Thrust Bearing Fail. WHAT HAVE I GOT TO LOSE?
04-16-2015, 09:16 PM
#16
Nordschleife Master
You've had this car for a few years haven't you? Good warning to all other auto owners to go measure their end play, and not just release the flex plate and assume its ok!
Right now, what you've got to lose by driving the car is the parts of the engine which haven't been damaged yet.. crank (maybe), rods, heads, cams etc.
My opinion is:
Strip the damaged engine - take the block and girdle to a local machine shop for an opinion/estimate, armed with the correct measurements (at least 2 S4's have been fixed from this situation - using shims and machining).
If its affordable, do it. If its not:
1. Strip any steel off, and take the damaged block to the recycler (or donate it to a suitably-tooled rennlister to experiment with repair on)
2. Part out the car and use proceeds to buy another S4
3. Use any new bits off your current engine that you've fitted (intake gaskets, knock sensors, timing belt stuff, hoses etc) and put on the replacement S4.
If it was a GT or GTS I'd say its more reasonable to fix - but cheap running auto 87's are pretty easy to find, just make sure you get a crank play measurement before paying for the car! (or get the car cheap enough that a rinse-and-repeat isn't an expensive nightmare).
Right now, what you've got to lose by driving the car is the parts of the engine which haven't been damaged yet.. crank (maybe), rods, heads, cams etc.
My opinion is:
Strip the damaged engine - take the block and girdle to a local machine shop for an opinion/estimate, armed with the correct measurements (at least 2 S4's have been fixed from this situation - using shims and machining).
If its affordable, do it. If its not:
1. Strip any steel off, and take the damaged block to the recycler (or donate it to a suitably-tooled rennlister to experiment with repair on)
2. Part out the car and use proceeds to buy another S4
3. Use any new bits off your current engine that you've fitted (intake gaskets, knock sensors, timing belt stuff, hoses etc) and put on the replacement S4.
If it was a GT or GTS I'd say its more reasonable to fix - but cheap running auto 87's are pretty easy to find, just make sure you get a crank play measurement before paying for the car! (or get the car cheap enough that a rinse-and-repeat isn't an expensive nightmare).
04-17-2015, 03:46 AM
#18
Intermediate
Join Date: Feb 2002
Location: Bellingham, WA
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Perhaps I have a too simplistic view, but if you have a failure of the lower end then why not look for another engine that had a failure to the upper end? Combine the two and win?
05-31-2016, 09:21 PM
#20
Rennlist Member
How did you make out on this one anyway?
05-31-2016, 10:18 PM
#23
Rennlist Member
Why not split the block and replace the thrust bearing? You are almost there anyway.
06-01-2016, 04:53 AM
#25
No comparison at all. Wings fall off you die. If engine seizes it will do so at low revs when friction exceeds engine power. Pull over and stop ( or stay stopped at the red light).
06-01-2016, 10:00 AM
#26
Rennlist Member
Thread Starter
Theory
Good Morning,
Upstate Bob,
I work flight clearances for DOD. I am the wiring SME (Subject Matter Expert and an A&P) for specific aircraft/weapons platforms, with flight clearance authority of denial.
So,
"is it just me or does this thread give anyone else the creeps? the lift strut pins on my airplane are getting kinda worn and sloppy. should I replace them or just see how long they last?"
Is a bit of a stretch..
This is just a car. One that has an engine that is close to its demise. I believe that documenting the eventual death is a reasonable path, and one that may add to the knowledge base that we all use on this forum.
...Plus, I have a fairly rare 1992 968 waiting in the wings. It was a TB fail that was left baking in the sun for 7 years. Heads were rebuilt but junk yard owner couldn't remember how to put it back together. TB and heads all put back together(VARIOCAM). Just waiting on my 15 Y/O son to decide to get interested...
After about a hundred miles or so I will get an oil analysis done then plan on regular analysis after that to understand the progression.
As I said this was taken on for several reasons.
