Open engine surgery
12-28-2005, 03:07 PM
#16
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Originally Posted by jetrainor
Well i think we are coming to the sad conclusion that this engine has thrust bearing failure...what we can't understand is why it sounded like rod bearing knock when we pulled it out of the car. With the pan off, we can try and move the rods but they are tight, so we're thinking its not rod bearing noise.
We also know from others that with TBF, there is no noise....just a quiet grinding away of the main journal where the thrust bearing no longer exists....could the noise be from a rod wrist pin allowed to move because of the play in the crank shaft. With a pry bar, the crank moves back and forth about one eigth of an inch. I don't know if this is enough to consider the block toast. You can definitely see where the crank lobe has rubbed against the back side main journal, basically smoothing it out however i wouldn't say it was 'grinding'. My initial thought was to re-bearing rods and mains, but without the knocking noise explained i guess we have to pull the whole thing apart. I've got a feeling the block is too worn on the main journal fora new main bearing to seat properly. Wish i had an exper ience set of eye's to give us a second or third opinion.
It really blows me that this thrust bearing issue, at least with auto's, is so deadly to these cars. This engine has 65.000 miles on it, didn't use a lick of oil, and after spending 7 thousand dollars on it this summer, was running awesome. The whole tourque tube, pinch collar, flex plate fiasco is just so bloody mickey mouse on such an otherwise overengineered, expensive piece of mac hinery
87 euro auto
We also know from others that with TBF, there is no noise....just a quiet grinding away of the main journal where the thrust bearing no longer exists....could the noise be from a rod wrist pin allowed to move because of the play in the crank shaft. With a pry bar, the crank moves back and forth about one eigth of an inch. I don't know if this is enough to consider the block toast. You can definitely see where the crank lobe has rubbed against the back side main journal, basically smoothing it out however i wouldn't say it was 'grinding'. My initial thought was to re-bearing rods and mains, but without the knocking noise explained i guess we have to pull the whole thing apart. I've got a feeling the block is too worn on the main journal fora new main bearing to seat properly. Wish i had an exper ience set of eye's to give us a second or third opinion.
It really blows me that this thrust bearing issue, at least with auto's, is so deadly to these cars. This engine has 65.000 miles on it, didn't use a lick of oil, and after spending 7 thousand dollars on it this summer, was running awesome. The whole tourque tube, pinch collar, flex plate fiasco is just so bloody mickey mouse on such an otherwise overengineered, expensive piece of mac hinery
87 euro auto
For what its worth...When I went through the TBF, I opted for the new (well newer) motor route. It was painful, but I'm glad I did it. Now, about 3 years removed from the incident, it just a bad memory that I'm doing my best to surpress. But my wife seems to bring it up every time I decide upgrade something on the car.
12-28-2005, 04:43 PM
#17
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FBII,
It is for real.
I suspect that the final moments of 2/6 going south might have accelerated the wear of the babbitt surface, exposing the bronze sub-plating.
If NOT....
Here's two more pictures of the rebuild. Start to Finish.
It is for real.
I suspect that the final moments of 2/6 going south might have accelerated the wear of the babbitt surface, exposing the bronze sub-plating.
If NOT....
Here's two more pictures of the rebuild. Start to Finish.
12-29-2005, 02:46 AM
#18
Burning Brakes
Thread Starter
Ed....the final picture is drop dead georgous....pretty much how mine looked after all the work this summer.....in the meantime......pulled the rod caps today.....and the bearings look like brand new...mechanic was concerned about the 'blueing' on the top of the crank lobs but we decided it can't be from overheating because the bearings look new.....friday we pull the rest of the motor apart and will take pics of the journals where there was some rubbing with the crank....the end play is almost exactly the same as the missing bearing shoulder on the center main.....hoping that a new bearing will seat properly and solve my problems.
87 euro auto
87 euro auto
12-29-2005, 04:30 AM
#20
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My motor came from 928 International. If you can't trust them, then you're pretty much out of luck. As for installing, that was a whole different issue. I had a bad experience with not to popular fellow in the 928 community. In the end I had to have the job completed by a very reputable mechanic.
