Two broken studs, repair in Charlotte?

[BSousa]

I know this topic has been bantered around but I thought I would hope there was someone local that could suggest a shop or provide some encouragement and direction to fix this myself. The situation is:

90 YJ, 2.5

Broken off deep front exhaust manifold bolt and according to the local jeep dealership a cross threaded broken rear bolt.

Their estimate was $700.00 to repair and wouldn't even guarrante that price.

I have some limited mechanical experience and a basic compliment of tools. The haynes manual I have is pretty limited and not sure it provides adequate step by step instructions.

Thanks,
Brian

[xjandyj]

geez,,,for 700 you could get a junkyard motor with less miles....heck you could even just get a head for dirt cheap

[Shadly1]

OUCH!!!

I've seen these go gracefully with just a drill out, and I've seen these go real bad. Most often with manifold bolts, they go real bad. You're going to have to drill it out. Start with a small drill bit and go as deep as you can. Those bolts are typically an inch to an inch and a half into the block. Move up drill bit sizes until you can get a bolt removal tool in there. If it doesn't come out, drill it out bigger and use the same tool if it's tapered. If the tool isn't tapered, hopefully you bought the set. Worst case scenario... drill it out all the way, tap it and use a thread insert to bring it back down to standard bolt size.

[BSousa]

I agree with all of the above, rebuilt heads with valves run in the 200+ range from what I have been seeing. How difficult is it to tackle head removal / replacement?

[Shadly1]

I agree with all of the above, rebuilt heads with valves run in the 200+ range from what I have been seeing. How difficult is it to tackle head removal / replacement?
Not hard at all. I'm sure it would take less time than trying to extract the bolt. Make sure you have a manual handy so you can get the torque settings right.

[BSousa]

Ok, I've loaded up with barbecue and beer.. lemondade for those who don't drink, and its a head removing party ha!

[John_5657]

How did they know the one in the rear was cross threaded if it was broken? I have a helicoil in the froont exhaust hole. It was a PITA to do but I think it was easier then taking the whole head off. The front one should be easier and accessible. Of course you will have to remove the manifolds. So I would remove them try to do it and if youre successful great if not your that much closer to removing the head

[BSousa]

Thats a good question. the cross thread comment was made over the phone. I'll go pick the Jeep up tonight and understand the "real" issue. I may give this a try after all...what the heck. can't be any worse then the bmw 2002 engine I pulled and rebuilt.

[Shadly1]

can't be any worse then the bmw 2002 engine I pulled and rebuilt.HA! You don't need any help with a head swap on a Jeep...

[BSousa]

yea right... all bolts on a BMW, once you loosen them will come off by hand. Just taking off my bumpers last night left me with a new respect for crappy bolts, crappy torx bolts, and crappy rust.... maybe its a confidence thing but all i can picture is ending up with a bunch of broken studs, bolts, and a huge mess but thanks for your vote of confidence.

ps... I love my Jeeps though....:)

[BSousa]

Ok here's the update, still havn't received the Jeep back from the dealer... good things happening though, turns out that the 90 jeep had two recalls which resulted in my brake rotors being totally replaced along with doing something to my emergency brake (unknown exactly what) . I did ask about the "cross threaded rear bolt" that they described. Turned out he said there were several washers on the rear bolt so they figured it was either cross threaded, or the old bolt was broken way inside and the new one only partially screwed in, or they replaced it with an oversized bolt that was to long. I may not touch it if it works till it breaks. The front is broken off way inside supposedly. I'll check out how far and attempt to drill it out in place when it comes back. They are failing my inspection for the leaky exhaust manifold though.

