The ol' Tahoe is down for the count - coolant in cylinder(s)

[DmaxMaverick]

That's a dirty engine (typical, really), but I like what you've found. It is definitive, which is what you want. No mysteries. Be optimistic about the rest.

Add a set of bearings to the list, since you're going in. They're relatively cheap, and the miles justify it.

[Robyn]

I agree with Maverick on the bearings.

Keep in mind....The 6.5 uses "Select fit" bearing shells......Generally these are not available in the after market....Std, -.010", -.020" and -.030 for grinding the crank

Don't be shocked to find upper and lower shells with different size markings...
The bearings will be marked as to what they are....

I have used the Stds in places where select fit came out. A good shot is .0025" clearance.....


Just an FYI
Great deals can be had on top name brand bearings and other parts on ebay...I saved big $$$$$$$$$$$$$ when I did the Dahooooley back a few years ago...

Get things apart and then get your parts coming......By the time you need the stuff you will have it in hand.

I am still puzzled at how coolant got on both sides of the engine........????????????????????

[Robyn]

A set of engine tech Rod bearings....$30
https://www.ebay.com/itm/274546090212?hash=item3fec38e0e4:g:GxEAAOSwvdJfoKL N



I have used this brand several times......About like what we used to call "White box" rebuilder parts.
I used this stuff on Dahooley and the Burb rebuilds.

I have a set of this brand sitting in the wings for my 406 cat engine.

Careful shopping can yield great cash savings and get good parts too..


https://www.ebay.com/itm/23252098611...YAAOSwlndZC1dk

[JohnC]

I am still puzzled at how coolant got on both sides of the engine........????????????????????

Open intake valves? If all three cylinders have open intake valves and coolant under pressure is being forced into #7... Is the intake manifold wet?

[DmaxMaverick]

Open intake valves? If all three cylinders have open intake valves and coolant under pressure is being forced into #7... Is the intake manifold wet?

Certainly possible. A perfect storm. Cylinders 8 and 7 are adjacent in the firing order and on the same journal, allowing both intake valves open at the same time. It may explain a condition if the other bank doesn't appear to be compromised.

[Old6.2]

I have not heard anyone mention the rings. If you are going this far down I would replace those due to experience. I replaced heads on a small block Chevy after a valve job and the oil consumption caused clouds of blue smoke. Since the valves sealed properly the weak rings allowed much blowby through the PCV and burned with the fuel. Not much additional $$ for piece of mind.

[DmaxMaverick]

I have not heard anyone mention the rings. If you are going this far down I would replace those due to experience. I replaced heads on a small block Chevy after a valve job and the oil consumption caused clouds of blue smoke. Since the valves sealed properly the weak rings allowed much blowby through the PCV and burned with the fuel. Not much additional $$ for piece of mind.

SOP for gassers, for sure. 376K miles on a Diesel with no cylinder ridge (very typical of most 6.2/6.5)? I wouldn't touch them unless there is some other indicator. I've never replaced the rings on a Diesel engine I didn't bore unless there was some other reason.

[Robyn]

I hate to toss cold water on the camp fire....but I will cast a dissenting vote.

I have yanked 6.2/6.5 down and found the rings pretty well stuck up...

I would vote to yank the slugs out...Clean them up well.
Use a bottle brush hone on the bores lightly and toss in a fresh set of moly rings.

This will give the best the little beast is going to do.

If the pan is off and the bearings are going to be out....An extra days work at most and the job will be a better one..

With the pan off....Timing set, seal and fresh gaskets would be smart too...

The talk was to replace the rear main seal.....

If it were me I would buff the head surfaces with the big 9" wire wheel to get the crud off..

Then pop out the valves and have a peek see.....EGR engines are notorious for clogging up valve pockets with carbon....

This junk falls off and can cause issues.

Look at the valves and seats....maybe lap them lightly with compound and call it a day.

Fresh valve seals would be a good idea....

It is hard to yank an engine out and not tend to some basics......

[arveetek]

This was me at 11:00 pm last night:



I am tired and sore. And the bummer is that I won't have much time to work on it in the next two weeks!

