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GMC 6.5 Dually

Redtruck97

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My pump arrived today, glad to get it. I have some other parts ordered so I can do a good job since I am going in deep with this repair. I'm going to clean as much of the engine as possible, I did spend some time pressure washing as much of it as I could, even laying down to clean the underside. All these AC Delco parts are made in freaking china!!!! So much for AMERICAN made. Anyway this old truck should run great and go for along time once I am done with it.
New hoses, belt, thermostats, crank position sensor, harmonic balancer and pulley, Holley fuel pressure gauge (electric), relocated PMD to bumper, KB Diesel plenum and piping. I will upgrade exhaust and turbo soon (money permitting). Glad to find this site, everyone has been very helpful and I appreciate it.
 

Redtruck97

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Happy May everybody! Well I am on my way to repairing my truck, got the pump last week and have the truck torn down to do the pump as well as several other repairs. A lot of my parts are original and need to be replaced. I have a question...if I am torn down this far would it be a good idea to put a new timing chain and gears? This old truck should be in pretty top shape once I am done with it. Hope everybody is having a great start to summer. :cool:
 

Redtruck97

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If you mean the time keeper, then no I won't be using those. I read a thread on another diesel site and the mechanic said to use chain and gears so if there is an issue the chain takes the brunt of the breakage and not the crank or cam. With unknown true mileage it might be a low cost insurance. Thanks.
 

Will L.

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If you mean the time keeper, then no I won't be using those. I read a thread on another diesel site and the mechanic said to use chain and gears so if there is an issue the chain takes the brunt of the breakage and not the crank or cam. With unknown true mileage it might be a low cost insurance. Thanks.
Really not an option even if you wanted it right now because Leroy has people on a waiting list until he feta enough to do an order for the next batch to be made.
But I do want to share- I did tons of looking and chased down multiple people that were supposed to have had issues from the dsg sets (which is what Leroy’s are copied off of). 2 people swear o having that had been their issue and 2 that said maybe. Opposed to hundreds and hundreds that had no issues including myself when I had a similar but not exactly the same design custom made for my nitropropane race truck engines that I was running sponsored by GM. They found ZERO added issues from it and one of the engineers commented several times he wished they went with Detroit’s and Stanandyne’s recommendations of gear drive instead of chain.

But my use was short life, hard use. So I asked around for folks that were going the opposite- normal power and long life. I had near 100 people responded running them that had from 25,000 miles to a couple dozen over 200,000 miles. Both DSG and
Then looking into how did Ford do with the same exact ip with gear drive- longer ip life, longer everything life infact.

So who else designs their diesels with gear drive and NOT a chain? Cummins, Detroit, Cat, Mercedes, International, Volvo, Aro, Perkins, bmw, Mack, Isuzu, Mitsubishi, Kubota, Rolls Royce, Styer, VW, Yanmar, and I am sure I missed many- like everything the Russian military runs...

So the hard part is finding a diesel engine that actually uses a timing chain. Think about a gasser engine- up to 9:1 compression ratio they run a single timing chain. Then 9.5 or 10:1 they had to run double rollers. So a gm 6.5 has double rollers and over 21:1. And the chain is allowed 1” stretch as ok?!?! It is simple- GM pinch d pennies because they could get away with it.

Find 2 people that can show a damaged camshaft. Heck- one of the reasons really high beefed engines go with gear drive in gasser world is to get away from chain slap. On and off throttle on a diesel? Never haha. Let’s see pictures of those cams, lifters, etc.

The people that swear the timing chain being replaced with gear drive caused crank issues that I found- had cracked main webs and had close to and over 200,000 miles on Factory harmonic balancer. In the fleet where we had tons of the 6.5 putting on over 100,000 miles per year: we learned that 100,000 miles is the time to replace the balancer. Doing just that we eliminated broken cranks and main webs- completely eliminated.

So feel free to run what ya want, obviously. But I try to dispell misinfo when I can.
And btw- have you tracked back the folks against all gears and noticed the leader of the pack sold timing chain sets and was declined being able to sell the dsg sets? Yeah...
There was rumors the fast truck the one guy had was with a chain with over 200,000 miles on it... yeah, I call BS - who builds a race engine doing all the ceramic coatings, block filler, and oh yeah- was supposed to push the 5,000 rpm limits with custom everything tbey could do at the time but purposely used a stretched out chain with over 200,000 miles rather than installing one of the brand ones he sells to people - c’mon man!

