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Unread 03-08-2011, 01:15 PM   #1
robojeep
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Quick timing chain question

Hi all,

I'm in the middle of replacing my harmonic damper since it was starting to fail, and I decided to replace my timing gears + chain at the same time. I'm glad I did, because the old chain had quite a bit of slack in it.

anyway, I'm installing a double roller set from Cloyes (part 9-3127,url) and I have a few questions:

How worried should I be about messing up the timing? since the crankshaft and camshaft ends are both keyed, it seems like it should be impossible: in other words, if the gears + chain are on all the way, does this mean the timing is correct? I'm worried because my chilton's manual states that there MUST be 15 pins between the two markings on the gears, but since the cloyes gears have more teeth and more pins, this doesn't apply.

I would think that once I have the gears oriented with the keying properly, i'm just good to go, yes?

finally, some pics of where I'm at:

before, old stock gears+chain:


after, new cloyes double roller gears+chain:


thanks!

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Unread 03-09-2011, 07:50 PM   #2
robojeep
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no one?

I never rotated either shafts without the chain attached between both gears, so I should be good right? How would you normally verify the timing is correct when working on the 4.0?

I'm just worried I somehow messed it up and the thing will explode...
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Unread 03-09-2011, 08:47 PM   #3
1990JEEPXJ
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you could turn the engine over to get piston #1 at TDC and check to see if the rotor in the distributor is pointed at the #1 plug. be sure its on the compression stroke.

how many miles are on your jeep? how much slack was in the chain? and one favor, can you report back if you notice any difference in the way your jeep runs after doing the chain?
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Unread 03-09-2011, 09:26 PM   #4
wgirvine
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Oh boy, I see problems in your future...

"How worried should I be about messing up the timing?"

Very worried. If you are off by only one tooth, the engine will not run right.

"...since the crankshaft and camshaft ends are both keyed, it seems like it should be impossible: in other words, if the gears + chain are on all the way, does this mean the timing is correct?"

Nope. Think about it... True, the gears can go on only one way (because of the key.) But there is nothing to stop you from turning the crankshaft just a bit, and then installing the gears. Another way to explain it: it's the position of the gears relative to each other that is critical. There should be timing marks stamped into the face of the two gears, typically they look like big dots. Usually they point directly at each other, but not always. Were there any instructions that came with the chain & gears set? Good luck.
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Unread 03-09-2011, 09:31 PM   #5
wgirvine
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Wait a minute... I looked at the website you linked to, showing the Cloyes gear & chain set. According to that page, the crank gear has 3 keyways (for fine-tuning the cam timing.) Which keyway did you use? They are NOT all the same.
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Unread 03-09-2011, 11:22 PM   #6
Reptile
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Wow! That is some SERIOUS stuff you're getting into. I dont think the engine would blow up if you miss by a bit, it just won't run and you'd have to take it apart... Since you're going with new gears, this is a all new game.

Quote:
It's the position of the gears relative to each other that is critical.
Totally agree with that. If you know you haven't moved the shafts, I wouldn't move them until I figure this out in case this is your only point of reference.

...and no I really thought she was 18.
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Unread 03-09-2011, 11:25 PM   #7
robsjeepxj
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I would put the old parts back on since they only have one key per gear and start over from TDC. If you mess this up it will be bad. You should have verified it was at TDC before you ever took it apart, if the Chiltons manual didn't tell you to do this first I would throw that thing in garbage. If you really want a quality repair manual you should buy yourself a Factory Service Manual for your year jeep.
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Unread 03-10-2011, 05:04 AM   #8
cruiser54
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TDC #1 first. Replace chain and gears second.
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Unread 03-10-2011, 01:20 PM   #9
robojeep
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finally some action!

Quote:
Originally Posted by 1990JEEPXJ View Post
you could turn the engine over to get piston #1 at TDC and check to see if the rotor in the distributor is pointed at the #1 plug. be sure its on the compression stroke.

how many miles are on your jeep? how much slack was in the chain? and one favor, can you report back if you notice any difference in the way your jeep runs after doing the chain?
how do I know when #1 is at TDC? it sounds like I'd need to re-install the old gears+chain, reinstall the the timing cover and the HB, then point the HB timing mark to "0" on the cover guide, right? in other words: start over?

also, the jeep has 175K on it, the chain itself had about an inch of slack either way on it. I'll report back here how it goes

Quote:
Originally Posted by wgirvine View Post
Oh boy, I see problems in your future...

"How worried should I be about messing up the timing?"

Very worried. If you are off by only one tooth, the engine will not run right.
I'm not worried about it not running right, I'm more worried about breaking things. If I have to open it back up and adjust the timing I will, after all, I'm learning here

Quote:
Originally Posted by wgirvine View Post
"...since the crankshaft and camshaft ends are both keyed, it seems like it should be impossible: in other words, if the gears + chain are on all the way, does this mean the timing is correct?"

