Rings and bearings while I have the engine out?

[malpana]

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.

[More Power]

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.

My guess is that your engine has a head gasket leak. I'd pull the heads to evaluate, and only then make any plans to go further. Your engine may not need anything else - if it's received reasonable service. If you decide to go further, this forum will help. I've written about the main/rod bearing replacement, piston replacement and a host of other stuff.

Jim

[malpana]

Thanks, Jim. I winced when I started losing cabin heat and much of my coolant blowing out the reservoir. A chem test confirmed the leak. I resigned myself to doing the head gaskets and am starting to wonder whether the knock/slap might be a sign the rod bearings need replacing. I'd re-ring it while I had the caps off. Is there a way to check the bearings without removing the caps? If not, would removing the caps make it necessary to replace them anyway?

[DmaxMaverick]

I agree, likely a head gasket failure. Less likely could be a cracked block/cylinder.

If you're only doing head gaskets, while they are easier to do with the engine out of the truck, overall it is much easier to do the job over the fenders. Bearings and/or pistons is an overhaul, and you won't want to stop at just that. If the engine is healthy otherwise, absent a real reason, don't fix what ain't broke. An actual rod bearing failure, or a knock associated with it, will likely be a terminal failure, as in, more likely a broken crank or cracked block main. 99% of Diesel "rod knocks" are injector related. If you don't know otherwise, consider them original, and due for replacement. They do go well past 90K miles, but also consider they're nearing 30 years old. As well, excessive coolant passing through the combustion process will also knock, and can cause terminal failure conditions, such as hydro-lock, when enough coolant leaks into a cylinder, it cannot complete a rotational cycle, and breaks stuff trying. Coolant system leaks go in both directions.

[JohnC]

An oil analysis might tell you if you have a bearing issue or not. If you do, you must fix it or you're wasting your time doing the head gaskets. On the other hand, DMax is right; most rod knocks are really injector issues. Can you still run it long enough to hear the knock? If so, try loosening the injector lines one at a time to see if the noise goes away. If it's a rod it won't go away completely.

[Robyn]

Glycol coolant will ruin the bearings fairly quick.
If there is coolant in the oil it has gone through the entire engine.....

May be a great idea to lower the coolant level.....Drain the oil (Get a sample tested) replace the filter....Add a full charge of ATF to the pan and run the engine at idle for a very short time to purge out the Glycol.....Drain the pan....

Get the engine out and on a stand.
When the heads are off check the block deck for erosion at the fire ring...(If the deck has a groove worn in it then the job gets tougher)

The front and rear cylinder deck area next to the coolant passage can and do erode .

Flip the engine upside down and get the pan off.....

The rods are not numbered.....Stamp the part line on each rod before removing.

Driver side 1-3-5-7 Pass 2-4-6-8

Stamp the rod and the cap......Then you can remove them and examine the bearings .....Caps must go back on the one it came off.

The bearing shells have sizes on them.....GM used "Select fit" bearings to allow for minor differences in sizes of rod bore and crank diameter.

You will be hard pressed to find the select fit bearings......But Standards and other under sizes are available.....If you see std that's easy....These are metric engines so all specs will be in mm.....

Main bearings can be checked as well and new shells rolled in....Be sure and mark the main caps.......

A fresh rear main seal is a good idea.....

Keep us in the loop.....Lots of pictures helps

Just heads up

The push rods on these engines can not be reversed.....Mark the end that is in the rocker arm....This end must always go in the rocker

Some push rids have a copper colored ball at the rocker...Some have a paint stripe at the rocker end ....Just be sure they do not get mixed up....

The ball at the rocker is hard....The other end is not...

If the head gaskets do not present as bad.....Check the number 8 cylinder at the rear top just down from the deck surface about 5/8"

These have been known to crack.
A cracked cylinder will show a strange colored area on this area....

Also.

Before (IF) you remove the injection pump ....Make a clean sharp scribe mark across the pump flange and the timing cover (Use a straight edge and a scribe) ...Line this up at reassembly and timing will be good

[DickWells]

If you get that "deep" into the engine, be sure not to neglect the timing chain and sprockets. If you do get that far into it, Jim's R&R books are well worth the money.

It might not be worth it to you, because it sounds like you don't intend to put that much mileage on, after you get the engine freshened up, but, the best thing, IMO, that I ever did to mine, was to swap out the timing chain for Phazer Gears. I don't even know if that kit is still being made, actually.

Regardless, you are already in touch with a great team. They've helped me out dozens of times, over some twenty-five years. Good luck.

[malpana]

Thanks for all the great help! I did replace the injectors about 40k ago and now wish I had checked them before tearing into it. I will get an oil analysis - been meaning to do that anyway, and now I have a good reason. Thankfully the gasket leak seems to be only cylinder-to-coolant - no oil and coolant mixing that I can see. I'm guessing I should drop the pan and take a look around for anything super obvious. Thanks again!

[Robyn]

The oil sampling will tell a big story.

If there is not any glycol in the oil (A very good thing) getting the heads off will tell the story.

Cracked heads can cause pressure to leak into the coolant .
The stock GM heads are not worth spending any $$$$ on.

The AM General heads are great heads.....A tad $$$$$$ but they are far better than the old GM stuff.

