Diesel Place banner
1 - 15 of 15 Posts

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #1 ·
At nearly 400,000 miles, is it possible that a 6.5 could reuse the original pistons and only hone the cylinder walls before Installing new rings? 400k is nothing for a heavy duty diesel like in a semi truck, and they can usually be overhauled "in frame" without being bored out and having to have oversized pistons and rings - but would o be lucky enough to get away with that on a 6.5? Id like to put in new rings, gaskets, bearings, oil pump, etc... But without the expense and time associated with new pistons and having the cylinders bored out. Something is up with my 6.5 and it won't make a full revolution anymore even with the glow plugs out and the torque converter unbolted - if you spin it all the way around either direction, it stops in the same spot every time. This is while turning the engine over with a 24" breaker bar using the crank pulley bolt. It has 3 or 4 tight spots on the way around, but this one spot it just won't rotate through - ive pushed and pulled so hard that I though I was going to snap the breaker bar or the enormous crank pulley bolt. Anyway, its probably going to have to be taken apart but I sure don't want, nor do i have, thousands of dollars to spend completely rebuilding this thing. I love the truck and I've had it for about 15 years now so I really hate to get rid of it. But, its got a decent amount of blow-by now and since it's going to need work internally now, now is gonna be the best time to do an overhaul if i can in fact get away with that. If not, I may have to get something else unfortunately. Anytime the word "diesel" is involved, even if it isnt an especially popular like the 6.5, the price of a replacement engine goes up. A lot. Looks like about $4,000 USD for a reman 6.5 and that's just ridiculous.

Anyway sorry for the rant - but what do you all think about a re-ring "overhaul" of a high mileage 6.5. Is it possible that it would work and be worth the cost and effort?

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #3 ·
I always say do not order ANY parts until AFTER the tear down and machine shop has inspected the parts.

If the engine will not turn one full revolution then you have some form of mechanical failure. Could be broken piston with piece hitting the cylinder head, broken connecting rod or even a broken crankshaft. Your cheapest option would to find (try) a running used engine that passes compression test and hot idle oil pressure specs.

You can't compare this engine to medium, let alone heavy duty, diesel engines. The in frame overhauls you mention many times includes new cylinder liners and pistons. They are wet sleeved engines so they don't get bored out.

A reman 6.5 with a warranty for $4k isn't ridiculous considering how hard it is to find good buildable cores. A brand new GEP Optimizer 6500 is probably around $8k these days.
The odd thing about this is that the engine ran fine last time I shut it off - the starter had broken its aluminum housing for the 2nd time in a week. The flexplate was pretty worn on the ring gear and had slowly gotten worse over the years. So after that I pulled the transmission and replaced the flexplate - id been pretty busy so it took me 5 or 6 months, and when I finally got ready to bolt the torque converter to the new flexplate, i was only able to get 5 of the 6 bolts in it - the engine wouldn't turn far enough to get to the 6th bolt. I took all the bolts back out thinking maybe the converter or transmission was hung up somehow but that wasn't the problem. The only thing I can think of is that maybe moisture from this humid climate condensed in one of the cylinders and rusted the cylinder wall enough to prevent it from being able to make a full revolution.

It had to turn a full 360 degrees when I took it apart because I removed all the torque converter bolts and pushed the converter as far back into the transmission as it would go before unbolting the transmission from the engine. So whatever the problem is, it occurred during the 5 or 6 months that it was sitting. I'm really disappointed, I was looking forward to having my suburban back. I've had it for about 15 years now and despite the fact that it has nearly 400,000 miles on it, it was still running great.

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #5 ·
Kind of sounds like hydrolock to me. Water or maybe fuel somehow got inside a cylinder when it sat all that time. You could try pulling the glowplugs and turning it over.
Already have the glow plugs out. Still have the same issue. I had wondered about that myself

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #9 ·
Do you have anything bolted to the rear of the crank now? If so remove everything and rotate the crank, you might have a bolt that is too long and touching something on the rear of the block.
Only the flexplate, and I can't remove it without removing the transmission

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #12 ·
Did you remove the valve covers afterward to find out whether a valve was stuck open?
Yep. The only ones that are open are the ones that the cam lobes are on - and they close when i rotate the engine they all seem to work ok. Next step i suppose is to pull the heads. There's nothing else in the way of that now on the passengers side - intake, IP, coolant crossover, exhaust, valve covers etc. And only the ps pump and exhaust manifold on the driver's side.

One thing that may or may not be important to know is that the passengers side exhaust manifold has been off most of this time and the air intake from the turbo has been uncovered. I didn't stuff rags into the exhaust ports or the upper intake, but I have kept the hood closed - it hasn't been rained on or anything like that.

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #14 ·
We're the glow plugs removed for the 4 or 5 months ? It's definitely possible there is some corrosion on the cylinder. This happened to me. I remedied it by using on blaster or other agent into the cylinders via the glow plugs holes and just worked the engine back and forth.

