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Can somebody clarify please... on a 16V 4.7 should the timing be locked and the belt swapped at TDC or 45 degrees BTDC? I'm either confused or there's conflicting information on this. Probably both.
The timing belt can be changed at either position but doing so at 45 BTDC is better practice and especially so if one has an interference motor which I suspect you may well have assuming you have a Euro S spec motor. At 45 BTDC you cannot clatter valves no matter what dumb *** thing you may do,
just did it yesterday at 45° BTDC … went perfect. Just mark your cam sprockets at that 45° crankshaft. Neither camshaft had the intention to rotate a bit , they stayed perfect at there place.
Belt was going on like it was ment to be and checking after a few revolutions driver side is spot on , passenger side a very little bit retarded, not 1/2 tooth . Perhaps with the right tension it will even also be better.
Must borrow a Kemph tool….
Can somebody clarify please... on a 16V 4.7 should the timing be locked and the belt swapped at TDC or 45 degrees BTDC? I'm either confused or there's conflicting information on this. Probably both.
Bit of both, most likely.
Either position will work. It's mostly personal preference which way you want to do it.
Doing it at TDC puts all the marks where they are supposed to be. That makes putting everything back together a bit easier. However, if you rotate a cam far enough with it set at TDC, you risk piston/valve contact.
Doing it at 45 degrees puts all the pistons partway down the cylinders, so you can rotate the cams as much as you want with no risk of damage. However, the timing marks on the cam gears won't mean much, so you have to make your own. A bit of paint is perfectly sufficient (put a dot on the gear, where the notch on the head is).
One warning: No matter where you do it, when you pull the belt one or both of the cams will likely move some. Not a lot, but there's a point where the valve spring pressure is 'balanced' and the cam will go to that. It doesn't move enough to contact valves, and you can simply rotate the cam back by hand when you string the new belt.
But it scares the crap out of some people when the cam jumps.
I did mine at TDC, and even though I knew this was going to happen, it made me nervous when it happened. I could move the gear by hand and feel that it was turning smoothly and nothing was hitting (obviously, I was only moving it back to where it belonged and a few degrees past the 'rest' spot).
It's difficult to photograph but one of the cams looked to be out by a tooth. The one with the marker is the one below (in the picture). The marks on the other cam and the harmonic balancer are dead on.
10-09-2019, 12:01 PM
Cambelt + 16V + "45 degrees" = confused
