I need to replace my timing chain on my 97 6.5TD it has 213K miles on it.

I know in the past it's been suggested to get a chain set for a 93 (thus avoiding the expense of the lower gear) and install the chain and the cam gear.

Autozone lists replacement chains minus the gears now for the 97 can I get by installing a new chain without replacing either gear?


Note I'm not wanting to spen lots or I'd buy the gear gear drive timing set.

I need to replace my timing chain on my 97 6.5TD it has 213K miles on it.

I know in the past it's been suggested to get a chain set for a 93 (thus avoiding the expense of the lower gear) and install the chain and the cam gear.

Autozone lists replacement chains minus the gears now for the 97 can I get by installing a new chain without replacing either gear?


Note I'm not wanting to spen lots or I'd buy the gear gear drive timing set.

If you are doing it, you might as wll go ahead and put in the gears. That is what I plan on doing. There is an article in the books I got from kennedy diesel about the switch.

http://www.dieselservices.com/html/gm_diesel/6_5_Turbo_Diesel/gm-diesel-special/dsg_dual_idler_gear_drive__phaser_kit_p122.cfm

i just bought a timing chain for my 98 from northern auto for $14 plus 10 shipping IIRC the set with both gears was $ 107 plus shipping


WITH THAT MANY MILES I WOULD CHANGE OUT THE WHOLE SET
BOTH GEARS AND CHAIN JUST MY .02

You can replace just the chain if dollars are tight and there is no damage to your gears, but gears and chains are best replaced as a set. The wear that is on your gears will cause the chain to wear faster than on a new set of gears. Also, look at the amount of time and other costs, ie gaskets, that go into a job like this. You may decide the cost of a gear & chain set is worth the extra over just a chain. Are you replacing based on miles or problems?

Sounds like a great time to put in a DSG gear set, but they do run into some bucks. I loved mine...til the motor blew!!!

Prollem with doing the chain-only is: the sprocket pitch diameter has changed, due to wear, resulting in unwanted slack with a new chain - don't fergit - it's not only pulling the camshaft in this engine, but also that 2000psi hydraulic pump associated with the FSD\PMD - causes a lot more wear than in a 454, fer example, and those are ready for file 13 at only 100kmi - you can doit, but it won't be as crisp as a new timing chainset - on the other hand, with all this crap coming in from sub-3rd-world countries, you may be better off with the oem sprockets.................

Use the 93 set. It will work great.

Get the whole timing set. Well worth the inverstement. Also just as valuable is to check the (and with that many miles should replace) is the harmonic balancer...

Here is my solution

I'd thought about replacing the chain only or even going with the earlier set and reusing the reluctor sprocket, then I found an online vendor who had one Cloyes C-3097 set (three piece set for '94 up), for $57 + ship, and made in USA.

This is one of those chores that I would hate to have to do again, so even though I happened to find a bargain, if I hadn't I would have sprung for the full set through a local supplier just so everything inside there got replaced. My truck is pushing 201k miles now and I'm hoping that when this goes on it'll make a difference.

my .02

Use the 93 set. It will work great.

What's special on the 93 set?

Well I decided to just do the chain. I'm hoping to make this engine last a couple of years of low mile driving and then get a new 6.5 for the truck. I want to do the gear set in the new engine.

That should do it for ya, then - goes without sayin', but B sure to check the HB and acc drive pulley while yer down there

That should do it for ya, then - goes without sayin', but B sure to check the HB and acc drive pulley while yer down there

Not check I'm going to replace them. I think that $$ spent there might prevent a broke crank.

What's special on the 93 set?

By using the 92-93 timing chain set you discard the crank sprocket and reuse the one on that's on the crank. The lower OEM sprocket has the reluctor built on to it so it makes the electronic set cost more.

It saves a little time as you don't have to pull the gear all the way off and you don't have to reset your timing.

Most major engine rebuilders use this method to save cost.

I have done several myself and the chain fits tight. Lower sprocket does not wear much at all.

