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Another 6.5 rebuild...

razur65

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So, after finally had enough of wheezing, gutless wonder towing runs, overheating pulling up hills, mysteriouly leaking coolant with no puddles or signs of fluid and generally every typical complaint echoed by failing GM 6.5 diesel drivers... I put the beast in the barn for a tear-down.
Pulled the front end and radiator support, inner fenders. The harmonic balancer was new 5 years ago, needs replacing again.
Compression test numbers I thought looked good, most cylinders nearing 400 PSI, only a couple in the 340 range.
Leak down test was disappointing, started on left side (driver) of block, all had leakage could hear blowing into crank case.
Right side was catastrophic, could feel pressure blowing out the intake ports on the head, end cylinder #8 was totally blowing out intake port.
Pulled right side head, I expected to find cracks and was not disappointed, found between every valve!
Prolly find same thing in left head, not sure what direction going for this motor, was hoping to redo top end, heads, injectors, turbo upgrade at least, and rebuild transmission with heavy duty plates. As always, best laid plans, etc, etc...
1997_DU compression test_1.01.JPG1997_DU compression test_1.02.JPG1997_dually upgrade_1.03.JPG6.5 Teardown 1.01x.JPG6.5 Teardown right Cyl 2 1.01x.JPG6.5 Teardown right Cyl 8 1.01x.JPG6.5 Teardown right head 1.01x.JPG6.5 Teardown right head Cyl 8 1.01x.JPG1997_DU Harmonic Failed_1.01.JPG
 

Will L.

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Yeah, now if could just have a $7000 rebuild budget, right? Been there, done that, doing it again right now...

Decision to stick with the platform helps swallow the pill of some of the upgrades. Balanced assembly, Fluidampr, billet pulley, timing gears, and getting everything coated.
all expense today, but buying lower cost long term. More is Studs save the headgaskets with studs and keep the mains together with studs there too.

The crack in the heads is fixable-
https://www.thetruckstop.us/forum/threads/cracked-head-what-do-you-think-about-it.45244/
But the inserts, new valve springs, valve job which you found is needed- might be better for new heads, provided they are new.

Or spend the big bucks for a killer set of ported and coated p400 heads from Chris...

Air chisel technique scared me when you did the intake and exhaust near finished areas, but effective. I like it. There is a ledge on the block by the 4 corner cylinders and slight recessed area on the heads engineered for a prybar for those that aren’t aware.

Fingers crossed everything else is golden.
 

WarWagon

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What are you using this truck for? How hot has it been? FWIW your oil cooler is trash as it's full of trash and not able to be flushed.
 

razur65

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When it is in work mode it's towing a 20' gooseneck flatbed with either equipment or scrap cars. Then there's the stock trailer, not used much for livestock lately, moved more firewood and household goods with it. Towing probably between 5k to 7k gross. And then there's the camper... 30' Jayco fifth wheel, 10k loaded for vacation. Before I bought it the truck it was a stake body and belonged to a commercial paving company, mostly highway contracts, don't work in the winter so it was not rusted out, was well maintained but also, rode hard and put away wet (in horseman's terms), more often than not.
When I towed with it kept closer eye on EGT than engine temps, but also when engine temps got close to 210 climbing hills I would back off throttle. I wouldn't let exhaust temps go above 1200. I added EGT and trans temp gauges when I bought it, when it was owned commercially there's no telling how hard it was run.
The greatest Achilles was transmission temps, even with larger cooler and electric fan trans temp would quickly shoot over 220 and take forever to cool down.
At this point in the tear down process I'm probably looking for a replacement 6.2 block and some new 6.5 heads. I've been reading up on some of the builds here and other sites, seems like if one wants to stick with the GM platform that's a safe bet.
Although if I get a winning scratch off ticket during coffee break some morning I could find myself ordering a more expensive upgrade! :cool:
 

WarWagon

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Do you have an aux cooler on the trans or just the radiator heat exchanger? Point of fact hottest oil to radiator first then to aux cooler. Get it backwards and the trans runs hot. You need to spin the engine to be sure it's flowing the way it should be.

It looks like you may have lost an injector with the piston melting. How many miles on them?

Very few understand working a rig that hard. So keep that in mind for your build. The grumbling about being a dog from a stop light is common for large turbos until you feel one big turbo hit hard on a grade where the GMx is giving your engine an asthma attack.

You can shove a Duramax in and blow it up too. Hint Cummins are not cheap either.

