Handclutch
Member
I am tearing down a 604 engine - heads and cylinders off and overhauled. Wasn't planning to remove the crank but when I dropped the rear bearing cover to replace the oil seal I found it fairly worn. When I took off the timing cover I was surprised to see the cam gear not lining up with the crank gear or the injector pump gear. Finally figured out what's going on - the cam gear is 3/16 narrower. They all line up across the back.
I found TDC on number 1 by 'reading' the cam followers but couldn't find any timing marks on the flywheel. I have since found the flywheel is off by about 120?. I checked in the pump window and the marks were near enough to lined up but there was no timing mark on the cam gear where I expected to find it. I did notice the 2 1 marks but didn't realise they are for timing - have been advised on a another forum, and read elsewhere, that is indeed what they are for. However, they are right opposite the punch mark I applied next to the crank timing mark.
So, lots of doubt. Was I off by 180?? I have checked and rechecked several times, put the cam gear back on enough to engage and wound it through, and got a second set of eyes to confirm TDC. I'm now sure that I have marked it correctly but am still concerned that the 1 2 is opposite where it should be. Don't want to put it back together and find that I've made a stupid mistake.
I suspect the cam gear isn't original. If it had been like this since new, you would expect the teeth on the crank gear to look different where they have never engaged. There is no indication of that at all.
This is the first MM engine I have pulled apart. I hope somebody with far more experience will be able to allay my concerns. I should add the engine was running quite smoothly beforehand.
Jack
