Camshaft Bolt Coming Loose After Perrin Pulley Install
 

I installed the Perrin pulley about one month ago. This afternoon I heard a chirping sound coming from under the hood. When I looked at the pulley the crankshaft bolt was slightly wobbly. When I installed the pulley the first time I followed the directions exactly. Today I tightened it again to the recommended lb ft and even a little more this time. Has this happened to anyone else? Anyone have any suggestions in case the camshaft bolt comes loose again?

I assume you mean crankshaft bolt. Torque is all it should need unless the threads got messed up with the switch.

You're right, I did mean the crankshaft bolt. I hand threaded the crank bolt in as much as I could until I needed to use my torque wrench. I didn't feel any issues with the bolt while I was tightening it.

Loctite?

Given the torque procedure and Perrin's instructions it seems like this bolt is torque to yield. If it's coming loose I'd replace it ASAP. Maybe talk to Perrin and get them to measure the bolts height down to the thousands of an inch and compare that to yours if you have the means. Otherwise, I'd be at the dealership tomorrow.

Damn thats scary. You're lucky you caught it before the bolt actually came out, that could have been pretty bad i'd imagine.

I ordered one of the pulleys, and now im scared lol. On previous cars i've used loctite on the threads, and put a little grease on the dowel. The pulleys on past cars never had instructions :(... curious to see how the Perrin pulley instructions go.

And I hope that your car is ok!

I'm confused. How loose was the bolt? Were you able to easily turn it with/without the wrench?
The wobble you saw could have easily been the normal vibrations of the engine.

Be very careful with this- It's easy to ruin a crank this way.

probably the scariest thread iv read all day

Yeah i will be checking mine tomorrow.

Yup I will also be checking mine tomorrow.

To the OP I would suggest going to the dealership website and ask to order a new one. They will most likely send you a diagram via email of the engine with a part numbers. Pick the corresponding one and order. Personally, I would never use loctite in that area.

Did it come loose again after you re-torqued it?

I guess I'll get some loctite before installing mine.

The bolt was still tight but I was able to turn it 3 or 4 times until it was fully retorqued. Once I retightened the bolt the bolt head did not wobble and the squeaking/chirping noise stopped. I haven't driven it more than 3 miles since then. However when the bolt was slightly loose the engine didn't feel like it was operating any differently. I am also unsure as to how long it was loose but it couldn't have been long at all since I didn't hear the squeaking/chirping until tonight. I will definitely be ordering a new crankshaft bolt tomorrow. I will be checking the bolt constantly until the new bolt is ordered/installed.

Is it possible that the crankshaft bolt was very overtightened and thus stretched out when it was installed at the factory? I only ask because it was definitely torqued to over 150 ft lbs because that is as high as my torque wrench goes up to and it took more torque than that to break it loose when I installed the pulley. Anyone have any thoughts?

You should probably edited the title to crankshaft bolt instead of camshaft bolt because some people might get scared that this kind of thing could happen.

What you coulf do since youve retightened the bolt, get the car to running temprature, loosen the bolt, drop it in room temperature water,dry, then retighten, this way you can effectively get the bolt tighter a few lbft due to thermal expansion of the threads and the bolt being unexpanded by the heat :)

Some bolts are designed this way. These are the 'torque to yield' bolts that Calum mentioned.

If that is what the crank bolt is, that means it is a single use/disposable bolt.

I would want 100% confirmation on what this bolt is before doing this mod.

I checked mine with a torque wrench this morning. After more than 2,000 miles it was still torqued to spec.

When is the last time your torque wrench was calibrated? Maybe you didn't tighten it nearly as tight as you think you did.

Just checked mine today as well, still locked on tight. I suspect an out of spec bolt, or it wasn't torqued on properly to begin with (not blaming the OP, his torque wrench could've been calibrated incorrectly).

I would make your way to a Toyota/Subaru dealership (that you don't plan on getting warranty work from :P) and get a new bolt.

In university for mechanical engineering, our mech design prof would always say to use the floating test. If you take a bolt out of something, put it in a bucket of water... if it floats it's good to reuse!

;)

I'd hate to buy new wheel bolts every time I had to take a wheel off! ;)

damnnnnn,you was lucky my friend.

200 miles since I installed mine and it's still torqued to spec. I will be monitoring it.

didn't read the whole thread but just an idea, when was the last time your torque wrench was calibrated?

A general rule is to not use torque wrenches to remove bolts, only to tighten them. It could damage the wrenches.