Timing Belt- Major Question!!!!!
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AudiWorld Junior Member
Joined: Nov 2014
Posts: 31
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Timing Belt- Major Question!!!!!
I and a couple of mechanics I know are just beyond stymied about my vehicle …I really need some experienced advice. First, I need to explain with a bit of detail, so please bear with me.
1999 A6 Quattro, about 210,000 miles, Timing belt was replace at around 158,000
About two years ago I was driving back to my place of employment in the mountains, heard a awful noise coming from the front, opened the hood and something flew right past my face- a blade off the fan clutch. I thought, I better slowly get this back up to my shop, but about 100 yards further the car died. Opened the hood and saw the whole fan clutch bracket was off the front of the engine toward the bottom and the belt was just destroyed, strings all wrapped around mostly the crank pulley.
Jumping ahead….I have been so busy that I haven’t been able to work on the A6, until this week, when I was invited to have a change in employment. The car has been up on blocks since then, been meaning to get to it. Since I needed to fix the fan assembly and it was getting near time for a new timing belt, I decided to do that while I had a good garage. Four days ago, I put the car in service position, looked at the fan bracket- to me it looks like with the fan was out of balance and it vibrated the bolts completely loose…they are still in the mount with no apparent damage. The accessory belt has pieces stuck behind the crank pulley.
I have the cam bar and the crank pin. The crank however would only move about 2 inches as I tried to get it to TDC. I pulled the plugs to relieve possible compression, and made sure it was in neutral - still wouldn’t hardly budge. I had an experienced foreign repair shop owner from the near town come up and look. His suggestion was to burp the crank by hitting the starter briefly until the the crank was at TDC…worked. However, we noticed the cam oval pieces with the two holes were straight up, not sideways like they were supposed to be, indicating major slippage.
We pulled the valve covers to check on any damage and could see none. Watched pistons move and ascertained that when at TDC the #3 piston was at the top (still assuming that is the first piston to fire). There is no evidence of any damage to the timing belt…no missing teeth, rubber, etc.
The question I have and 3 different mechanics I have conversed with have is how could the original problem with the fan clutch have caused this apparent misalignment of the valves. Is it possible this particular engine has a different arrangement for the holes on the cams? If the only connection to the actual timing system is the crank pulley, could the breaking belt have caused that massive of a jump? Am I looking at major damage or this just some weird aberration. One mechanic said I might be able to just remove the old timing belt and hand turn the cam wheels into the correct position based on his experience …
Like I said, it’s not just me that’s stumped ….3 mechanics including a very well seasoned one.
Input anyone?
1999 A6 Quattro, about 210,000 miles, Timing belt was replace at around 158,000
About two years ago I was driving back to my place of employment in the mountains, heard a awful noise coming from the front, opened the hood and something flew right past my face- a blade off the fan clutch. I thought, I better slowly get this back up to my shop, but about 100 yards further the car died. Opened the hood and saw the whole fan clutch bracket was off the front of the engine toward the bottom and the belt was just destroyed, strings all wrapped around mostly the crank pulley.
Jumping ahead….I have been so busy that I haven’t been able to work on the A6, until this week, when I was invited to have a change in employment. The car has been up on blocks since then, been meaning to get to it. Since I needed to fix the fan assembly and it was getting near time for a new timing belt, I decided to do that while I had a good garage. Four days ago, I put the car in service position, looked at the fan bracket- to me it looks like with the fan was out of balance and it vibrated the bolts completely loose…they are still in the mount with no apparent damage. The accessory belt has pieces stuck behind the crank pulley.
I have the cam bar and the crank pin. The crank however would only move about 2 inches as I tried to get it to TDC. I pulled the plugs to relieve possible compression, and made sure it was in neutral - still wouldn’t hardly budge. I had an experienced foreign repair shop owner from the near town come up and look. His suggestion was to burp the crank by hitting the starter briefly until the the crank was at TDC…worked. However, we noticed the cam oval pieces with the two holes were straight up, not sideways like they were supposed to be, indicating major slippage.
We pulled the valve covers to check on any damage and could see none. Watched pistons move and ascertained that when at TDC the #3 piston was at the top (still assuming that is the first piston to fire). There is no evidence of any damage to the timing belt…no missing teeth, rubber, etc.
The question I have and 3 different mechanics I have conversed with have is how could the original problem with the fan clutch have caused this apparent misalignment of the valves. Is it possible this particular engine has a different arrangement for the holes on the cams? If the only connection to the actual timing system is the crank pulley, could the breaking belt have caused that massive of a jump? Am I looking at major damage or this just some weird aberration. One mechanic said I might be able to just remove the old timing belt and hand turn the cam wheels into the correct position based on his experience …
Like I said, it’s not just me that’s stumped ….3 mechanics including a very well seasoned one.
Input anyone?
Tech Guru
Joined: Oct 2002
Posts: 34,430
Likes: 130
Your situation is not a surprise at all. When the serp belt grenades and the engine continues to run, the strands get wrapped around behind the crank pulley and they force the timing belt off the sprocket, causing the car to jump time. You most like have bent valves.
Unfortunately I think you now have a parts car.
Unfortunately I think you now have a parts car.
AudiWorld Junior Member
Joined: Jan 2018
Posts: 27
Likes: 1
I agree with the above post, since the cam sprockets aren't keyed to the cams so it's very possible for them to slip out of time when met with that kind of resistance. The easiest way I can think of to see where you stand is pulling all the spark plugs again and doing a compression test on all cylinders, spinning the engine by hand if it'll let you. Spinning by hand will also let you feel for piston/valve contact if there is any. Sadly in your situation, the chances that there isn't any is very slim, so you may have not gotten that lucky.
Tech Guru
Joined: Oct 2002
Posts: 34,430
Likes: 130
The easiest way I can think of to see where you stand is pulling all the spark plugs again and doing a compression test on all cylinders, spinning the engine by hand if it'll let you. Spinning by hand will also let you feel for piston/valve contact if there is any. Sadly in your situation, the chances that there isn't any is very slim, so you may have not gotten that lucky.
AudiWorld Junior Member
Joined: Jan 2018
Posts: 27
Likes: 1
You are indeed quite right. Forgive my momentary lapse in thought process, my mind scrambles a bit sometimes lol.
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