1. I believe this damage occurred before I owned it and noticed no detrimental running conditions. Aside from an audible knock every once in a while. I released the flex plate tension the day after I bought it. I wasn't able to take a crank play measurement. I drove it as a daily driver for 2-3 years before I pulled the motor for a slew of preventative maintenance actions. More to stop myself from driving it with a TB that was due and gears that were toast.
2. $$. Did not see the immediate need to trash an engine that was running well. The plan to do all of the maintenance that could transfer to another engine at a later date seemed viable to me.
3. The inconvenience of it leaving me stranded one day is not a huge concern. I have a cell phone. The possibility of it taking the heads out was, and is a calculated risk. I do not plan on re-using any of the engine internals.
4. I saw a need to document the demise of one of our engines. In the hopes that others may benefit and prolong their driving experience with some mediation efforts to mitigate the damage that has already occurred. As I said, I have a documented baseline for crank travel. I believe that with care, and surveillance, these engines can survive past the posted crank play limits (It currently has a travel that is 3.5 times beyond the posted limits and was running well). IF I made my living as a professional P mechanic I would never recommend this to a customer...Unless they understood that it was just a matter of time before it ate itself up and your wallet was going to get lighter by about $2-3K in parts for the next engine.
5. Time. I did not have the time to wait for a newer engine. My window of rebuild was limited..
My amazing wife was working on her masters. So, she was doing homework late into the evenings. This left me free to work in the garage without feeling guilty for not spending time with her. She finished her masters 1 week before I turned the key..lol..She has already begun a line item in our budget for a newer engine.
6. I wanted to see if a $100.00 water pump with a warranty was as huge a risk as was advertised( Block is already damaged from crank).
7. I wanted to see if I could do a reasonable job of rebuilding the injectors.
8. I wanted to see how big a deal it was to build an engine harness with more robust components.
(Not a big deal. Cost was about $200.00, with lots of components left over and upgraded wire.)
9. Wanted to see if the price I paid for premade injector pigtails was viable. ($36.00 for all 8) and they are very robust with long pigtails and boots.
10. I was curious if DIY steering rack rebuild was a good bet. I had heard of a 50% failure rate. It was a calculated risk as was the compressor rebuild.
Anyway, I appreciate all of the great feedback and help that has been proffered here. I just hope that I can add some alternative ideas to scrapping a motor as a first response to being out of limits.
Just to keep it rolling for a bit longer.
Many times I have started threads on this forum, just for the interaction of the community. Maybe this is frowned upon at times, because the search option is a great tool. But, I enjoy the dialogue.
So, if you see a post from me, I will admit up front that there may be the occasion where I just weighed the risk of the time spent searching verses the rewarding interaction and occasion dig from someone that search is your friend. I would just say that I see this forum not only as a tool to keep these cars rolling but opportunity to join others in useful dialogue with a common enjoyment of these BADASS cars.
Be Well,
John
Upstate Bob,
I work flight clearances for DOD. I am the wiring SME (Subject Matter Expert and an A&P) for specific aircraft/weapons platforms, with flight clearance authority of denial.
So,
"is it just me or does this thread give anyone else the creeps? the lift strut pins on my airplane are getting kinda worn and sloppy. should I replace them or just see how long they last?"
Is a bit of a stretch..
This is just a car. One that has an engine that is close to its demise. I believe that documenting the eventual death is a reasonable path, and one that may add to the knowledge base that we all use on this forum.
...Plus, I have a fairly rare 1992 968 waiting in the wings. It was a TB fail that was left baking in the sun for 7 years. Heads were rebuilt but junk yard owner couldn't remember how to put it back together. TB and heads all put back together(VARIOCAM). Just waiting on my 15 Y/O son to decide to get interested...
After about a hundred miles or so I will get an oil analysis done then plan on regular analysis after that to understand the progression.
As I said this was taken on for several reasons.
1. I believe this damage occurred before I owned it and noticed no detrimental running conditions. Aside from an audible knock every once in a while. I released the flex plate tension the day after I bought it. I wasn't able to take a crank play measurement. I drove it as a daily driver for 2-3 years before I pulled the motor for a slew of preventative maintenance actions. More to stop myself from driving it with a TB that was due and gears that were toast.
