500, 472, 425, 368 Discussion, Header gaskets... in Cadillac Engine Discussion; Hey guys, just wondering something...
The gaskets on my exhaust headers are completly shot so I have soem major exhaust ...
The gaskets on my exhaust headers are completly shot so I have soem major exhaust leaks. Anywho I need to replace them. Do I need to torque them to a certain extent or what? I can get ahold of a torque wrench but don't knwo how to use one. Any help here?
Automobile(s): 1995 ETC, 75 Deville, Cad500 powered 73 Apollo, 94 Mark VIII
Re: Header gaskets...
Haynes lists these torque specs.
Exhaust manifold to cylinder head
Long Bolt 35ft.lbs.
Short Bolt: 12ft.lbs.
Says you should work from the center outward.
Just to clarify, headers are a tube (primary) for each exhaust port that dump into a collector. An exhaust manifold is basically a single tube for all the ports, which is what you have (or at least what's original on these cars.)
you must retorque header (or manifold) gaskets, especially the paper ones.
About the next five or so times you drive the car, go and retorque all the bolts (after it has cooled). Both the bolts from the header to the engine, and exhaust to header.
The LARGE temp swings that these parts take makes the retorquing nessacary. Really, you should keep torquing them between drives untill you don't have to turn them any more for them to be torqued.
You're probably going to work pretty hard to keep from breaking the exhaust manifold bolts. I'd spray them with a good penetrating oil every day for a week or so before even trying to loosen them. When you do start to loosen them, use some heat and then move the bolt back and forth (loosen then tighten a little......repeat) until they are removed. It'd be a good idea to continue to spray them as you loosen them too.
I've been spraying the bolts for about 3 days now. Going to keep going at it until the new gaskets arrive (3-5 days) I'm using that PB stuff.
Just wondering, when you say that I should use heat, what kind of heat are you talking about? I know I can't use a flame of any kind due to teh fact that there will be loads of highly flammable penetrating catalyst everywhere...
Thinking about breaking the bolts has really got me worried about all of this. Is it really that easy to break a bolt?
Just looked again, and it says 35ft lbs for long bolt and 12 for short bolt. What length would be considered long? What length would be considered short? I'm going to get new bolts and just need to knwo this.
You can use propane around PB Blaster, I have. Yes, it burns, but it isn't like gas or anything. You'll see some yellow flame when you have the torch on a puddle of the PB, but it doesn't continue burning after you take the torch away.
If you're really nervous, just give it a day without spraying the PB blaster before using heat.
Well, once you have the bolts out, it should be apparent which are long and short. Just take those to the hardware store and get some nice grade 8 replacements of the same size/length.
You will probably want to put washers under the new bolts, unless you can find bolts that have the same flat shoulder that the stock ones have.