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Join Date: May 2008
Posts: 1,700
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Cam Gear Will Not Budge....Is This OK?
Cam tower is back on (no belts yet). Crank and Cam are at TDC. The cam gear will not budge...at least not by hand.
I put the lifters in place with assembly lube, including tops (cam lobe side) - so I would expect that despite the spring pressure I should be able to move the cam gear back and forth slightly with firm hand pressure (just enough to check resistance, not to mash valves)...but I cannot. Looks like intake valve #3 is near its maximum downward travel...at a point of maximum resistance - so maybe I've answered my own question. It just seems that the timing belt should not have to work this hard. Sorry if I sound obsessive about this, but this is my first rebuild/reseal, and I don't want to wreck my engine. Any comments? Thanks! |
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08-28-2010, 05:11 AM
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As long as you set the flywheel to TCD and aligned the cam gear to the distributor timing mark before you installed the cam tower, you should be OK. I am assuming that you know that you should not attempt to turn the cam gear itself.....any turning must be done after the timing belt is installed to maintain alignment and prevent bent valves. If in doubt, read the procedures outlined in "Clarks garage' or any workshop manual.
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1988 944 Turbo Guards Red - Black Leather Autothority Stage 2 Chip Set Weltmeister Strut Tower Brace 1984 944 - Sold to rcecale |
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08-28-2010, 05:49 AM
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The flywheel is off (engine on a stand)...but I set the crank to TDC with the head off, so I could simply rotate the crank by hand to put #1 up to the top of its travel - then I made a reference mark which I can check with the head back on - while I install the cam assembly with its gear set to TDC also. Seems to me like this should be foolproof.
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08-28-2010, 07:21 AM
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Join Date: Mar 2008
Location: Chicagoland
Posts: 2,695
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...that's wierd. even w/o the belt, the cam gear should be hand turnable until the valve contacts the piston. don't try to force it though cause u'll bend the valve face.
was the cam gear turnable when the tower was off the head? |
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08-28-2010, 07:34 AM
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Redline Racer
Join Date: Jan 2007
Posts: 2,444
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I've found the cam to be very difficult to impossible to turn by hand once installed, due to valve spring pressure. If you rotate the crank 90 degrees from TDC either way, you can turn the cam all you want without risk of damage in order to determine that it's not jammed or was just trying to push a valve into a piston. Just re-set the cam TDC mark and slowly rotate the crank 90 degrees back to TDC.
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1987 silver 924S made it to 225k mi! Sent to the big garage in the sky |
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08-28-2010, 07:56 AM
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I removed the cam yesterday and verified that its working fine. As I reinstalled the cam, with the bolts pulling it towards the head, I could see that those valves that should be engaged were moving (and those that weren't weren't moving), so nothing is stuck there. So I'll just chalk it up to spring pressure for now...and see how it goes after I get all the pullys and belts back on - when I will try cranking the engine via a socket on the crank bolt.
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08-29-2010, 02:36 AM
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Join Date: Dec 2009
Posts: 825
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you will need to turn camshaft with a wrench is normal the valve spring pressure is what makes it feel like it is locked up you will be fine when turning crankshaft bolt with cam belt on but better to be safe than sorry. best regards tom
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08-29-2010, 09:11 AM
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