[wildtyphoon]

drilling out broken studs really isnt that bad IF you have good sharp drill bits, and if you keep your drill square.

i use cobalt bits, they cut very nicely through them as long as the broken stud hasnt been heated with a torch. i always use 1/8 for a pilot and whatever size you need for the final hole, then either tap it or helicoil it.

it is VERY imporntant to keep your drill square after you start though, if you side load those drill bits, even a little it will break off in the hole then you are really screwed. (guess how i know that)

even if you are off slightly its better to finish the hole, most manifolds have a little bit wiggle room that would accomodate a slightly cockeyed bolt.

also i use the other holes to measure how deep i need to drill, and make a mark on the drill bit, that way you dont drill to deep.

really once you have done it a few times, its not so bad, id definately be drilling out broken studs before pulling the head because of them.

[Mechman71]

Yup, oil the drill bits too, before and during the procedure. Make sure you keep the drill straight at all times - if you break a bit off in the bolt, you'll be in deep kimchee. All in all, I'd pull the head and drop on a rebuilt one - send your problems in as a core.

[BSousa]

Ok, here's what I did. Pulled both the exhaust and intake manifolds. Turned out all the holes were good except for the front bottom one. The stud was broken off right inside the hole. I purchased a left hand titanium drill set along with a 3/8's bolt extractor. Center punched the stud as best as I could and drilled a little ways with the smallest drill in the set till I broke it off. No problem as it wasn't very deep, guess I got over aggressive with the drill pressure. Continued with the 3/6 which what the extractor called for. Hammered in the extractor and gave it a go. ( lots of PB the night before) Twisted very gently on the extractor thinking all the time I'm going to break this off and then I'll be in a jam. Not wanting to push it I gave up on that and went to progressivly bigger bits> Finished with the one that was slightly smaller then the inside thread diameter. After this was complete there was still some residual of the old bolt in the hole which I attempted to knock out with a small sharp punch. Most of it came out. I then chased the hole with a 3/8's tap. I would guess I have about 25 to 50% of my threads and it appears that I can torque the bolt to specifications and it holds. I looked at NAPA for something that would take up the slack and was temepted to screw the bolt in with some JB weld but decided against it. Assembled everything back together except for the throttle body, some hose and the electrical connections. Those will go on tomorrow. All the bolts appeared to torque to the spec, 23 ft-lbs. I did use a combination intake / exhaust gasket to help seal. The store guys from NAPA also recommended me to use some high temp RTV but I decided again against it. Throttle body gasket just came in, we'll see what happens tomorrow. Any thoughts or comments are welcome and appreciated on the above.

will it hold?
should I used JB weld ?
should I used the High temp rtv?
etc.... :)

Thanks all for the comments and advice. I hope I saved myself a bit of hard earned cash.

[Shadly1]

Good work. If the threads bit in, I'd leave it alone. I mean, do you really have a reason to take it off again? If so, you can deal with it then.

[Mechman71]

Woohoo! Nice save. If they all hold torque and you don't have a leak, then job well done! If the threads give out, you will probably have to helicoil the hole. chances are that it'll work fine though.

If you're going to put anything on the threads, use a small amount of thread locker on that bolt only, and you should be fine.

Again, nice save!

[John_5657]

Good Job you just saved 700 bucks. Only thing I would add is the threadlocker or lock washers. The manifold bolts have a tendancy to loosen up over time. But since you have it together already I would just leave it that way and keep an eye on it. If 6 months from now you hear an exhaust leak you will have to find which bolt is loose and tighten it down or take it out use thread locker and/or a lock washer. GOOD JOB welcome to jeep problems

[BSousa]

Throttle body back on and everything seems tight. I have a bog now when the engine heats up, sounds like its getting to rich. I'm not sure I got all the emmision hoses in back the correct positions. One particualar question is the hose that comes off the back firewall and I believe goes down to one of the two nipples on the rear , topside of the intake manifold. Does anyone have a picture of the rear of the engine showing tube locations? The book is not very clear. Thanks everyone again for your help. Heck, I even came out of the deal with a new torque wrench and one broken sears 1/2 inch drive. I'll go try sears and test their return policy :).