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Timing Belt / Cam Timing / DOHC / Mazda


jmabbott
10-03-2003, 10:08 PM
This is about a 1994, Mazda, Protege, 1.8, DOHC.

I removed the timing belt to replace the water pump. In my manual, in both the water pump replacement section and the timing belt replacement section are there NOT any warning, cautions or mention of special cam holding tools when it describes removing the timing belt. Just remove it.

When I removed the timing belt both cams turned about 2 teeth (in opposite directions) to a natural resting position. This appears to be the place where no lobe is pushing on any valve. At this point the stamped mark on the side of the teeth of the cam sprockets are not pointing at the reference marks on the cover plate. Intake is two teeth clockwise and exhaust is two teeth counterclockwise from their marked "TDC" positions. Iassum that I have to hold the sprockets at "TDC" when replacing the timing belt. I have two issues.

1. When I run the new timing belt from the crank, to the right, over the
idler and up to the exhaust sprocket - the belt and sprocket meet tooth to
tooth. I must turn the sprocket 1/2 tooth off the mark to engage the belt.

2. The next step in the book is to turn the crank 1-5/6 turns to the tension mark. I assume that at this point the belt on the tensioner pulley (left) side should be slack so that the tensioner can take up the slack. Instead, at this point the tensioner side is taut and the idler side is loose. I have the expected condition between 1-3/6 to 1-4/6 turns but just at 1-5/6 turns the two cam sprockets turn clockwise on their own and tighten up the tensioner side of the belt. If I take the belt off at this time the intake sprocket doesn't move but the exhaust turns clockwise, on its own, quite
a bit as it go to the "natural resting position."

(If I mount the timing belt with the cams resting at their "natural resting position" I still get the same results at 1-5/6 turns of the crank.)

Help!!! What's up?

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