Timing belt broke
#11
05-06-2011, 10:02 AM
Regardless, I checked the timing mark on the crank pulley/HB. It actually had stopped virtually right on the mark!! The cams were 180 off from where they should be for changing the belt, so I turned it over by hand. The driver's side sprocket was maybe 1-3 teeth off? I continued to turn it over another full timing cycle (ie 2 full turns of the crank) to ensure everything was ok. No noises, no sticking points, no interference. All seems ok internally.
Now I need to get my timing kit from Blauparts and work on port matching my IM. Hopefully by the start of summer I'll be done!
#12
05-06-2011, 06:13 PM
I was driving and yes the engine died. I did not hear any bad noises during the shut-down. While it was idling an hour or so previous to this, I could hear a rattle from the timing belt area. I opened the timing cover to check the belt tension and it was "loose". (This was the driver's side cover) I figured the tensioner was going out (I was new to the Audi engines at the time) and it was Sunday in rural Illinois, so I continued to drive it.
I realize that this is usually what causes the timing belt to break on people. The idler or tensioner wear out and smoke the belt. So yes I am extremely lucky I guess.
So in order for the timing to be off, the belt would have skipped some teeth, correct? Also I thought that the 12V V6 does not have any cam timing marks. I guess I am wondering how the cams "know" where they are. Do the valve springs force all valves closed, positioning the cam where it should be relative to TDC? I have read that the cam sprockets are to be aligned with the proper tool and then pulled off (not completely unless replacing cam seals). Does this allow the cam to be positioned perfectly for the reasons I stated above?
I realize that this is usually what causes the timing belt to break on people. The idler or tensioner wear out and smoke the belt. So yes I am extremely lucky I guess.
So in order for the timing to be off, the belt would have skipped some teeth, correct? Also I thought that the 12V V6 does not have any cam timing marks. I guess I am wondering how the cams "know" where they are. Do the valve springs force all valves closed, positioning the cam where it should be relative to TDC? I have read that the cam sprockets are to be aligned with the proper tool and then pulled off (not completely unless replacing cam seals). Does this allow the cam to be positioned perfectly for the reasons I stated above?
#13
05-06-2011, 09:23 PM
If the cams were 180 off, but the crank only a couple teeth, it spun like crazy out of time. you can't just slap it all together....if you can you're the luckiest guy in the world.
Also this is why you change the damn pulleys when you change the belt!
Turning it by hand is no indicator. You arent turning it fast enough, and with building compression (I'm assuming you didn't pull plugs) you wont have a good feel for whats going on in there. Even with plugs pulled you might not feel it, unless something is totally jammed up.
And yeah, you need a tool for aligning the timing marks, its a bar that hangs onto the cams. There are 2 bars, one for 12v and one for 30v. You can get away without it, but it's not really fun.
Also this is why you change the damn pulleys when you change the belt!
Turning it by hand is no indicator. You arent turning it fast enough, and with building compression (I'm assuming you didn't pull plugs) you wont have a good feel for whats going on in there. Even with plugs pulled you might not feel it, unless something is totally jammed up.
And yeah, you need a tool for aligning the timing marks, its a bar that hangs onto the cams. There are 2 bars, one for 12v and one for 30v. You can get away without it, but it's not really fun.
Last edited by RandomAudiOwner; 05-06-2011 at 09:30 PM.
#14
05-07-2011, 12:00 AM
If the cams were 180 off, but the crank only a couple teeth, it spun like crazy out of time. you can't just slap it all together....if you can you're the luckiest guy in the world.
Also this is why you change the damn pulleys when you change the belt!
Turning it by hand is no indicator. You arent turning it fast enough, and with building compression (I'm assuming you didn't pull plugs) you wont have a good feel for whats going on in there. Even with plugs pulled you might not feel it, unless something is totally jammed up.
And yeah, you need a tool for aligning the timing marks, its a bar that hangs onto the cams. There are 2 bars, one for 12v and one for 30v. You can get away without it, but it's not really fun.
Also this is why you change the damn pulleys when you change the belt!
Turning it by hand is no indicator. You arent turning it fast enough, and with building compression (I'm assuming you didn't pull plugs) you wont have a good feel for whats going on in there. Even with plugs pulled you might not feel it, unless something is totally jammed up.
And yeah, you need a tool for aligning the timing marks, its a bar that hangs onto the cams. There are 2 bars, one for 12v and one for 30v. You can get away without it, but it's not really fun.
1: Larger ovals both facing "in" = The correct position to use the timing bar tool.
2: 180 degrees opposite of this; ie the larger ovals facing "out".
(The crank turns twice for every full cam revolution.)
I'm not sure why you think I didn't pull the plugs - I did. The belt is on, but not held tightly because the rollers are kaput. Leaving the plugs in would've been a sure way to build compression and potentially allow the belt to skip.
I'm fairly confident that turning it over by hand would reveal bent valves. If they are bent, they will not fully close and as such the piston would make some sort of contact, correct?
#15
05-07-2011, 09:41 AM
My 12 v blew up on me when my tensioner went to ****. Finally getting my car back together now, PITA. That tensioner in the pic looks like **** btw lol
#16
05-15-2011, 01:00 PM
sorry to butt in. just changed my belt after it stripped, and naturally i'm hoping that my valves have miraculously avoided destruction, and now i have it timed and its cranking, but its not firing.
Questions:
#1: so, if the valves are returning to the correct position then that is good indication that the stems might not be bent, right?
#2: and after buttoning everything back together was there any sensors that needed resetting?
#3: and finally... when i test for compression should i remove only the plug i am testing in or all the plugs?
thanks in advance,
G
Questions:
#1: so, if the valves are returning to the correct position then that is good indication that the stems might not be bent, right?
#2: and after buttoning everything back together was there any sensors that needed resetting?
#3: and finally... when i test for compression should i remove only the plug i am testing in or all the plugs?
thanks in advance,
G
#17
05-15-2011, 06:59 PM
When I put mine all back together it tried to crank but never fired, my valves were fucked! Hope it's not the case with yours man, good luck
#18
05-16-2011, 08:11 AM
Some food for thought, once you bent all the valves they are now clearenced for the pistons, probably. I think what everyone is saying is that if it's even a little bit out of time the odds are you have damaged the valves. I wouldn't post too much more until you actually get the t-belt kit and install it. Sounds like there's not much we can say to convince you that you may have bigger problems...
#19
03-14-2012, 04:52 PM
Almost one year later! Yikes. Anyways, I recently got it all back together and gave it a trial run with the front end still off in case anything major went wrong.
It started and ran. However I have a "clacking" coming from the passenger side head area.
I am led to believe that it is possible lifter/tappet/cam follower noise?
It HAS been sitting for well over a year now. Chances of lifters not operating properly? Or taking 20-30 mins to "pressurize"?
What would actual valve interference noise sound like compared to lifter noise? I don't think it would run if the valves were damaged, would it?
Compression shows 120-140 for all cylinders.
Don't know oil pressure on passenger side. Anyone know how to check?
It started and ran. However I have a "clacking" coming from the passenger side head area.
I am led to believe that it is possible lifter/tappet/cam follower noise?
It HAS been sitting for well over a year now. Chances of lifters not operating properly? Or taking 20-30 mins to "pressurize"?
What would actual valve interference noise sound like compared to lifter noise? I don't think it would run if the valves were damaged, would it?
Compression shows 120-140 for all cylinders.
Don't know oil pressure on passenger side. Anyone know how to check?
#20
03-14-2012, 04:56 PM
Plan on heads , gaskets , t-belt , wp , tensioner , rollers , probably a good idea to clean out the egr port while the intake is off.