Stubborn crankshaft pulley bolt - any tips?

mathewjamesnewton · 2013-05-11T18:05:23+00:00

I'm changing the cambelt on my wife's 2002 1.25L Fiesta, or at least trying to as I haven't even got to the fun bit yet... The crankshaft pulley bolt is proving to be a right pain. I just can't shif t it. I've got one of those 12v impact wrenches which, up until now, has be en surprisingly effective at loosening the most stubborn nuts/bolts on both our cars which are both 10+ years old so plenty of time and opportunity fo r parts to weld themselves together. I just seem to be getting nowhere with this so wondered if anyone can offer any advice? I'm bracing the crankshaft pulley with a wedged-in sprocket ho lding tool (Laser 2869) and so I'm confident I'm getting maximum impact thr ough by not allowing the pulley to turn. Out of sheer frustration I even tr ied the breaker-bar-and-brief-crank-with-the-starter trick but that didn't work either. I only tried twice as I wasn't comfortable with that method. Do you think a flywheel locking tool (Laser 4275?) might give a bit more st ability with locking the engine than my sprocket tool can so I can then go at it again with the impact wrench or ever-increasing lengths of breaker ba r + extensions? I am reluctant to throw the towel in and take it to a garage, not least giv en all the necessary bits are off the engine now (why didn't I try the bolt first as now I've got the 'rebuild of shame'!), but also because I've boug ht the necessary timing tools (Laser 4347) and have spent a fair bit of tim e reading up and understanding the theory that to give all that up now woul d be a real let down. I'm hoping a beer and a call for some advice might be all that's required s o if you can oblige it'd be greatly appreciated... Mathew

May 11, 2013 44 Replies

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Mathew Newton 13 years ago

I have now! :-)

I finished the job this morning and all went well.

When torquing up the crank bolt to 40Nm + 90deg I was curious as to how tig ht it was going during the angle tightening so I continued to use the torqu e wrench after the initial 40Nm and it max'd out at 200 Nm / 150 lbft at ab out 45 degrees. Switching to the 2' breaker bar finished it off nicely.

All in all it was a nice introduction to cambelt changes for me and there w ere enough hurdles to give me the confidence to do more now!

Thanks everyone for the help, particularly MrCheerful who stayed for the du ration!

One final question though; how many miles to you have to drive before you s top worrying if the bolts are going to loosen?! ;-)

Mathew

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Mrcheerful 13 years ago

how long is the piece of string I saw last week?

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Peter Hill 13 years ago

I had an oil filter loosen and wind off 2 turns after 4K miles. Hitting the limiter hard in 2nd was probably a large part of the cause.

Angle tightened bolts don't come undone and don't need a re-check at a short interval after fitting. You have put a stretch in the bolt, pitch x angle / 360. If the bolt isn't replaced then they calculated the stretch to be elastic and the bolt returns to it's original length when undone. Usually there is "replace if length exceeds xxx.xx mm" in the workshop manual. Other angle tightened bolts are taken past yield and will have a permanent set, these should always be replaced.

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Mathew Newton 13 years ago

This one was a 'must not reuse' bolt.

I must say, it did kind of feel 'different' to a normal bolt insofar that i t was very smooth to rotate, despite the high torque. Perhaps I was imagini ng it because I knew it was stretching, but then thinking about it if it is stretching more than a 'normal' bolt then it stands to reason there's a bi t more give.

Or perhaps that's a 2' breaker bar for you!

Mathew

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