01-03-2006, 02:57 PM
#21
Burning Brakes
Thread Starter
Prognosis not encouraging.....pulled the cradle and the center main bearing has spun with the backside thrust bearing wearing into the journal...the crank looks like toast under the bearing....mechanic, who is not familiar with these engines, but has rebuilt many others says to him it looks like the engine was starving for oil, as well as the thrust bearing issue....can't say for sure i guess b ut the crank lobe on the center main is very blue.....so i guess its block and crank foobarred. The rod bearings look like new so i think heads are okay...sooooooooo, i need a long block or a short block to stuff some parts into. I'd be willing to drive into the states with my pickup rather than go through the hasstle of shipping, duty, etc. I will try to post pics from home of the crank and bearing but not sure how to download those.
87 euro auto
87 euro auto
01-03-2006, 04:08 PM
#22
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Are you gonna have this mechanic do the work? There are bound to be some pretty well informed 928 experts in your area (of the world)....hell, maybe you can take some really good picts and post them here.....Also there are a bunch of real 928 wizzards in the Pacific Northwest region. I am suggestion in so many words that you get an opinion you are sure is an informed one.....these engines are not always comparable to anything else a mechanic has ever seen......If it was starved for oil, YOU should find out why.......
One other question, has the car ever had; tranny, torque tube, torque converter work done on it? How long ago?
One other question, has the car ever had; tranny, torque tube, torque converter work done on it? How long ago?
01-03-2006, 04:57 PM
#23
Burning Brakes
Thread Starter
Gretch....no previous work that i'm aware of, other than TB/WP, motor mounts, wires, etc....which i did this summer....at a Porsche Mechanic. I'll try to post some pics from home tonight if someone can give me a heads up on how to do it.
87 euro auto
87 euro auto
01-03-2006, 05:05 PM
#24
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Go to advanced post, manage images, browse, find a picture on your system....pretty straight forward, help in the general directions area.....limited to about 125 mbs though.....been so long that I looked I am sure my references are not "precise"
There are almost 0 Porsche mechanics that have any familiarity with the innerds of a shark motor....This guy work at a dealership?.........If he does...."Danger Will Robinsion, Danger!!!!"
There are almost 0 Porsche mechanics that have any familiarity with the innerds of a shark motor....This guy work at a dealership?.........If he does...."Danger Will Robinsion, Danger!!!!"
01-03-2006, 05:51 PM
#25
Burning Brakes
Thread Starter
The Mechanic who did the work this summer is an independant and known throughout the pacific northwest, apparently, as a top 911 engine guy.....the reason i didn't have him pull the motor and tear it down was he really wasnt interested quite frankly....just as well because the diagnosis would be the same at 3 times the price. The rebuild will be local. I've got an offer from another rennlister to post pics for me if i can't figure it out.
Thanks for the help and interest to this point......my wife and I are off to China and Thailand for January. My son lives in China where he teaches English and is married to a mainland Chinese girl. In the meantime keep me in mind folks for the bottom half of a 5 liter.
87 euro auto (heartless)
Thanks for the help and interest to this point......my wife and I are off to China and Thailand for January. My son lives in China where he teaches English and is married to a mainland Chinese girl. In the meantime keep me in mind folks for the bottom half of a 5 liter.
87 euro auto (heartless)
01-03-2006, 05:58 PM
#26
Burning Brakes
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I don't understand the part of your preceding post where you say..."the rod bearings look like new, so I think "heads are OK"...that doesn't make any sense to me. I agree, to snap some high res digital photos and post them. Sure to be some positive help here, and the price is right too. Good luck.
01-03-2006, 06:32 PM
#27
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enjoy China man, the shark will be there when you get back. Sounds like you may have the right level of help......you got the right attitude about 911 mechanics......not that they don't know their stuff and all....they just do not know 928s.
good luck.
good luck.
01-03-2006, 10:59 PM
#28
Concerning the knocking. Just a hunch but it appears the forward movement of the crank would cause stress and uneven wear on the piston wrist pins. Has anyone torn a TBF engine down far enough to check the damage in that area?
Dennis
Dennis
