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Discussion Starter #1
I'm working on a mechanical 6.5 turbo diesel and while I have the front cover off my buddy wants me to replace the timing chain. Problem is that I don't know how to get the old chain off. Once the big bolt in the center of the cam gear is off what else do I need to do because the gears and chain won't slide all the way off. Do I need a puller to get the crank gear off? And is lining the timing marks up even necessary since everything is keyed and can only go in one way?

I read though the GM service manual and it simply says to "remove timing set" after the front cover is off. Really helpful. No wonder even GM techs screw things up when doing repairs. If someone can break it down and give me the "for dummies" version of how to do this I'd really appreciate it. Thanks
 

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Line up the dots before disassembling. Mostly for the IP gear since it can mesh anywhere.

Put a little pressure on the lower gear with a 2 jaw puller. Heat it slowly with a mapp torch (or similar) and it'll POP!. Apply light heat the rest of the way off, should be fairly easy. Don't heat the crank or the main bearing behind the gear too much.

Heat the new one and slide it on. Don't go crazy with heat, should only need (250*-300*) Make sure the chain is on it before it goes all the way in. Easy peasy.
 

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And don't forget loc-tite on the cam bolt and IP gear bolts. Sucks when you realize you forgot and already have the timing cover back on : )
 
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I'm working on a mechanical 6.5 turbo diesel and while I have the front cover off my buddy wants me to replace the timing chain. Problem is that I don't know how to get the old chain off. Once the big bolt in the center of the cam gear is off what else do I need to do because the gears and chain won't slide all the way off. Do I need a puller to get the crank gear off? And is lining the timing marks up even necessary since everything is keyed and can only go in one way?

I read though the GM service manual and it simply says to "remove timing set" after the front cover is off. Really helpful. No wonder even GM techs screw things up when doing repairs. If someone can break it down and give me the "for dummies" version of how to do this I'd really appreciate it. Thanks

Is this the manual you read??


Here is the 1995 C/K truck manual, section 6 Engine in pdf. format
Timing chain replacement starts on page #18
http://www.dieselplace.com/forum/attachments/63-gm-diesel-engines/21-6-5l-diesel-engine/331010d1428773045-6-5l-faqs-master-list-information-6-5-answers-1995-sec-6-6.5l-engine.pdf
 

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Discussion Starter #5

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Discussion Starter #6
Line up the dots before disassembling. Mostly for the IP gear since it can mesh anywhere.

Put a little pressure on the lower gear with a 2 jaw puller. Heat it slowly with a mapp torch (or similar) and it'll POP!. Apply light heat the rest of the way off, should be fairly easy. Don't heat the crank or the main bearing behind the gear too much.

Heat the new one and slide it on. Don't go crazy with heat, should only need (250*-300*) Make sure the chain is on it before it goes all the way in. Easy peasy.
Thanks. Is it a just a tight press fit and the heat loosens it up? How do I go about putting it back on, with a rubber mallet? So I line up the dots on the crank and cam gears so one is at 12 and one is at 6 or get them both at 12 o'clock position? I have never done a timing chain on anything before so this is all a new world for me looking at this.
 

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Discussion Starter #7 (Edited)
One more question, the IP and front cover are already off so will that matter when I go to turn the motor over to line up the dots on the crank and cam gears?
 

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One more question, the IP and front cover are already off so will that matter when I go to turn the motor over to line up the dots on the crank and cam gears?
There's full instructions in the service manuals in the FAQ area. I don't want to mis quote them but i'd recommend grabbing them and taking a look. Just because they are keyed doesn't mean you can't get the chain off a tooth.

All I remember was having the big dot on the outer cam gear at 12 O'Clock so I knew where to put the IP gear back.
 

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Just found this after I typed the last post. I rotated it so the dot on the outer cam gear was at 12 O'Clock and the dots on the timing chain gears matched up. That ensures you get it all back where it needs to be.


 

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Discussion Starter #10 (Edited)
Ok I'm going to have to find that manual and read up on this because I'm slightly more confused now than before :HiHi:

Does it matter if the engine is turned over without the IP installed?
 

