TINING BELT REPLACEMENT WOES

More
08 Dec 2015 12:01 - 08 Dec 2015 12:02 #18634 by Old Dude
1980 EURO
I'm having trouble finding timing marks on the cam sprockets. I see some etched lines, but they don't jive with each other or the back cover. The harmonic balancer is light blue, so apparently not original. It has regular timing marks up to 35 BTDC, but then has a pronounced stamped line (like with a chisel) about 45 deg ATDC. This is where the left cam sprocket appears to line up some marks, best as I can tell. I know your supposed to change at 45 deg BTDC, but wonder if 45 ATDC would be the same?! I suppose you can change the belt anywhere as long as the sprockets don't move?!
What say ye?
Last edit: 08 Dec 2015 12:02 by Old Dude.

Please Log in or Create an account to join the conversation.

More
10 Dec 2015 17:01 #18635 by y33trekker
Have you posted your question on the Rennlist 928 forum? You'll find a bit more traffic there and likely a quick answer.

Don't know much about these cars at this point or I'd be able to help more.

Please Log in or Create an account to join the conversation.

More
15 Dec 2015 12:08 - 15 Dec 2015 12:12 #18637 by 928mac
Replied by 928mac on topic TINING BELT REPLACEMENT WOES
Hey there Old Dude, no it is not a good idea to change the belt in any position.
The reason is the valves may contact the pistons when you are rolling the cams by hand to get them into their correct position.
this job takes a bit of strength and tim to set it up right.
Have you looked in our tech how to do it area? Technical Library, I believe there is step by step with pictures.
Yes it took me 3 mins to find this link, hope it helps.
www.928oc.org/technical_library/1979_Tim...r_Pump_Procedure.pdf

Last edit: 15 Dec 2015 12:12 by 928mac.

Please Log in or Create an account to join the conversation.

More
22 Dec 2015 08:10 #18647 by Old Dude
The 1980 is a "non-interference" engine. Found marks on left side, made marks on the right side. Due to using TDC vs 45 deg resulted in cams moving upon belt removal. I could move them back and get them to precariously stay on the mark due to valve spring pressure. New pump installed, tensioner cleaned with new boot. Deciding to replace tensioner bolt or not as suggested by the PDF you posted. Slowly getting it back together...

Please Log in or Create an account to join the conversation.

Moderators: Rich928mm928billvvOC

Don't have an account yet? Register Now!