timing chain

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timing chain

Post by Action » Thu Oct 05, 2017 3:57 pm

The engine I just took out is a 1996. I put in a 2007. The 1996 doesn't have a timing chain. It just has two large gears. I didn't think they used those that long ago...

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Re: timing chain

Post by dilvoy » Thu Oct 05, 2017 6:32 pm

Gear Drives are nothing new. Big engines have used them for decades and Chevy Guys put them in their engines so they make more noise and scare all the cats out of the neighborhood.
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Re: timing chain

Post by JuanPrado » Thu Oct 05, 2017 6:54 pm

Many straight in line 6 cyls like gm 230,250,292 and Ford 300 used them for a long time starting maybe mid 60 ish from what I remember in my other lifetime selling parts.

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Re: timing chain

Post by Action » Fri Oct 06, 2017 5:29 am

I know they have been used for some time. I meant specifically in the gm 6.5 TD.

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Re: timing chain

Post by dilvoy » Sat Oct 07, 2017 10:51 pm

The 2008 TM's show a timing chain still being used. There must be a story to that engine of yours.
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Re: timing chain

Post by Action » Sun Oct 08, 2017 6:39 am

Date code is J126
This motor ran great. It was pressurizing the coolant system, so I bought a 2007 motor to put in. The water pump whines on the replacement, so I took the old one off before I did the work to the newer one to see how easy it will be.
What is the plunger for in the center of the upper gear?

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Re: timing chain

Post by Retired War Horses » Sun Oct 08, 2017 7:46 am

The timing chain is only seen and accessible if you remove the front housing...the timing gear set up
Is stock in all 6.2-6.5 TD motors.
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Re: timing chain

Post by dilvoy » Sun Oct 08, 2017 8:40 am

There is a strong spring behind that button. It controls thrust of the gear.
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Re: timing chain

Post by 86humv » Sun Oct 08, 2017 8:22 pm

As Steve says...
Those gears are normal, and have a timing dot on each one.
Chain and its gears are under that cover....lower end of chain goes to crank.
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Re: timing chain

Post by dilvoy » Mon Oct 09, 2017 7:54 pm

Just to add, the lower of those two large gears is attached to the cam shaft and is placed in front of the upper timing chain sprocket.
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Re: timing chain

Post by Action » Tue Oct 10, 2017 3:27 am

dilvoy wrote:
Mon Oct 09, 2017 7:54 pm
Just to add, the lower of those two large gears is attached to the cam shaft and is placed in front of the upper timing chain sprocket.
That makes sense. I couldnt see how another gear fit between the ip and the big upper gear. :?

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Re: timing chain

Post by dilvoy » Tue Oct 10, 2017 3:44 pm

When gears are used as these are, the rotation is reversed so if you were to use gears as timing gears between the crankshaft and camshaft, they can't touch each other. they need a separate gear(s) to carry the movement between them.
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Re: timing chain

Post by SinDiesel » Mon Oct 16, 2017 5:36 pm

The gear on the crankshaft drives a chain which drives the gear on the camshaft at a ratio of 2:1 in the same rotational direction.

Also on the camshaft is another gear in front of the chain driven one which drives the gear used to drive the injection pump. The injection pump is reverse rotation as seen in Jason's photo.

Some engine builders opt to select gear drives over chains for the camshaft in order to avoid eventual "chain stretch". These gear drives always use an intermediate/idler gear on either one side or an extra set on both sides to maintain correct rotation.


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