Hello all I’m new but have read plenty lately. I recently acquired a ‘99 ST with 45K miles. I have been working my way through all of the usual maintenance. I decided to change the timing belt as 25 years seemed like long enough for the original. Also want to check valve clearance at same time. Despite my best efforts the left pulley moved 1 tooth forward. Should I pull the cams and reset all? I’ve already got valve covers off and familiar with the pertinent markings. This all said I’m no pro just a determined DIY and not sure exactly what I’m into here. Any advice appreciated, thanks.
Left drive pulley moved one tooth
- Thread starter Adamz
- Start date
Hello . I am assuming you lined up the timing marks like photo below, before you started. I would think you can just rotate it (left pully) one tooth back, and install belt . However - You must check that All the timing marks on the ALL belt pullys (3) must line up correct afterwords .- like in the work shop manual . And when your done - belt tensjoner tight ,with spark plugs out , rotate the engine carefully by hand (rachet) , 2 or 4 rounds -what ever the workshop manual says. They should still line up . If so - Your good. Good luck !
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Yep everything was spot on before starting and spot on after belt removal. Right pulley and crank still good. Pully doesn’t seem to want to rotate back easily but I haven’t applied any real force for fear of causing damage.
Hmmm . Likely one or both cams on the left are under tensjon from depressing two or more of the valve springs. Normally there shouldn't be anything preventing it from moving back one tooth ,unless there is something special with an ST11 engine. You can take a look at the cams on the left bank ,and see if they are compressing any valve springs (tighter). If so , I would think that is the resistance
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That is a good thing for me to consider James. I’m going to give the matter a fresh look with rested eyes tomorrow. I read with interest Pedo post from past summer he had similar situation on same side. He pulled cams and reset, however he had issues installing the exhaust cam due to valve compression. Thanks for the suggestions.
This is just a follow up to my situation. Before removing cans I applied a bit of pressure to try and rotate back one tooth. This inadvertently caused the drive pulley in question to spring forward several more teeth. Once I calmed down (haha) I was then certain the cams needed to come off. I had come across a previous post by member Peto from summer of 2023 his pictures and situation was identical to mine. I will be forever grateful for him and those who have taken the time to document their experience as it proved invaluable and calming to relate to another’s similar situation. This said I feel I have correctly remedied things and have the new belt on and have moved on to valve clearances. This is a 99 ST1100 with 45k. I find all intake clearances in spec and all exhaust just out of spec so will make adjustments. Heck I’ve already got experience removing cams so seems easy! Haha. Many thanks to member Peto.
When I replaced the belt on our 1991, I removed all the covers. Already had the radiator off and out of the way. I highlighted the index markings with Whiteout, yea...I still had several bottles of typing correction fluid. I'm using silver paint pens now. Alignment of all the timing marks are quickly verifiable.