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Exhaust Studs??? can they be repaired


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22 replies to this topic

#1 beataru

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Posted 02 June 2007 - 04:51 PM

OKAY!!! I finnaly remembered to ask this. On my roo, I tried removing the exhaust studs with the good old 2 bolt method (which is how you are supposed to do it) but Good old aluminum in the heads decided NO WAY!!! and gave all the threads that I had in one of them.

so I made up some JB weld and pushed it up into the hole, let it cure for about a week, hehe, and drilled and tapped it.... well guess what... JBWELD STINKS, its good for somethings and not for this, A porsche tech AKA my bro inlaws co-worker said that he has had no success doing this with JBweld also, but red loctite he said is much stronger and that I should give this a try.

Now I am not one for jerryrigging if I dont have too so what I want to ask is, Can heads be welded somehow to fill the hole up with aluminum weld and then be drilled and tapped??? like has this been done before!!! I am seriously interested and I know a few welders who got TIGs, oh by the by sorry for the life story! Oh yes and I did try Heli coil and Also Threadsirts, (threadsirts are like helicoild times a million in coolness) and they worked fine but the one I need welded, has been made bigger by, yours truly!!!
If any of you remeber, I have been having exhaust leakage troubles since I even thought about making my car faster... so No its still not running even close to full boost yet, This pig has trouble getting out of its own way.... and DONT EVEN DARE TELLING ME TO GO N/A turbos Badass and once I make a stinking header for this piece, and get the turbine spooling, This things getting hot cams, ported and polished and maybe even some nice rods and pistons forged babey.... sweet jebus, I just made a big post..... :dead:

#2 Gloyale

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Posted 02 June 2007 - 06:26 PM

Tap the hole with a 7/16 tap. Drill it to size before tapping since you added JB, but in most cases you can tap the stripped hole directly. Just use lots of oil and tap it slow. Don't push once the tap bottoms or you''ll rip out you're new threads. Install a 7/16 exhaust stud with Blue locktite. Get a 7/16 nut and washer and bolt er up.

If you really want to stick to the OEM Metric size stud then the option is to drill out the hole and helicoil it. The 7/16 stud can be installed with the manifold in place, for the cost of a tap, a stud, and a nut. The helicoil kit will run you 35 bucks and you have to remove the crossover pipe to do it.(or drill out the flange holes,either is a PITA)

There is a thread about this where variations of the same method are used. Search "helicoil exhaust"

#3 brat82

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Posted 02 June 2007 - 07:40 PM

Yep...as gloyale said, if you hadn't used the jb weld, you could just tap the exsisting hole to the next size, metric,standard...doesn't matter...I've done this in a variety of situations...tap new threads, put in stud or bolt...in the exhaust systems I always use some kind of thread ease/never sieze, on the nut/bolt threads that will always be removed...which helps when its time to remove exhaust items, or the water pump threads...anything that will rust or heat weld to the block etc...

#4 beataru

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Posted 02 June 2007 - 08:01 PM

Oh belive me, I did, I retapped it with a bigger thread pitch and size, and the stupid things still ripped, and I didnt crank on them either, I just watched the pice of crap rip as I was trying to sinch up the bolts!!! AHHHHHHHH!!!! so then as a last resort I tried the JBweld, and belive me all of the JB weld is out of the hole, It all came out with the stud in one big fat clump!

#5 LPGsuperchargedBrumby

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Posted 02 June 2007 - 08:20 PM

yeah it can be welded....i had to do it on my brumby not long after i bought it......what i did was drilled out the hole as big a i was prepared to risk(don't remember size offhand...it was a about 5 years ago) then i preheated it and hit it with a mig, filled up the hole and the ground it flat with a flap disk on a 5' grinder.....then marked, drilled an taped to original thread

#6 beataru

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Posted 02 June 2007 - 08:22 PM

:clap: :clap: Sweet So you used a MIG wirefeeder and obviously you had it fitted to weld aluminum right??? So did it fill it right up or just the surface??? IM SO EXCITED AND I JUST CANT HIDE IT!!! DOOT DEE DA DA!!! I seriously thought that I was going to need to buy another set of heads, I plan on building these up to the moon just for fun... once I win a billion dollars!!!

#7 LPGsuperchargedBrumby

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Posted 02 June 2007 - 08:28 PM

:clap: :clap: Sweet So you used a MIG wirefeeder and obviously you had it fitted to weld aluminum right??? So did it fill it right up or just the surface??? IM SO EXCITED AND I JUST CANT HIDE IT!!! DOOT DEE DA DA!!! I seriously thought that I was going to need to buy another set of heads, I plan on building these up to the moon just for fun... once I win a billion dollars!!!


i filled it right up......thats why you need the bigger hole so you can get it to weld starting right at the bottom and build up from there....too small a hole and it'll arc onto the side's and could leave a hole at the bottom of the hole

#8 beataru

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Posted 02 June 2007 - 08:49 PM

Alright thanks man! as soon as something Breaks on my engine... which i hope is later than sooner, I will do this and hopefully get my blueroo running with maximum boost!!!

