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My 79 rebuild is going along quite well with one exception. My timing belt is not tracking straight. A little history for those not following my "79 5spd save" thread.
This is a fresh belt with rebuilt tensioner, new pulleys, new water pump, new bushings etc. This is a 81 engine with square tooth steel gears. No oddities in gear condition etc.
Engine first started last Saturday, since then it has run for approximately 2 hrs total. Not driven yet. Highest RPM was 3000 to properly time it. Runs very well so far.
I pulled the cover to double check tension and found this condition. Side of belt shows some abbrasion. Driver side is the same way. Rechecked tension and found it withing the window of the Kempf tool but towards the back of the window. Engine was warm during this test.
Now, I did have one "oh $hit' moment. Somehow in my assembly, I neglected to torque the crank bolt. So during a start up I noticed the pulleys were not spinning. I then torqued the bolt and noticed that the balancer had "walked" out a bit. I am now wondering if the crank gear moved slightly as well which caused the belt to tracking towards the front. Or is something else amiss?
Guy its best to post pictures of the damper,
a video of the belt running with the right cam cover removed is also good
Thanks Stan. Will try to add a video tomorrow. This is the damper as installed currently. The more I think about this, I am pretty certain that the belt must have walked with the crank gear slightly as the damper moved. Now that it's all torqued back the belt likely rode along the crank gear retension washer. Stupid mistake on my part!
it would be more informative if the timing numbers were also view able .
That said the usual ways the timing belt will get abraded are if the thrust washers are not properly installed with the curves facing away from the timing gear,
and or if the tensioner pivot bushings are worn or the pivot bolt is bent,
this will let the tensioner roller move closer to the rear of the damper and then the belt will rub on the back of the damper.
NOTE if you were prying on the thrust washers and could have scarred the faces of them then its possible that the belt is being cut down with the scarred thrust washer .
The belt will usually rub on the front thrust washer
Here is a better picture. I believe the damper is properly seated and installed currently. I know the washers were undamaged and installed properly. From further examination, it looks like the belt walked with the crank gear when the crank bolt was loose. I think it rubbed the tensioner arm during that period.
So I guess I run the car with the cover off and see it the belt migrates forward, if it does......replace belt and pivot bolt. The pivot bolt was not replaced but the bushings were.
its time to remove the center cover.
the oil fill tube has to come out ,
some oil about 2 QTS needs to be drained off so it wont come out of the fill tube.
its time to remove the center cover.
the oil fill tube has to come out ,
some oil about 2 QTS needs to be drained off so it wont come out of the fill tube.
Will do. I figure I am in for a belt replacement either way. Will report back on Monday. Thanks for all the help.
I had the same problem on my -86 16v. The pivot arm (2 on the picture) was bent. I adjusted it with some heat and a small sledge hammer. Now it works perfectly! Do I have to say that you have to be careful if you try this...
The belt will always ride towards the front of the gears.
Still a good idea to check the pivot bolt though.
Thanks. I guess my real concern was the abrasions. The belt is now nearly 1/8 inch narrower then the original it replaced. I basically wore the side of the belt down to the point where it now clears.
I have a new pivot bolt on order and have a few arms to chose from should this one be bent. Sucks having to do this twice.
the other thing to know is that witness marks will also let you know where the belt rubber has been wearing .
These areas will be on the inside of the timing cover
this will be an area where there is lots of black dust ,
when you find this area then look on the belt run just before this area and you will find the culprit.
before you remove the crank damper look at the rear where the tensioner roller is,
see if its letting the belt rub on the back of the damper pulley
What a mess. Mrmerlin was correct, looks like it was rubbing on back of damper and also on the pivot arm. I didn't take it any further apart at this time. I am assuming that the pivot bolt is bent. We will know soon enough.
Took an hour to get the covers off, accessories etc. Nice when everything is clean and fresh!
02-10-2017, 10:49 PM
Timing Belt Not Tracking Straight - Opinions?