So I waited patiently, for a couple years until sets were available again and bought a set for myself shortly after they became available.

For now, if you are going to swap your old chain set out- buy a good set, not cheap set.
imo the price is worth it. But check the slack. iirc 0.8” is max allowed but if you have 0.4” or less, the leave it.
I also recommend everyone does a new front seal while there, and ds4 folks get a new Delco cps in there while it is easy to reach.
 

FellowTraveler

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Really not an option even if you wanted it right now because Leroy has people on a waiting list until he feta enough to do an order for the next batch to be made.
But I do want to share- I did tons of looking and chased down multiple people that were supposed to have had issues from the dsg sets (which is what Leroy’s are copied off of). 2 people swear o having that had been their issue and 2 that said maybe. Opposed to hundreds and hundreds that had no issues including myself when I had a similar but not exactly the same design custom made for my nitropropane race truck engines that I was running sponsored by GM. They found ZERO added issues from it and one of the engineers commented several times he wished they went with Detroit’s and Stanandyne’s recommendations of gear drive instead of chain.

But my use was short life, hard use. So I asked around for folks that were going the opposite- normal power and long life. I had near 100 people responded running them that had from 25,000 miles to a couple dozen over 200,000 miles. Both DSG and
Then looking into how did Ford do with the same exact ip with gear drive- longer ip life, longer everything life infact.

So who else designs their diesels with gear drive and NOT a chain? Cummins, Detroit, Cat, Mercedes, International, Volvo, Aro, Perkins, bmw, Mack, Isuzu, Mitsubishi, Kubota, Rolls Royce, Styer, VW, Yanmar, and I am sure I missed many- like everything the Russian military runs...

So the hard part is finding a diesel engine that actually uses a timing chain. Think about a gasser engine- up to 9:1 compression ratio they run a single timing chain. Then 9.5 or 10:1 they had to run double rollers. So a gm 6.5 has double rollers and over 21:1. And the chain is allowed 1” stretch as ok?!?! It is simple- GM pinch d pennies because they could get away with it.

Find 2 people that can show a damaged camshaft. Heck- one of the reasons really high beefed engines go with gear drive in gasser world is to get away from chain slap. On and off throttle on a diesel? Never haha. Let’s see pictures of those cams, lifters, etc.

The people that swear the timing chain being replaced with gear drive caused crank issues that I found- had cracked main webs and had close to and over 200,000 miles on Factory harmonic balancer. In the fleet where we had tons of the 6.5 putting on over 100,000 miles per year: we learned that 100,000 miles is the time to replace the balancer. Doing just that we eliminated broken cranks and main webs- completely eliminated.

So feel free to run what ya want, obviously. But I try to dispell misinfo when I can.
And btw- have you tracked back the folks against all gears and noticed the leader of the pack sold timing chain sets and was declined being able to sell the dsg sets? Yeah...
There was rumors the fast truck the one guy had was with a chain with over 200,000 miles on it... yeah, I call BS - who builds a race engine doing all the ceramic coatings, block filler, and oh yeah- was supposed to push the 5,000 rpm limits with custom everything tbey could do at the time but purposely used a stretched out chain with over 200,000 miles rather than installing one of the brand ones he sells to people - c’mon man!

So I waited patiently, for a couple years until sets were available again and bought a set for myself shortly after they became available.

For now, if you are going to swap your old chain set out- buy a good set, not cheap set.
imo the price is worth it. But check the slack. iirc 0.8” is max allowed but if you have 0.4” or less, the leave it.
I also recommend everyone does a new front seal while there, and ds4 folks get a new Delco cps in there while it is easy to reach.
I was one of those who found an issue with the DSG gear-set after removal, "the gears were severely pitted like the surface hardness gave way & not re-usable".
I had posted the gear-set for sale on this site after I disassembled the 6.5 to sell the parts, however; after a good clean the damage became apparent. I had one buyer and told him I was pulling the ad for the set because of the pitting, he insisted buying them at a discounted price, perhaps to duplicate them, I just do not know.
I may have the images archived, if so I will post.
 

