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Timing belt

Tiny
RONTS
  • MEMBER
  • 1989 MAZDA 929
  • 3.0L
  • V6
  • RWD
  • AUTOMATIC
  • 51,000 MILES
My vehicle with only 85,000 km on it, in mint shape. I replaced the timing belt and it ran for a week alright. My daughter drove it to a town 1.5 hours away she turned it off and the next day it would not start. I am thinking maybe timing belt jumped a few teeth. When I changed the belt I marked where crank gear was and cam sprockets marks are still the same but mark is gone off crank sprocket so I do not know if that had changed. But now how do I set it by TDC. I have a diagram that shows the arrow above the crank gear but what mark is on gear to align with is it the key slot? Also the cam gears have the dot but what mark is there on heads to align with. I am hoping that valves are not ruin now. I could really use your help on this. The car is a dream to drive and it looks brand new.

Ron
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Saturday, September 10th, 2016 AT 7:58 AM

16 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
The crank pulley is going to be hard to see as it is a screwy mark on it. I would put a paint mark on front for next time. See attached photo.
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Sunday, September 11th, 2016 AT 8:25 AM
Tiny
RONTS
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The crank pulley or the harmonic balancer I have off. Your diagram shows a black mark on the crank gear. I don't see this on mine. Also what mark am I looking for on heads for cam sprocket? How do I do it by TDC?
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Monday, September 12th, 2016 AT 6:14 PM
Tiny
HMAC300
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It has to be done by TDC and the mark as I said will be very hard to see so I would suggest cleaning pulley to see it better if you can. It is not a very good system itming gear for cams are dot to dot kind of if you look at pic, click on pic to enlarge it.
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Tuesday, September 13th, 2016 AT 6:50 AM
Tiny
RONTS
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Would this be the mark just under the arrow?
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Tuesday, September 13th, 2016 AT 1:49 PM
Tiny
HMAC300
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Is the piston at tdc on #1 if it is I would say yes or if no other teeth on pulley look like that i'd say yes. Like I said it's a very poor setup especially for cam timing.
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Tuesday, September 13th, 2016 AT 3:00 PM
Tiny
RONTS
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  • 12 POSTS
How do I check if piston at TDC? If it is at TDC and I turn it one complete turn will it be at TDC again. If that is the mark and given that the cams are off a bit does that mean the valves got damaged?
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Tuesday, September 13th, 2016 AT 4:47 PM
Tiny
HMAC300
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You have an interference engine so if timing belt broke pretty much some valves got damaged compression check will tell when it back together. For tdc try sliding balancer back on a little ways and see if mark lines up the mark on crank should be TDC. If you look carefully on pic that I sent the keyway for pulley is at about 11 O'clock at tdc. See other instructions i'm sending. You need to go two complete turns for tdc but do only with cams working as well or belt hooked up
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Wednesday, September 14th, 2016 AT 6:35 AM
Tiny
RONTS
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As I explained at the start the timing belt did not break. I changed the belt when I had to change water pump. I marked the 3 sprockets before removing but not with lining up marks on cam or crank because I did not know where they were. The car ran ok for a week turn it off then went to start it up next day it would not. I had a compression test done at a local garage it was low at 30lbs. Again I still do not know when #1 piston is at TDC if I have to go two complete turns or are you saying if the mark is at arrow and keyway is at 11:00 o'clock it is TDC. What mark are you saying now on balancer and crank?
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Wednesday, September 14th, 2016 AT 7:50 AM
Tiny
HMAC300
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First thing if compression is 30 psi then you probably have a bent valve at least on that cylinder. If the key way is at 11 and you can actually see the crank mark that you sent then it is more than likely at TDC if you can remove a spark plug you can stick a screwdriver in the hole be it lon gor short and should be able to feel piston to verify that it is TDC. By your own pic your crank keyway is at about 11 o clock and mark is at pointer so I would say you are at tdc. This car with 30 psi is going to run like crap and gas mileage will be poor to say the least. Hopefully you can understand what I have said in this and other email.
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Wednesday, September 14th, 2016 AT 9:31 AM
Tiny
RONTS
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Ok I will reposition timing belt once I know #1 cylinder is at top and hope for the best. Thanks

You did not explain the balancer and crank marks?
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Wednesday, September 14th, 2016 AT 10:03 AM
Tiny
HMAC300
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If the balancer has a mark on it for #1 as not all do then seeif you can slide it on and see if themarks on that line up.
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Wednesday, September 14th, 2016 AT 11:58 AM
Tiny
RONTS
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Lined up all the marks using the pinhole for a mark on crank gear. Put everything back together and started up OK. Does not sound like valves were damaged. Time will tell if I did it right. Thank you for all your help.
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Friday, September 23rd, 2016 AT 2:33 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Glad we could get it fixed please use 2CarPros. Com anytime we are here to help.

Hmac300 is one of our best mechanics!

Best, Ken
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Saturday, September 24th, 2016 AT 4:08 PM
Tiny
RONTS
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  • 12 POSTS
Just one more thing that is bothering me. On the cams they click three times going around, on the right cam one of the clicks will stop and align both marks but the left did not, I had to carefully turn it to the mark without a click. Does this seem correct?
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Sunday, September 25th, 2016 AT 8:01 AM
Tiny
HMAC300
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Yes
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Sunday, September 25th, 2016 AT 8:03 AM
Tiny
RONTS
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Great thanks again. I just have to figure out how to set timing and then I am good to go.
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Sunday, September 25th, 2016 AT 2:09 PM

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