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spankyjr1, Small Engine Technician
Category: Small Engine
Satisfied Customers: 2663
Experience:  Journeyman TechnicianWorked on small to large engines for 30 yearsGas,LP,Diesel
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Hello I have a STIHL FS 250 strimmer thats worked fine

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I have a STIHL FS 250 strimmer that's worked fine for the past 4 years but now the head, containing the line, keeps falling off. Yes, I have checked and double checked that the line is threaded in the correct direction! Any help would be gratefully appreciated, thank you.

Hi Greg, my name is XXXXX XXXXX having trouble today.I will do my best to assist you in resolving your issue.

Sorry for long delay.

Are you saying the entire head is coming off or just the cover for the string?

Let me know Please.

Customer: replied 3 years ago.

Thanks for geting back. It's the entire head that's coming off.

I just used the strimmer for an hour, it worked fine, but when I shut the motor off the whole head fell off once again!



Thanks for info Greg.

This time before installing head put some blue thread lock on threads and screw head back on.
If you can wait one day for it to set up and dry completely it's best,,,,,if you can't wait use a hair drier to help speed up drying then let sit a couple hours before using.
That will keep head from coming off.
If you ever need to remove head and are having trouble getting off use a hair drier again to heat up and then it will come off.

These trimmers when they get out of balance for any reason cause heavy vibrations and loosen heads the thread lock will help keep in place.

The blue is not as strong as red but if you use red it is a lot harder to get off.
Just apply on threads and install as usual.

Customer: replied 3 years ago.

Thanks for this, Spanky.


Just a couple of points.


I normally have to take the head off several times to renew the cable, untangle it, etc. It's going to be a pain if I need to go through the procedure of using a hairdrier to remove it then reapplying and waiting for it to reset every time!


Enlarging the picture I notice the one in the blue tube is called "Threadlocker Red" and the one in the red tube is called "Threadlocker Blue"!! Confusing! How do you know which is which?


Also, because I live in France, it may be impossible to find threadlocker anyway. Is there any other remedy you could suggest? Many thanks,


Hi Greg.

You don't have to use hair drier to remove ,,,,,,it just won't spin off as easy.
It is the equivilant of,,,,, instead of just spinning a nut off after you loosen nut with a wrench,,,,,, it can be spun easlily without the wrench,,,,,when you use thread lock ,,,,,you would have to use the wrench all the way off.

You can also use non hardning pipe dope or tape to make it harder to get off.(plumers dope or plumers tape)
All you are trying to accomplish is make the threads tighter.

Blue locktite is blue in color,,,,,,,,,,,,red locktite is red in color.
Don't worry about color of tube just color of locktite.


Customer: replied 3 years ago.

Thanks Spanky, sorry to be thick but what's "plumers dope" - is it jointing compound? And "plumers tape" - is that PTFE tape ?

No problem Geg you are not bothering me.

Yes joint compound or ptfe tape will work.

Loctite works best since it's made specificly for bolts and nuts loosening up but you have to work with what you have available.

If nothing is available you can even take a hack saw blade and cut the threads in 3 spots evenly around ;ength of threads,,,then spin on and it acts like a lock nut.

Best of luck to you
spankyjr1 and other Small Engine Specialists are ready to help you
Thank you for the positive rating Greg very much appreciated.

Take care