Bolt at AC pulley bracket is stripped

[bytes311]

I went ahead and changed out the old ac belt for the first time in my ownership. I unfastened the two bolts holding the bracket with the idle pulley and slipped the belt on. When I went to tighten it all down, I noticed there were strips of aluminum on the thread of the bottom bolt, so the PO must have over-torqued it. I can get it snug but it'll spin in place if I try and tighten it down.

What options do I have to repair the hole? Helicoil? And does that hole go all the way through into the crankcase? My main concern now is potential oil seepage.

Thanks.

[DMC5180]

Photos would help. But you?ll need to heli-coil it for sure though. What size was the bolt head?


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[bytes311]

Photos would help. But you?ll need to heli-coil it for sure though. What size was the bolt head?


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69169

The bolt is an M7.

[DMC5180]

I?m fairly sure that?s through hole. But to be sure, just stick something smaller in the hole to see if it bottoms out. Were the ends of the bolts dry or oily? that?s the tell tale sign.


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[Ethan Rode]

Both holes are blind; they don't go all the way through.

you can use an M7 Helicoil to repair these threads. If you have an angle drill, you should be able to do the repair without removing the rear fascia. Be sure to use a drill stop so that you don't drill through the back of the hole. Additionally, since Helicoil taps aren't a "plug-style" tap, you may need to trim the insert slightly to make it flush with the surface of the timing cover. I believe I had to trim off a thread and a half when I did this repair.

Best of Luck.

[82DMC12]

Both holes are blind; they don't go all the way through.

you can use an M7 Helicoil to repair these threads. If you have an angle drill, you should be able to do the repair without removing the rear fascia. Be sure to use a drill stop so that you don't drill through the back of the hole. Additionally, since Helicoil taps aren't a "plug-style" tap, you may need to trim the insert slightly to make it flush with the surface of the timing cover. I believe I had to trim off a thread and a half when I did this repair.

Best of Luck.


Do you have any advice for figuring out the depth/length of the helicoil to order for a repair like this (blind hole)?

[painterdave72]

also had to do both of mine.. its a stupid design as it is aluminum and you have to loosen those bolts quite a bit to change belt or bearing etc....Like Ethan said its fairly simple but u will have to cut the helicoil a little to get it to sit flush....

[Rich]

Do you have any advice for figuring out the depth/length of the helicoil to order for a repair like this (blind hole)?

This isn't an uncommon [LINK] problem on this engine (https://dmctalk.org/showthread.php?3013). I don't know the answer to your depth question. One easy way to check the depth of the threaded area of your timing cover casting at that location without a teardown is with a modified right angle [LINK] parts pick (https://www.autozone.com/test-scan-and-specialty-tools/hook-and-pick-set/p/surebilt-hook-and-pick-set-4-piece/141461_0?rrec=true) or something like it you can use as a blind depth gauge. You could even use a sharply-bent section of small gauge solid steel or copper wire for this probe/gauge (make it long enough that it won't fall into the hole)

Clip or saw off most of the bent end of the pick or the wire so the 90deg bent end is just 2-4mm long after the sharp 90 deg bend and you can insert the shaft with that bent end straight into the stripped bolt hole.

Insert the 'depth gauge' into the hole, shove it to one side so the bent section hangs up on the inner wall of the casting, then pull on it so the bent end hangs up against the inner wall of the cover. Then apply some tape or a permanent marker line on the exposed shaft of the pick/gauge flush with the outer boss on the cover.

Remove the gauge, measure distance from near side of bent pick/wire to the mark/tape you put on the shaft. That's the casting depth. Do it again to see if you get the same reading.

[TheStoot]

Do you have any advice for figuring out the depth/length of the helicoil to order for a repair like this (blind hole)?

I replaced mine over the summer I believe it was 40mm

[Ethan Rode]

Do you have any advice for figuring out the depth/length of the helicoil to order for a repair like this (blind hole)?

The hole is 21.3mm deep. The casting is about 24mm total, so be careful.

[Andrew]

Perhaps a self-tapping M8 or 5/16 bolt would work.