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06-19-2018, 03:52 PM | #1 |
Scooby Newbie
Member#: 233047
Join Date: Dec 2009
Location: Northern Minnesota
Vehicle:2004 WRX Silver |
Can the timing be off if all marks are lined up
Alright so I got a jdm motor and had everything centered and lined up with the timing marks. When I loosened the belt pulley to replace the timing kit the two cams on the right side (drivers side) spun. I have a friend telling me that if the crank spun that it could be a 180 degrees off. Is this true? Or if I realign all the timing marks and spin the two cam shafts the correct direction will the timing be on even if the crank did spin an extra rotation? How do people rebuild a motor and do the timing? I assumed as long as all the timing marks are on that it would be fine? Please HELP
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06-19-2018, 03:56 PM | #2 |
Scooby Newbie
Member#: 468498
Join Date: May 2017
Chapter/Region:
MWSOC
Location: Columbus, OH
Vehicle:2014 WRX Hatch WRB |
Just re-align the timing marks and you should be good. Hopefully there wasn't any v2v contact when they spun.
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06-19-2018, 04:49 PM | #3 |
Scooby Specialist
Member#: 182415
Join Date: Jun 2008
Chapter/Region:
Tri-State
Location: New York
Vehicle:1999 RS Aspen White |
If the two driver side cams spin they can hit the valves and bend/chip them. You should put the belt back on, align everything and leak test those two cylinders to be sure nothing was damaged. If you drive with damaged or bent valves it'll destroy the seats which can either drop into the cylinder or crack/break a valve, both lead to catastrophic failure.
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06-19-2018, 06:24 PM | #4 |
Scooby Guru
Member#: 71875
Join Date: Oct 2004
Location: Montana
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When they spin, after you take the belt off, that is all the valves closing. They are not going to hit each other.
The thing you do need to do is make sure to turn the cams the right way in the right order, because you can have the valves contact each other turning both cams back to the correct place. Upper gear clockwise, lower gear counter clockwise. Key thing is rotating the 2nd gear the right direction and only the specified amount. With the crank in the "set timing" position you can individually spin any of the cams all the way around without anything hitting anything else because the pistons are halfway down the bores and all the other valves are closed. |
06-20-2018, 03:58 PM | #5 |
Scooby Newbie
Member#: 305707
Join Date: Jan 2012
Chapter/Region:
International
Location: AUS
Vehicle:1999 WRX WRC Blue |
Jamal is spot on. If you turn the cams the wrong way on that side of the engine you will bend valves, even so slightly it is not visible to the naked eye. It can be picked up on when valves are refaced. If you did that and run the engine it will slowly "burn out" the bent valves.
Another trap for young players is using the triangle mark on the crank to align the timing. That is the TDC mark, not the timing belt mark. |
06-23-2018, 09:59 PM | #6 |
Scooby Newbie
Member#: 233047
Join Date: Dec 2009
Location: Northern Minnesota
Vehicle:2004 WRX Silver |
so...
So if the timing marks are all aligned there is no way for it to be on the wrong stroke? My friend is saying that the motor could spark when the exhaust valve is open.
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06-24-2018, 05:48 AM | #7 |
Scooby Newbie
Member#: 292653
Join Date: Aug 2011
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06-24-2018, 03:41 PM | #8 |
Scooby Newbie
Member#: 305707
Join Date: Jan 2012
Chapter/Region:
International
Location: AUS
Vehicle:1999 WRX WRC Blue |
If you use the correct alignment mark on the crankshaft and all of the other marks line up it will be on the correct stroke. The cams on the bank that spun when you had the marks lined up are slightly open when they are on the marks. That is why they spun, and they will be trying to jump off again when you do the new belt, which is the only tricky part of this activity. You can spin that crankshaft around 100 times and put it back on the alignment mark and it will be on the right stroke.
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06-24-2018, 05:53 PM | #9 |
Scooby Newbie
Member#: 452713
Join Date: Aug 2016
Chapter/Region:
Tri-State
Location: Central jersey
Vehicle:02 Impreza WRX Grey |
So now when I took the timing belt off my ej251 I had the crank on the square not the triangle/arrow. When I go to put the motor back together I leave the crank on the square and line up the cams? Or have the crank on the triangle/arrow and line up the cams?
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06-24-2018, 10:14 PM | #10 |
Scooby Guru
Member#: 71875
Join Date: Oct 2004
Location: Montana
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The triangle is for top dead center of cylinder 1 (and 2). DO NOT USE THAT MARK TO SET TIMING. The rectangle/hash is the one to use.
I don't know what that even means. |
06-25-2018, 09:09 AM | #11 |
Scooby Newbie
Member#: 233047
Join Date: Dec 2009
Location: Northern Minnesota
Vehicle:2004 WRX Silver |
Thank You ripman and everyone else... Just don't want to put the timing kit on and get everything back in the car and it not start.
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06-27-2018, 04:51 PM | #12 | |
NASIOC Supporter
Member#: 30669
Join Date: Dec 2002
Chapter/Region:
Tri-State
Location: USA, North NJ, 07456
Vehicle:1998 Legacy 2.5GT Silver Sleeper BK, 5MT |
Quote:
Do NOT use marks on the front of the crank gear for timing belt alignment. The proper crank mark has the pistons at mid stroke, not TDC. |
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