Dropped a valve, repaired and now its chattering like crazy
08-07-2018, 10:12 PM
#1
AudiWorld Member
Thread Starter
Dropped a valve, repaired and now its chattering like crazy
hello all, i have a 03 D3 with a 4.2 bfm engine.
just 2 weeks ago the exhaust valve dropped its head into the rear cylinder (back right when facing the engine from front of car). is smashed the head to bits and there was a huge hole in the piston.
i have finally repaired it by replacing the head and piston (piston has new rings).
everything went very well, timed the engine up and put oil in. it runs well, but there is this loud chattering sound and i have no idea what is going on or where its coming from and i have no clue as to what to do next. by chatter i mean a consistant chatter, but with a slight click every now and then. it is not tapping, but like.. well, a chatter. the timing did not jump and all other cylinders are clean only the one cylinder had an issue. it almost sounds like chain chatter, but its so central and i cannot figure it out. sounds almost like its coming from the center of the engine. at first i thought it could be either the crank or the oil pump, but i checked the oil pump before i put it back together and it seemed fine (no debris - pulley turned okay), and i know the crank is good.
might i add that the head came from a 4.2 A6 with engine code ASG. the part number for the head is exactly the same as my original head which is 077103373AN. the cams are the ones from the C6. do you think it might be worth putting my original cams into the ASN head?
so, my question is, if you was in my situation, where would you start looking first?
thank you for your help, i have to get this done by the end of august because im in Germany and i need to get the car back to the UK running sound
just 2 weeks ago the exhaust valve dropped its head into the rear cylinder (back right when facing the engine from front of car). is smashed the head to bits and there was a huge hole in the piston.
i have finally repaired it by replacing the head and piston (piston has new rings).
everything went very well, timed the engine up and put oil in. it runs well, but there is this loud chattering sound and i have no idea what is going on or where its coming from and i have no clue as to what to do next. by chatter i mean a consistant chatter, but with a slight click every now and then. it is not tapping, but like.. well, a chatter. the timing did not jump and all other cylinders are clean only the one cylinder had an issue. it almost sounds like chain chatter, but its so central and i cannot figure it out. sounds almost like its coming from the center of the engine. at first i thought it could be either the crank or the oil pump, but i checked the oil pump before i put it back together and it seemed fine (no debris - pulley turned okay), and i know the crank is good.
might i add that the head came from a 4.2 A6 with engine code ASG. the part number for the head is exactly the same as my original head which is 077103373AN. the cams are the ones from the C6. do you think it might be worth putting my original cams into the ASN head?
so, my question is, if you was in my situation, where would you start looking first?
thank you for your help, i have to get this done by the end of august because im in Germany and i need to get the car back to the UK running sound
Last edited by chudlin; 08-08-2018 at 04:02 AM.
08-08-2018, 07:16 AM
#4
AudiWorld Super User
First, chill pill. You posted at 11pm/2am EDT PDT last night for example, and wanted an answer by 5 am PDT, 8am EDT? You are on a predominantly USA board, not a Euro one though the more the merrier. Calling it factually; not a reasonable expectation.
On substance, first use a mechanic's stethoscope to isolate noise. Or the poor man's version if you don't have one, a long screwdriver with blade pressed against metal and other end up to your ear.
You don't mention doing any head rebuild work, which I would have in a situation like that. Better to dissassemble a head when it is off anyway, typically to at least clean valves thoroughly and to change valve stem seals. At same time you can inspect for any signs anything is bent, overly worn, weak springs (just by comparing heights), and so on. BTDT on my 2000 A6 4.2.
You would have to find cam specs for the two motors to see if they are the same or not. Cams themselves are not going to be a noise issue though except in extraordinary bearing surface failure or screwed up lobes. The more likely question is whether the valve timing is the same between the motor variants, which is important for all of performance, emissions compliance, and relative smoothness side to side. But as to noise, my two first suspects would be either the cam chain tensioner (which controls relative cam timing too) or one or more hydraulic lifters. The lifters require very deep head disassembly, typically off the car; very small relatively precision parts on on a 5V type head like 4.2. Tensioner is easier, though belt has to come off again. You remove the cam assembly along with tensioner and its chain as an overall unit.
