't intend to keep my rig forever and don't use it much or really push it.

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PXL_20250328_224710592.PORTRAIT (Large).jpg

PXL_20250328_224721793.PORTRAIT (Large).jpg
 
Have it polished & see how far it would have to go to fix the nicks.

When removing or installing conn rods- put rubber or plastic protectors over the rod bolts- few bucks is a smart investment.

Are you balancing the rotating assembly? A wise investment if you can afford it. When they do this usually a crank polish is a tiny add on.
 
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