Broke my bolts that go to my thermostat housing. What size replacement bolts?

[dpuma8]

I ran a search on multiple sites and I see that the size mentioned is M8x1.25 but what about the length of the bolts? I am asking because I lost the bolts that fasten the thermostat housing to the head.

 

Any idea?

Edited April 17, 2014 by dpuma8

[Phantom]

You need sufficient length to get through the thermostat housing and at least 2X the diameter of the bolt into the engine block. Confirm by inserting a pencil into the bolt holes and measuring their depth. You want the bolts to end about 5mm from the bottom of the hole. Then buy a standard length bolt that is somewhere between the 2X and ending at least 5mm from the bottom of the whole. This isn't that hard.

Also - metric bolts come in various hardness. You'll want the 8.8, not the 12.9. The 12.9 is too hard and you will have to put too much torque into it to get it to properly stretch and that will risk stripping the threads in your block.

[NewZed]

Take the housing to the hardware store and stick a bunch of M8 x 1.25 bolts through the hole until one looks right.  Check the thread pitch and size in the holes on top of the housing.  Torque to factory spec.