idabomb00

1994 Firebird Formula m6

So while back I decided to delete my EGR while fixing an intake leak. I bought the block off plates and they went on fine on the back of intake.

Went to remove the EGR pipe from the exhaust manifold and all hell broke loose... The bolt broke!!! So currently, the car doesn't run due to some issues that are being handled but while it does run it obviously has an exhaust leak, a rather nasty one.

My question is, can the exhaust manifold be removed from the car without lifting the motor? My plan is to get the hole welded closed at work if its possible to remove this way.

fbody_brian

Yes, the exhaust manifold can be removed from the car without lifting the motor

Catmaigne

iTrader: (6)

You can get the manifold out no problem. The biggest issue will be shearing bolts in the head or on the flange that goes to the y-pipe. Once you get it out then you have to deal with welding onto cast iron. If the weld cools too quickly it will probably crack.

Personally, I would rather just put some headers on to make some room. Manifolds are bulky and weight a good bit.

idabomb00

Thanks!
What do you mean shearing bolts? Breaking?
I thought about headers but its costly. Do you know of a cheap pair with o2 sensor holes and no air pump holes or EGR holes? Also bolt to the stock flanges...

Catmaigne

iTrader: (6)

Yes, breaking bolts. Every car is different but it's not uncommon for a steel bolt to get seized up in aluminum heads. You can use penetrating oil all you want but some will never come out easy. My car had 82k when I pulled my manifolds to install long tubes and I didn't have a problem with shearing (however, a 12pt HFT socket rounded one of the bolt heads). A friend of mine installed headers at 130k and sheared a bolt right in the middle of the head. There was only about 1/4" stud left sticking out and it wouldn't budge. However, I know of another car with less miles than mine that sheared 2 bolts in one head. I usually have less luck with higher mileage cars but I can't speak for everyone.

Your only options for headers that can be used with the stock y-pipe are shorties and mids. I'm not sure of any without emissions hookups because the only real reason to not go with long tubes is to stay emissions legal and keep your cat in the stock location. It really depends on where you live because some places will let you slide with long tubes, aftermarket Y, and a high flow cat.

idabomb00

Currently I don't have emissions testing where I live and I probably won't have to worry about it for a long time (I live in the middle of nowhere).

The reason I want it to bolt to the stock y pipe is for cost and time reasons. My car is at 138k miles which is probably why I had a bolt break in the first place.

However, I want a solid fix on the exhaust manifold so I think I'll take it off. I don't want to chance carbon monoxide poisoning and its a little cold right now to drive with the windows down to ensure fresh air.

Thanks for all your help, one more quick question, are the exhaust manifold bolts 3/8"?

fbody_brian

I went through the same thing. I just waited until I found a cheap set of used long tubes. I just couldn't see spending money on a used manifold when it could just crack again.

Yes they are 3/8-16

Valkyn

iTrader: (8)

You could probably get a used manifold for dirt cheap if you can't get the broken bolt out of yours

idabomb00

I really won't spend much, a new exhaust manifold gasket and possibly a few new bolts.

I'm having it welded for free at work by a well seasoned welder.

fbody_brian

Sounds like a good plan. Get some anti-seize for putting the bolts back in.

leadfoot4

iTrader: (1)

If you successfully remove the manifold, why not try getting the broken bolt out??

Secondly, when you re-install the manifold, use a generous amount of anti-seize on the bolt threads.

Catmaigne

iTrader: (6)

Honestly, I would just replace the bolts.

idabomb00

Will do with the anti seize.
My new plan is to tap out the hole and put a bolt and washer in the tapped hole, then tack it with weld. Unless you genuinely believe it would be better to remove the broken bolt then use a new bolt to hold on the aluminum block off plate...
I can aquire zinc coated bolts for free, if this is okay would grade 8 bolts be better than grade 5?
I am by no means an expert which is why I ask so many questions...

Catmaigne

iTrader: (6)

Definitely not grade 5, will rust and snap real easy after being heat cycled over and over. I would opt for something with a black oxide coating or even stainless (but not the hardware store crap, get something good). Mr Gasket has decent black oxide bolts you can get at any auto parts store for pretty cheap.

idabomb00

These are the ones?
http://www.ebay.com/itm/Mr-Gasket-916-Pontiac-Allen-Head-Header-Bolts-Black-Oxide-Steel-MRG916-/151205960675?pt=Race_Car_Parts&hash=item233493dbe3&vxp=mtr
What about the flange bolts? Is it a good idea to run a 3/8-16 tap in the head after I remove the exhaust manifold?

leadfoot4

iTrader: (1)

I think a thread chaser would be better. Those bolts are spec'd for headers, which have a thinner flange than the cast manifolds. In other words, they'd be too short, especially the front-most bolt, which, if I remember correctly, is actually one of those bolt/stud combos, and it holds a support bracket for the alternator.

Not to be annoying, but I think that once you get the manifold off, your welding buddy should be able to help you get the broken bolt out without too much trouble.

idabomb00

Ah I see, I'll find the right ones. I can remove the bolt and I'll put the block off plate on it then tack it. Thanks for the help!

Catmaigne

iTrader: (6)

Those bolts look too short, I think you need 1" typically. All the other Mr. Gasket bolts look like they're only Grade 5 so I don't know. I went with ARP on my car for assurance but it's more money. You'd probably be fine with full thread hardware store grade 8 if it has the coating on it (makes it look yellow) but I'm not sure how long they'll stay rust free. The stainless stuff is questionable. I guess use a lot of antiseize and you'll be fine.

idabomb00

I know zinc coated grade 8 would work and hold well but getting them out in the future may be a different story.

So yeah I went with ARP black oxidized.