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Timing belt / marks alignment & TDC of cylinder #1
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nwfixer
Novice
Apr 6, 2012, 8:39 AM
Post #1 of 8
(4779 views)
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Timing belt / marks alignment & TDC of cylinder #1
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Is aligning the timing marks on the camshafts and crankshaft enough when changing a timing belt?
I have a 1989 Dodge Raider (Mitsubishi Montero) and I am in the process of replacing the timing belt. I've successfully lined up all three timing marks and installed the belt, but I've read on a couple of forums that I should also check and make sure the #1 cylinder is at top dead center. Others have mentioned the position of the distributor rotor as something to watch. While I understand caution is needed when doing this repair these additional steps don't make make sense to me.
My knowledge of engines is far from complete, but from what I've learned it does not seem possible for the #1 piston to be in the wrong position when the timing mark on the crankshaft is correctly aligned. The #1 piston should come to TDC each time the timing mark is lined up - if it doesn't I have much bigger problems than a timing belt. Is that correct or am I missing something fundamental?
Likewise for the distributor rotor. I've verified the rotor turns once for each turn of the camshaft that drives it. It doesn't seem possible to have the rotor in the incorrect position if the camshaft timing mark is in the correct position.
Is verifying the alignment of the timing marks
sufficient or do I need to take additional steps to make sure this
repair is done correctly?
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 6, 2012, 9:05 AM
Post #2 of 8
(4770 views)
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Re: Timing belt / marks alignment & TDC of cylinder #1
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You're right. That stuff only matters when installing the distributor.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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nwfixer
Novice
Apr 7, 2012, 10:29 AM
Post #3 of 8
(4708 views)
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Re: Timing belt / marks alignment & TDC of cylinder #1
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Thanks much for the reply. I'll stop worrying now...
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Discretesignals
Ultimate Carjunky
/ Moderator
Apr 7, 2012, 11:17 AM
Post #4 of 8
(4702 views)
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Re: Timing belt / marks alignment & TDC of cylinder #1
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What most don't understand is that when you go to align your marks the piston for number one is going to be TDC no matter which stroke. Which stroke it is on, compression or exhaust, when the piston is top dead center is determined by the position of the camshaft(s).
As long as you don't remove the distributor and your marks on the cam sprockets and crank gear are lined up correctly. It should start right up. Even if you were to have your camshaft spockets 180 degrees from the marks, but your crank was TDC, it will still start up and run.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Apr 7, 2012, 11:36 AM)
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nwfixer
Novice
Apr 7, 2012, 4:45 PM
Post #5 of 8
(4681 views)
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Re: Timing belt / marks alignment & TDC of cylinder #1
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It started right up and runs better than it has in years. Thanks much for the help. Now I just have to figure out why the AC compressor won't come on. If it's not one thing it's another.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 8, 2012, 5:26 AM
Post #6 of 8
(4666 views)
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Re: Timing belt / marks alignment & TDC of cylinder #1
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Compressor - if it gets power could be that clutch air gap is excessive. Free to check. Should be too tight or close to a standard folded biz card if it gets power and too wide it wont pull in. A careful tap on outer head would make it engage if all else if right,
T
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nwfixer
Novice
Apr 9, 2012, 9:11 AM
Post #7 of 8
(4648 views)
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Re: Timing belt / marks alignment & TDC of cylinder #1
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Turns out to be either low pressure in the AC system or a pressure switch failure. Starting a new thread on this one.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 9, 2012, 3:29 PM
Post #8 of 8
(4636 views)
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Re: Timing belt / marks alignment & TDC of cylinder #1
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This will be read only now but do make new threads for separate issues. Hard for us or anyone to follow if too much in one thread,
T
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