onspeed

Copy/paste from my thread on the 951 subforum.

In the middle of a timing belt job... got a problem.

I'm not using a flywheel lock, I read that most people here don't when only changing the belts.

Before I removed the belts, I verified that it was set at TDC. Cam sprocket lined up and the mark on the flywheel lined up under the car. After removing the belt, the cam sprocket is still lined up, but the mark under the flywheel is off by about an inch. Am i screwed?

Also, once i made sure both marks were lined, i put the car in fifth but didn't check the bottom again. Is it possible shifting the gear moved the flywheel?

Only way I could think that it could have moved would be loosening the tensioners... although the cam sprocket and balance sprockets are still ined up with the markings.

CorsePerVita

The only reason you need the lock is so that it doesn't move when the belts are off. If you are changing the timing belts when EVERYTHING was perfectly in time and you are just putting new belts on, assuming /nothing/ moves then you should in theory be able to slide the new one on and it will be "in time". However, things happen, we bump things, space is tight, etc etc..

However, if your mark is off on the flywheel, then /something/ moved during the process. If it's off, it's off.. Everything needs to line up. Shifting a gear shouldn't change the timing mark, but if you engaged/disengaged the clutch and you moved things around you may have moved it over.

Double check it, line up your marks. These are spendy engines to mess up. Off by an inch isn't much to move over, can you move the crank with a socket? If so when you move it move it VERY TINY bits at a time. You don't want to move it over with too much force and whack a valve in there and end up causing yourself headache. Keep in mind, 2 rotations for every 1 rotation.

Double check your marks, line them up, be careful, then double check again, then triple check, pray to the porsche gods, do a rain dance, buy some taco bell and get a beer and you should be fine.

AND before you even think about turning the car on, when the belt is on, everything is "ready to go" TURN THE MOTOR OVER MANUALLY... SLOWLY... to make sure there is no interference! It's far easy to do this and make sure you did it right than to turn the key over and the "moment of truth" way of finding out something was off. This way you can make sure there's no interference.

Always a good idea to use one, I used a lock on mine just to be safe for reasons like this.

onspeed

I didn't use the clutch to shift gear.

What I don't understand is that all the other markings are spot on, but the flywheel is suddently 1 inch clockwise too much. The timing belt was carefully removed, and I didn't touch anything after I removed it..

In any case, it's safe to just rotate the flywheel backwards so the mark lines up?

CorsePerVita

Should be, if it moved clockwise when it was already lined up, and there is no interference upon where it was "in time" before it moved then it is logical to say it should be just as safe to move back. It's obvious that it likely did not move counter-clockwise since you'd notice that large of a rotation. Like I said, if you move it, do it SLOWLY and just inch the bugger teeny bits at a time. When I move timing on stuff like that with a socket i'll just do tiny little bumps tiny pieces at a time (we're talking small as in mm at a time etc, small tiny incriments). If it bumps with no hesitation or force then there is no interference. If it resists and won't budge then there /is/ interference. Just a teeny little nudge, go check, if no resistance, go back, nudge a hair, go back check, etc etc. An inch is very little. The reason I recommend the "nudge tiny bits" at a time technique is because if you barely nudge it and are moving teeny portions at a time the weight of things inside won't bend a valve or hurt anything as you can promptly move it back. It's worth taking your time to make sure you do incriments.

onspeed

Ok done. Should I center the notch on the bottom, or the OT line with the notch on the top? When the bottom perfectly centered, the OT line is ever so offset with the notch on the bellhousing. Like by a hair's width.

CorsePerVita

The "OT" line should match up with the timing notch. You should be able to look directly down on top of it and it should line up.

Here's a really good article on TDC for the 944 on clarks-garage with a picture in case there is any confusion.
http://clarks-garage.com/shop-manual/eng-13.htm

xsboost90

no big deal moving alittle- just line up the cam, line up the LOWER timing mark to the notch in the bellhousing and put the belt on. You would have to move the crank quite alot and really whack a valve to worry about bending it. Line things up, put the belt on, check both marks. Turn it over four full crank rotations, then check the marks again. If its good and the belt is tensioned ok- you are good to go.

CorsePerVita

And then have a beer to celebrate. You just saved yourself a $1000 job at a dealership HAHA!

onspeed

Ok. All is back together. Car runs fine.. seems better but this might just be in my head. I replaced the o2, put a new potentiometer on my APE maf harness, removed the extra spacer from my reference sensor, and put in a different IC to TB hard pipe. Been experimenting with an aftermarket set and the stock... I feel like the aftermarket one increases lag. Is this possible or just in my head?

Also, I noticed the car runs a tad hotter than normal. Usually, my temp needle will be a hairline above the 1st marking. I noticed it ranges from the 1st mark to the middle. Is it possible I overtensioned the timing belt or something? I used the Krikit to tension, and the 90 degrees method, and the video of Van's timing belt... still not too confident in my timing belt skills yet. I turned the crankshaft a few times, then went to TDC, then turned it counter clockwise to make it a tooth and a half back. Removed the idler pully and water pump bar, and took tension right there. If I push down at the area where the timing belt is closest to it's other side, it just barely won't touch.

CorsePerVita

I've never had an issue with the car running "hotter" after a belt change. Did you end up taking any hoses off or anything that could get bubbles in the system during the change? Did you install a new pump when you did this?

The krikit is a bit tricky. Took me a while to figure out the tension. My temperature usually floats between the 1st and middle mark. But I am also on a 944/1, i think your dash may be different from mine (in which case, I think is hotter on those marks).

onspeed

No new water pump. I don't see any reason that there would be air in the system, although I'll do a check tomorrow.

CorsePerVita

Well if you didn't open anything up (like remove hoses etc) then I don't see why that would be a factor. Was just asking because some people actually remove a bunch of things (like the radiator) to do it even though you don't need to etc...

Off the top of my head that sounds weird. Unless the sensors are creating a lean condition and she's running a bit more lean than she normally would?

I guess through process of elimination you could test and find out to be certain with the sensors. Problem is that running the car and swapping sensors can be a PITA, if you find out that's not the cause.

onspeed

Lean is a possibility... new o2 sensor, plus the new potentiometer on the MAF. Although, the pot is set at the proper 2.2k ohm, and the o2 sensor is wired up properly... no wbo2 yet.

Actually, I think I was running rich previously. MPG was low, thus the reason I changed the potentiometer, and o2. Also, found out one of my spark plug wires wasn't contacting properly... cylinder 2 on the distributor had a nice bronze tint. After fixing all that, maybe it's running normal now, and thus a little warmer?

CorsePerVita

Potentially. If anyone could confirm on their car would be easier to tell.

onspeed

There's no air in the system. So either I've leaned the car out from the rich-condition and it's running normal temperature now, or I tensioned the timing belt too much and screwed the water pump? Is that even possible? It doesn't run hot, like in the red zone, but definitely hotter than it use to.

Also, there's a whinning noise that I'm like 90% sure i've always heard from the car, but my mind might be playing tricks on me. I think it sounds like it's coming from the upper balance shaft sprocket, if i place a screw driver on it, or in the little fitting where the airtube is supposed to connect, and listen to it I can hear it and it'll change with RPM. It's not like a loud high-pitch one like the arnnworx overtightened balance belt demo ( http://www.arnnworx.com/MOV00999.MPG ) but I just want to check if this is normal. I'll get a video as soon as my camera battery charges.