How close does a timing chain have to be?

Question

I'm following a Haynes manual for my 2002 Ford Escape. It says to remove the timing chain by turning the crankshaft until the keyway is at 11.

There are no markings near the crankshaft to let you know when it's at 11 though. I figure since they were being so cavalier I would too so I printed up a clock, adjusted for the angle of the engine and took my best guess at 11.

The camshafts have marks on them but it's really hard to tell what position on the clock the camshaft marks are at.

So I relied on the crankshaft being at 11 and removed the timing chain. Immediately after doing so I realized I could put my finger on the tooth above the exhaust camshaft mark and move my head to the other side to verify that it was at 12 o clock. Well, guess what? It was at like 12:45.

Then I noticed you could move the camshafts by hand so I did that a little bit and they're probably in the same position but who knows, they could be off by a tooth or two. Fortunately someone put a marks on the timing chains (the factory??) So I can line everything back up probably.

1. I was just wondering how accurate this has to be. Will it destroy my engine if it's off by a tooth or two?
2. As long as I don't rotate things too much more and put the timing chain back on so the marks on the chain match the marks on the sprockets I can safely assume I am back at step 0, right?
3. Since the pistons are approximately at the neutral position anyways technically I could just mark a line from the sprockets to the heads and then when I put it back together use that mark, right?

Thanks for your help!

Answer 1

Being off by one tooth will not work. Here is a quick tip: Do your best setup and put index marks everywhere. Choose the one sprocket that you are most unsure of. Try moving that sprocket one tooth in either direction. If those spots are definitely bad, then the one in the middle is good. Use a straight edge ruler and a sharpie to make your own marks on masking tape. Use the plus/minus tooth method to confirm.

Answer 2

Here is what I always do:

First, before removing the old timing belt (or chain), mark each belt ridge (or chain link) and the specific point on each sprocket where they touch. I use whiteout to mark these points.

Second, take the belt off and then transfer the marks from the old belt to the new one, making sure the exact number of ridges are between each mark on the new belt as on the old.

Lastly, put the new belt on, making sure all the marks match up. This way even if a camshaft has gotten rotated *slightly with the belt off, you just have to turn it back to match the mark on the belt. The exact positions don't matter, as this method preserves all the relative positions of the camshafts and crankshaft. Though it is still a good idea to rotate to TDC before starting this procedure.

*slightly, is the keyword here, as you would never want to turn the camshaft 180 degrees to get it to line up!