Casey

[Robyn]

LOOKS VERY VERY GOOD to see the beast hanging on the lift.....

Looking forward to seeing what else presents itself in that critter...

Ahhhhh

Take the time to make a sharp scribe line across the injection pump flange and the front cover at the top before you remove the IP ....

Align the marks when you put the IP back on and it will go right to work and no other fooling will be needed.

The computer will remember where it last found things and it will be happy...

[Yukon6.2]

Working on things when you would rather be doing something else
That was me the Christmas of 2019,the wife at the time and my Daughter decided to have Christmas without me on the other side of the country
So instead of sitting in a house alone i pulled the 7 speed tranny out of my 2004 7500 Topkick

[arveetek]

Take the time to make a sharp scribe line across the injection pump flange and the front cover at the top before you remove the IP ....

Align the marks when you put the IP back on and it will go right to work and no other fooling will be needed.

The computer will remember where it last found things and it will be happy...

I'm hoping to leave the pump alone. I replaced the timing chain, water pump, and balancer 3 years ago as preventative maintenance.

Casey

[Robyn]

Copy that.....

But if you end up removing it.....just a great way to eliminate problems.....

[More Power]

Casey,
You've identified the cause as being head gasket failure... Most likely, a result of just end of life... sorta like the head gaskets on my '01 GMC. As long as you can't identify any other damage, I'd inspect the heads (for fire-ring wear groove, flatness, cracks, etc), and if good just clean them up, and re-install with new Fel-Pro head gaskets and Fel-Pro TTY head bolts. Remember that Fel-Pro produces +.010 over head gaskets for heads/blocks that have been decked. If you need it, send me your current mailing address, and I'll send you the current Troubleshooting & Repair Guide, which will walk you through the process of how I did our 6.5TD Power Project engine assembly - including head gaskets.

[arveetek]

Casey,
You've identified the cause as being head gasket failure... Most likely, a result of just end of life... sorta like the head gaskets on my '01 GMC. As long as you can't identify any other damage, I'd inspect the heads (for fire-ring wear groove, flatness, cracks, etc), and if good just clean them up, and re-install with new Fel-Pro head gaskets and Fel-Pro TTY head bolts. Remember that Fel-Pro produces +.010 over head gaskets for heads/blocks that have been decked. If you need it, send me your current mailing address, and I'll send you the current Troubleshooting & Repair Guide, which will walk you through the process of how I did our 6.5TD Power Project engine assembly - including head gaskets.

That is my plan! She was running great with no issues, no abnormal smoking, no blow-by, etc. No symptoms to make me think it needs a head job or ring job.

I need to look and see if I have that guide, I don't recall. I've got several of the DP books. I will let you know. Thank you!

Casey

[arveetek]

I haven't had much time to work on the ol' Tahoe lately, but this afternoon I finished my tear down to inspect the bottom end. The bearings didn't look too bad for 375K miles, and I'd be tempted to run it as is, but I did find something that gave me pause for concern - there's a typical crack in the block originating from the outer main bearing hole on main cap # 4, on the cylinder 7 side. It's about an inch long:












So the question is now what should I do? I assume it would not be wise to continue running this engine with the crack, correct?

This is a 1995 929 block with 376K miles. I also have in my possession a 1997 506 block with around 100K miles; however, there is some issue with that engine - when I pulled it, it was running, but had no compression on cylinder 1. I never tore into it to see what the problem was. I am guessing it would be prudent at this point to go ahead and tear into the 1997 block and see what it looks like to see if it's a good candidate for a rebuild....

Casey

[Robyn]

You can install one of the LOCK AND STITCH inserts in the cracked hole....

At 375K
Myself, I might be quite willing to clean things up, install fresh head gaskets and run it until it gives up again.

Unless that crack gets into a cylinder wall or worse it's not going to hurt much...
Knowing when it got there is not possible....
50K miles...100K miles, 200K miles....Maybe sooner or later....

I have torn into six and a half's with under 100K miles that were a cracked mess....

Don't lay awake nights trying to figure it out...

