Rogue XJ
07-29-2007, 03:14 PM
It started out as a noticable sound when I started up a few weeks ago. You know the sound, one that sounds like the engine is going to pitch a rod or something... the kind of sound that makes you cringe, and picture your bank account being sucked for a hefty sum.
I dare say, and am glad, that I have actually heard many a different sound during my tenure as an auto mechanic, and on checking a happy oil pressure gauge, decided that the sound was probably either a cracked flexplate (the automatic transmission's equivalent of a flywheel) or loose flexplate )to torque convertor) bolts since the sound seemed to happen under low rpm, maximum pulsation conditions, and didn't happen under moderate or higher rpm loads.
Given that I'd owned the vehicle for a year, it seemed strange to me that loose torque convertor bolts might occur, but the possibility was still there.
As the I continued to drive the vehicle (without much choice, being my primarly/only transportation) toward the weekend when I'd be able to finally get it up on the rack to pull the inspection cover, the noise continued to worsen, now occurring at stops lights/idle conditions, especially under load, with a/c on.
Once on the rack, I attempted to remove the inspection cover and found that one of the bottom bolt/nut combos had been installed by the previous owner or shop facing the wrong direction, while the exhaust was out for whatever reason, and now the bolt was too long to be remeved without dropping the exhaust, so I used a cutting wheel to cut off the head so it could be removed, replacing the bolt later with one similar.
With the inspection cover removed, I could easily see the dust traces from beneath each convertor bolt head on the flexplate due to movement, but further teardown was indicated, to accertain the damage. Once removed, I could see the bolts had sustained minor, but notable damage, and decided to replace them with bolts of similar strength, very slightly longer, to be able to use washers with them in order to distibute the clamping force some, as the flexplate holes too had sustained minor damage. Locktite was used on the bolts to prevent their backing out, finally torquing the bolts to specs.
Glad I am, that it wasn't a cracked flexplate, requiring transmission removal to replace, and the cost of a new flexplate... like I say... better just loose convertor bolts, caught in time.
Hope this article helps anyone with similar problems now or in the future.:)
___________________
ASE Cert Master Auto Tech, L1 endorsement
Bosch BSC1, 2, 3, 4.
I dare say, and am glad, that I have actually heard many a different sound during my tenure as an auto mechanic, and on checking a happy oil pressure gauge, decided that the sound was probably either a cracked flexplate (the automatic transmission's equivalent of a flywheel) or loose flexplate )to torque convertor) bolts since the sound seemed to happen under low rpm, maximum pulsation conditions, and didn't happen under moderate or higher rpm loads.
Given that I'd owned the vehicle for a year, it seemed strange to me that loose torque convertor bolts might occur, but the possibility was still there.
As the I continued to drive the vehicle (without much choice, being my primarly/only transportation) toward the weekend when I'd be able to finally get it up on the rack to pull the inspection cover, the noise continued to worsen, now occurring at stops lights/idle conditions, especially under load, with a/c on.
Once on the rack, I attempted to remove the inspection cover and found that one of the bottom bolt/nut combos had been installed by the previous owner or shop facing the wrong direction, while the exhaust was out for whatever reason, and now the bolt was too long to be remeved without dropping the exhaust, so I used a cutting wheel to cut off the head so it could be removed, replacing the bolt later with one similar.
With the inspection cover removed, I could easily see the dust traces from beneath each convertor bolt head on the flexplate due to movement, but further teardown was indicated, to accertain the damage. Once removed, I could see the bolts had sustained minor, but notable damage, and decided to replace them with bolts of similar strength, very slightly longer, to be able to use washers with them in order to distibute the clamping force some, as the flexplate holes too had sustained minor damage. Locktite was used on the bolts to prevent their backing out, finally torquing the bolts to specs.
Glad I am, that it wasn't a cracked flexplate, requiring transmission removal to replace, and the cost of a new flexplate... like I say... better just loose convertor bolts, caught in time.
Hope this article helps anyone with similar problems now or in the future.:)
___________________
ASE Cert Master Auto Tech, L1 endorsement
Bosch BSC1, 2, 3, 4.