If you find just a blown gasket and no other issues then a set of gaskets and head bolts should get you going..

The bolts used on these engines are "TTY" (Torque to yield) and a one time use fastener....

Felpro head gaskets are the best in the business...

[More Power]

Human psychology is such that we tend to assume the worst, especially with engines. Don't invest/plan on an expensive solution for what may not be a problem till you've had a look.

To eliminate an injector problem that might be causing a knock, you can loosen one injector fuel line fitting at a time to eliminate the injectors. With a loosened fitting, that cylinder won't fire - sorta like pulling a spark plug wire(s) to find a cyl miss/knock.

Our "6.2L/6.5L Diesel Troubleshooting & Repair Guide" has been a popular addition for many 6.5 owner's toolbox (see link below). That'll help.

Jim

[malpana]

Thanks for talking me off the ledge, Jim! I wish I had known about injectors before tearing it apart. Next time (hoping there isn't one) I'll stop by here first.

I'm planning to get the engine out and take a good look around. I already have a lot of stuff out of the way and wouldn't mind getting a good look at the engine mounts while I'm at it.

[Robyn]

These are not at all bad to pull

With the engine out you get get quite intimate with it and see very well too...

Hope this goes well..

[Yukon6.2]

Make sure you have a good engine stand as these puppies are heavy

[malpana]

The engine is out and coming apart. Please watch this video and tell me whether this kind of rocker arm movement is normal. Does the amount of play vary from one to the next because of whatever position the cam lobes happen to be in?

https://ln5.sync.com/dl/b44f4c100/i7...25675548950005

[malpana]

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.

PXL_20250328_211111228 (Large).jpg

PXL_20250328_224639032 (Large).jpg

PXL_20250328_224710592.PORTRAIT (Large).jpg

PXL_20250328_224721793.PORTRAIT (Large).jpg

[Robyn]

Always use a some 3/8 fuel hose shoved over the rod bolts ...Poor mechanics crank journal protectors....

Yess
The rockers are guided by the plastic buttons in the shaft....The side play is perfectly normal.
Replacing the buttons is a good idea on a high mile engine.....

Yup
Gotta smooth out those dings.....
As long as they are below the surface you will be fine.....NO BUMPS ALLOWED.....Get the ding smoothed off and polish the journal with 600 grit emery strip.....
Around the journal.

Get some 3/8" fuel hose and cut off some pieces that can go over the bolts.
THESE KEEP THE DINGS from happening.

The copper in the bearings is showing the wear.....

Did you mark the rod and caps to keep them in pairs ????

[malpana]

Ugh, what a newb mistake. I'll be fixing it myself, so thanks for the tip. I did mark the rods and caps.

I rolled out the mains and am wondering if anyone has recommendations for rod and main bearings. I'm not looking for the cheapest option.


Also, since I don't know the 6.5 production history, I'll ask about my heads. I have the International Optimizer block dated 2003. Was International making the heads then too or just the blocks? I have the diamond pre-cups, but, apart from that, I don't know anything about exactly what heads they are. And does it matter anyway?

[DmaxMaverick]

In 2003, the Navistar castings were only sold as complete long blocks, or complete replacement heads. Bare or short blocks were only available through the back door (ask Robyn about that). Unless your heads have been replaced and downgraded, they are Navistar castings.

[Robyn]

Search ebay for bearings......Measure the crank to see what the journal sizes are
Standard size will probably work....The bearing shells will be marked.
Get a piccy (Close hi res) and post it here...We can see what you have now.

Clearances in the .002" to .0025" will work fine.

GM originally assembled with a bit tighter....I prefer .002"

The select fit bearings (No longer available) allowed tweaking the clearance down some...

Mic the crank....Go from there.

The bare partially finished block I bought from a local rebuilder in Portland just needed the bores finished.

Story was that the bores could be finished to ether 6.2 or 6.5 Sounded reasonable.

We finished up to 6.5 Standard....

I started the assembly and the main bearings had "ZERO" clearance.....~!@#$%^
So I started digging into the blocks history.

There had been a batch of blocks at the Navistar facility that ended up with an error in the main bearing bore in the block.

THERE WERE MANY
The high muck mucks at AM GENERAL and Navistar decided that rather than farm these out to be repaired (Factory machining line can not be set up to go back and do one operation easily) So there was much concern that these blocks might get stolen or ????? during the transfer and having the mainline honed to size....

I was decided that the blocks would all be sent back to the Navistar facility and recycled ..

A bunch were shuffled out the back door and sold on venues such as ebay and other outlets.

The shop I bought from had several....Maybe 10 or so.....

I should have bought them all....aha well


So aside from finishing the cylinders ...All we needed was to align hone the main line of the block .0025" and GOOD TO GO...

These were the good AM General blocks.

That was an interesting exercise to say the least..

Check out thew link
I have used Engine Tech bearings

https://www.ebay.com/itm/27593323932...Bk9SR9qCpMC9ZQ

[malpana]

Sounds like an adventure, Robyn!

Here are the pics. All rod bearings:
all rods.jpg


Mains 1, 2, 4, block side:
main block 1.jpg


Main 3, block:
main block 3.jpg


Main 5, block:
main block 5.jpg


Main 1, cap:
main cap 1.jpg


Main 2, cap:
main cap 2.jpg