Redtruck97

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Zephyrhills, Florida
Really not an option even if you wanted it right now because Leroy has people on a waiting list until he feta enough to do an order for the next batch to be made.
But I do want to share- I did tons of looking and chased down multiple people that were supposed to have had issues from the dsg sets (which is what Leroy’s are copied off of). 2 people swear o having that had been their issue and 2 that said maybe. Opposed to hundreds and hundreds that had no issues including myself when I had a similar but not exactly the same design custom made for my nitropropane race truck engines that I was running sponsored by GM. They found ZERO added issues from it and one of the engineers commented several times he wished they went with Detroit’s and Stanandyne’s recommendations of gear drive instead of chain.

But my use was short life, hard use. So I asked around for folks that were going the opposite- normal power and long life. I had near 100 people responded running them that had from 25,000 miles to a couple dozen over 200,000 miles. Both DSG and
Then looking into how did Ford do with the same exact ip with gear drive- longer ip life, longer everything life infact.

So who else designs their diesels with gear drive and NOT a chain? Cummins, Detroit, Cat, Mercedes, International, Volvo, Aro, Perkins, bmw, Mack, Isuzu, Mitsubishi, Kubota, Rolls Royce, Styer, VW, Yanmar, and I am sure I missed many- like everything the Russian military runs...

So the hard part is finding a diesel engine that actually uses a timing chain. Think about a gasser engine- up to 9:1 compression ratio they run a single timing chain. Then 9.5 or 10:1 they had to run double rollers. So a gm 6.5 has double rollers and over 21:1. And the chain is allowed 1” stretch as ok?!?! It is simple- GM pinch d pennies because they could get away with it.

Find 2 people that can show a damaged camshaft. Heck- one of the reasons really high beefed engines go with gear drive in gasser world is to get away from chain slap. On and off throttle on a diesel? Never haha. Let’s see pictures of those cams, lifters, etc.

The people that swear the timing chain being replaced with gear drive caused crank issues that I found- had cracked main webs and had close to and over 200,000 miles on Factory harmonic balancer. In the fleet where we had tons of the 6.5 putting on over 100,000 miles per year: we learned that 100,000 miles is the time to replace the balancer. Doing just that we eliminated broken cranks and main webs- completely eliminated.

So feel free to run what ya want, obviously. But I try to dispell misinfo when I can.
And btw- have you tracked back the folks against all gears and noticed the leader of the pack sold timing chain sets and was declined being able to sell the dsg sets? Yeah...
There was rumors the fast truck the one guy had was with a chain with over 200,000 miles on it... yeah, I call BS - who builds a race engine doing all the ceramic coatings, block filler, and oh yeah- was supposed to push the 5,000 rpm limits with custom everything tbey could do at the time but purposely used a stretched out chain with over 200,000 miles rather than installing one of the brand ones he sells to people - c’mon man!

So I waited patiently, for a couple years until sets were available again and bought a set for myself shortly after they became available.

For now, if you are going to swap your old chain set out- buy a good set, not cheap set.
imo the price is worth it. But check the slack. iirc 0.8” is max allowed but if you have 0.4” or less, the leave it.
I also recommend everyone does a new front seal while there, and ds4 folks get a new Delco cps in there while it is easy to reach.
Thanks Will, well I am trying to get the best advise I can about parts for this old girl and I try to research as much as possible. I am changing out the harmonic balancer and pulley just for safe measure, I am sure this engine is over 100000+ miles and while I am freshening it up I just thought I would ask the question. Yes Leroy is out of stock but I can't wait until he has more. I can tell it has some play but it was running pretty good until the pump failure so I'll just do what I am doing and put it back unless it fails. I appreciate all the help and advise. I am becoming more familiar with the engine and I hope to get many more miles from it.
 

Will L.

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Yeah- thats what most of us done is just best we can with what we got.
Just wanted you (and others) to know what I found out because then when there is a short window in the future of them becoming a available again people an decide ahead of time if they want one. Some of us plan to run these engines until no parts are available anymore, others are just trying to oeep it alive until they can afford a newer truck.