2. $$. Did not see the immediate need to trash an engine that was running well. The plan to do all of the maintenance that could transfer to another engine at a later date seemed viable to me.
3. The inconvenience of it leaving me stranded one day is not a huge concern. I have a cell phone. The possibility of it taking the heads out was, and is a calculated risk. I do not plan on re-using any of the engine internals.
4. I saw a need to document the demise of one of our engines. In the hopes that others may benefit and prolong their driving experience with some mediation efforts to mitigate the damage that has already occurred. As I said, I have a documented baseline for crank travel. I believe that with care, and surveillance, these engines can survive past the posted crank play limits (It currently has a travel that is 3.5 times beyond the posted limits and was running well). IF I made my living as a professional P mechanic I would never recommend this to a customer...Unless they understood that it was just a matter of time before it ate itself up and your wallet was going to get lighter by about $2-3K in parts for the next engine.
5. Time. I did not have the time to wait for a newer engine. My window of rebuild was limited..
My amazing wife was working on her masters. So, she was doing homework late into the evenings. This left me free to work in the garage without feeling guilty for not spending time with her. She finished her masters 1 week before I turned the key..lol..She has already begun a line item in our budget for a newer engine.
6. I wanted to see if a $100.00 water pump with a warranty was as huge a risk as was advertised( Block is already damaged from crank).
7. I wanted to see if I could do a reasonable job of rebuilding the injectors.
8. I wanted to see how big a deal it was to build an engine harness with more robust components.
(Not a big deal. Cost was about $200.00, with lots of components left over and upgraded wire.)
9. Wanted to see if the price I paid for premade injector pigtails was viable. ($36.00 for all 8) and they are very robust with long pigtails and boots.
10. I was curious if DIY steering rack rebuild was a good bet. I had heard of a 50% failure rate. It was a calculated risk as was the compressor rebuild.
Anyway, I appreciate all of the great feedback and help that has been proffered here. I just hope that I can add some alternative ideas to scrapping a motor as a first response to being out of limits.
Just to keep it rolling for a bit longer.
Many times I have started threads on this forum, just for the interaction of the community. Maybe this is frowned upon at times, because the search option is a great tool. But, I enjoy the dialogue.
So, if you see a post from me, I will admit up front that there may be the occasion where I just weighed the risk of the time spent searching verses the rewarding interaction and occasion dig from someone that search is your friend. I would just say that I see this forum not only as a tool to keep these cars rolling but opportunity to join others in useful dialogue with a common enjoyment of these BADASS cars.
Be Well,
John
06-01-2016, 10:14 AM
#27
Rennlist Member
Good Morning,
Upstate Bob,
I work flight clearances for DOD. I am the wiring SME (Subject Matter Expert and an A&P) for specific aircraft/weapons platforms, with flight clearance authority of denial.
So,
"is it just me or does this thread give anyone else the creeps? the lift strut pins on my airplane are getting kinda worn and sloppy. should I replace them or just see how long they last?"
Is a bit of a stretch..
This is just a car. One that has an engine that is close to its demise. I believe that documenting the eventual death is a reasonable path, and one that may add to the knowledge base that we all use on this forum.
...Plus, I have a fairly rare 1992 968 waiting in the wings. It was a TB fail that was left baking in the sun for 7 years. Heads were rebuilt but junk yard owner couldn't remember how to put it back together. TB and heads all put back together(VARIOCAM). Just waiting on my 15 Y/O son to decide to get interested...
After about a hundred miles or so I will get an oil analysis done then plan on regular analysis after that to understand the progression.
As I said this was taken on for several reasons.
1. I believe this damage occurred before I owned it and noticed no detrimental running conditions. Aside from an audible knock every once in a while. I released the flex plate tension the day after I bought it. I wasn't able to take a crank play measurement. I drove it as a daily driver for 2-3 years before I pulled the motor for a slew of preventative maintenance actions. More to stop myself from driving it with a TB that was due and gears that were toast.