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Ok I'm going to have to find that manual and read up on this because I'm slightly more confused now than before :HiHi:

Does it matter if the engine is turned over without the IP installed?
no. You can manage without it installed
 

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I would reccommend going a step further and remove the timing cover to put a gasket in between the timing cover and block. They came with only anarobic sealer[no gasket]. I had 2 engines develop coolant leaks there after replacing only the water pump.

cam timing: crank sprocket at 12 o'clock cam sprocket at 6 o'clock

IP timing: engine must be rotated 180 degrees from cam timing position. Cam gear 12 o'clock IP gear 6 o'clock
 

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I would reccommend going a step further and remove the timing cover to put a gasket in between the timing cover and block. They came with only anarobic sealer[no gasket]. I had 2 engines develop coolant leaks there after replacing only the water pump.

cam timing: crank sprocket at 12 o'clock cam sprocket at 6 o'clock

IP timing: engine must be rotated 180 degrees from cam timing position. Cam gear 12 o'clock IP gear 6 o'clock
Good point. I've also had awesome luck so far with Permatex "the right stuff" after cleaning all the anaerobic crap off. This is high torque gasket maker and I used it for the timing cover, water pump, and oil pan. Just try not to fill the bolt holes with it so everything torques properly. It's the only stuff that would finally seal the turbo oil drain plate too. First time in years this thing hasn't leaked oil from every orifice :HiHi:
 
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Discussion Starter #14 (Edited)
Ok I got the old chain off. Hooked up the three jaw puller and was able to get it off just turning the bolt on the puller by hand. Cam gear at 6 crank at 12. Thanks guys.
 

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Discussion Starter #15
I would reccommend going a step further and remove the timing cover to put a gasket in between the timing cover and block. They came with only anarobic sealer[no gasket]. I had 2 engines develop coolant leaks there after replacing only the water pump.

cam timing: crank sprocket at 12 o'clock cam sprocket at 6 o'clock

IP timing: engine must be rotated 180 degrees from cam timing position. Cam gear 12 o'clock IP gear 6 o'clock
I've been reading all I can about what to use on the timing cover and I've decided to use anaerobic sealer like the factory uses. I think it's a great choice for the application. I could be wrong but I think you're supposed to reseal the timing cover when replacing the water pump. Something about it breaks the anaerobic seal on the cover when the pump is removed. Can't remember for sure. We'll see how it works when I get the motor back up and running.

Thanks for the help with the timing marks :thumb:
 

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Good point. I've also had awesome luck so far with Permatex "the right stuff" after cleaning all the anaerobic crap off. This is high torque gasket maker and I used it for the timing cover, water pump, and oil pan. Just try not to fill the bolt holes with it so everything torques properly. It's the only stuff that would finally seal the turbo oil drain plate too. First time in years this thing hasn't leaked oil from every orifice :HiHi:
Quadstar, if you read this had a question about "the right stuff" I've read nothing bad about it. I actually used ultra grey a couple years ago with felpro paper gaskets on my wp, backing plate, and timing cover to engine block with no leaks thus far. At least that's what I think. I have a small leak from the bottom side of my water pump when I shut the truck down so I bought a new water pump (gates for 98) and timing chain set (cloyes) to jnstall. Couple questions.
1. Do I need a jaw type puller? I have a timing gear puller, and a master bolt grip set will I be able to remove the lower sprocket with this? Also I have a otc pulley holding tool and a harmonic installer kit with the correct M16x1.5 adapter will this install the new crank gear?
2. Any suggestions other than reading the manual? I have it downloaded just haven't looked.
3. Has anyone used the right stuff that says return to immediate use. It says "1 minute" or something to that nature. I don't want to make it a 2 day project and would like to get it done in one day.
 

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The 3 jaw or a 2 jaw puller would work.Thats all i ever used on these engines.I like the permatex ultra black myself.Always had good success with it.For the bottom crank gear you could warm up the gear in a tin or galvanized container with engine oil.The gear would expand slightly allowing easier installation or press it on with the tool you have in mind.
 
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The right stuff is much better IMO and yes it's instant service. I let it dry for a couple hours but that's it.

A little heat on the sprocket is the only 'trick' you'll need other than the manual to line up timing marks before and after taking the gears and chain off. And don't get too much sealant in the bolt holes for the timing cover and hydraulic them when tightening. The few that go into the water pump passages are the only threads that need sealed.
 

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The only thing that leaks on my truck now are the half ass rebuilt Badger injectors (only have about 15k on them). Leaking out the bodies much like Grabowski's were. Have a few sets on the way that are not going to give me problems.
 

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The only thing that leaks on my truck now are the half ass rebuilt Badger injectors (only have about 15k on them). Leaking out the bodies much like Grabowski's were. Have a few sets on the way that are not going to give me problems.
Sucks big time the injectors are leaking.Nothing worse especially on the turbo side.
 
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