Cross Threaded Timing Belt Tensioner Bolt

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mfox808

mfox808

Joined
Jan 10, 2020
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Location
Maui
timing belt replacement was going well enough until tonight. I stripped the threads on the bolt and I’d imagine the spot it goes into on the timing belt tensioner pulley. Pictured below. It’s the one with the funny sized bolt with the 10mm hex head.

Seeing as this is my first time cross threading/stripping a bolt in this fashion, what remedies are available to me to get out of this terrible quagmire?

Thanks to all for the timing belt write ups they’ve been very helpful thus far.

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Did you strip the bolt threads (the male part) or the threads in the hole (the female part)?

In general you can “chase the threads” with a bottoming tap for the hole and a die for the bolt.

If there is enough meat left over just put the bolt back in and torque to spec.

If the threads don’t hold you will need a thread repair insert like a helicol
 
Octous said:
Did you strip the bolt threads (the male part) or the threads in the hole (the female part)?

In general you can “chase the threads” with a bottoming tap for the hole and a die for the bolt.

If there is enough meat left over just put the bolt back in and torque to spec.

If the threads don’t hold you will need a thread repair insert like a helicol
Click to expand...
I definitely stripped the bolt threads, I wasn’t able to get a good look in the hole to see if those are any good.
Does anyone know what size these are?
 
Aluminum can be tricky when it comes to stripped bolts/threads. Luckily you didn't break the bolt off in the hole, that is usually worse and requires a welder. You have two ways to fix this.
  1. Buy new OEM bolt, buy a tap with the same thread pitch, clean out the threads and be done
  2. If the threads in the hole are stripped beyond repair, you should be able to drill and tap in a slightly bigger size.
If you happen to have a AC/DC TIG welder laying around you could fill/drill/tap in OEM size but tbh thats overkill and very time consuming.

EDIT: ignore #2 looks like you can't fit a larger bolt on the tensioner side of things.
 
I ordered part number 13556-50010. Gonna take a week to make it out here from the mainland. Does anyone know the size or thread pattern of that bolt so I can go about acquiring the right tap? Or how I could find out without having the bolt in hand?
 
I think you need a helicoil or timesert. You're not trying hard enough in the garage until you've gotten yourself into a situation where you need a helicoil or two, haha.

The threads in the hole look to be gone. The bolt picture shows (I think) aluminum material in the threads of the bolt. I think you bolt is fine (you should still use a new one) and the aluminum in the hole gave way. It would be extremely unlikely/impossible to strip steel threads out on an aluminum hole. Steel is much stronger.

I assume you have a Home Depot. At Home Depot, they have a wide array of bolts and even taps and dies. I believe that is an M8 or M10, but if it's really big it might be M12. Generally, Toyota motors will only contain those bolt sizes and only the fine thread JIS thread. Go to home depot with your stripped bolt and see if you can match the size and thread to one of their example thread plates or to the random bolts in the special hardware trays.

A good tap and die set is a good investment if you're going to do home mechanic work. You'll need it more than once.

I have this: https://www.amazon.com/GearWrench-82812-Piece-Large-Combination/dp/B001GMVA64/?tag=ihco-20

But this would also work: https://www.amazon.com/GearWrench-82812-Piece-Large-Combination/dp/B001GMVA64/?tag=ihco-20

The tap and dies won't fix your hole in this case, but you could clean up that bolt.

Here's a helicoil set: Amazon.com: Helicoil 5543-10 M10 x 1.25 Metric Fine Thread Repair Kit: Home Improvement


Be careful fixing this. It's kinda like surgery. You can fix it, but you could also makes things a whole lot worse if you don't know what you're doing.
 
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suprarx7nut said:
I think you need a helicoil or timesert. You're not trying hard enough in the garage until you've gotten yourself into a situation where you need a helicoil or two, haha.

The threads in the hole look to be gone. The bolt picture shows (I think) aluminum material in the threads of the bolt. I think you bolt is fine (you should still use a new one) and the aluminum in the hole gave way. It would be extremely unlikely/impossible to strip steel threads out on an aluminum hole. Steel is much stronger.

