I replaced my leaking radiator today, all good and no issues there. But when replacing my thermostat, the thermostat housing top bolt snapped inside my cylinder head when I tightened the bolt. Unsure if I tightened the bolt a bit too hard or because it is old.

QUESTION FOR MY FORUM MATES: Anyone ever encountered this? Any magic fixes I don't know of? I know... most likely it's busted...

On my list was to replace the entire cylinder head with a new TUPY from Windy City or Clearwater. I have A 2001 XJ with original head and 120k miles, so perhaps now is the time to replace this too! The Xj journey continues...

Any guidance would be appreciated.

 

I would get a center punch with a pilot mark center and get a good left handed drill set start with about 1/8'' and drill out slowly then work up and it should unscrew don't get in a hurry and it shouldn't be that big a deal have done it several times!

 

They sell easy out kit that has a centering guide for the drills . I've used them at work and they will center the drill . If you cant get the old bolt out you can use a tap and cut new threads in the head and just install a new bolt .

 

Ah beautiful! Thank you. Greatly appreciated! Now I just have to find another bolt!

 

Thank you! I'm looking into the square style extractors easy out with left-hand drill bit. Thanks for the helpful info.

 

There's a new tool on the market now that has a left-hand centerdrill on one end and an extractor on the other. It's hexagonal and fits into a standard drill-driver that most people now own. From the looks of your picture, that bolt has been cracked for some time.

 

Thanks Dave, and every one for the responses! Ordered a left-hand drill set from Drill Hog and extractors from William, will receive Wednesday and give it a go then!

FOR THE BOLT: Does anyone know what material is best? Aluminum or Bronze? Is Stainless steel ok? What grade, 5 or 8?

 

Steel is fine. Use anti-sieze. Always wire wheel the threads before reinstalling.

 

Use grade 8 unless you want to snap them the next time you change a thermostat! Take both bolts up hand tight before you torque them. Otherwise you can crack the mounting flange. Also make sure the thermostat is in the recess provided for it in the housing.

 

Thanks a lot for the info! Do you know the torque specs? And bolt size? I know 5/16 x 18 - but on the forum someone said top bolt is 1 3/4" and bottom is 3/4. But my bottom I took out measures 1 ", and top bolt is broken at exactly 1 3/4" so I know there is more...

Know the exact measurements?

Appreciated!

 

The parts catalog for your year should have either the part number or the bolt size. If it's the part number you can look up the part number and possibly find an exact length.

That is, unless someone knows off the top of their head

 

Ha. Lol. Just realized it was a crazy ask! Will look it up and post here once I confirm!

 

I was surprised at how low the bolt torque was (at least on my 95).. it was in Inch/lbs and not a lot of them IIRC.

 

Good luck getting that bolt out if it's bottomed in the thread! You may have to drill it all the way thru. There's no reason in hell to use a bolt longer than 1 inch to hold a simple flange housing. That would put about 5/8" of thread into the head. More than enough to hold the pressure. The bottom bolt can be shorter because it's threaded into the water jacket and you don't want rust on the part that sticks thru. I think the specs are for a 1" and a 3/4"

 

Thanks! I foudn these specs:

The thermostat housing bolts are 1 inch and 2 1/4 inch long.
The diameter of the shaft is 5/16"
Thread pitch is 18.
Hex head uses 1/2" socket size not 13mm

I believe the torque is 13 lbs. But still have to confirm.

I ordered the bolts on EBAY here:
5/16-18 x 2-1/4 Grade 8: https://www.ebay.com/itm/262064263214
5/16-18 x 1 Grade 8: https://www.ebay.com/itm/252102719480

Will update everyone to see how it goes.