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Setting TDC
I am attempting to set TDC now so I can pull the timing belt for my head gasket job. For some reason, though, the car is fighting me. Every time I turn the crank pulley clockwise with a 24mm socket, the belts pull it right back to where it was.
When Matt (bluebullet) was here a week ago to help me do compression/leakdown tests, the crank turned with no problem. The only things I've done since then were drain the oil, remove the intake, and replace vacuum lines. The only factor among those that I can see having any impact on turning the crank would be the oil, but the headgasket procedure I am using tells me to drain the oil anyhow (http://members.rennlist.com/tom86951/headgasket.htm) Why is the car fighting me all of a sudden? Am I missing something glaringly obvious?
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Current Stable: Black 07 Porsche 987 Cayman S: Long-Tube Headers; FabSpeed Exhaust; VividRacing ECU Tune; IPD Plenum; 997GT3 Throttle Body. Blue 1983 Porsche 928S. 1985.5 Porsche 944 Rat Rod. 2011 Acura MDX. 2008 Mazda 3. Gone But Not Forgotten:Garnet Red 86 Porsche 951("The Purple Pig"). Alpine White 83 Porsche 944 ("Alpine Wolf"). Guards Red 84 Porsche 944. |
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03-23-2008, 09:25 AM
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Registered
Join Date: Mar 2008
Location: Northen Va.
Posts: 8
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Just a thought
I'm no great mechanic, so take this only as a suggestion.
My buddy was just working on another vehicle (chevy of some sort) that was also a zero interference engine. When he was trying to crank the fly wheel it wouldn't go, even with 125 Ft. Lbs (he was playing with his new torque wrench). Come to find out, there was a chunk of carbon about 1/8 of an inch thick that kept being compressed each time he would try to turn the flywheel and that inturn was binding the engine not allowing it to continue rotating. Might be applicable, might not. It's worth a thought at least. |
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03-23-2008, 09:35 AM
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Well, the crank would turn... but then as soon as i let pressure off the ratchet, the belts would pull the crank right back to where it was. I'm stumped.
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Current Stable: Black 07 Porsche 987 Cayman S: Long-Tube Headers; FabSpeed Exhaust; VividRacing ECU Tune; IPD Plenum; 997GT3 Throttle Body. Blue 1983 Porsche 928S. 1985.5 Porsche 944 Rat Rod. 2011 Acura MDX. 2008 Mazda 3. Gone But Not Forgotten:Garnet Red 86 Porsche 951("The Purple Pig"). Alpine White 83 Porsche 944 ("Alpine Wolf"). Guards Red 84 Porsche 944. |
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03-23-2008, 10:38 AM
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Okay, I just had a head-slapping moment.
Car was in gear. Put it in neutral and it cranks fine 
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Current Stable: Black 07 Porsche 987 Cayman S: Long-Tube Headers; FabSpeed Exhaust; VividRacing ECU Tune; IPD Plenum; 997GT3 Throttle Body. Blue 1983 Porsche 928S. 1985.5 Porsche 944 Rat Rod. 2011 Acura MDX. 2008 Mazda 3. Gone But Not Forgotten:Garnet Red 86 Porsche 951("The Purple Pig"). Alpine White 83 Porsche 944 ("Alpine Wolf"). Guards Red 84 Porsche 944. |
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03-23-2008, 10:59 AM
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I hate it when that happens!
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Tom 1990 944S2 Cabriolet 2002 Chevy Silverado 2500HD 2003 Maroon Ford F350 dually |
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03-23-2008, 11:19 AM
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Exactly what I meant when I said "something glaringly obvious". Man, for all my fancy book-learnin, I can be pretty dumb sometimes...
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Current Stable: Black 07 Porsche 987 Cayman S: Long-Tube Headers; FabSpeed Exhaust; VividRacing ECU Tune; IPD Plenum; 997GT3 Throttle Body. Blue 1983 Porsche 928S. 1985.5 Porsche 944 Rat Rod. 2011 Acura MDX. 2008 Mazda 3. Gone But Not Forgotten:Garnet Red 86 Porsche 951("The Purple Pig"). Alpine White 83 Porsche 944 ("Alpine Wolf"). Guards Red 84 Porsche 944. |
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03-23-2008, 11:27 AM
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Back from Beyond
Join Date: Nov 2004
Location: Alberta, Canada
Posts: 2,697
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I may get flamed for this, but if you're pulling the head off, why bother with TDC? Obviously everything was timed before you started (the car ran) and you'll have plenty of time to figure out TDC as you reassemble.
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'88 944 Auto - project, kinda '87 944 Auto - died saving my wife '84 944 5SP - crushed under shop roof during snow storm All others GONE! |
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03-24-2008, 11:07 AM
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Registered
Join Date: Apr 2007
Location: Fairbanks, Alaska
Posts: 345
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I'm with CJ on this one (except for leaving it in gear!). Set TDC at the beginning before something has a chance to screw up.
Now for the confindent mechanic it may not matter but for the rest of us it would help a little and every little bit helps.
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Red 83 944 |
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03-24-2008, 11:24 AM
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I would set it after it's apart like Slam, but to each their own.
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Tom 1990 944S2 Cabriolet 2002 Chevy Silverado 2500HD 2003 Maroon Ford F350 dually |
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03-24-2008, 09:18 PM
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Thanks for the tips, guys. When it comes to things like TDC, I am going to take my time and do everything the right way, double-checking everything to make sure I did it the right way. This is my first head gasket job, and I remember some posts from the past where a careless head gasket job ended with bent valves. Hence, I am erring on the side of caution (I hope!)
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Current Stable: Black 07 Porsche 987 Cayman S: Long-Tube Headers; FabSpeed Exhaust; VividRacing ECU Tune; IPD Plenum; 997GT3 Throttle Body. Blue 1983 Porsche 928S. 1985.5 Porsche 944 Rat Rod. 2011 Acura MDX. 2008 Mazda 3. Gone But Not Forgotten:Garnet Red 86 Porsche 951("The Purple Pig"). Alpine White 83 Porsche 944 ("Alpine Wolf"). Guards Red 84 Porsche 944. |
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03-25-2008, 04:51 PM
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Redline Racer
Join Date: Jan 2007
Posts: 2,444
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We all know we've done that at least 2 or 3 times, right? I remember the first time I did it..."OMG these are really high compression engines!...doh!"
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1987 silver 924S made it to 225k mi! Sent to the big garage in the sky |
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03-25-2008, 08:32 PM
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2007 Porsche Cayman S
The Viridian Falcon
SOLD! -- The Purple Pig
SOLD! -- Mighty Mouse
SOLD!! -- Alpine Wolf
