Timing belt questions
05-12-2006, 03:48 AM
#1
VIP Member
Thread Starter
Join Date: Nov 2004
Location: Japan, where the term "JDM" doesn't exist
Posts: 270
Car Info: '94 WRX, '97 Forester S/Tb, '95 WRX-RA
Timing belt questions
I just replaced the timing belt on my 98 STi (DOHC EJ20K). I have a few questions I need answers to in order to put my mind at ease.
Is it common for the double lines on the cam pulleys to not line up exactly perfect? The belt is a genuine Subaru part and the marks on the belt line up with the single marks on the cam and crank pulleys, which line up with the notches on the cover, yet the double marks at the bottom and top of the cam pulleys are maybe 1mm off (like a 1/2 tooth width). If I were to slip the pulley a tooth over toward the direction they need to go to line up, it would be way off.
Next, if one of the cams were a tooth off, would I immediately notice? Nothing seems wrong, the car runs fine, but until the above question gets answered, I have concerns about silently damaging my engine.
Last one... and this is a just a myth buster type question:
I am being told that if the timing belt on an EJ20 breaks, the engine will not suffer catastrophic damage like most vehicles due to the fact that the valves and pistons have enough clearance to never make contact, even in a mis-timing situation. Dunno if this is BS... any info? Thanks!
Is it common for the double lines on the cam pulleys to not line up exactly perfect? The belt is a genuine Subaru part and the marks on the belt line up with the single marks on the cam and crank pulleys, which line up with the notches on the cover, yet the double marks at the bottom and top of the cam pulleys are maybe 1mm off (like a 1/2 tooth width). If I were to slip the pulley a tooth over toward the direction they need to go to line up, it would be way off.
Next, if one of the cams were a tooth off, would I immediately notice? Nothing seems wrong, the car runs fine, but until the above question gets answered, I have concerns about silently damaging my engine.
Last one... and this is a just a myth buster type question:
I am being told that if the timing belt on an EJ20 breaks, the engine will not suffer catastrophic damage like most vehicles due to the fact that the valves and pistons have enough clearance to never make contact, even in a mis-timing situation. Dunno if this is BS... any info? Thanks!
Last edited by Toiletbrush; 05-12-2006 at 05:33 AM.
05-12-2006, 01:26 PM
#2
Admin v2.0
iTrader: (9)
Join Date: Nov 2002
Location: Alameda, CA, USA
Posts: 6,965
Car Info: 02 Black Legacy GT
1. It is fine. It is more important that the marks on the timing belt line up with marks on pulleys. Not how marks on pulleys line up to other marks on pulleys. You would notice it if it was off by a tooth.
2. Not sure, but some engines are "non-interference". That means that the piston cannot touch the valves even if the valves are fully open and the piston are all the way out. However, that does not mean that the valves cannot hit each other. If IN and EX valvles are both open, they will most likely hit each other.
2. Not sure, but some engines are "non-interference". That means that the piston cannot touch the valves even if the valves are fully open and the piston are all the way out. However, that does not mean that the valves cannot hit each other. If IN and EX valvles are both open, they will most likely hit each other.
05-13-2006, 09:14 PM
#3
Registered User
Join Date: Dec 2004
Location: california
Posts: 14
Car Info: 02 WRX, XS Intake, HKS down pipe, up pipe, Apex-i
Originally Posted by Toiletbrush
I just replaced the timing belt on my 98 STi (DOHC EJ20K). I have a few questions I need answers to in order to put my mind at ease.
Is it common for the double lines on the cam pulleys to not line up exactly perfect? The belt is a genuine Subaru part and the marks on the belt line up with the single marks on the cam and crank pulleys, which line up with the notches on the cover, yet the double marks at the bottom and top of the cam pulleys are maybe 1mm off (like a 1/2 tooth width). If I were to slip the pulley a tooth over toward the direction they need to go to line up, it would be way off.
Next, if one of the cams were a tooth off, would I immediately notice? Nothing seems wrong, the car runs fine, but until the above question gets answered, I have concerns about silently damaging my engine.
Last one... and this is a just a myth buster type question:
I am being told that if the timing belt on an EJ20 breaks, the engine will not suffer catastrophic damage like most vehicles due to the fact that the valves and pistons have enough clearance to never make contact, even in a mis-timing situation. Dunno if this is BS... any info? Thanks!
