checking timing chain and etc.

[sask3500]

Hey there, I have a few questions regarding the timing system on the 6.5.

I am a novice 6.5 mechanic, so more information is better.

First I need some clairification on how to guesstimate chain slack, one part is the "timing mark on the damper" referred to in the diesel page troubleshooting book. Where is it and what is it in relation to; is there a matching mark to line it up with? Do you just do some math and mark 3 degrees on the damper and make a tempoary pointer to reference?

The other part is how can the crank be turned without removing the drive pulley to get at the damper nut? Is the drive pulley easily damaged?

Then, if the chain seems to be nearing the wear limit according to this technique, can the timing be set (with a scanner) with a chain near the slack limit? Should it be set to allow for a small amount of future wear? How much?

I know this is a mouthful, but these are all questions I need awnsers to before it goes to the shop. I am trying to prevent the shop from surprising me with a chain in need of replacement.

Thanks for the collective awesomeness here,
Justin

[DaveBr]

If it's a high miler you probably need a chain. You should have a signature so we know what we are dealing with.

[sask3500]

What I am trying to find out is if I can quickly assess the chainset condition to decide if the $180 to get the timing set by scan tool is wasted money, or if that is all that is needed for awhile.

If I can tell if the timing chain is definately okay without removing the front cover, I'll get the timing checked. If not, a timing set goes on the list of parts to order.

I am running thru a list and trying to assess the condition of this motor, it's a wrecker engine and mileage is unknown. There is nothing in particular pointing to a timing issue, merely checking normal wear items and prioritizing what gets fixed first.

And I have been checking "show sig"... assumed it was working.

Justin

[JohnC]

Take the oil fill pipe out. turn the engine clockwise to remove the slack in the chain, then counterclockwise until it just starts to move the injection pump gear (visible through the hole for the oil fill pipe). The amount of crank movement is the slack in the chain.

[Robyn]

Most high milers are going to need a chain.

The electronic IP will be adjusted to compensate for the chain stretch, but the valve train will be retarded.

The sprockets in these engines rarely wear much. Usually just a chain will do the trick.

Just rocking the crank back an forth gently will show the slack.

The crank and pistons will move easily, but the valve train takes more pressure to move it.

Gently rock the crank and just when the effort to do so becomes more severe, stop and go the other way.

With the ballancer timing mark near the indicator or ?? you can see the amount of slack.

If you can move the crank more than a very few degrees the chain is shot.

If the front end of the engine has to come off for ??? I would say, replace the chain.

Missy

[sask3500]

So... if the rock auto catalog is right the balancer works out to 1.74mm of circumference per degree of rotation. A finger on the driven gear should pick up a few thou of movement. Close enough?

How many degrees of retard can the motor handle on the valves?

Back off the accessory belt, turn the crank with a hand on the balancer pulley? Or will it take a bar thru the pulley? Feel for a bit of movement in the gear, measure balancer movement and if it's less than 3 degrees or so get the timing checked and set. If not, new chain.

Sound good?

And thanks,
Justin