dreadedhead

ok so i was changing the thermostat in my 92 xj, after putting the housing back on a snapped the head of the lower bolt off...i was able to pull the rad and drill in with a tap..when i turned the tap i snapped that off into the bolt that i had just drilled. i redrilled the bolt with a bigger tap and was able to extract the bolt. i did not relieze it is a oem spec bolt for the housing and went down to lordco. the dude there matched the head and threads but i was unaware that the bolt i got from him was a quarter inch too long. i cranked the new one in and at the final turn heard a cracking sound. i took the bolt out and saw a hairline crack on the inside of the cylinder head. the crack starts at the and then v's out like a crows foot. i tried to use a jb weld on it but the leak still remains. it looks as thou the leak is coming through from the bolt (went and got a oem from a pullapart). im thinking that when i put in the bigger extracter it might have expanded the the threads where the bolt goes so there is still coolant leaking through...can this be machined or do i have to replace it? if so then how hard is the job? should i just bite the bullet and get a mechanic to fix it for something ridiculous like $1,000.00. this has been a 10 minute job turned into a nightmare please help.
thanks,
Dreadedhead in B.C.

cherokee4meplz

if it's coming out of the bolt hole behind the head of the bolt, you may have to get creative and put some permatex on it. if that is not doing it step up to a copper washer behind the bolt head and see if that helps. Silicone/ RTV may just be enough to save you. Coat the last threads closest to the head and the back of the head.

dreadedhead

ok so i have done this...the sealant did not help 1 bit...the copper washer might do the trick...but there is a built in washer in the bolt...

jpdocdave

your head is junk, and judging from you thermostat experience, take it to a mechanic

you just cost yourself a grand by trying to save less than a hundred bux.

dreadedhead

ya thanks....i guess..doesnt really help thou.

jpdocdave

what help do you need? there is no way to repair or seal the crack in the head, and like i said, judging from your post, it would not be a good idea to replace the head yourself.

a used head, gaskets and labor is gonna be probably a little over a grand.

cherokee4meplz

before you go buying a new head why not try to tap the leaking hole a couple sizes bigger and use the appropriate bolt for the threads of that tap? Once it's sealed it's good as new- seal it.

BuckB91XJ

Dreaded, take this as a learning experience. I know it sucks. It's going to cost you a couple hundred bucks even for a used JY head.
I cannnot stress it enough. Always torque everything with a torque wrench. The torque on those waterneck bolts is very little. Nowhere near enough for you to have snapped the bolt off. You can do this. I bet you can even swap out the head but, you need to get yourself a Haynes Manual, Chiltons or FSM. My Haynes has step by step directions for changing a T-stat and changing a head. If you can read, and I'm sure you can, you can do basic maintenance on your Jeep. So, my message is this. Don't give in because you made a mistake. Definitley don't take your Jeep to a mechanic when you can fix it yourself. Keep on wrencjing and keep on learning!!

jpdocdave

post a pic of it. it isn't gonna be sealable. its cracked, the bolt he ran in was too long and cracked the head at the back of the bolt hole, thats how i read his first post. he's tried more than once to seal it already, and if by some miracle it seals, it will not be right or last, the head is still cracked.

BuckB91XJ

I wasn't recommending trying to seal the head. I was saying replace the head himself and follow a manaul and do it right. Don't have somebody do it for him just because he goofed up once. Man, I've lost count of the dumb mistakes I've made over the years tinkering on everything from bicycles to musclecars to 4x4s. Just learn something each time and pay the consequences and move on.

jpdocdave

ya, i was still typing when you posted. and i agree with what you're saying. i became a mechanic cuz i wanted to fix my stuff, and didn't want anyone else to. but you have to have a natural aptitude for it. and if you don't, after that thermostat fiasco, jumping into replacing the head might not be a good idea. snapping small bolts, breaking extractors, and then installing the wrong bolt and cracking the head is pretty bad. you have to know how bolts feel, you have to have a feel for a wrench, thats all i'm saying. the head is now junk, if that gets screwed up the block could be next. and lets face it, thermostat is about the most remedial repair, and cylinder head is slightly advanced.

maybe get a buddy that might have some more experience to help out. i'm all for learning and diy, and we can help here to, but its a good lesson in how things can go wrong.