Third Alternator Bracket Broken
 

I have now had my third alternator bracket to break. I thought the first two may have been due to bad metallurgy or hairline fractures since they were used, but this latest one was brand new - straight from the dealership. They each last about two or three months, then break.

The bracket is the weakest mount link in the serpentine belt circuit, but obviously something is exerting a lot of pressure to make these brackets continue breaking. The metal in the bracket is probably 3/16" thick. I can't imagine that the tensioner spring is too strong. The alternator works fine, and the pulley turns freely. The a/c compressor works fine, but maybe the pulley or clutch is in a bind and exerting pressure above on the alt bracket.

Any ideas?

I had the same problem on my wifes 98 Accord. What i ended up doing was taking the old bracket and copying the shape and holes and making my own out of some really heavy duty metal from my friend welding shop. I had three go out in a week and my mechanic was baffled.

did you ck to see if car is part of the timing belt pulley alignment problem (recall)
ck with acura on that 1 800 382 2238 x5
some late 02 early 03 had that issue ,,and it could extend to breaking alt mounts

Thanks for your responses, guys.

Rybin, had your wife's Accord been in an accident? My car is a rebuild, so just wondering if there is a commonality there. The original bracket was slightly bent, and thus the alt pulley visibly out-of-alignment (albeit only slightly), but the second bracket was fine and things align perfectly now.

The car runs and performs exceptionally well, but this bracket thing is a real mystery. I guess I will suck-it-up and check with the dealership about potential causes, including the timing belt pulley issue.

I'm due for timing belt/water pump maintenance, and was going to install an aluminum underdrive pulley in the process. Maybe an underdrive pulley would lessen the torque put on the bracket.

I think I found the problem. It seems that the threads in the hole for the bottom mounting bolt are stripped. This is the hole in the engine block where the large bottom 14mm bolt goes in. Without the alternator in place, the bolt goes in all the way, bottoms-out, and will hold since the deepest threads are fine. But with the alternator mounted, the bolt doesn't need to bottom-out, and the threads at the critical contact point are stripped.

When I replaced the last broken bracket, I remember thinking that that bolt wasn't tightening very well, but I thought it would hold. It must have worked it's way loose over time, which in turn put all the stress on the bracket, and it finally broke. I'm not sure if I stripped it myself during earlier repairs, or if it happened in the accident.

A steel bolt in an aluminum block is a tricky thing. For some installations, a bolt doesn't need to be super-tight, so you can stop before reaching the danger zone. But for mounting an alternator, you would think it needs to be fairly tight, and you can easily strip it if not careful. I know using a torque wrench and tightening to factory specs would prevent it, but a big thick torque wrench head would not have enough clearance in the case of this alternator bolt. The tensioner pulley is in the way, so that would probably have to be removed first in order to use a torque wrench on that alternator mounting bolt.

So...any ideas for fixing the threads in the block? I guess there are kits for such things, but it seems that I will have to use a larger bolt if I have to bore-out the hole.

drill it out and use a helicoil kit to insert new threads

you can be a human torque wrench by trying to tighten.. then loosen.. a bolt with known value- using a regular wrench--

your muscle memory will be able to reproduce the pull required when at proper torque

Thread insert is about all you can do short of drilling it larger & tapping for a bigger bolt.

I've been researching a bit, and helicoil is the ultimate fix. However, getting a straight hole drilled in that location may be a challenge; clearance is an issue for a drill. The threads are still somewhat intact, so I may try a tap first and go from there. I also saw that some people have used J.B. Weld successfully for this type of fix.

J. B. Weld- I forgot about that stuff. That may be worth a try. Would a right angle drill work?

I have the exact same problem with my rebuilt CL-S. I am on my 4th bracket now, and i just replaced the alternator. How did you finally fix the problem? threads on the lower bolt?

Id either tap the threads for a slightly larger bolt or a heli coil

I did finally fix it. I tried a tap first. It cleaned up the threads, but they still wouldn't hold. I was going to try and drill it, and then install a helicoil, but there was not enough clearance for a drill - even a right-angle drill. The frame is in the way, so there is only about 4 inches of clearance. The motor mounts would have to be removed, and the engine jacked-up to get enough clearance for a drill.

So, I ended up using JB Weld. I wrapped the bolt in teflon tape, then applied a coating of JB Weld to the bolt, smeared a little into the bolt hole opening, then screwed the bolt all-the-way in and let the epoxy set overnight. The next day I was able to unscrew the bolt (thanks to the teflon tape), then install the alternator as usual. Of course the new threads held, or I wouldn't be writing this.

A few notes about the process. I prepped the bolt hole by first cleaning the threads with a tap once again, blowing the hole out with compressed air, then using a Q-tip and acetone (or fingernail polish remover) to remove any residue inside the hole. The tap was a 10mm with 1.25 metric threads. Incidentally, I had to find a short tap handle that would fit in the space. When applying the teflon tape to the bolt, I was very careful to only wrap one thin layer with as little overlap as possible between wraps. I wrapped in the direction of the threads very tightly in order to get the tape into the threads as much as possible. I carefully inspected how the tape was seated in the threads, and used my fingernail to press the tape into the threads where needed. Even if a slight tear occurs while pressing the tape into the threads, that is better than having flat threads due to the tape not being seated correctly.

I actually did a test run of the process using a spare bolt and a piece of wood. I drilled a hole that was slightly larger than the bolt shaft into the wood, and did the same routine of wrapping the bolt with teflon tape and applying a layer of JB Weld. I pushed the coated bolt into the hole in the wood, let it set overnight, then successfully extracted the bolt the next day. It left very clean threads in the hardened JB Weld. In fact, I tried tightening the bolt in the hardened epoxy in an attempt to strip the threads, but the bolt just kept going deeper, even to where it was starting to break through the bottom of the wood and come out the other side. I took some pics along the way, so maybe I'll post them if anyone is interested.

Great fix. That's using the noggin. Thanks for sharing.

I agree, great workaround for a tight place to get at.:thumbsup:

same exact problem. ordered both brackets, the alternator one and the AC compressor one, new alternator. pulled the bolt out and noticed the threats were stripped, just like yours. lifted the block off the mounts, tapped and used a helicoil. Seems to fit perfectly now with good grip. Keep me posted on yours, i'll let you know if mine is fine.

Under-engineered
 

I found this thread while looking for the torque specs for 3G TL alternator stay bracket to alternator bolt, which isn't in AllData for some reason.

My opinion is that Honda chintzed on the bracket to save $0.02. At least they learned. 3G TL alternator stay bracket is solid steel, without the two square holes on your brackets.



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