And for all of you that say different, You have never done it. :rolleyes:

I've been an old man longer than most of you have even been alive, and an adult longer than some of the rest of you have been alive, so imagine how many times I've never replaced a timing chain-set, eh? :eek:

Installed a '49 303cuin V8 Olds engine and hydramatic transmission in a '35 Dodge coupe when I was 16rs of age, back in middle 1950's - shortened and mated the 2 different-style oem driveshafts using a pair of rollerskates as a 'lathe' - think a timing chain-set is a mystery to me? :rolleyes:

Ha!!! :p:

Sprocket pitch diameter decreases with wear, greater decrease with higher mileage - 200kmi is a LOT of higher mileage - yeah, they'll still usually function long enuff to get the customer's job out the door, just not fer me.

Knowwhuttimean, jellybeans? :cool:

Thanks for input TD!

Now you guys got me all worried with this talk of "high mileage" about 200k needing chain replacement.

What's the problem? Do they break catastrophically or just stretch? If they stretch, doesn't that cause pump time to retard? That would be noticed in performance wouldn't it? That is the way it was with my Mercedes and my Peugeot IIRC.

Geez, I just got new injectors and glow plugs last week. About 275K miles.

The 6.5 chain stretches. The engine will run better with a new chain. Valve timing and injection timing are both effected. Never saw one break catastrophically.

Now you guys got me all worried with this talk of "high mileage" about 200k needing chain replacement.

Join the club, I'm at 201k and this is a worry of mine too.

What's the problem? Do they break catastrophically or just stretch? If they stretch, doesn't that cause pump time to retard? That would be noticed in performance wouldn't it? That is the way it was with my Mercedes and my Peugeot IIRC.

They better not just break catastrophically or I'm up shite crick!

Geez, I just got new injectors and glow plugs last week. About 275K miles.

I've slowly been picking up new parts and gaskets to do a bunch of things, but injectors I don't have yet.

The way I figure is if I'm going to do timing chain I should wait until after that for coolant replacement. If I'm going to relocate PMD, I need to wait until I have the "F" intake (should be here in a week...me thinks). And finally, I should do valve cover gaskets (RTV) also, which means that I should wait on injectors / glow plugs and do all at the same time since I'll have the turbo and the top pulled apart too. I prolly should check the rocker plastic bits too while I'm in there!

On the 6.5 you kind of have to do everything that needs doin while you're in there, since it's a pita to go back in again.

Ok - 'nuther myth to dispel - gather 'round, kiddies, for a catastophic tale of terror - and, please.......do try this at home -

Back in the late '60's-early '70's the old fogies then in residence at GM decided that the then-current steel-on-cast-iron timing chain-sets were upsetting the purple-haired grannies with the excessively toothy noises filtering back thru the insulated firewalls of those Buicks and Oldsmobiles, and the other marques, including the working-man's and racing-man's Chevies.

So, they cleverly designed the collective cam-sprockets to be of precision-cast cast-aluminum, needing no further machinework (had the bean-counters drooling unashamedly), and layered in a thick coating of pristinely nylon-coloured.....well......nylon - no way was that steel-link chain gonna resonate on that large sprocket-wheel, driving granny to two bottles of hadacol per day.

Alas, success - until granny's big 4-door Olds fell down on it's knees in rush-hour traffic, all the valves crunched into the piston-crowns when the nylon sprocket-teeth cracked, split, and crumbled due to deterioration by hot engine oil - seen a few of those hapless engines in the boneyards - talk aout yer "stretched" timing chain! - but never saw a car or truck engine with steel on cast-ion with even a split cast-iron sprocket, much less broken chain.

Which leads us to the myth - "timing chain stretch" - neber hachee, folks - not even if you got one of those 3rd-world jewels made of annealed wrought-iron with nails for pivot-pins.

Timing chain "stretch" describes a conditon where the chain length has obviously increased - it is very loose on the sprockets, gotta lotta slop and flap, and is much longer than the new replacement when measured center-to-center between the sprocket bores - gotta be because the links stretched, right?

Technically, the steel segments in those links will stretch, but it would be exceeding difficult for you to measure it, there in the shade of yer favorite tree - and that increase would not contribute significantly to the looseness you can observe - what really happens, such that it is easily noticeable and measurable, is the link pivot-points wear into each other.