#9 Gloyale

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Posted 03 June 2007 - 12:33 AM

Oh belive me, I did, I retapped it with a bigger thread pitch and size, and the stupid things still ripped, and I didnt crank on them either, I just watched the pice of crap rip as I was trying to sinch up the bolts!!! AHHHHHHHH!!!!


So if you did it all right and it ripped out, why would filling it up with aluminum and retapping help? Something must not have been done right. Rather I suggest trying again with the tap. And if need be, using a helicoil kit. It will be stronger than the original if done right

With good gaskets and properly seated studs, tightening to torque will work. There are to many people who have had no problem fixing this for it not to be true. Sure you used a 7/16 tap with either fine or course thread to match the studs you used? If it's stripped out to muchfor that move up to M12.might be harder to find studs but you could cut bolts or just use bolts:( How tight is "not cranked"? 19-22 ft-lbs is the spec.And are you using new gaskets?

#10 grossgary

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Posted 04 June 2007 - 08:02 AM

i can't imagine resorting to welding to fix this. helicoils work every time if done right and so does drilling and tapping. figure out how big the hole is and use the appropriate sized tap/bolt. use your drill bits to "measure" the hole, then tap accordingly.

this is hard to imagine, but if the hole is really huge, then tap it for some steel threaded rod and insert that flush to the block with red locktite. then drill and tap inside that steel rod whatever you can get to fit. 8x1.25 will definitely work as you can do that inside the stock studs...so if this is as bad as you say it is, and you have to go this route you can do this steel rod method and probably drill and tap to the original 10x1.25.

#11 beataru

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Posted 04 June 2007 - 01:54 PM

I prefer the original Type of metal to be used as my threaded piece, I did do Helicoils, and Threadsirts, which are 1000000 times better than heli-coil the metal on my heads seems to be soft... I dont know, I do know that it will be fixed as soon as the engine needs to come out of it cave!!!

#12 grossgary

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Posted 04 June 2007 - 02:03 PM

a machine shop can make a threaded insert for you as well. any material, size, shape you want.

#13 Gloyale

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Posted 04 June 2007 - 02:03 PM

I prefer the original Type of metal to be used as my threaded piece, I did do Helicoils, and Threadsirts, which are 1000000 times better than heli-coil the metal on my heads seems to be soft... I dont know, I do know that it will be fixed as soon as the engine needs to come out of it cave!!!


Whatever man. There is no need to weld it. The helicoil will be stronger than the original metal. I'm betting on causing more damage than fixing by welding. Aluminum welding is very tricky and if you don't know what you're doing it's easy to melt away what you were trying to fix. Espescially with a cheap wirefed Mig unit.

We've offered valid solutions other than wleding that will work, but if you want to destroy your head go for it.

#14 grossgary

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Posted 04 June 2007 - 02:07 PM

I did do Helicoils, and Threadsirts, which are 1000000 times better than heli-coil the metal on my heads seems to be soft

thread repair inserts are excellent, and should work every time they are installed properly, particularly in this application...they are used very extensively in exhaust manifold threads. so i'm not sure what happened but they certainly did not come out or fail because they can't do the job. they were installed improperly, either the wrong size was used or they weren't installed right.

#15 beataru

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Posted 04 June 2007 - 02:08 PM

trust me, I wont be the one welding it, someone who knows what they are doing would, I opend this thread for options not to be told what to do and how to do it! My car. my decision.
thank you.

#16 grossgary

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Posted 04 June 2007 - 02:21 PM

your car, your decision, thanks for the humor!! i don't care what you do to your car any more than you care what someone suggests you do to your car. that very common repairs didn't work sounds odd, so it would make sense to figure out why they didn't work before just jumping to more extreme measures. that's why we're asking. but you're not telling what you did, why they don't work, what size you used, how the threads got messed up to being with...so it's hard to answer the question properly. in the end, this would be good info for the next time you have to deal with this. in my oppinion welding should be a last resort for various reasons, there are very easy fixes to this that are far less riskier than welding, and that's not normal to choose more labor intensive, expensive and riskier repairs than are available. i understand that you want to weld it, but don't fault us for trying to steer you the more common route.

if welding is how you want to proceedd then the bottom line is that as long as the same person doing the welding isn't the same person who couldn't get the helicoils to work, you should be fine.

