Help - Engine cover / alternator bracket
02-28-2017, 11:59 PM
#16
And...I can see how that aluminum part could fail because of what it takes to rotate the alternator counter clockwise after removing the longer bolt on the high side of the alternator.
03-01-2017, 08:30 AM
#17
Rennlist Member
18 year old plastic is going to be fragile...
05-25-2017, 05:32 AM
#18
8th Gear
Join Date: May 2017
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First I want to thank Cru_Jones for the original post, it was instrumental in repairing my car.
Our alternator bracket failed 600 miles after I had replaced all of the SAI valves. When replacing the SAI and check valve, everything went back together and the bracket, from my recollection, was fine and showed no signs of emanant failure. After a trip from LA to Vegas and back (by way of Angles Crest) the bracket had failed, the alternator shifted up and to the right, and the alternator pulley started to wear through the oil filler tube.
With the air box out I started to piece together what could have happened (and might explain other failures). The sliding bushing had given enough to let the alternator out easily enough but, what I did not realize was, it barely moved when I tightened it. So when I torqued the long bolt to 34ft/lbs of torque I was tightening the bolt to the bushing but not getting the contact between the bushing and the channel that is needed. Over those 600 miles I think that the belt tension eventually managed to get the bolt to slide up and out of the channel. At that point the tab of the bracket had to fight twisting forces it was not intended for and failed. My guess is that the moral of the story is that the bushing is critical to preventing this failure.
Also, I decided to replace my lower idler pulley when fixing the bracket and the bolt sheared on the way back in. Like Cru, there was plenty sticking out of the block so it was easily removed. But the sinking feeling of a bolt that is not tripping the torque wrench a few clicks in is a horrible feeling.
Again, thank you to all for the advice, part numbers, and pictures.
Our alternator bracket failed 600 miles after I had replaced all of the SAI valves. When replacing the SAI and check valve, everything went back together and the bracket, from my recollection, was fine and showed no signs of emanant failure. After a trip from LA to Vegas and back (by way of Angles Crest) the bracket had failed, the alternator shifted up and to the right, and the alternator pulley started to wear through the oil filler tube.
With the air box out I started to piece together what could have happened (and might explain other failures). The sliding bushing had given enough to let the alternator out easily enough but, what I did not realize was, it barely moved when I tightened it. So when I torqued the long bolt to 34ft/lbs of torque I was tightening the bolt to the bushing but not getting the contact between the bushing and the channel that is needed. Over those 600 miles I think that the belt tension eventually managed to get the bolt to slide up and out of the channel. At that point the tab of the bracket had to fight twisting forces it was not intended for and failed. My guess is that the moral of the story is that the bushing is critical to preventing this failure.
Also, I decided to replace my lower idler pulley when fixing the bracket and the bolt sheared on the way back in. Like Cru, there was plenty sticking out of the block so it was easily removed. But the sinking feeling of a bolt that is not tripping the torque wrench a few clicks in is a horrible feeling.
Again, thank you to all for the advice, part numbers, and pictures.
08-05-2017, 06:36 PM
#19
Been busy on other things for a couple of days, but I put everything back together today... started first time, which is always reassuring ;-)
I need to fit a different alternator shroud (from an NA) as the original shroud now fouls the steering rack.
Also, I had to bodge a repair on the vacuum line that has the banjo bolt connection to one of the intercooler pipes, which has finally split. Black silicone sealant and gaffer tape. It's not pretty, but it looks like it'll hold until I can replace it with something more permanent. I replaced all the smaller vacuum lines a couple of years ago, but this makes me think it may be time to replace the bigger ones as well.
I need to fit a different alternator shroud (from an NA) as the original shroud now fouls the steering rack.
Also, I had to bodge a repair on the vacuum line that has the banjo bolt connection to one of the intercooler pipes, which has finally split. Black silicone sealant and gaffer tape. It's not pretty, but it looks like it'll hold until I can replace it with something more permanent. I replaced all the smaller vacuum lines a couple of years ago, but this makes me think it may be time to replace the bigger ones as well.
05-09-2018, 11:05 PM
#20
2nd Gear
Join Date: Feb 2018
Location: Houston, Texas
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Does anyone know whether there is suppose to be a support bracket for the back underside of the alternator to support the weight of the alternator or a sleeve that inserts in the upper alternator mounting hole that would stabilize the alternator from twisting. I've already replaced 3 Engine Block Water Cap 996-101-021-51 on my 2001 996. Any suggestion on how to keep this from breaking again?
05-09-2018, 11:30 PM
#21
Rennlist Member
Does anyone know whether there is suppose to be a support bracket for the back underside of the alternator to support the weight of the alternator or a sleeve that inserts in the upper alternator mounting hole that would stabilize the alternator from twisting. I've already replaced 3 Engine Block Water Cap 996-101-021-51 on my 2001 996. Any suggestion on how to keep this from breaking again?