Before either of these, I would try an internal engine cleaner with oil change. The kind you put in your oil, idle for 15-30 minutes, and then change. For any internal work like was done, I would change oil after 500-1000 miles again anyway. Those cleaners (like old Riselone or Gunk in USA) can sometimes deal with the old sticky lifters and such--which leads to the clicking type noises. If clicking is isolated to a few apparent valves and locations when you try the stethoscope/screwdriver listening, be thinking sticky lifters. And a head or donor motor sitting around for who knows how long could have developed some too. If generalized across head, then systemic and more likely the tensioner related operation. Could also be the oil antidrainback valve on that side (buried under V below intake under a plate) that collected some debris or got stuck a bit, but that would more likely have noise predominantly right near start up. Oil based internal engine cleaner might help there too. Not directly related to work though, so not so high on my suspect list.
On substance, first use a mechanic's stethoscope to isolate noise. Or the poor man's version if you don't have one, a long screwdriver with blade pressed against metal and other end up to your ear.
You don't mention doing any head rebuild work, which I would have in a situation like that. Better to dissassemble a head when it is off anyway, typically to at least clean valves thoroughly and to change valve stem seals. At same time you can inspect for any signs anything is bent, overly worn, weak springs (just by comparing heights), and so on. BTDT on my 2000 A6 4.2.
You would have to find cam specs for the two motors to see if they are the same or not. Cams themselves are not going to be a noise issue though except in extraordinary bearing surface failure or screwed up lobes. The more likely question is whether the valve timing is the same between the motor variants, which is important for all of performance, emissions compliance, and relative smoothness side to side. But as to noise, my two first suspects would be either the cam chain tensioner (which controls relative cam timing too) or one or more hydraulic lifters. The lifters require very deep head disassembly, typically off the car; very small relatively precision parts on on a 5V type head like 4.2. Tensioner is easier, though belt has to come off again. You remove the cam assembly along with tensioner and its chain as an overall unit.
Before either of these, I would try an internal engine cleaner with oil change. The kind you put in your oil, idle for 15-30 minutes, and then change. For any internal work like was done, I would change oil after 500-1000 miles again anyway. Those cleaners (like old Riselone or Gunk in USA) can sometimes deal with the old sticky lifters and such--which leads to the clicking type noises. If clicking is isolated to a few apparent valves and locations when you try the stethoscope/screwdriver listening, be thinking sticky lifters. And a head or donor motor sitting around for who knows how long could have developed some too. If generalized across head, then systemic and more likely the tensioner related operation. Could also be the oil antidrainback valve on that side (buried under V below intake under a plate) that collected some debris or got stuck a bit, but that would more likely have noise predominantly right near start up. Oil based internal engine cleaner might help there too. Not directly related to work though, so not so high on my suspect list.
Last edited by MP4.2+6.0; 08-08-2018 at 07:38 AM.
08-08-2018, 09:35 AM
#5
AudiWorld Super User
I take it you removed the head and oil pan to remove the piston & connecting rod, correct?
was the wrist pin snug in the piston & rod? No chance of a tolerance issue causing the noise?
was the wrist pin snug in the piston & rod? No chance of a tolerance issue causing the noise?
08-08-2018, 11:46 AM
#6
AudiWorld Member
Thread Starter
First, chill pill. You posted at 11pm/2am EDT PDT last night for example, and wanted an answer by 5 am PDT, 8am EDT? You are on a predominantly USA board, not a Euro one though the more the merrier. Calling it factually; not a reasonable expectation.
On substance, first use a mechanic's stethoscope to isolate noise. Or the poor man's version if you don't have one, a long screwdriver with blade pressed against metal and other end up to your ear.
You don't mention doing any head rebuild work, which I would have in a situation like that. Better to dissassemble a head when it is off anyway, typically to at least clean valves thoroughly and to change valve stem seals. At same time you can inspect for any signs anything is bent, overly worn, weak springs (just by comparing heights), and so on. BTDT on my 2000 A6 4.2.
You would have to find cam specs for the two motors to see if they are the same or not. Cams themselves are not going to be a noise issue though except in extraordinary bearing surface failure or screwed up lobes. The more likely question is whether the valve timing is the same between the motor variants, which is important for all of performance, emissions compliance, and relative smoothness side to side. But as to noise, my two first suspects would be either the cam chain tensioner (which controls relative cam timing too) or one or more hydraulic lifters. The lifters require very deep head disassembly, typically off the car; very small relatively precision parts on on a 5V type head like 4.2. Tensioner is easier, though belt has to come off again. You remove the cam assembly along with tensioner and its chain as an overall unit.