Nope. Think about it... True, the gears can go on only one way (because of the key.) But there is nothing to stop you from turning the crankshaft just a bit, and then installing the gears. Another way to explain it: it's the position of the gears relative to each other that is critical. There should be timing marks stamped into the face of the two gears, typically they look like big dots. Usually they point directly at each other, but not always. Were there any instructions that came with the chain & gears set? Good luck.
True, I could manually spin either of the shafts independently and my timing would go right out the window, but if I didn't do this, I should be good right? while torquing any of the bolts the gears+chain were installed, so both shafts always spun together. The cloyes instructions do show that the timing dots should be facing each other, so tonight I'll have to spin the shafts and see where they fall.

Quote:
Originally Posted by wgirvine View Post
Wait a minute... I looked at the website you linked to, showing the Cloyes gear & chain set. According to that page, the crank gear has 3 keyways (for fine-tuning the cam timing.) Which keyway did you use? They are NOT all the same.
Forgot to mention that, I'm using the factory keyway

Quote:
Originally Posted by Reptile View Post
Wow! That is some SERIOUS stuff you're getting into. I dont think the engine would blow up if you miss by a bit, it just won't run and you'd have to take it apart... Since you're going with new gears, this is a all new game.
I'm not super worried about it actually blowing up (4.0 is a non-interference engine, meaning the pistons shouldn't eat anything if I'm wrong). I just want to make sure this will be a learning experience that doesn't end with my wallet empty...

Quote:
Originally Posted by robsjeepxj View Post
I would put the old parts back on since they only have one key per gear and start over from TDC. If you mess this up it will be bad. You should have verified it was at TDC before you ever took it apart, if the Chiltons manual didn't tell you to do this first I would throw that thing in garbage. If you really want a quality repair manual you should buy yourself a Factory Service Manual for your year jeep.
yep, nothing mentioning TDC in the chiltons, only that 15 teeth thing and that the dots should face each other.

Quote:
Originally Posted by cruiser54 View Post
TDC #1 first. Replace chain and gears second.
live and learn!

I think I'm just going to verify the dots on the gears face each other, button it up, verify TDC #1 with it all together, and go from there. It's not easy working on this thing on city streets...

one of the few non rainy days this month:
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Unread 03-10-2011, 02:27 PM   #10
robsjeepxj
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All you have to do it put the chain and gears on and put the bolt on hand tight, the same with the cover just two or three bolts handtight and slide the balancer on just a little so it's in the key. Then you can verifiy the 0* mark on the balancer AND that the marks are lined up on the gears. If you have BOTH lined up you should be at TDC. Then you have solid reference point to start with and duplicate with assurance. Good luck bro. I'm with you on the whole "fix where you have to" thing, I built my whole jeep outside mostly on the street too but my street on a hill, it sucks I know but you'll be the most prepared when it comes to "on the trail" fixes in the end. I've got that same pair of well used overalls too, that's funny Keep up the good work.
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Unread 03-10-2011, 05:07 PM   #11
robojeep
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thanks for the vote of confidence! the timing set was kind of a last minute inclusion, but since I was doing the HB and the water pump I figured I might as well swim a bit deeper and really get in over my head

work isn't gonna let me try this out tonight, but this weekend I'll go back to the original gears+chain and "reset" back to a known starting point, then work forward again. what's a few more days work!?
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Unread 03-10-2011, 05:34 PM   #12
rawk hard xj
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If you didn't rotate either the cam or the crank, it is timed. Assuming that it was timed when you started.
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Unread 03-19-2011, 03:19 PM   #13
robojeep
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ok! good news first, got humpty dumpty back together again.

bad news! she won't start

I double checked with the old timing gears that yes, she was still timed correctly. Then, with the new gears on I was able to see that yes, she was still timed correctly. In this pic you can see the two "dots" on the gears still line up (sorry for the blurry pic):



Also I was able to verify that with the two dots above lined up, the harmonic balancer's notch pointed to 0 on the timing cover. So with armed with new found confidence, I put everything back together and tried to start.

I'll try to take a video of what it sounds like when it tries to start, but basically: it sounds like normal at first, you can hear the engine almost get started (a slight "chug") then nothing, and the starter just keeps spinning. There's also a feint smell of gas in the engine bay after cranking it...

so, most likely this is timing related, but before I tear everything down, what can I try with it still together? I did have the battery disconnected for over 2 weeks, could that have messed anything up with the computer?

still learning, so at least that means I'm livin!
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Unread 03-19-2011, 03:24 PM   #14
robsjeepxj
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Did you remove or do anything to the distributor? My first guess is that's not in right. If you smell gas that probably means you have either no spark or it not at the right time.
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Unread 03-19-2011, 03:29 PM   #15
robojeep
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Nothing with the distributor, but I did quite a lot of work this go around. Here's a list of things I did while she was apart (note that she started and ran perfectly before)

1) Removed oil pan to replace RMS and oil pan gasket. This required removing the starter

2) New oil filter and oil pressure sender (broke it trying to get the filter off)

3) New water pump, t-stat, and t-stat housing

4) New timing cover (old one had grooves in it from the HB)

5) New HB

6) New serp belt

edit: also, thanks everyone for their help so far! beers for everyone if you're ever in seattle!
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