2. $$. Did not see the immediate need to trash an engine that was running well. The plan to do all of the maintenance that could transfer to another engine at a later date seemed viable to me.
3. The inconvenience of it leaving me stranded one day is not a huge concern. I have a cell phone. The possibility of it taking the heads out was, and is a calculated risk. I do not plan on re-using any of the engine internals.
4. I saw a need to document the demise of one of our engines. In the hopes that others may benefit and prolong their driving experience with some mediation efforts to mitigate the damage that has already occurred. As I said, I have a documented baseline for crank travel. I believe that with care, and surveillance, these engines can survive past the posted crank play limits (It currently has a travel that is 3.5 times beyond the posted limits and was running well). IF I made my living as a professional P mechanic I would never recommend this to a customer...Unless they understood that it was just a matter of time before it ate itself up and your wallet was going to get lighter by about $2-3K in parts for the next engine.
5. Time. I did not have the time to wait for a newer engine. My window of rebuild was limited..
My amazing wife was working on her masters. So, she was doing homework late into the evenings. This left me free to work in the garage without feeling guilty for not spending time with her. She finished her masters 1 week before I turned the key..lol..She has already begun a line item in our budget for a newer engine.
6. I wanted to see if a $100.00 water pump with a warranty was as huge a risk as was advertised( Block is already damaged from crank).
7. I wanted to see if I could do a reasonable job of rebuilding the injectors.
8. I wanted to see how big a deal it was to build an engine harness with more robust components.
(Not a big deal. Cost was about $200.00, with lots of components left over and upgraded wire.)
9. Wanted to see if the price I paid for premade injector pigtails was viable. ($36.00 for all 8) and they are very robust with long pigtails and boots.
10. I was curious if DIY steering rack rebuild was a good bet. I had heard of a 50% failure rate. It was a calculated risk as was the compressor rebuild.
Anyway, I appreciate all of the great feedback and help that has been proffered here. I just hope that I can add some alternative ideas to scrapping a motor as a first response to being out of limits.
Just to keep it rolling for a bit longer.
Many times I have started threads on this forum, just for the interaction of the community. Maybe this is frowned upon at times, because the search option is a great tool. But, I enjoy the dialogue.
So, if you see a post from me, I will admit up front that there may be the occasion where I just weighed the risk of the time spent searching verses the rewarding interaction and occasion dig from someone that search is your friend. I would just say that I see this forum not only as a tool to keep these cars rolling but opportunity to join others in useful dialogue with a common enjoyment of these BADASS cars.
Be Well,
John
Upstate Bob,
I work flight clearances for DOD. I am the wiring SME (Subject Matter Expert and an A&P) for specific aircraft/weapons platforms, with flight clearance authority of denial.
So,
"is it just me or does this thread give anyone else the creeps? the lift strut pins on my airplane are getting kinda worn and sloppy. should I replace them or just see how long they last?"
Is a bit of a stretch..
This is just a car. One that has an engine that is close to its demise. I believe that documenting the eventual death is a reasonable path, and one that may add to the knowledge base that we all use on this forum.
...Plus, I have a fairly rare 1992 968 waiting in the wings. It was a TB fail that was left baking in the sun for 7 years. Heads were rebuilt but junk yard owner couldn't remember how to put it back together. TB and heads all put back together(VARIOCAM). Just waiting on my 15 Y/O son to decide to get interested...
After about a hundred miles or so I will get an oil analysis done then plan on regular analysis after that to understand the progression.
As I said this was taken on for several reasons.
1. I believe this damage occurred before I owned it and noticed no detrimental running conditions. Aside from an audible knock every once in a while. I released the flex plate tension the day after I bought it. I wasn't able to take a crank play measurement. I drove it as a daily driver for 2-3 years before I pulled the motor for a slew of preventative maintenance actions. More to stop myself from driving it with a TB that was due and gears that were toast.
2. $$. Did not see the immediate need to trash an engine that was running well. The plan to do all of the maintenance that could transfer to another engine at a later date seemed viable to me.