Before either of these, I would try an internal engine cleaner with oil change. The kind you put in your oil, idle for 15-30 minutes, and then change. For any internal work like was done, I would change oil after 500-1000 miles again anyway. Those cleaners (like old Riselone or Gunk in USA) can sometimes deal with the old sticky lifters and such--which leads to the clicking type noises. If clicking is isolated to a few apparent valves and locations when you try the stethoscope/screwdriver listening, be thinking sticky lifters. And a head or donor motor sitting around for who knows how long could have developed some too. If generalized across head, then systemic and more likely the tensioner related operation. Could also be the oil antidrainback valve on that side (buried under V below intake under a plate) that collected some debris or got stuck a bit, but that would more likely have noise predominantly right near start up. Oil based internal engine cleaner might help there too. Not directly related to work though, so not so high on my suspect list.
On substance, first use a mechanic's stethoscope to isolate noise. Or the poor man's version if you don't have one, a long screwdriver with blade pressed against metal and other end up to your ear.
You don't mention doing any head rebuild work, which I would have in a situation like that. Better to dissassemble a head when it is off anyway, typically to at least clean valves thoroughly and to change valve stem seals. At same time you can inspect for any signs anything is bent, overly worn, weak springs (just by comparing heights), and so on. BTDT on my 2000 A6 4.2.
You would have to find cam specs for the two motors to see if they are the same or not. Cams themselves are not going to be a noise issue though except in extraordinary bearing surface failure or screwed up lobes. The more likely question is whether the valve timing is the same between the motor variants, which is important for all of performance, emissions compliance, and relative smoothness side to side. But as to noise, my two first suspects would be either the cam chain tensioner (which controls relative cam timing too) or one or more hydraulic lifters. The lifters require very deep head disassembly, typically off the car; very small relatively precision parts on on a 5V type head like 4.2. Tensioner is easier, though belt has to come off again. You remove the cam assembly along with tensioner and its chain as an overall unit.
Before either of these, I would try an internal engine cleaner with oil change. The kind you put in your oil, idle for 15-30 minutes, and then change. For any internal work like was done, I would change oil after 500-1000 miles again anyway. Those cleaners (like old Riselone or Gunk in USA) can sometimes deal with the old sticky lifters and such--which leads to the clicking type noises. If clicking is isolated to a few apparent valves and locations when you try the stethoscope/screwdriver listening, be thinking sticky lifters. And a head or donor motor sitting around for who knows how long could have developed some too. If generalized across head, then systemic and more likely the tensioner related operation. Could also be the oil antidrainback valve on that side (buried under V below intake under a plate) that collected some debris or got stuck a bit, but that would more likely have noise predominantly right near start up. Oil based internal engine cleaner might help there too. Not directly related to work though, so not so high on my suspect list.
sorry about the urgency, but as i mentioned im going back from gemany to uk in less than 3 weeks and i got to get it sorted.
i also thought tensioner. i want to also have a look at the oil pump chain, so ill check this later
tank you though
08-08-2018, 11:50 AM
#7
AudiWorld Member
Thread Starter
ive swapped the cams over to my original one along with my old tensioner to see if it makes a difference but i cant start it because th battery is dead so just waiting for it to charge.
if it rattles again, ill check the chain on the oil pump. when i took the rocker back off today after running yesterday there was minimal oil in the head but its full, so ill drop the oil and have a look. i ordered an endoscope so hopefully ill be able to see things better
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08-08-2018, 03:28 PM
#8
AudiWorld Super User
Not true FWIW. Any used head will have some level of valve deposits, whether pre- or post FSI. I get that the old head was destroyed, but that is independent of best practice installing any used head, whether a replacement or the same one. Audis historically wear valve stem seals too. The more they wear, the more oil you suck through them...and onto the tops of the valves... Fortunately stem seals seem to be more durable on newer Audis I have owned than old ones were. What's done is done, but way easier to do the cleaning, inspection and minor parts changes with a head off. You also want to straight edge it for any warping, or if it needs planing. Fortunately again, newer Audi heads seem more stable than they used to be.
