Nav Vet

I am in the process of removing the transmission from my C4.
In the process of removing the exhaust, a couple of the studs holding the Y pipe to the exhaust manifold broke.

Does anyone have recommendations on good ways to get the studs out, and not damage the tread? Also, where can new studs be gotten from?

It's a 91 C4 6spd, L98
Thanks!

bogus

this is what I did... the studs are not mandatory... Get the manifold off the engine (which isn't that hard) and work on the flange that way.

I would soak the threads in PB Blaster, that might help release them. The threads get heat cycled and hit with moisture, so rust is the fatal problem here. In fact, it could be so bad that it could weld itself into one mass.

Remove whatever is left of whatever you are working with...

Then get a drill and clean out the threads!

Get grade 8 flanged bolts, nuts and lock washers and replace accordingly.

Coat all threads with Anti-Sieze. That will keep them from rusting up. Anti-Sieze will withstand up to 1800* F.

This will be easier to deal with down the road, and you don't have to worry about the threads.

Also, be careful, the weld that holds the flange on the manifold can crack, so don't force the issue.

billybonesmusic

i agree! you can use heat (propane torch) to get the bolts out too, i dont think pb blaster is flammable, but wd40 is, so be careful your local ace hardware store should have the bolts, just make sure they are grade 8, you can get a tap there also to straighten out the threads in the heads too.

Vic'89

I installed headers when that happened to me.

Vic

86PACER

Remove the manifold from the car and use heat or PB blaster on the stud as mentioned. Studs spin off the flange with vise grips. New studs can be purchased at an exhaust shop. Get new nuts too. Use anti seize on the new studs.

Aggravated4life

I took the manifolds off the car and brought them to a local muffler shop and had them remove all the bad ones and reinstall all new studs.Saved me time and cost like 9-12 bucks or so,but that was many years ago.
I cant recall for sure the exact...

Cant imagine it being much higher than 15 bucks or so,depending where ya live.

I also bought stainless steel nuts to use on the studs to hold the Y pipe in place and they resist rust very well and usually wont seizeweld to the studs.Use a little antiseize on the threads as well.

pianoguy

*commits this to memory - perfect story to explain to wife why I need headers*

Nav Vet

Thanks for the replies!

I didn't know about the grade 8 thing....headers may be the way to go!!

(besides...it's Christmas time)

comp

Strick

Go with new headers. You'll be glad you did.

CFI-EFI

If it weren't for smilies, comp would have a total of 9 posts instead of 73,000+ that he has.



Me too. Grade 8 bolts will withstand a greater amount of tensile stress than say a grade 5. That is a property that is meaningless in a manifold studs.

RACE ON!!!

comp

and how would you know this

pablocruise

Oxy-accetylene torch.

bogus

from my perspective, the price difference between grade 8 and grade 5 isn't worth the savings... I just get grade 8... it's a habit.

CFI-EFI

Grab what is closest, because there is no advantage to the grade 8. One second of searching for that unneeded bolt or stud will cut into your wrenching or racing time.

RACE ON!!!

CFI-EFI

Because I haven't seen where you have typed even one letter since the last time I made the same observation a couple of years ago. Is it because you don't know where caps and punctuation goes?

RACE ON!!!

redrose

best to remove the manifold from the car, can be done ''installed'' (muffler shops do ''installed'' all the time)...oxy-acetylene torch highly preferred, mapp-gas maybe, propane makes life tough...replace all three studs, you might just be the 'next guy'...manifold should be secured to prevent movement while un-screwing old studs.

1) heat all three STUDS to 'bright' red, but not to melting point...heat just the studs by directing the 'heart' of the flame onto the end of broken studs, near base of unbroken studs...use a big enough flame to do each stud in abt 10 sec.

2) allow manifold assy to cool to touch.

3) heat FLANGE adjacent to longest remaining 'old' stud to 'dull' red...apply 'vice-grips' or 'stud remover' tool to stud and immediately unscrew from manifold while maintaining heating...do not use extremely high flame to heat cast iron exhaust manifold flanges as they may explode violently if rapid localized expansion creates high stesses in casting (i HAVE seen this done)...'chill' tool....move to next highest remaining stud and repeat, etc

the above process will remove 'most' studs...if not,subject the stud to TWO cycles of heating to bright red + air cool to 'anneal' (soften) it... cut/grind the exposed end of the stud off SQUARE at flange, 'center-punch' the end of the stud and drill pilot hole thru with a 3/16'' drill bit, then enlarge pilot hole with 5/16''...very often the remains of the old stud will cling to the drill bit just as it breaks thru, if not- use a tap to 'chase' the threads in the manifold.

for reinstallation of flanges which will be removed in near future, i use a short length of 5/16'' all-thread rod with nuts/washers TOP and BOTTOM in lieu of oem 3/8'' studs...clamping/retaining force of the smaller 'bolt' is satisfactory, and during future disassembly the 5/16'' low-strength all-thread will shear and be readily replaced, rather than repeating the 'blue-tip' act.

comp

no,,you just like being a smart azz,,,

CFI-EFI

Nothing "smart azz,,, " about my comments. Just an observation on a huge, on going, waste of band width. Still no caps, and commas where a period belongs. Illiterate???

RACE ON!!!

comp

ya' you a ****
Oh and nice hy-jack