Mucus

Setup: 1989 V6 3vze
Job: Water pump / timing belt replacement
Issue: timing

Evening all! I was wondering if anyone can explain the mechanism and relationship between the timing belt, cam gears, and ignition timing.

With my recent replacement, I have encountered an issue with my timing as it was approximately 30 degrees off when I fired it up. I have read that potentially, If i am off a tooth on my install, then the resulting timing would be around 27 degrees off. I can not reason a logical conclusion as to why this would be.

Needless to say I am tearing her back apart to attempt to resolve the issue and I am looking for some guidance!

MudHippy

Timing belt spins the LH camshaft.

Camshaft timing gear spins the distributor.



These are the instructions for an 89 timing belt removal and install.



Here's the FSM pages for distributor installation. Pay no attention to the fact that the distributor looks slightly different, it doesn't matter.
http://personal.utulsa.edu/~nathan-b...13distribu.pdf

Mucus

Thanks MudHippy!

When I installed my new belt and put it all back together, I believed that I was right on the marks all the way around and my buddy even confirmed it. It seemed to be all correct to the naked eye and as far as the tension, I thought that was dialed in as well. I guess that these engines are so picky and the adjustment is so subtle that I over looked the alignment and now have this timing issue.

Anyone else care to help shed some light on this issue???

scope103

MudHippy covered it mostly. Remember: you can get the VALVE timing exactly right (that's the timing belt), and still have the IGNITION timing way off. They are related in the way that MudHippy describes, which is they are not very closely related at all.

27 degrees? The drive gear on the distributor shaft has 13 teeth. If you get it off by one tooth it is off by 360/13 = 27.7 degrees. Since you're off by 30 degrees (+/-), that is almost certainly what happened. But don't feel too bad. The mistake is easy to make (the drive gear is helical so it rotates when you slide it in), and easy to fix.

Mucus

Marvelous! Thanks Scope and thanks again MudHippy!

Mucus

Okay... So I broke it all down and realigned everything and it looks to me as though everything is just as it should be. However I thought everything was just as it should have been the first time!!!???!!!
So All my timing marks are lined up, I am at 0 degrees TDC, and when I spin the crank twice, I fall right back lined up on all the marks. I cannot figure as to why I was around 30 degrees off the first time I put it back together. I have the tension set properly, actually one friend thinks it may be too tight, and I have everything lined up the way the FSM says to.

Now, I didn't remove the distributor in the process of swapping water pumps and timing belts, however it did appear to be close to 30 degrees off, so I guess it could be a tooth there... When I line the crank up with 0 degrees, and I pull the distributor cap, the rotor appears to be at the end of the #1 cylinder stroke. Is this a possible indicator of being a tooth off? I am about to put it back together and time it in again but I still am not sure what was causing my issue in the first place? Could the incorrect tension account for that much inconsistency? Could it possibly run and be timed in correctly even if the distributor was off a tooth? Keep in mind it ran fine and was in time before the water pump failure and I am wondering if I have been off a tooth on the distributor since my rebuild???? Seems unlikely though! Please Help!

Mucus

Oh... my rebuild was 16,000 miles ago and it has been running fine since then. The timing was correct after the rebuild, yes i checked it. It also passed smog right before the water pump went out... If only i would have replaced the water pump during the rebuild, but i over looked the seven P's.

OldBlue93

Mucus, did you ever figure out what was up with the ignition being aoub 30 degrees off? I´m in the same boat and haven´t been able to nail down what I did wrong when I put the timing belt and distributor back....

scope103

When you put the distributor back in, you were off (rotated) 1 tooth (27 degrees). Just pull the distributor straight out (the rotor will turn because the drive gear is helical), rotate it 1 tooth in the direction you want to go, and gently slide it back in.

http://www.ncttora.com/fsm/1990-1995...e/distribu.pdf (bottom of page 26)

OldBlue93

thanks for the reply scope...tried that a couple times in both directions, but either way the recommended timing 10º BTDC is at the absolute extreme of what I can adjust the distributor to. Might be the timing belt wasn´t aligned correctly, though I´m almost certain I lined everthing up right on the cams and drive shaft.

scope103

Then something else is wrong. The adjustment of the distributor is a little more than 27 degrees, meaning that you can set the timing "anywhere" with the combination of mis-setting the helical gear and the adjustment range.

And, as you expect, 10 degrees should be somewhere in the middle of the adjustment range.

I suppose a mis-installed timing belt could shift the 10 degree point to one end, so maybe it would be worth pulling the upper timing belt cover to look.

Mucus

Sorry I have been away for a while, and I am sad to report that no I have not figured this out yet. Since my last post, I have replaced my distributor, checked all the alignment yet again and just as Old Blue, the situation remains the same. However, I have a new thought about this issue regarding the timing and I would like to bounce it off everyone before I rip my motor open. If the Knock Sensor was going bad, would this cause the strange timing condition? What exactly are the signs of a bad knock sensor and what would happen if it failed completely? Also, when I cross the diagnostic jumper, the idle does not jump or advance at all as in the timing procedure. Is it possible that a bad knock sensor would prevent this timing advance as well?

TNRabbit

No, not your knock sensor.

scope103

A disconnected knock sensor will a) throw a code, and b) retard the timing about 10-15 degrees.

TNRabbit said it best.

badbob94

I'm having similiar issues. I'm advanced at about 30 BTDC, and the engine idles at 2500rpm! I must have the timing off.

My questions is this. if you follow the FSM in regards to installing the distributor and line up the marks but the gear rotates as it goes down, then how to you insure that it is lined up properly once fully installed.

When i install my the distributor rotor cap is in the 11 o'clock position.

Thanks,

Badbob

scope103

There are 13 teeth on the distributor drive gear. So that means one tooth will move you ... 27 degrees. And you're at 30 degrees? Coincidence? I think not.

If you follow the FSM and match the marks, it will go in correctly. But there is not much room for error, so it is an easy mistake to make.

Just figure out which way you need to go, carefully remove the distributor, and turn the gear that way. Put it back in and set it with a timing light. You'll be good to go.

banoobee17

Ok i got a question i replaced my timiming belt lined up the marks cams and crankshaft rotated it twice and its good and the distributor pointed at piston 1 TDC what kind of ignition timing would i have if i didnt time it with a timimng light

phildelfino

probably the same as you had before. when i did mine i had no problems afterwards and just put a timing light on it, got it to 10* BTDC and it ran alot better than it had ever ran before.

scope103

Uh, the wrong timing?

You just saved yourself $500 by changing your own timing belt. Do you want to throw away all that good work to save $20 on a tool you really need? http://www.harborfreight.com/xenon-t...ight-3343.html

And if anyone suggests you can set your timing by ear, ask them if pre-detonation can blow a hole in a piston.

banoobee17

Oh €&@$ yea i got a 3vze swaped in my runner did all the good stuff and lined up TBC and started it and adjusted the dist to a good idle I didnt think bout the timing