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Can you send me some pictures of the belt and where is running off and the tensioners and the idler bearing and water pump?
Just got the info I have to step out for and hour or so. I will review this evening and get back to you.
The pictures not quite crystal-clear but it looks like your problem stems from the fact that that front cam gear on the front bank by the radiator is on backwards you need to take a cam gear often flip it around so that the outer ring keeps the belt from walking off the back camshaft drive gear ring is on the back side towards the plate or the engine.
If that is the case you should be fine once you flip the gear around or you can post clearer pictures if I'm not seeing it correctly.
No worries I am about 90% certain I am seeing it correctly. Front pulley has to be taken off in order to loosen up the backing plate if the water pump is ever replaced and it looks like someone just put it on backwards.
On second thought I was replaying a timing belt I just did over the weekend in my head it's the back cam gear that keeps the belt from walking off the front of the engine that gear appears to be on backwards.
Okay those pictures work fine. It is 100% certain that that back camshaft sprocket is on backwards. The flange on that sprocket keeps the belt from walking off the front of the gear and the bank two or front bank sprocket on the camshaft keeps it from walking off the back of the pulley. the timing marks are stamped on both sides of the gears because the gear is the same for front and back you just flip them around, it doesn't change the timing..
Here's a picture you can basically make the outline of the land on the back bank and none on the front bank
Also just as an FYI if that belt still has the original timing marks or paint marks make sure that when you put the belt back on that the arrows on the belt are facing away from the engine that will throw the cam timing out if you put the belt on backwards.
Once you get that pulley swapped around on the back put a 17 mm wrench on it and once that ***** *****nes up on the backing plate or you have the paint marks still on the original belt will be a sweet spot where it will actually line up with the mark and should stay in place. I use a pair of needle nose vise grips to clamp very lightly over the pulley so the belt can't come loose then I take the belt under the upper bearing and over the front camshaft down to the crank I put it on the crank and over the lower tensioner bearing last. I keep all the slack on the downward or forward side of the belt until I get line on the crank then slowly put pressure on it to bring all the slack up on the tensioner side. And yes the arrows should be pointed away from the engine on the belt towards the passenger will well.
The cam snapping back is due to the lobe location on the valves. I don't recommend turning it one way or the other I suppose you could as long as the marks on a brand-new belt line up. to get the sweet spot it'll stay where it's supposed to and then you know for sure that you have it in time. If you have not done so please do not forget to rate the assistance I provided to you at three or higher.
I set everything at 0°. Once you install the timing belt and all the marks are lined up and you 100% certain you are good to go. Once you crank it over the marks will not line up again for about 32 revolutions. I'm not a real big fan of Gates drive belts or timing belts. If there is any debris or glazing worn into the pullys you might get some noise from them.