So budget? You can look at my build with a military surplus 6.2 for frugal. A new Optimizer with better turbo and a Triple Disc lockup converter would help a lot. Stall it to match the turbo you choose. Budget: my ATT paid for itself in fuel savings.
 

razur65

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Do you have an aux cooler on the trans or just the radiator heat exchanger? Point of fact hottest oil to radiator first then to aux cooler. Get it backwards and the trans runs hot. You need to spin the engine to be sure it's flowing the way it should be.

It looks like you may have lost an injector with the piston melting. How many miles on them?

Very few understand working a rig that hard. So keep that in mind for your build. The grumbling about being a dog from a stop light is common for large turbos until you feel one big turbo hit hard on a grade where the GMx is giving your engine an asthma attack.

You can shove a Duramax in and blow it up too. Hint Cummins are not cheap either.

So budget? You can look at my build with a military surplus 6.2 for frugal. A new Optimizer with better turbo and a Triple Disc lockup converter would help a lot. Stall it to match the turbo you choose. Budget: my ATT paid for itself in fuel savings.
Installed Aux cooler, Derale plate & fin type, piped from radiator into cooler, then to transmission, made transmission pump fluid to verify supply and return so lines not reversed.
Odometer says 274k, I was told that motor wasn't original, replaced at just over 100k and transmission was rebuilt, when I bought the truck. Have thought for a while was getting real salesman treatment. No offense to any salesmen reading this... So to answer how many miles? A "touch too much" to quote AC DC.

I live in the Northeast where vehicles rust and rot away before their useful life is done, in some cases, so occasionally a donor vehicle prospect comes up on CL or FB, Duramax conversion wouldn't bother me except for know problems with injectors and pumps that can cost a small fortune, plus cost of retrofit wiring harness, making it all work with 1997 cab, doesn't intimidate me, just not that ambitious anymore. Would rather stick with the 6.5 platform before go to Duramax.

Cummins 12 valve or even a 24 valve converted to P-pump interests me, but there's the transmission red flag and aggravation, don't really want to deal with aftermarket controller for 4L80E, so donor vehicle needs 47R or NV4500 to complete the swap. Did I also mention mine is 2 wheel drive, and everything I possibly find for donor truck is 4WD? My truck is a pavement runner, don't even want to think about changing to 4WD so then there's that...
I have read through your build thread, that's pretty much where I got the idea of using a 6.2 with 6.5 heads. Then I don't have to mess with transmission except for rebuilding it, that it needs anyway. Keeping 6.5 simplicity (sort of) IDI fuel economy, upgrading turbo possibilities, get the truck more work power ready. What it really boils down to is luck, what I can find for a 6.2 block, or Cummins donor truck... that's not 4WD.
 

razur65

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More work done, opened up drivers side of engine, looks like I found where coolant was disappearing. Rear of head had some orange color on head and gasket, head bolt out of that corner was rusted also. Cylinders, however, looked great, completely different from other side of engine, can even see faint traces of cross-hatch pattern on cylinder walls.559155591655918
5591955920
There she sits, broken hearted... TO BE CONTINUED...
 

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razur65

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Yup, head is same as other side, cracked every one between the valves.
#7 cylinder wasn't cracked, it's just reflection from way pic was taken.
I made some numbers for what I wanted to do to this motor, over 9k on wish list, and prolly needs more...

GM 6.5 Diesel "Refurbish" Budget
ESTIMATED COST $ 9,123
ModCost
Pistons $ 800
Timing gears $ 400
Heads $ 1,900
Injectors $ 400
Pump $ 900
Turbo $ 1,200
Exhaust complete $ 500
Air Filter intake $ 300
Inter-cooler parts kit $ 200
Fluid Damper $ 425
ARP head studs $ 180
Gasket set $ 120
Misc pieces n parts $ 799
Transmission Rebuild $ 999
Torque Converter $ 700
Crankshaft (?) $ 420
 

Twisted Steel Performance

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Well you could spend a bunch of cash on a "rebuild" on a known risky block & head, GM, GEP, they all crack at some point.

Or you could spend that much on a crate P400 that is a much much stronger platform, add some cash in mods and have a motor that you will still be running years from now...

Depends on your budget and plans for the truck 10-15yrs from now....
 

WarWagon

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You maybe confusing the separate serpentine belt damper $99 with the harmonic damper behind it. Picture above of the serpentine belt damper is shot.