#17 Gloyale

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Posted 04 June 2007 - 03:08 PM

We've offered valid solutions other than welding that will work, but if you want to destroy your head go for it.


I think this is telling you to do what you want. Sorry if the tone was rough in my post. But really. There are way easier fixes for this than pulling the whole head off and wleding up the hole. I'm glad you won't be the welder, but that means all the more an expensive option this would be. I have had heads welded before and it is fine if you pay a good welder. But that was for cracks in the heads, not an exhaust stud. It would be way more work, money, and risk than nessecary.

We're all trying to help. We want you're Subaru experience to be a good one. Not one filled with wallet robbing expense and endless hours of uneeded work.............................Althought that's bound to happen anyway lol ;)

#18 beataru

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Posted 04 June 2007 - 03:08 PM

thats what exactly what I was thinking about the Welding ofcourse I wont weld it... Only, I wasnt doing the Helicoil, My Brother in law was, because If I get "caught working" in the shop, the big bald boss gets all woried about insurance reasons, I'm positive that we could get it to work if the heads were off, and we had more acess to the engine. All In all, I want to weld it because some of the gasket mating surface is actually carved out, a tiny bit, so Welding it would fix that, and give me a fresh start.

#19 Gloyale

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Posted 04 June 2007 - 03:16 PM

thats what exactly what I was thinking about the Welding ofcourse I wont weld it... Only, I wasnt doing the Helicoil, My Brother in law was, because If I get "caught working" in the shop, the big bald boss gets all woried about insurance reasons, I'm positive that we could get it to work if the heads were off, and we had more acess to the engine. All In all, I want to weld it because some of the gasket mating surface is actually carved out, a tiny bit, so Welding it would fix that, and give me a fresh start.


Really man, You are going to pull the heads for this? replacing the head gaskets is not a small job. Plus the cost of replcing the gaskets. And Doing all that work instead of a 15 minute fix is crazy. Now if you are ready to replace you're timingbelts, Headgaskets, intake gaksets, water pump and reseal the whole front of motor including oil pump then it would make sense to do it then(almost, except the extra cost of welding). But if all you are trying to fix is the exhaust there's no reason to tear down the motor.

#20 beataru

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Posted 04 June 2007 - 03:21 PM

Oh no, I am going to wait untill I am ready to rebuild the beast and replace everything on the front cover. I wont take them out just to do the exhaust.

#21 Gloyale

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Posted 04 June 2007 - 03:46 PM

Oh no, I am going to wait untill I am ready to rebuild the beast and replace everything on the front cover. I wont take them out just to do the exhaust.


Don't wait to fix it if you're car is a Turbo. You can damage you're motor by running with a before turbo exhaust leak. Plus you're losing horsepower and that sucks. You should fix it or don't drive it.

#22 beataru

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Posted 04 June 2007 - 03:52 PM

its now leaking Primeraly at the upipe to turbo connection, NEVER BUY NUTS AT LOWES they were the wrong thread pitch, Only one of them in the bag of 12 I bought fit the threads on my turbo. the rest are on their and will have to be broke off. so I am going to make a new header for it soon! then I should have my power back, and luckily it is only a leak under full throttle so, it works fine until i pedal to the metal so, I fixed it, I just dont go pedal to the metal!!! I cant wait to pull this motor out this summer!!! big cams, 3angle the valves, Get me my standalone engine management, and my gt28r off of an old isuzu truck!!! YAY!!! have you ever noticed how difficult it is to type a post and watch comedy central at the same time??? anyways thanks for the suggestions, oh and generation 3 heads??? they were only installed at the dealer right? or could my car possebly have them, Its a rebuilt motor by some company.....

#23 Gloyale

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Posted 04 June 2007 - 04:38 PM

If any of you remeber, I have been having exhaust leakage troubles since I even thought about making my car faster... so No its still not running even close to full boost yet, This pig has trouble getting out of its own way.... and DONT EVEN DARE TELLING ME TO GO N/A turbos Badass and once I make a stinking header for this piece, and get the turbine spooling



its now leaking Primeraly at the upipe to turbo connection, ...................
............. then I should have my power back, and luckily it is only a leak under full throttle so, it works fine until i pedal to the metal so, I fixed it, I just dont go pedal to the metal!!!


No matter what, you're exhaust is leaking and you aren't getting full boost. If it leaks at full throttle it's leaking at idle. You just aren't noticing it as much. If you're turbo is not spooling properly you don't get boost. Turbo cars are not the ones to have the "it'll work for a while if I......" attitude with. They'll bite ya real quick




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