Paul Waterloo

I've had the car for 4 years, drove it 2K miles, the previous owner drove it less than 10K miles in 10 years. He replaced the water pump during the engine out service when he did a bunch of upgrades, but didn't do the timing belt, as I recall, because the previous owner had just completed it. I have most of his receipts, he replaced the water pump and thermostat, they have less than 3K miles on them, so I am not going to touch them.

The real reason I am doing it is to change the front crank seal, as the engine leaks oil when it is static, i.e. during storage. I have the new oil pump gear, plus I bought the seals and spacers for the camshaft, and both balance shafts in case I find them leaking. If not, I'm not going to touch them and return the parts.

I was on the fence where to buy the parts, in the end, and I figured I sure didn't want to do this twice, so I bought Porsche OEM parts from Sonnen. Here is the pricing and parts:



Done many timing belts in my life, but never on a 951 or Porsche, looks easy enough. Just did the timing belt on my new to me 2004 Toyota Sienna so I am in practice!

My 25 year old son is coming home in two weeks to help, I told him that once we are done, I will keep the car for a week and drive it to make sure it's okay, and then I am going to let him take it to Ft. Wayne, IN where he lives and keep it for a year. I don't drive it much, he loves the car as much as I do, sold his Mini Cooper S last year, so I thought it would be nice.

Cloud9...68

The job isn't difficult, just tedious. I've always found the most aggravating part of the job to be setting the timing belt tension (many methods - I do it by feel - it should tighten when pushed against the water pump pulley) while setting the clearances using the eccentric adjusting bolt. The problem is that everything interacts - adjusting the tension causes the clearances to move, typically not in the direction you want, so you have to go 'round and 'round, over and over, until you get everything right, or you're so frustrated that you settle for "good enough". Also, look carefully at the diagram in the manual showing the clearances. The "clearance" along the top of the balance shaft belt isn't actually a clearance; it's a deflection. It's very small, so it probably doesn't matter, but the belt is actually supposed to be slightly pushing against the pulley, not separated from it.

The other challenging part is putting the timing belt back on correctly. Make sure you carefully count the number of belt teeth between reference points on the crank and the cam gear, and make sure you put the new belt on with the same number of teeth between these locations. It takes quite a bit of tugging and pushing to get the belt on correctly.

Oh, and of course, make sure you have the correct flywheel lock. It is literally impossible to do the job without it. Good luck

divil

I've never counted the teeth. Just line up the timing marks. If you turn it through a full revolution afterwards and the marks still line up, you're good to go.

I agree 100% about the flywheel lock though.

Paul Waterloo

Funny that you say that about the teeth. On the Toyota Sienna, the belt comes with three white lines on it, one you line up with the crank mark and the other two line up with the cams.....it took a bit to figure out how to get everything on, but once I did, I was like "this set up is genius"! LOL. Drove the car from Chicago to FL and left it at my house there that was recently purchased and is going through a major remodel. The Sienna is awesome. Parts are stupid cheap.

jerome951

I've never counted teeth either. I also just did the job w/o a flywheel lock. Seemed to go OK, though I wasn't removing the crank gear and pulley.
Do yourself a favor and pull the spark plugs (good time to change them if needed).
Also read Clark's Garage writeup on removing and reinstalling the distributor cap. That can be a frustrating step. I've found a stubby screwdriver pressed in with my palm works just fine.

Cloud9...68

Hmmm... It's always been a major battle for me to stretch the belt enough to end up with the right number of teeth between the cam and crank gears. If I just drop it into place without making sure I have the right number of teeth, the belt is invariably off by one tooth, leaving it saggy-loose. Maybe I've been doing something wrong all these years...

mahoney944

I rotate the gears in a tiny bit from the reference marks and install the loose belt. Once you tighten the belt slack, it pulls the gears back to the reference marks. There was a diagram somewhere explaining which way to rotate each one accordingly about 1 degree. Basically, line up the timing marks, slip the belt on, then rotate the cam clockwise a bit. With the teeth now grabbing the gears, rotate the cam back to the marks and tension the belt. With the crank locked at DTC this is quite easy. The slack should be at the tensioner when you go to tighten the belt

Cloud9...68

Thanks - that sounds easier than my method, which was to jam a piece of wood against the back side of the belt and push with all my strength to get the belt onto the gears with the right number of teeth between the cam and crank gears, and therefore no slack. I should have realized there must be an easier way. Any comparable tips for that infernal balance shaft belt tensioning/clearancing/deflectioning nightmare?

And Jerome951, how on earth did you remove the bolt for the crank gear without a flywheel lock??!

mahoney944

I use the same method for the balance belt, turn the gears in a bit then rotate it away once the belt is on, crank locked at tdc.

Paul Waterloo

Cloud: Go to about 4:00 on this video, he basically puts the cam at 1 tooth forward of the cam timing mark, puts the belt on, then moves it back and it takes the slack out of the belt and it's pretty much spot on.

Chris White

just remember the correct directions to apply tension to the belts - one is clockwise and the other is counter clockwise. I wonder why Porsche did it that way every time a do a belt job!!
BTW - if it leaks only when static there might be something else going on. The oil level in the sump is well below any of the seals.

Cloud9...68

That's a geat video - thanks! I'm due for a belt job, so it will come in very handy, seeing as it's been three years since the last time I did one.

Chris White

Public Service Announcement:
I always hate it when its called a 'belt job'. its not the belts that fail - its the tensioner/rollers. When they fail the belt goes (either snaps or gets it teeth cleaned off).
Belts don't fail by themselves!!

jerome951

Left the crank gear on..

Cloud9...68

Must be a 944 thing (yes, I realize this is a 944 forum...) - I don't think that's possible with a 968.