I just hate that there is misinformation spread so one or two guys could make a quick buck, but the knowledge of what’s actually best gets muddied.

Right now in the Hummer & hmmwv world (same engine, trans, misc parts) there is 2hummer specialized companies that are both known for charging crazy high prices in a YouTube war. Years ago I brought out info showing one of them was selling what was then an Airtex $30 lift pump with their label on it for over $100 and touting it as the best high performance lift pump available anywhere. But testing was done and showed that it was an inferior part - like out of several (8 iirc) tested it actuallyhad shortest life and after like 20 hours of pumping had lowest pressure and volume. And now the other company they are in battle with is selling 6.2 mechanical lift pumps as a good option. At least not saying its amazing and only doubles the cost to consumer instead of over triple. But it is too weak for the ds4 pumps from day one. And GM quit running them when they learned failure of the mechanical bladder causes fuel to wash out the engine oil and ruin engines. GM put out a notice of upgrade to the electric lift pump for older 6.2 trucks as a recommendation to fleets and government agencies, and obviously would sell the upgrade to regular people too. Kinda aggravating that places do this kinda stuff Because both of thise places actually have a lot of really good products. All expensive, but if a guy can afford it -much is worth it. But they just look for a way to make profit even if it is at the expense of average joe, while acting like experts in the field just to sell their wares.
 

Redtruck97

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Zephyrhills, Florida
Yeah- thats what most of us done is just best we can with what we got.
Just wanted you (and others) to know what I found out because then when there is a short window in the future of them becoming a available again people an decide ahead of time if they want one. Some of us plan to run these engines until no parts are available anymore, others are just trying to oeep it alive until they can afford a newer truck.

I just hate that there is misinformation spread so one or two guys could make a quick buck, but the knowledge of what’s actually best gets muddied.

Right now in the Hummer & hmmwv world (same engine, trans, misc parts) there is 2hummer specialized companies that are both known for charging crazy high prices in a YouTube war. Years ago I brought out info showing one of them was selling what was then an Airtex $30 lift pump with their label on it for over $100 and touting it as the best high performance lift pump available anywhere. But testing was done and showed that it was an inferior part - like out of several (8 iirc) tested it actuallyhad shortest life and after like 20 hours of pumping had lowest pressure and volume. And now the other company they are in battle with is selling 6.2 mechanical lift pumps as a good option. At least not saying its amazing and only doubles the cost to consumer instead of over triple. But it is too weak for the ds4 pumps from day one. And GM quit running them when they learned failure of the mechanical bladder causes fuel to wash out the engine oil and ruin engines. GM put out a notice of upgrade to the electric lift pump for older 6.2 trucks as a recommendation to fleets and government agencies, and obviously would sell the upgrade to regular people too. Kinda aggravating that places do this kinda stuff Because both of thise places actually have a lot of really good products. All expensive, but if a guy can afford it -much is worth it. But they just look for a way to make profit even if it is at the expense of average joe, while acting like experts in the field just to sell their wares.
So true all the scammers out there. All I can do is rely on honest people to do the right thing. I hope my Pump from Quadstar holds up and does a good job. the old pump had a sticker on it from 2013 so the pump was changed at that point, it still had the Stanadyne data plate on it.
 

Will L.

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Get the best water separator and fuel filter on there you can afford.
Mount a pressure gauge in the dash you see all the time driving that is tapped at the metal inlet at the ip itself.
Low pressure/ flow kills the ip- just like water, fuel bugs, or dirt.

The many new fuel filters are pulling down to 1 or 2 microns. But they are more trouble if you are in an area of gelling fuel temperatures you will have more plugged filters from it. Not worth the hassle for some- definitely worth the hassle to save fuel system for others.
 

Redtruck97

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Get the best water separator and fuel filter on there you can afford.
Mount a pressure gauge in the dash you see all the time driving that is tapped at the metal inlet at the ip itself.
Low pressure/ flow kills the ip- just like water, fuel bugs, or dirt.