I assume you have a Home Depot. At Home Depot, they have a wide array of bolts and even taps and dies. I believe that is an M8 or M10, but if it's really big it might be M12. Generally, Toyota motors will only contain those bolt sizes and only the fine thread. Go to home depot with your stripped bolt and see if you can match the size and thread to one of their example thread plates or to the random bolts in the special hardware trays.

A good tap and die set is a good investment if you're going to do home mechanic work. You'll need it more than once.

I have this: https://www.amazon.com/GearWrench-82812-Piece-Large-Combination/dp/B001GMVA64/?tag=ihco-20

But this would also work: https://www.amazon.com/GearWrench-82812-Piece-Large-Combination/dp/B001GMVA64/?tag=ihco-20

The tap and dies won't fix your hole in this case, but you could clean up that bolt.

Here's a helicoil set: Amazon.com: Helicoil 5543-10 M10 x 1.25 Metric Fine Thread Repair Kit: Home Improvement


Be careful fixing this. It's kinda like surgery. You can fix it, but you could also makes things a whole lot worse if you don't know what you're doing.
Click to expand...
Awesome thanks for the tips. I think you’re right about the bolt being ok but the hole internals being flat. I’ll bring the Bolt to Home Depot tomorrow and figure out the size and get the right helicoil kit. I think I could get away with reusing the bolt but I already ordered the new one, might as well wait for it to make sure it’s done right.
 
I was skeptical of helicoils at first but they are effective and easy to use provided you can access the hole. We’ve used them on old boat motors several times - i’m a believer!
 
This exact thing happened to me except it happened when I was removing the tensioner. The threads came out of the hole with the bolt. I tapped and helicoiled it. Been great for 32k miles so far.

I have the details here in my build thread...

Hokie LX said:
...

Everything was going great until I went to take out the timing belt pulley tensioner and the threads came out with the bolt. So I got to say some of my favorite 4 letter words and got to do this...


Tapped and put a helicoil in and it's as good as new!
Click to expand...
 
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I'd use a thread chase rather than tap, if available.

If I get time. I'll see if I've the oil pump housing, and see which thread chase size fits. But you can just match up to bolt.
004 (2).webp
 
2001LC said:
I'd use a thread chase rather than tap, if available.

If I get time. I'll see if I've the oil pump housing, and see which thread chase size fits. But you can just match up to bolt.
View attachment 2233768
Click to expand...
What’s the difference?
Never mind. Google solved it. Should I try the chase first then if that doesn’t work use the helicoil kit?
 
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mfox808 said:
What’s the difference?
Never mind. Google solved it. Should I try the chase first then if that doesn’t work use the helicoil kit?
Click to expand...

Chase is a great first option if you have threads to work with. It sounds/looks like you might not. If you can get a chase, go for it. If not, I wouldn't fret it too much since it appears most the aluminum thread has escaped the engine and found a new home on that bolt. ;)
 
Worth a shot. But not likely going to work, if threads are indeed stripped.

Clean hole, cover chase in grease and give it a try..
10X 1.25 mm chase threaded in by hand very nicely.
IMG_4924.JPEG
IMG_4925.JPEG
 
2001LC said:
I'd use a thread chase rather than tap, if available.

If I get time. I'll see if I've the oil pump housing, and see which thread chase size fits. But you can just match up to bolt.
View attachment 2233768
Click to expand...


^^^^^

Yes Sir,

If you work very much on your own vehicle (or others) a Thread Chasing Kit is an indispensable tool. I have pretty much the same set as yours and it has come in handy quite a few times.

Thrd Chase1.jpg

Thrd Chase2.jpg
 
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After wasting all but 3 of the inserts, I was able to get one all the way in! Thanks for all the help. To anyone reading this in the future make sure you also get the drill bit specified on the helicoil package (seems obvious I know) but I ordered online and didn’t know a drill bit was needed and had to make another trip to the store to get one. I was lucky they had the right size.
 
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