The outside widest links are bored to interference-fit dimension, where the pivot pin is press-fit into each of the segments - the inside link segments are bored to precisely fit over those pivot pins, providing a rotating, or pivoting, joint - as the joint pivots around the diameters of the sprockets, the pins wear smaller and the link bores wear larger due to that pivoting and the extreme pulling force required to rotate the camshaft, and in 6.5 case, the additional force required to rotate the 2000psi hydraulic pump

The pins get smaller, the bores get larger = chain "stretch"

Now, let's talk about the pressed barrel-type pivot pins and the links bored to pivot on those barrel\pins in our double-row 'roller' chainset, and how the non-rotating barrels might reduce sprocket pitch diameter by that same wearing action.........no, let's don't - I think you can ascertain the concept

So, here's how you can determin chain-wear "stretch" in your very own backyard under your shady tree with nothing more than the old and the new chainsets, a piece of heavy paper or cardboard, a sharpened pencil, and a ruler

Lay the sprockets in the chain as per the configuration on yer engine - cam sprocket at the top, crank sprocket underneath at the bottom

lay the assembled chain-set on your cardboard or paper

spread the sprockets apart until the chain is tight, then trace the sprocket bore i.d.'s on the paper, maintaining your spreading pressure on the sprockets

measure from the upper arc of the circle representing the bore in the cam sprocket to the upper arc of the circle representing the bore of the crank sprocket - that will indicate the center-to-center dimension of the sprocket bores with timing chain installed.

Why, you could even compare the old chain-set to the new chain-set using that method - you could even lay the old chain on the new sprockets, lay the new chain on the old sprockets, lay the new chain and new cam sprocket with the old crank sprocket - lay the ol...........but, I think you get my drift, right?

Even more difficult, but more precisely telling, is to prove that stuff by laying the chains and sprockets in-place on the actual cam and crankshaft in the actual engine block - and if you have several short\longblocks available, you could also see how all 6.5's ain't created equal.

Oh, yeah - there's a +\- spec on the actual cam-to-crank centerline dimension - imagine gettin' a block that stacked up to the outside dimension, such that all chains are max tight, requiring a liberal dose of K-Y to get it in........er....on.

'Magine, also, the pore sap that gets a block that's to the inside dimension, and all new chainsets are loose, eh?

But, there's my tale, scary or entertaining, and I'm stickin' to it............

Hellava tale there ole boy......
So I'm gathering that by changing all them parts (chain and gears) will fo sho take up any block wear..??

New timing chain and both sprockets will eliminate retarded timing differences resulted from combined wear of the original, worn chain-set

Man o' man!! What an entertaining and informative piece of classic 'merican auto literature. No timing gears for me. Next water pump change will include timing chain set change complete! Man, I may even do it next time I check the oil!
I have a buddy who's a very successful Hollywood screenwriter. I'll show him this post and who knows......, starring Tim Allen.....!:D :D
seriously gmctd, great post!

Ok - 'nuther myth to dispel - gather 'round, kiddies, for a catastophic tale of terror - and, please.......do try this at home -

Back in the late '60's-early '70's the old fogies then in residence at GM decided that the then-current steel-on-cast-iron timing chain-sets were upsetting the purple-haired grannies with the excessively toothy noises filtering back thru the insulated firewalls of those Buicks and Oldsmobiles, and the other marques, including the working-man's and racing-man's Chevies.

So, they cleverly designed the collective cam-sprockets to be of precision-cast cast-aluminum, needing no further machinework (had the bean-counters drooling unashamedly), and layered in a thick coating of pristinely nylon-coloured.....well......nylon - no way was that steel-link chain gonna resonate on that large sprocket-wheel, driving granny to two bottles of hadacol per day.

Alas, success - until granny's big 4-door Olds fell down on it's knees in rush-hour traffic, all the valves crunched into the piston-crowns when the nylon sprocket-teeth cracked, split, and crumbled due to deterioration by hot engine oil - seen a few of those hapless engines in the boneyards - talk aout yer "stretched" timing chain! - but never saw a car or truck engine with steel on cast-ion with even a split cast-iron sprocket, much less broken chain.