The many new fuel filters are pulling down to 1 or 2 microns. But they are more trouble if you are in an area of gelling fuel temperatures you will have more plugged filters from it. Not worth the hassle for some- definitely worth the hassle to save fuel system for others.
I'M looking into a water/fuel separator. I did purchase a fuel pressure gauge from Holley, I'll have that mounted in the cab. I am going to relocate my stock fuel filter as well. Soon I will get some fuel conditioner, maybe the Stanadyne from Amazon and see if that helps as well. I'm going to keep fixing the truck up.
 

WarWagon

Well it hits on 7 of 8...
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:facepalm: Why are you anywhere near the chain just swapping the IP? It's a good idea to change it anytime after 30K miles if you are there. Regardless the IP gear bolts come out through the oil fill and you bar the engine over for the next bolt. No need to pull off the entire front of the engine.

Chains go on tight new. At 30K they have stretched out some from the injection pump's shock loading. A new Cloyes chain is a good idea. No not the reboxed parts store brand from the reject pile where the sprockets were not centered on the factory tooling. Tight slack tight slack as the engine rotates by hand made me think I had a bent crank, but, no a garbage chain set.

Chain slop.... Some vids of it from a junk engine some scumbag vendor sent me in my project link below.


That much slop likes to fatigue hammer the exhaust valve tips. Poor @Will L. as he forgot the blue and flaking camshafts I had from chains. :angelic: Also the Cummins 5.0L V8 diesel has/had (no longer offered in the Titan) a chain drive CP4 (Also Yuck!) HPCR pump as well as the new 3.0L GM diesel and for even more fun the 3.0L GM is a rear chain drive. GM isn't about to let others take away their put lemon laws on the books unreliable diesel engine crown.

Really... others are trying to kick GM off the unreliable diesel mountain.

It's only 116F out when this 5.0L Cummins Nissan Titan pic was taken from the comfort of my 2018 RAM 6.7 Cummins.

50Cummins_Nissan.JPG
 

Redtruck97

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:facepalm: Why are you anywhere near the chain just swapping the IP? It's a good idea to change it anytime after 30K miles if you are there. Regardless the IP gear bolts come out through the oil fill and you bar the engine over for the next bolt. No need to pull off the entire front of the engine.

Chains go on tight new. At 30K they have stretched out some from the injection pump's shock loading. A new Cloyes chain is a good idea. No not the reboxed parts store brand from the reject pile where the sprockets were not centered on the factory tooling. Tight slack tight slack as the engine rotates by hand made me think I had a bent crank, but, no a garbage chain set.

Chain slop.... Some vids of it from a junk engine some scumbag vendor sent me in my project link below.


That much slop likes to fatigue hammer the exhaust valve tips. Poor @Will L. as he forgot the blue and flaking camshafts I had from chains. :angelic: Also the Cummins 5.0L V8 diesel has/had (no longer offered in the Titan) a chain drive CP4 (Also Yuck!) HPCR pump as well as the new 3.0L GM diesel and for even more fun the 3.0L GM is a rear chain drive. GM isn't about to let others take away their put lemon laws on the books unreliable diesel engine crown.

Really... others are trying to kick GM off the unreliable diesel mountain.

It's only 116F out when this 5.0L Cummins Nissan Titan pic was taken from the comfort of my 2018 RAM 6.7 Cummins.

View attachment 64866
Well like any good mechanic I can't leave anything alone, plus I am repairing oil leaks and doing some new gaskets. Too many old original parts that need replacing. I have arthritis in my left hand so not as much strength as when I was younger and it's not a "pump and go". I want to take a little time and update some things. If I do replace TC/G it will be a Cloyes or Melling set. I'm also going to change the crank position sensor since I'm doing the balancer/pulley-seems easy to get at it from that point. All the rubber items seem like original and cracking and old, so all new rubber hoses, fuel lines and heater hose. New thermostats, seals, new vacuum pump, serp belt, oil/filter and antifreeze.
 

Will L.

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Hey, the fuel line needs to be sae30R9 or higher to withstand the new alcoholic fuel we have.

yeah @WarWagon- ya got me. Lots of crappy diesels made with timing chains. However the list of good diesels with timing chains is mighty short! Haha
 
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