3. The inconvenience of it leaving me stranded one day is not a huge concern. I have a cell phone. The possibility of it taking the heads out was, and is a calculated risk. I do not plan on re-using any of the engine internals.
4. I saw a need to document the demise of one of our engines. In the hopes that others may benefit and prolong their driving experience with some mediation efforts to mitigate the damage that has already occurred. As I said, I have a documented baseline for crank travel. I believe that with care, and surveillance, these engines can survive past the posted crank play limits (It currently has a travel that is 3.5 times beyond the posted limits and was running well). IF I made my living as a professional P mechanic I would never recommend this to a customer...Unless they understood that it was just a matter of time before it ate itself up and your wallet was going to get lighter by about $2-3K in parts for the next engine.
5. Time. I did not have the time to wait for a newer engine. My window of rebuild was limited..
My amazing wife was working on her masters. So, she was doing homework late into the evenings. This left me free to work in the garage without feeling guilty for not spending time with her. She finished her masters 1 week before I turned the key..lol..She has already begun a line item in our budget for a newer engine.
6. I wanted to see if a $100.00 water pump with a warranty was as huge a risk as was advertised( Block is already damaged from crank).
7. I wanted to see if I could do a reasonable job of rebuilding the injectors.
8. I wanted to see how big a deal it was to build an engine harness with more robust components.
(Not a big deal. Cost was about $200.00, with lots of components left over and upgraded wire.)
9. Wanted to see if the price I paid for premade injector pigtails was viable. ($36.00 for all 8) and they are very robust with long pigtails and boots.
10. I was curious if DIY steering rack rebuild was a good bet. I had heard of a 50% failure rate. It was a calculated risk as was the compressor rebuild.
Anyway, I appreciate all of the great feedback and help that has been proffered here. I just hope that I can add some alternative ideas to scrapping a motor as a first response to being out of limits.
Just to keep it rolling for a bit longer.
Many times I have started threads on this forum, just for the interaction of the community. Maybe this is frowned upon at times, because the search option is a great tool. But, I enjoy the dialogue.
So, if you see a post from me, I will admit up front that there may be the occasion where I just weighed the risk of the time spent searching verses the rewarding interaction and occasion dig from someone that search is your friend. I would just say that I see this forum not only as a tool to keep these cars rolling but opportunity to join others in useful dialogue with a common enjoyment of these BADASS cars.
Be Well,
John
06-01-2016, 06:42 PM
#29
Rennlist Member
i say, run amsoil and see how long it lasts! 
seriously though, if he decided to put it back in .. what is the worse that can happen. more wear and particlate in teh oil, that shouldnt get fed to the heads, because the oil filter keeps that from happening? if that thrust bearing is gone, do you risk damaging the block where the counterweights are hitting the sides of the girtle? damage to the crank?
of course the best thing to do is just rebuld the bottom end, maybe just replacing the mains. but then again, it doesnt take much effort to just put it back in and remove it later if it gets a lot worse. I see both sides. (as greg b. shakes his head....
)
seriously though, if he decided to put it back in .. what is the worse that can happen. more wear and particlate in teh oil, that shouldnt get fed to the heads, because the oil filter keeps that from happening? if that thrust bearing is gone, do you risk damaging the block where the counterweights are hitting the sides of the girtle? damage to the crank?
of course the best thing to do is just rebuld the bottom end, maybe just replacing the mains. but then again, it doesnt take much effort to just put it back in and remove it later if it gets a lot worse. I see both sides. (as greg b. shakes his head....
)
06-01-2016, 06:51 PM
#30
Rennlist Member
is there constant force on the flex plate which pushes on the crank to wear that thrust bearing? as far as i can remember, thats the only surface that keeps the crank in position. is the force worse on 5 speeds where pushing in the clutch, obviously puts load on that surface too. more than autos?
just trying to understand the reason that the autos have this issue and not the sticks. also, if it moves, can it hurt a bearing in the transmission. if so, that would be a reason not to run it to failure.
just trying to understand the reason that the autos have this issue and not the sticks. also, if it moves, can it hurt a bearing in the transmission. if so, that would be a reason not to run it to failure.