08-08-2018, 05:46 PM
#9
AudiWorld Member
Thread Starter
Not true FWIW. Any used head will have some level of valve deposits, whether pre- or post FSI. I get that the old head was destroyed, but that is independent of best practice installing any used head, whether a replacement or the same one. Audis historically wear valve stem seals too. The more they wear, the more oil you suck through them...and onto the tops of the valves... Fortunately stem seals seem to be more durable on newer Audis I have owned than old ones were. What's done is done, but way easier to do the cleaning, inspection and minor parts changes with a head off. You also want to straight edge it for any warping, or if it needs planing. Fortunately again, newer Audi heads seem more stable than they used to be.
https://www.ebay.de/itm/Zylinderkopf...53.m2749.l2649
yes i know that audis do what they do, but the head has only done 95k.
i know that the head is fine, i understand your reasoning, but ive done most of the checking for this, but this wont solve the chattering issue that i have
08-08-2018, 08:27 PM
#10
AudiWorld Super User
okay, so, the head i bought was chemically cleaned, it looked brand new. there was not a single bit of deposits. you can see in the listing yourself:
https://www.ebay.de/itm/Zylinderkopf-Audi-A6-C5-4-2-quattro-ASG-077103373AN-DE193323/322501822736?ssPageName=STRK%3AMEBIDX%3AIT&_trksid =p2060353.m2749.l2649
yes i know that audis do what they do, but the head has only done 95k.
i know that the head is fine, i understand your reasoning, but ive done most of the checking for this, but this wont solve the chattering issue that i have
https://www.ebay.de/itm/Zylinderkopf-Audi-A6-C5-4-2-quattro-ASG-077103373AN-DE193323/322501822736?ssPageName=STRK%3AMEBIDX%3AIT&_trksid =p2060353.m2749.l2649
yes i know that audis do what they do, but the head has only done 95k.
i know that the head is fine, i understand your reasoning, but ive done most of the checking for this, but this wont solve the chattering issue that i have
Internal engine solvent? They are smaller on modern Audis, but lifters and lifter noise has been around since I was a kid many decades ago now, and valve ticking on solid lifters like old Audis first had too. Variable valve adjusting and intercam chain drive and tensioner? Screwdriver or stethoscope to the ear test to track down the sound beyond reference only to center of the motor? The more obscure anti drainback valves...which BTW are sort of in deep center; those can lead to under oiling of head and then the ticking stuff.
If you are hoping someone posts the magic cure all on a ten year old motor and now with ave 3rd to 5th owners, go to the parts store and order the xy23Z1 slash 2, rev 3 part for a really cheap (or any) price, FWIW it isn't going to happen in my experience and having the 4.2 back to 19 years on now. And likewise being one of I think a handful on the board way inside it--for what turned out to be damaged block at one specific cylinder on extreme bottom of bore. For starters, I think you need to dive in there diagnostics and specificity wise like sound detection. Generalized ears usually don't get very close to exactly where an internal motor noise is. Then I would probably do some old fashioned pre electronics stuff most likely such as the solvent that may or may not get anywhere, but is good practice anyway for the oil and filter change again shortly after any deep dive internal motor work. Still way more labor and parts effective than a complete timing belt removal again to get into the intercam drive as the next logical guess, without so far well accepted sound checking at the relevant end of the motor on given side. As you know from being in there on the bottom end, beyond the oil pump area, nothing else obvious moves down there. The oil squirts the underside of the pistons, but that is a pressure fed system, not directly mechanical. There is that metal baffle pan/plate around the oil pick up area, so if you went at any of the fasteners there (I couldn't pull mine due to other parts interference), I suppose a very small percentage chance would be something like that now rattling. But hopefully you are confident in the iower internal work and re assembly.
For other random ones, recheck water pump and other belt drive items. Usually you can get some sense of where noises are with the power steering and alternator, but the water pump can be vaguer. Ticking and chattering really sounds like valve train related though rather than water pump bearing rumble and deep grinding stuff. Sound probing as bottom line will really help get beyond the broad area guesses.
Last edited by MP4.2+6.0; 08-08-2018 at 08:37 PM.