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Overhauling a 6.5

4449 Views 49 Replies 14 Participants Last post by  Dadddyoh
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?

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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

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Yeah, reread you original post and missed that.
At 440,000 mine finally blew a head gasket. We tore it down to the short block, still in the truck, and simply replaced everything from the heads up (except the injection pump), including the turbo, timing change, damper, rocker arms, etc. I also replaced every rubber hose under the hood I could find, being careful to use the correct hoses for things like the turbo oil return. It runs great, no issues at all. Once thing I didn't do that I wish I had, when the heads are off, replace the lifters. Removing the heads in the only way to get them out so take advantage of that. I didn't know that until after the heads were back on.
"At 440,000 mine finally blew a head gasket." Only 440,000 miles and the piece of crap blew a head gasket? GM junk.
I remember reading that article several years ago. Yeah, interesting perspective. Here's my story: this spring I overhauled a LeRoi Dresser 2 stage air compressor I've had for about 30 yrs. The thing is about 60 yrs. old and had a rod bearing knocking. The overhaul kit had two new pistons, rings, etc. and all needed for an overhaul. There were never any oversize pistons made for these and if the cyl. was worn past limits, you had to replace it. The high press. cyl. (2 in. bore) was about 1 thou. past limits. The only new cyl. I could find on the internet was insanely expensive. I'm lucky to have a very good machine shop close to me and they bored and sleeved that worn cyl. to original bore size. The low press. cyl.(4 in. bore) was still well within limits on bore. I had no cyl. hone big enough for this 4 inch. low press cyl., so just put in the new piston and rings and no honing. High press. cyl. got the same and the sleeved original size bore. Put it all back together and this thing was taking way too long to get to cutoff press. 180 psi. Much longer than before I tore it down. There's a chart in the back of the maint. manual on the compressor that shows the different models and how long they should take to get to different cutoff pressures. Mine was out of whack according to the chart. I ordered a new ball hone big enough for the unhoned low press. cyl., took it back off, honed it and put the compressor back together. I'd already rebuilt all the suction and discharge valves. Nothing else was touched except to hone the low press. cylinder. Ran it up to cutoff press. and the first time I ran it, the compressor made it to cutoff press. much faster. And got there in a shorter time the more I ran it. There's only one thing that was changed. Honing of a cylinder. No, it's not a gas or diesel engine, but it's cast iron cylinder and aluminum pistons. I'm calling BS on that article.
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The machine shop did a nice cross-hatch on the new sleeve in the high press. cyl. Don't know if it was a ball hone or not. After seeing the way this compressor pumps after I ball honed that low press. cyl., the issue is settled for me. That guy that wrote the article is just wrong on this.
I believe you've got the cylinder taper backwards? Isn't the wear on a high mileage engine at the top of the bore more compared to the bottom.
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