Changing Thermostat, problems with bolt

[Speckled wood]

Have tried to change the thermostat on my 1.3L Cannot undo bolt nearest engine mounting, tried WD40 but coming to stage where socket is slipping off bolt, any ideas?

Cheers

SW

[Simon]

This is a well known problem caused by bi-metallic corrosion between the steel bolt and the aluminium alloy stat housing casting. There's a few ways to rectify this problem but the one that has always worked for me involves sawing down the stat housing alongside the stuck bolt, effectively riuning it and allowing the remains, along with the bolt to be twisted/unscrewed off. Obviously another housing and bolt/s will be needed but if you are stuck then this method does work. Minimise the problem occuring next time by coating the bolts in copper based grease.

[Monty O]

Have you tried using a quality 6-point socket?

I had similar problem, got an impact socket off ebay for a quid, much better!

[MCi Automotive]

As Monty O says, something like Snap-on's flank drive should reduce rounding off.

[Jeff Turbo]

If you invest in a quality socket set, most bolts don't shear. Try plus gas aswell, that's excellent stuff

[E_T_V]

6 sided socket and an impact gun help but they can be impossible to remove sometimes. Use LOTS of grease when you replace it.

[Liam]

Agreed, an impact socket makes all the difference.

[maestro vans]

Have done a number of these over the years....Here's what to do
I seem to remember its a 11mm bolt. Apply liberal amounts of WD40 or plus gas .A plasticine funnel madw around the bolt filll with WD40 or plus gas and leave over night. Place 11mm ring end of spanner on bolt preferably a six sided one Now whilst maintaining a pressure in the undo direction. Get an assistant to provide continual light to moderate blows to the top of the bolt, which will protrude slightly above the ring spanner. this is in effect the same as an impact wrench but will not shear the bolt because you will have the feel of how much pressure you are applying, unlike the impact wrench which will shear the bolt. Once out make sure you give the threads and hole a good clean out. Apply plenty of coppaslip or grease to the bolts when reassembling, This stops the indifferent metals corroding again.
Good Luck....Let us know how you get on.


Maestro Vans

[bmcecosse]

Apply heat with a gas blow torch. WD40 is NOT a release oil - use proper stuff. If all else fails, yes you need to break or saw the cover. Before refitting - run a drill through the holes to ease them out slightly - and apply lashings of grease/copperslip on the mounting bolts/studs.