27 replies to this topic

[robbie-woods]

tried to replace my thermostat today i have the one without the sandwich plate, the bolt was a bit rusted and snapped when i tried to undo it, it snapped at the top of the thermostat so will have alot showing when i take the thermostat off. whats the best way to get the snapped bolt out??

[Cooperman]

Weld a nut onto the stub and the heat may release the stub. If it doesn't, you need to cut the stub off flush with the head, drill & Heli-Coil the hole and then all is OK again.

[The Otter]

I had this problem a while back, what I did was find two nuts with the same thread as the bolt, screwed them on to what's left of the snapped bolt (if you can) and then when you undo the bottom nut, it sort of locks on to the top one and you can use a spanner on that bottom nut to undo the snapped bolt (f that all makes sense). I don't know if this method is frowned upon at all, as I suppose it could just snap again, but hey, it worked for me.

Of course you'll need to get another thermostat bolt to replace the broken one as well, don't want to get it out and not have another one to go in, but that goes without saying really.

Sven.

[robbie-woods]

okay is there no chance i can get a pair of grips on it? dont own a welder is all

[Twisty]

i would go with the two nut option as stated above by J322 put the first nut on then tighten the second nut down on top of the lower nut and undo from the lower nut and this will unwind the stud from the block.

You can also use some penetrating fluid or heat if its being a bit stubborn

good luck

[Cooperman]

If it sheared it must be well corroded into the thread. You can try grips, or even a stud extractor, but it may well just shear off lower down. Drilling and heli-Coiling is the real solution. Thread is 5/16" UNC and you can buy Heli-Coli kits, which include the drill and tap, from Namrick Ltd. by mail order.

[robbie-woods]

ahh okay will there be and thread left then as ive got the studs and not the bolts i looks like is was just the bolt that was rusted which is why it snapped

[AndyMiniMad.]

If you gat a set of mole grips onto whats left of the stud/bolt, then heat the block with a paint stripper or hairdryer, Wiggle the stud back and forth and maybe it will come loose.. But only go 1/4 turn at a time back and forth, spraying a decent penetrating fluid at it all the time... It may come out or it may snap again but you wont be any worse off than you are now.

Edited by AndyMiniMad., 24 October 2011 - 08:18 PM.

[robbie-woods]

cheers mate. whats rest of the bolt looks quite clean and the engine was rebuilt about 6 months ago so hopefully will have a bit of luck and it comes off

[AndyMiniMad.]

Just before you start wiggling...With the block warm,,,whack the top of the stud with a hammer...sounds strange but it may shock the bolt enough to loosen the threads..

[robbie-woods]

ahh okay buddy cheers. is it worth running the car for a while first so the block gets quite warm then undo it all, i know it will be bloody hot but will that be better than just a hair dryer

[AndyMiniMad.]

you would be surprised how hot you can get things with a hairdryer...But running the car up for a few mins will do the same job...Be prepared to get things wet though. the water punp will still be trying to circulate the fluids..

[lapider]

i had this exact problem i took the whole thermostat casing and remaining bolts out then dropped a bit of heat proof board around the surrounding leads and delicate bits. then i used a blow torch then WD40 at regular intervals then get a tight connection with the grips and keep on wiggling it can take quite a while when i did it first time with the engine in the car it took 30 mins then i removed a stud from a spare head and that took like 5 mins. watch out the WD40 may catch every now and then if you put to much on and put the torch on it, but it is relatively easy to blow out.

Edited by lapider, 24 October 2011 - 09:07 PM.

[charliedurrant]

I can't think of a more annoying problem than a snapped bolt or stud. A five minute is now an hour!

I recommend the following stud extractor tool combined with heat and WD40.

 stud-extractor.jpg   6.13K   2 downloads

Charlie

[Mattster]

I had the same problem recently. I got a Laser Tools 1/2 drive stud extractor, as Charlie Durrant suggests above. I didn't need heat or WD40, it came straight out...