Is it common for the double lines on the cam pulleys to not line up exactly perfect? The belt is a genuine Subaru part and the marks on the belt line up with the single marks on the cam and crank pulleys, which line up with the notches on the cover, yet the double marks at the bottom and top of the cam pulleys are maybe 1mm off (like a 1/2 tooth width). If I were to slip the pulley a tooth over toward the direction they need to go to line up, it would be way off.
Next, if one of the cams were a tooth off, would I immediately notice? Nothing seems wrong, the car runs fine, but until the above question gets answered, I have concerns about silently damaging my engine.
Last one... and this is a just a myth buster type question:
I am being told that if the timing belt on an EJ20 breaks, the engine will not suffer catastrophic damage like most vehicles due to the fact that the valves and pistons have enough clearance to never make contact, even in a mis-timing situation. Dunno if this is BS... any info? Thanks!
05-14-2006, 04:32 AM
#4
VIP Member
Thread Starter
Join Date: Nov 2004
Location: Japan, where the term "JDM" doesn't exist
Posts: 270
Car Info: '94 WRX, '97 Forester S/Tb, '95 WRX-RA
Looking at the engine, the arrow should be pointing in a clockwise direction and you should also be able to read the belt numbers. If the numbers are upside-down and the arrow is pointing the other way, then the lines won't match up with any of the marks on the cam sprockets.
My car runs fine after the swap. I just get paranoid after any critical work that needs to be done precisely by the book, and I DON'T have the book to refer to.
The thing that gets me is, SOJ recommends changing the belt at 100K Kilometers... SOA recommends the change at 105K MILES?! That means Subarus in the states get about a 40% extension on distance before this has to be done. Doesn't make much sense to me. Better safe than sorry?
My car runs fine after the swap. I just get paranoid after any critical work that needs to be done precisely by the book, and I DON'T have the book to refer to.
The thing that gets me is, SOJ recommends changing the belt at 100K Kilometers... SOA recommends the change at 105K MILES?! That means Subarus in the states get about a 40% extension on distance before this has to be done. Doesn't make much sense to me. Better safe than sorry?
05-15-2006, 09:41 AM
#5
Registered User
Join Date: Dec 2004
Location: california
Posts: 14
Car Info: 02 WRX, XS Intake, HKS down pipe, up pipe, Apex-i
Originally Posted by Toiletbrush
Looking at the engine, the arrow should be pointing in a clockwise direction and you should also be able to read the belt numbers. If the numbers are upside-down and the arrow is pointing the other way, then the lines won't match up with any of the marks on the cam sprockets.
My car runs fine after the swap. I just get paranoid after any critical work that needs to be done precisely by the book, and I DON'T have the book to refer to.
The thing that gets me is, SOJ recommends changing the belt at 100K Kilometers... SOA recommends the change at 105K MILES?! That means Subarus in the states get about a 40% extension on distance before this has to be done. Doesn't make much sense to me. Better safe than sorry?
My car runs fine after the swap. I just get paranoid after any critical work that needs to be done precisely by the book, and I DON'T have the book to refer to.
The thing that gets me is, SOJ recommends changing the belt at 100K Kilometers... SOA recommends the change at 105K MILES?! That means Subarus in the states get about a 40% extension on distance before this has to be done. Doesn't make much sense to me. Better safe than sorry?
05-15-2006, 01:36 PM
#6
VIP Member
Thread Starter
Join Date: Nov 2004
Location: Japan, where the term "JDM" doesn't exist
Posts: 270
Car Info: '94 WRX, '97 Forester S/Tb, '95 WRX-RA
I don't know if it is necessary or not, but the timing marks are on the crank pulley and outside of the belt cover above the crank pulley. The ECU advances and retards the timing as necessary and I don't think there is any way to adjust it yourself without engine management (power FC, E-manage) and the software to control it.
Thread
Thread Starter
Forum
Replies
Last Post
Heedz
NorCal Classifieds
114
03-15-2015 04:32 PM
CCC
Engine and Drivetrain
0
02-02-2012 10:09 AM
mattrudella
Engine/Power - EJ20T (pre-2006 WRX and JDM)
12
09-09-2003 09:26 AM