NOTE...NOTE....NOTE
IF you go with the 97 block....THE BELL HOUSING BOLT THREADS ON THE 96 AND LATER ARE METRIC.
The 95 was the last year that used SAE threads ON THE 6 BOLTS BACK THERE

The 3/8 bolts will thread into the metric hole....but will not hold.....

Doing the LOCK N STITCH inserts is not hard....and they do pull the area together.

Are the outer holes the large or small bolts ????

[arveetek]

You can install one of the LOCK AND STITCH inserts in the cracked hole....

At 375K
Myself, I might be quite willing to clean things up, install fresh head gaskets and run it until it gives up again.

Unless that crack gets into a cylinder wall or worse it's not going to hurt much...
Knowing when it got there is not possible....
50K miles...100K miles, 200K miles....Maybe sooner or later....

Are the outer holes the large or small bolts ????

I was wondering about that... no telling how long the crack has been there. It could go a long, long time as is. The outer bolts are large - same diameter as the inner bolts.

Casey

[Robyn]

If everything else is good....I would say that installing the insert would be a good idea if you were going to spend time and $$$ to do a serious refresh on the engine.

If you are still thinking about just patching it up and then back together.....Run it as is.....

Doing the insert means stripping the block down all the way so you can get tools on it to drill out the hole and install the insert.

The chips and such from the job require careful cleaning afterwards to make sure none of the junk gets into the inner workings.

I did a couple blocks a few years back.....I machined up a steel plate that has openings for each of the outer main bolt holes and the plate fastens to the pan rail holes.

I used a magnetic drill press to drill the holes.

Simply use a steel rod that will just slip into the threads (I grabbed a hardened transfer punch that just slid past the threads) Stick the rod in the drill chuck and align the drill to the hole. .....Use the drill provided in the kit.... drill the hole out and down to the prescribed depth...Tap the hole deep enough that the insert will thread in tight and so the top of the insert is Flush to .002" below the main web mating surface....

Clean the hole with Brakleen and blow dry...Do one last final check fit.....Clean the hole and insert and dry....add loctite RED and tighten that bad boy up......

After this two small holes are drill along side the insert and hardened pins are driven in to permanently secure the insert so it can't unscrew.

Very simple procedure to do.....

The other choice is to find a shop that can do it that has a milling machine large enough to sit the block on the table...

If the block is otherwise good....A great save.

Or....Check out the 97 block and see wassssup there.

The 97 block is likely a squirt block and will have smaller outer bolt holes.

SQUIRT BLOCKS USE A HIGH OUTPUT OIL PUMP.....YOU MUST USE THE PROPER PUMP OR THE OIL PRESSURE WILL BE NEAR ZIP AT IDLE


I happened to have a large mag drill so the choices I made were based on that....

This can't be done free hand.....a good mag drill will do it.
The steel plate was simply a means to attach the mag drill to the block.

Most drill press tables are not large enough to handle the block.


If you get hot on the 97 block.....Clean it good and make sure it is not cracked.

Besides the main cap bolt holes.....carefully check the oil squirt holes in the main webs for cracks too.

Some early squirt blocks (506 blocks ) had larger oil squirt nozzles in them and the holes would crack into the main webs and into the cylinder wall at the bottom.

Be sure to remove all 8 squirt nozzles and replace them after cleaning just before you drop the crank in..

If one falls out...you have a huge oil leak.
The squirt nozzles are a small aluminum piece with a tiny hole in the end facing towards the cylinder. Small end of the nozzle goes toward the cylinder.

Usually the nozzles can be removed with a small hard wood dowel and a plastic hammer and tap them back towards the main saddle.

Keep us in the loop.....

Lots of options..

[arveetek]

I definitely don't have the skills or tools to do the insert repair myself. I was bummed when I found the crack since I knew that meant stripping it down to a bare block and then hoping to find a local machine shop able to make the repair. More down time that I wasn't planning on.

I think my next move is to tear into the 97 engine and see what she looks like inside. If that doesn't pan out, I'm leaning towards slapping some head gaskets in the 95 engine and moving forward as is. Then start looking for a replacement engine to a complete, thorough rebuild on as time allows. I need my vehicle back on the road more than anything; I can't afford much more down time (and now is not a good time to be looking for a used truck!).

Thanks!

Casey