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General Information => Troubleshooting => Topic started by: Snmbsc on September 08, 2011, 07:30:36 pm
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Doing a routine check on my 1.6 NA I noticed an intermittant ticking around the timing belt cover. Shut the engine down, took off the cover and saw that the belt was at the edge on the I.P. sprocket. It looks like the IP sprocket is not parralel to the cam sprocket but its axis is tilted towards the cam. Laid a straight edge across the cam sprocket and confirmed that the IP sprocket is not parralel. There is about an 1/8th inch gap on the inboard edge of the I.P. sprocket. There are no loose bolts and the I.P. Mount is solid with no evidense of movement. Tapped the I.P. sprocket to see if was loose and it feels solid. Plan to put it to TDC and put the pin and cam lock on before investigating further. Car has 220k and the pump is a rebuilt with about 30k (miles that is). Any idea?
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If the belt was put on too tight it would have worn the bushings in the pump and allowed the pump shaft to no longer be running true. I would think you would see a leak at the shaft if it was that bad though.
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Possibly due to worn pump bearing due to a to tight cam-belt, but another possibility is the conical nut and bolt has dropped out. This lives beneath the injection pump, on the end opposite the sprocket. If missing, this can cause the belt to track wrong. If you need a spare, something bodged from the bearing cones on an old bicycle might do.
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Both very good ideas. I'd start at the conical nut. Then check the the tension on the belt. If the tension is too tight, it's time to also check the intermediate shaft bearings.
I had the trifecta on a customer's car: missing conical nut (plus other mounting), led to overtightened belt to compensate, which caused worn intermediate shaft bearings
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The belt should have some slop in it when tensioned. I used to think (as per book) that as long as I could twist it 45 degrees it was good but that's a faulty method. It should easily deflect close to an inch without having to "stretch" the belt.
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my understanding is that tracking near or at the edge of the belt is acceptable, just no overhanging at all.
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If this is something that came on recently,
with no maintainance then it is probably a bushing that is worn.
Check the 2 bolts that hold the injection pump bracket to the block,.. the ones behind the pump..
I've had them come loose/fall out before and they are generally what's used to line up the belt after a rebuild.
I do prefer the belt to ride closer to the pump but not off the edge.
Seems to ride in the center of the idler better.
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If this is something that came on recently,
with no maintainance then it is probably a bushing that is worn.
Check the 2 bolts that hold the injection pump bracket to the block,.. the ones behind the pump..
I've had them come loose/fall out before and they are generally what's used to line up the belt after a rebuild.
I do prefer the belt to ride closer to the pump but not off the edge.
Seems to ride in the center of the idler better.
my car has a new timing belt, tensioner, and injection pump.. it still tracks at the edge of the pulley.. doesnt ride off ever tho. just CLOSE to the edge.. like 2-3mm from the edge. its always run like that since day one..
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2-3mm doesn't sound near the edge.
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ok, maybe its not 2-3mm.. but its way closer to the outside edge, than it is to the inside edge, thats for sure..