What is loctite?

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lazza
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What is loctite?

Post by lazza »

Hi

Haynes manual referes to using "Loctite" when replacing the Crankshaft pulley bolt....

a. What is it? can i get it in Spain? if not what other product is equivalent?
b. Do i have to use it? Or can i just put the bolt back on?

Thanks as ever

Larry

ps apologies for double posting, last one seemed to go into blogs ?
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Post by hobblerian »

Loctite is a thread retainer or sealant, it is used to prevent bolts from working loose after fitting. As far as i'm aware loctite is available all over the world, probably loctite 242 would be ample. You just need to coat the first 3-4 threads before winding the bolt in, you need to don't use too much.

There are other manufacturers including 3M Rite-lok.

I would definitely use it as the last thing you want is your pulley bolts working loose with vibration.
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Post by Old-Guy »

Haynes are a bit naughty. "Loctite" is a proprietary brand name for a range of industrial adhesives and sealants. Like "Hoover", the name has become synonymous with the type of product, first and biggest.

Any reputable thread locking compound will do the job.

You REALLY do need to use thread-lock and a NEW bolt. Crank-shaft pulley retaining bolts on the XUD engines have a bad reputation for two things:

- working loose (if not locked).
- snapping like a rotten carrot if re-used.

The brute force that has to used to get them undone often weakens the bolt which then shears - either when being done up, or later.

A new bolt is less than £2 in the UK.
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Post by lazza »

right thanks for the warnings! Any chance of it shearing when trying to take it off???

The reason I want to change it is that it looks like it has been damaged at some stage and a bit wonkey and has a chip in it. However, the auxiliary drive belt is not affected really by it and functions correctly.

I will be renewing that this week, hence why I thought to change the pulley too.

If there is this risk, as I have no decent drill etc, I may leave that job... until i have means of removing a sheared bolt if necessary!

Thanks
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Post by citroenxm »

Theres a even better damage done when it comes undone without notice... the pully comes away and rattles away at the keyway... which in turn damages the Crank shaft!!! It can also cause the bolt to JAM in the crank, and as Old-Guy says snap when trying to remove it!!

Ive had this on 2 Xantias and a 306! I always use loctite now, with a bar.. although strnagely, Ive never had a bolt snap when NOT abused and fitted correctly, or removed...

Old-Guy, Could the bolts you've experianced have been abused by previous owners?? Thats a new one on me, they look VERY strong bolts to me..

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Post by Xaccers »

When going to remove the crank bolt, get the engine nice and warm as it can help weaken the locktite that's factory fitted.
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Post by MikeT »

I think Citroen advise you don't re-use the bolts (aren't they stretch type?) and their new ones come with threadlock already applied. But they are very substantial bolts and I'd like to meet the man that can shear one as it takes all my strength just to get them undone!
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Post by dieseldoggy »

you can even use nail varish/oil based paint ie gloss or eggshell plus few other things that escape me? if you're stuck for it. used to know an old boy when was in garage that knew every trick in the book? could always pull an ace out of his sleeve anytime you was stuck.used to tell me lots of little tricks that were realy usefull esp if you was out in middle of no where!

the thing with stretch bolts is in the material? as when you torque them up the grain goes one way and gets set then when you undo you alter the structure of the steel which then shears.have a look on net about it as to long to go on about here.but hardening and steel tensile strength is quite an acute science.
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Post by Old-Guy »

I've never had a bolt shear because I've only taken one pulley off! However, I was warned by a mechanic who has some experience of "old" Berlingo vans (XUD9 engines). He has had to fix the result of crank-shaft bolt failures and warned me to use a new bolt every time and tighten it correctly!

When a 'stretch bolt' is tightened correctly the first time, it is permanently stretched and thus slightly weakened. What happens if the bolt is re-used is fairly complicated depending on what further stresses occurred in breaking the thread-lock and then in re-tightening. And let's not forget that a used bolt CANNOT be tightened correctly since it has already been stretched.

Even if the rather brutal technique of a 'flick' on the starter has to be used to get a bolt undone, I don't believe there's a serious risk of a single-use bolt breaking.
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Post by dnsey »

you can even use nail varish/oil based paint ie gloss or eggshell plus few other things that escape me? if you're stuck for it.
I agree that this will be OK in some non-critical situations, where the risk is just from vibration etc, and have used it myself occasionally, but I don't think I'd risk it on a crank bolt.
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Post by myglaren »

Ross_K wrote:eBay, Loctite
Ross' link lifted from the duplicate thread.
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Post by Pleiades »

Hi All.

As stated already, loctite is a brand name and loctite comes in all sorts of varietys from super glue to high strength retainer.

The loctite branding is identified by numbers, one that we use a lot is Loctite 603 retaining compound, this can be used on the outside of seals such as camshaft, crankshaft and diff seals, it is not allways needed but it is a belt and braces approach and helps to fill any imperfections or scratches in the seal seating area.

Loctite on bolts is a bit like using nylock nuts, it's just to stop them from coming off on their own.

I have never heard of the nail varnish trick, but I guess that anything that sets will work.

Top Tip from the potting shed....

If you have loctite on a nut and it will not budge, then rub it with a bar of soap, then heat it up, the soap will turn black at 300 degrees and also the loctite will give up it's strength at 300 degrees.

This system should not be used where seals can get damaged by the heat, unless of course they are being replaced.

Regards
Martin.
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