Which leads us to the myth - "timing chain stretch" - neber hachee, folks - not even if you got one of those 3rd-world jewels made of annealed wrought-iron with nails for pivot-pins.

Timing chain "stretch" describes a conditon where the chain length has obviously increased - it is very loose on the sprockets, gotta lotta slop and flap, and is much longer than the new replacement when measured center-to-center between the sprocket bores - gotta be because the links stretched, right?

Technically, the steel segments in those links will stretch, but it would be exceeding difficult for you to measure it, there in the shade of yer favorite tree - and that increase would not contribute significantly to the looseness you can observe - what really happens, such that it is easily noticeable and measurable, is the link pivot-points wear into each other.

The outside widest links are bored to interference-fit dimension, where the pivot pin is press-fit into each of the segments - the inside link segments are bored to precisely fit over those pivot pins, providing a rotating, or pivoting, joint - as the joint pivots around the diameters of the sprockets, the pins wear smaller and the link bores wear larger due to that pivoting and the extreme pulling force required to rotate the camshaft, and in 6.5 case, the additional force required to rotate the 2000psi hydraulic pump

The pins get smaller, the bores get larger = chain "stretch"

Now, let's talk about the pressed barrel-type pivot pins and the links bored to pivot on those barrel\pins in our double-row 'roller' chainset, and how the non-rotating barrels might reduce sprocket pitch diameter by that same wearing action.........no, let's don't - I think you can ascertain the concept

So, here's how you can determin chain-wear "stretch" in your very own backyard under your shady tree with nothing more than the old and the new chainsets, a piece of heavy paper or cardboard, a sharpened pencil, and a ruler

Lay the sprockets in the chain as per the configuration on yer engine - cam sprocket at the top, crank sprocket underneath at the bottom

lay the assembled chain-set on your cardboard or paper

spread the sprockets apart until the chain is tight, then trace the sprocket bore i.d.'s on the paper, maintaining your spreading pressure on the sprockets

measure from the upper arc of the circle representing the bore in the cam sprocket to the upper arc of the circle representing the bore of the crank sprocket - that will indicate the center-to-center dimension of the sprocket bores with timing chain installed.

Why, you could even compare the old chain-set to the new chain-set using that method - you could even lay the old chain on the new sprockets, lay the new chain on the old sprockets, lay the new chain and new cam sprocket with the old crank sprocket - lay the ol...........but, I think you get my drift, right?

Even more difficult, but more precisely telling, is to prove that stuff by laying the chains and sprockets in-place on the actual cam and crankshaft in the actual engine block - and if you have several short\longblocks available, you could also see how all 6.5's ain't created equal.

Oh, yeah - there's a +\- spec on the actual cam-to-crank centerline dimension - imagine gettin' a block that stacked up to the outside dimension, such that all chains are max tight, requiring a liberal dose of K-Y to get it in........er....on.

'Magine, also, the pore sap that gets a block that's to the inside dimension, and all new chainsets are loose, eh?

But, there's my tale, scary or entertaining, and I'm stickin' to it............

What do you think?............Think he knows what he's talking about?.......You got to love it when the guy that knows something says something, BUT you heard something else, and you think you can get away with it (and maybe you can)...........Then the guy that knows something backs up his something with roller skates and purple hair (you can't make that stuff up!).......AND then after that story, to do anything else would be a STRETCH.........Hey you don't want to clean your timing set grounds, thats fine ...... trust me I've had many, well, but , maybe, if and or's .....Now I just do what he tells me, so I don't have to listen to story's about purple rollerskates.

Louis

Back in the 'day, my dad had a pontiac bonneville. One day it just quit running, and was belching fire out the carb. He checked around, and then we tore the timing cover off and what did we find? Nylon cam gear, split and busted apart all over the place. Well after seeing that, we had to pull the pan, more nylon in there too. Next of course was METAL timing gears, chain, oil pump and engine bearings. Damn nylon had went everywhere during it's falling apart. Nasty experience. Next time i do a waterpump on the old 6.5, it will get a new chain and both gears. Parts Not made off-shore if i can help it.
Don