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931Owner · Joined: 14 Feb 2009 Posts: 352 Location: Chicago NW Suburbs

Just doing some trouble shooting and notice that the alternator belt was loose. When I tightened the belt and turned it by hand... it turned the turned the alternator, water pump and AC as well as the oil pump pulley but not the cam.
It's a bad thing right?

Can the cam belt be tightened or replaced while the engine is in the car? It has the cam cover on as well... but it doesn't want to come out... looks like too much stuff in the way.

Thanks
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1980 Turbo
-too many cars and too many motobikes

Paul · Posted: Sun May 17, 2009 11:34 am Post subject:

Don't crank the motor or you will bend valves if the cam really is not turning when the crank does!!!!!

Have someone check your timing belt immediately.

Are you sure the crankshaft was turning?
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

931Owner · Joined: 14 Feb 2009 Posts: 352 Location: Chicago NW Suburbs

The front oil pulley is definitely turning so is the pulley with the teeth turning but the cam belt is not, therefore the cam isn't.

I cannot remove the cam belt cover without dismantling a whole bunch of other things so I cannot double check to see if the crank is turning for sure.
_________________
1980 Turbo
-too many cars and too many motobikes

Paul · Posted: Sun May 17, 2009 1:03 pm Post subject:

If the timing belt gear on the crankshaft is turning and the camshaft isn't you most likely have bent valves.

Do not attempt to turn the crank until you take a look at the belt.

It's not that hard to get the cover off, just remove the air clearer, the alternator belt and the AC belt.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

+1 to what Paul said. In fact, +100.

As Paul said, you just have to remove the AC and Alt belts, as well as the airbox. There are three bolts that hold the cover on. Two are up top on either side of the head, and the third is down under the water pump near the end of the long portion of the cover. Be careful when removing the bolts not to loose the washers or little metal inserts that go into the grommets on the cover. Once you have the three bolts out, you have to sort of maneuver the cover, kind of twist it toward you as you pull it up.
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erstwhile owner of just about every 924 variant ever made

931Owner · Joined: 14 Feb 2009 Posts: 352 Location: Chicago NW Suburbs

931Owner · Joined: 14 Feb 2009 Posts: 352 Location: Chicago NW Suburbs

So much for being a minimalist, ended up taking the bonnet/hood off as well as a bunch of other things.

Well... the belt is trashed... broken teeth and everything! Looks like the belt was due for a replacement which I was going to do anyway.

So... is it time or a head rebuild? How can I test if the valves are actually bent without taking the head off?

I don't recall hearing the typical hitting of the valves against the piston... which I've heard in the alfa, would a borescope help?

Thanks
_________________
1980 Turbo
-too many cars and too many motobikes

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Valves are bent, you can count on it.
_________________
erstwhile owner of just about every 924 variant ever made

931Owner · Joined: 14 Feb 2009 Posts: 352 Location: Chicago NW Suburbs

Paul · Posted: Fri May 22, 2009 1:11 pm Post subject:

The valve job and clutch can be done with the motor in place.

If you want to rebuild the bottom end or install new rings or rebuild the turbo, I'd pull the motor.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

931Owner · Joined: 14 Feb 2009 Posts: 352 Location: Chicago NW Suburbs

924guy · Posted: Fri May 22, 2009 7:20 pm Post subject:

oil residue in the air box is not uncommon, chances are the drain tube from the oil separator to the block is collapsed, its a hard to get at and usually overlooked part.
given that your looking at a valve job, and a clutch job, id recommend just pulling the engine, its allot easier that way. in the time you spend being a contortionist to get at the assorted manifold bolts alone trying to do the job with the engine in the car, you can pull the whole engine...
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Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
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