Looking at both sides is a perfect example of the imbalanced water pump GM simply missed when they decided to spin it backwards over the V belt.

Anyway you missed the cracked mains or cracked head bolt hole... IMO that block will be scrap.

Your budget can get a lower mile running truck without a trans or engine rebuild need. Reg cab 2wd Duramax is in this range.
 

Will L.

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The trans rebuild with tc makes it look worse, being listed with engine rebuild. The crankshaft cost is a thing where I see $ savings by getting a take out gep crank (which I think but not proven is a scat). The price on the heads is questionable, but depending on build and use could be ok.
the 799 in misc parts pieces- I hope that includes having the lower end balanced.

Have you seriously looked at what Chris mentioned? About 5100 towards current engine...
 

razur65

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You maybe confusing the separate serpentine belt damper $99 with the harmonic damper behind it. Picture above of the serpentine belt damper is shot.

Looking at both sides is a perfect example of the imbalanced water pump GM simply missed when they decided to spin it backwards over the V belt.

Anyway you missed the cracked mains or cracked head bolt hole... IMO that block will be scrap.

Your budget can get a lower mile running truck without a trans or engine rebuild need. Reg cab 2wd Duramax is in this range.
I admit, I did mistake the pulley damper for the real thing... was replaced in 2014 and now all cracked up again.

The numbers definitely make the point of spending money on a P400 smarter.

I've got time on my side (I think..) so I'll push this off to the side of the barn and throw a tarp over it for now.
I can locate a decent donor truck and work on re-powering the dually. Was thinking about selling it but won't get anything for it and besides, I've got a great frame, body, interior because I made it that way.
Cummins and Duramax powered trucks with rotted frames or wrecked come up on CL occasionally, just a matter of getting lucky and having the cash at the time I find one.
 

WarWagon

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Step on a plane and pickup a rust-free AZ or western pickup and put your interior in it.

Cummins is proud of their parts. Side by side a picture of a rod and piston is a clear example of "industrial" vs. "Light Duty" diesel. I have $10,000 in my common rail Cumapart, P L U S $3500 in injectors, $1500 in a turbo, $1000 trans refresh, $2000 in clutches/labor... paint job, HVAC doors and needs "BOAT" for a new dash and $500 for a new EV fan clutch this year. (Bring On Another Thousand) So it's $500 and $1000 me to death. The first rebuild I had done only lasted 500 miles(!) 🤦:banghead:

After rebuilding the 1993 truck several times some have suggested "insanity" and they are 1000% correct. It's history is a father-son project several times over in the past so it's value to me is all that matters. I figure to be under $4K when all said and done.

Several ways to repower yours on the Frugal side. Note that if it's stolen or a Total Loss your insurance isn't paying s#it and outside of a declared value commercial policy (or "Classic" insurance you can't use the truck like you do) on all your investment into fixing up a sub $4,000 value pickup. It's not 4x4 so the book value is really bad. Go ahead and ask for a declared value policy on your truck - it ain't out there aside of the two paths I noted and Commercial is $$$$ expensive.
 

razur65

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No need for plane ticket, mine was hardly used in winter so it's not rusted out underneath. Heck the most it was driven in winter was last year when the 02 busted front wheel bearing. I keep the frame and underneath well coated with used oil and that helps keep any rust at bay.
My truck is value to me alone also, I made it what is today, piece by piece, Craig list part by part, it's wearing the second box I've put on it, originally truck was a stake body. I bought this box sight unseen, drove almost to Philly from Central NY, 5-1/2 hours one way "bob-tailed" after staying up all Friday night rebuilding the differential just to make the trip on Saturday. The doors and nose are all from a 96 suburban I bought just for the body. Transmission was whipped in it so I got a deal, drove three hours North with gooseneck in tow to bring those parts home. When I installed all those pieces I wired the power windows, door locks including remote key receiver, everything works like factory. Truck went from rubber-matted crank window work cab into a carpeted, bucket seat (comfy ones too) luxury truck. I have literally built this truck into what it is today.
I guess I'm already at a loss if it's totaled or stolen, but if it is then "it is what it is" as our company motto says (unwritten in employee handbook for some reason). More than likely I'll find some other $3000 wreck and start all over. For what it's worth $3k is what I originally paid for this one. So it literally doesn't owe me anything at this point.
Prolly will wind up spending 10k before all is said and done, engine, transmission, wheels, fresh custom paint, one things for sure it'll be one of kind, not another one like it around here anyway.
 

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