drilling bolts out

[rpcee]

Not really maestro specific, but I just attempted to undo the bolts for the thermostat housing and sheared one bolt and the other will shear if I apply the same force. So (a) how much smaller a drillbit do I use to drill it out, (b) Presumably someone somewhere has the data for all the bolt specifications for a maestro (there's plenty others need replacing even though they came out), and (c) is there something I can do to keep them from seizing in the future.

Thanks.

[B18 GPC]

Oh the fun.. get get this on new cars.. have that silly screw to hold the disk on .. great.. they rust in ..

use a drill bit the size of the core of the screw...

So if its an allen key , use a bit that just turns in the head of it.. if not . go small and get bigger until the unit falls off. Weather it goes right or not is good or bad lack..

good luck :thumbup: :o :thumbup:

[Miracle maestro]

You really need a set of special set of tools for the task.(can't remember name)
But these have a left-hand thread that grips the inside of the hole you drill and unscrews the broken bolt.

But be careful not to damage the thread with the drill.
Carefully centre punch the middle as accurate as possible, drill the smallest hole possible that the tools will fit in.

I know its not an easy task- best of luck.

regards
Darren.

[metro]

You really need a set of special set of tools for the task.(can't remember name)
But these have a left-hand thread that grips the inside of the hole you drill and unscrews the broken bolt.


I believe you are thinking of easi-outs. In my experience, if a bolt has sheared, easi-outs will not touch it either. You just end up with a broken stud that now has a broken easi out stuck in it.

[mgdavid]

firstly you needed to soak the bolts in releasing agent (Plus-Gas or WD40 ) for a couple of days before trying to remove. If the break is just below the bolt head, best method is to remove the thermo housing in sections by hacksawing it to pieces, leaving the long stubs of bolts sticking up, then heat them up with a plumbers blowtorch and remove with 2 pairs of molegrips. Prevent it happening again by liberal use of Coppaslip on the bolts and threads. (I have spare thermo housings if you need one).

[E_T_V]

Yup I'd agree with Davids suggestions. Sometimes it is possible to remove the thermostat housing in one piece it depends on how corroded it is. Copper grease is definatly your friend when reassembling. Coat all of the bot in grease so that it doesn't corrode to the thermostat housing again (which is probably the cause of the sheared bolt this time).

[Slaphead]

firstly you needed to soak the bolts in releasing agent (Plus-Gas or WD40 ) for a couple of days before trying to remove. If the break is just below the bolt head, best method is to remove the thermo housing in sections by hacksawing it to pieces, leaving the long stubs of bolts sticking up, then heat them up with a plumbers blowtorch and remove with 2 pairs of molegrips. Prevent it happening again by liberal use of Coppaslip on the bolts and threads. (I have spare thermo housings if you need one).

Hi David,
I need a housing for a 1600 Maestro,if you have one? (The one with the outlet/inlet on top,that the small pipe from the expansion tank goes on).

Thanks,
Craig.

[Rich]

If this is a 1.3 then those stat bolts are a nightmare. I think I remember the bolts being a UNC thread. Its certainly not metric. New bolts are/were available from Rover recently, but there about £1.50 or somthing like that each.

As for getting the studs out, my way would be to find out the size/thread of the bolts. If no one knows on here, get some new ones, and use them to find out the thread size. Drill the old bolts out as described on here, and try not to hit the original thread. Once you get the hole to its tapping size, you can re cut the thread with a tap using first cut and plug taps, which will remove all the rest of the old bolt, and clean the threads out.

The only way to stop this happening is to loosen then tighten up the bolts every now and again, to keep them moving. When re assembling the stat, use loads of copper slip grease, and change, or at least remove and replace the stat and housing every 10k miles or so. This will stop it seizing up again!

HTH Rich

[rpcee]

Thanks for all your help - I'll give it a go. I think I'll be doing the head gasket at some point too so maybe I'll group it all together (once the welder's told me whether it's feasible to get it roadworthy etc etc).

[rpcee]

well, long time no see, but my MG is just back from the welders and MOT, it's now for the first time fully legal for the next year but with the same temp. gauge problems. Is the offer of the thermostat housing still available? Not a hint of a maestro or montego at the local scrapyard, and I still have the sheared bolt problem, so if anyone has such a construct I'd be happy to take it off their hands.

Thanks, Richard.