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Balance belt

chrisg

chrisg

Member
Ian I have never actually done this procedure myself but I'm familiar with the front part of the engine and I know that the balance shaft pulleys have notches and 0 and 1 marks on them. I understand that they can easily be transposed by mistake. I know it sounds like stating the bleedin obvious, but my suggestion would be take a large number of digital photos of the setup once you've got the engine locked at TDC for both the timing belt pulley AND the balance belt. That way you can refer to them afterwards. I would also highly recommend the expertise and recent experience of the right honourable Oliver AKA Zacgop who has recently done this job himself on an S2 and is very skilled at doing this particular job !
 
Hi,

I have just started changing the timing and balance belts on my car. There are lots of good videos and written articles so I have pretty much got the process sorted in my head. One thing that is bothering me before i continue further. The balance shaft rotates in agreed sync with the engine to minimize vibration. After I have locked the engine at TDC it is apparent that the cam shaft and crankshaft will be locked in position but how is the relationship between the balance shaft locked? are there marks on the shafts/pulley.

Ian

 
i did this recently and seemigly successfully, I have done loadsa belts on many cars but for some reason on my 944 turbo i was apprehensive, guess cause its a Porsche and I aint done one of them before. However compared to some modern cars the belts are actually fairly easy to do, mainly because once everything is stripped out there is excellent access compared to most transverse engined modern hatches etc. Take the pics as suggested and mark the balance belt pulleys before taking the belt on after locking the crank. The balance belts are slightly confusing but I suggest you look at the videos on this on ebay although they are for a 8v turbo and not an s2 and refer to all the reference material you can find, defo take a pile of pictures. As a note, I borrowed the tensioning tool to do this and spent ages getting both belts spot on, however after tensioning the timing belt it felt exactely like a normal "90 degree on longest stretch of belt with thumb and forefinger" so eckon you could do it without tensioning tool if you have done belts before and have a good feel for tension. However a correctly tensioned balance belt feels way loose and counter intuitive, but apparently they are meant to be. I have never done an S2 but the normal good rules apply, take loadsa pics, get a feel for how the belts are before taking them off, draw a wee diagram if it helps of the pulleys and watch the balance belt marking as the have two keyways on them, although hopefully an S2 guru will come along shortly and fill in the gaps in my knowledge, good luck
 
Hi Ian, There's a pretty good description of how the marks work here.... http://www.clarks-garage.com/pdf-manual/eng-08.pdf
 
Pictures being taken as I go already been useful!! i am also really surprised how loose the balance belt is.
 
There is an O and a U on the balance belt pulley. O is for Oben, German for up and U is for Unter which is under. The O is in the round window, the U goes into a slot. There are 2 slots on each balance belt pulley so make sure you get the right one. I will be doing a belt install on Steve Simkins turbo quite soon so will take a few pics and do a tutorial! Alasdair
 
For reference (although I know Ian is now stuck into the job), the belts on an S2 (and therefore any 944, I assume) are not hard. There is a lot of mystique around them, but they are just belts. Getting the U and the O in the right place on the balance belt pulleys sounds daunting, but if you look at everything carefully when you take it apart then it makes good sense. A useful tip is to have a bottle of tip-ex (or nail varnish) on hand when you dismantle, and put marks on everything. If you put a largeish mark on the balance pulleys then you can very very easily see if you have reassembled it correctly or not, and it will all make sense when you are in there. The tension is a good point. As Alex said, the 90-degree-twist-on-longest-stretch test applies to the cam belt, and the balance belt needs to appear to be dangerously loose. As has been said on here before, a good way of gauging the tightness is to look at the belts while the engine is running, and get a feel for the amount of flapping around there is. (FWIW, I've seen two ex-OPC Porsche techs testing belt tension and both did it this way, preferring it to using the tightness gauge.) The tensioner on the cam belt is a useful tool - I know that my tensioner gets the belt a little too tight, so I know that if I use this to find a given point of tightness, and slacken it off a smidge, then I am nearly there. Best of luck with the job Ian, and don't forget to re-check the tension after 1500 miles. Oli.
 
Timing belt and all rollers/guides now replaced with new. Timing belt re-tensioned, in fact my spring tensioner tightened it to the exact tolerance so that was Ok. balance belt on tonight! All reasonably straightforward. Crankshaft bolt the biggest issue as obviously the garage before misunderstood 210Nm of torque and did it at 500nm and then welded it on just to be sure and then to be sure araldited it!!. It took a 24" breaker bar and a 4foot scaffold tube before it went and I was straining so hard I think I p**ped myself. And I am very fortunate in that I have an inspection pit in my garage (previous owner installed) so I was able to get an ideal angle. Quite difficult, not sure if mine was a one off but, if attempting at home Buy a 24mm deep socket as well and have a scaffold bar handy. I guess they may use an impact hammer in a garage but, that would require the removal off the rad and fan set to get clearance. Forwards we go. Ian
 
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