It goes without saying but you're going to want to blow all the crap outa the cylinders before you even think of putting those glow plugs back in there unless you want a grenade.
No the glow plugs I just removed a few days ago. The exhaust manifold and turbo has been off the whole time tho. There was potentially one valve open or partially open and exposed to air during that time, but nothing liquid. The hood is on and kept closed when im not actively working on anything.

And yes I always check any openings for contaminants before putting any back together. And I like to keep the area around me clean, so i have rags, an air blow gun and a shop vac (if necessary) handy to clean up the areas that im working in - i used the shop vac to clean around the intake before I pulled it off, and again after it was off ( its amazing all the crap that finds its way into the valley under the intake).

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #15 ·
It’s Pretty strange this sort of thing has happened.It was okay when you last parked the vehicle and now it can’t be rotated a full rotation.Awfully strange circumstances to say at the very least.
I know. There's got to be an explanation for it though, only disassembly is going to reveal it tho it seems.

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #17 ·
Hopefully you’ll find something when the heads are taken off.
Yeah hopefully. If not, it'll be time to pull the entire thing out. It irritates me to know that I put all that effort into reinstalling the transmission only to have to undo everything again because of a serious, unusual and certainly unexpected problem. It's not any fun handling that 4l80e. I can't believe how heavy it is.

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #27 ·
Ok here's an update. I finally got a chance to pull the heads off. Without the heads on, the crank and cam both make full 360 degree revolutions without an problems. There was antifreeze in the passengers rear cylinder, but I believe that it came from the head as I removed it. It tipped backwards as it pulled upwards on the front to loosen it up after removing the bolts.

Therefore I believe that there must be a stuck valve in one of the heads, i cant think of any other explanation. There's no way it could've been hydrolocked even if the antifreeze i saw in the cylinder was already there (i assure you that it wasn't, tho) since the glow plugs were out of it.

I am amazed that even after 385,000 miles, you can still see the crosshatch marks in the cylinder walls. I've been inside many gasoline engines with far less miles than this on it that had far more wear in the cylinders. They've always had a ridge at the top that you could feel with your fingers and never any visible crosshatch.

With this said, I think that I could hone the cylinders and install new rings on the existing pistons without any problems.

The cylinder heads however i am not sure about. There appears to possibly be cracks in between the intake and exhaust valve for 3 or 4 different cylinders. The cracks don't appear to stop at the valve seat, and not into the valve seat nor any further up than that. The valves and seats all look pretty good to me, but there is/was some really really tough carbon or something built up on a few of the intake valves. I scraped and wire brushed them while trying not to gouge or score them up any. The intake ports were oily and the intake valve seals (o-rings) were brittle and fell apart on the few valves that I have removed so far. See the attached pictures and tell me what you all think about them. I talked to to the machine shop today and they said they would clean/check and do a valve job if necessary for $315 (plus parts) for the pair which sounds pretty good to me. The only thing I am concerned about is those cracks between the valves.


Sent from my Pixel 2 using Tapatalk
 
  • Like
Reactions: 56pan

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #30 ·
Looks like one side is running better than the other with one head valve surface being black from I would assume diesel sludge.
I must've cleaned that one up some before I took the picture there's no gasket crud in the water jackets or anything like that in that picture like there is on the other head...

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #31 ·
Looks like one side is running better than the other with one head valve surface being black from I would assume diesel sludge.
Upon looking at the pictures again, picture 4 is the passengers side head and picture 9 is the drivers side head, before any cleaning was done. I remember because the first head i pulled was the passenger side one and i stood it up on its end in front of the truck on a piece of tar paper that was laying there for some unknown reason. The drivers side head I laid down on it's side on a red block. The other pics of the heads are after i cleaned the bottom side so I could see things better.

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #33 ·
Is that piston melted or is it just me?
Ill look at it closer but I don't think so, it has a lot of carbon built up on it tho

Sent from my Pixel 2 using Tapatalk
 
  • Like
Reactions: Dadddyoh

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #35 ·
That motor is past wore out, just because you can see what looks like cross hatch, doesn't mean there is anything there for the rings to seat to...
I think the rings are worn out, but I think the cylinder walls are OK. It had blowby, so something is certainly worn out. I think im going to hone the cylinders and put in new rings when it gets put back together tho. The cylinders look great to me.

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #38 ·
Are you going to send the heads in to have them checked and at least surfaced.
Yes. The machine shop I use is running a month behind on work right now though. I'm going to look and see if I can find another one that can get to it quicker because I really want this truck back asap.

Sent from my Pixel 2 using Tapatalk
 

·
Registered
Joined
·
2,734 Posts
Discussion Starter · #39 ·
My eyes aren't good enough to gauge taper and roundness.
No, but not having any ridges or scratches in the cylinder walls is certainly a good thing. Its better than any gasoline engine that ive ever had apart.

Sent from my Pixel 2 using Tapatalk
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top