Looks like I'm going to tackle an exhaust leak on my truck; 1973 W200 crew 360 2bl auto, all stock, as far as I know. Leak sounds like it's coming from the driver's side, and sounds like the exhaust manifold gasket needs replacing. No idea if the gaskets are factory, or if the PO put these on years ago.

In reading on here and another forum archives first, it sounds like the factory didn't always send these out the door WITH gaskets, but sometimes did???? My first question is, should I put new gaskets back on this motor, or take the manifolds to a machine shop and have them true these up, and then re-install w/o gaskets?

Next question is, if I need to go WITH gaskets, should I still have a machine shop true these manifolds up first?

Next question is, if gaskets SHOULD be used, what type/brand gasket would be best? I see on RockAuto a set from Felpro, and a set from Mahle (graphite???), along with a much cheaper set (composite?) from Mahle. Any recommendations here?

Finally, the hardware. I started on getting them loosened from the engine today. I let the engine run for a while to get warm, then cool down a little bit, and then started working the bolts and nuts loose. Some loosened up on this first try. Those that didn't, I hit with PB Blaster, let the truck get warm again and then cool a bit, and worked on again, and was able to get them loosened and started out. So, I think I can get these all safely out.

Would it be best to replace all this hardware with new stuff?

From my reading, it appears that on SB's the 2 outer studs on each manifold go into the water jacket, so when replacing them back, sealant MUST be used to stop water. What sealer is best, and do I put it all over the threaded end that threads into the block, or just the tip of those studs?

Is it a good idea to use the anti-seize stuff on all other threads, to prevent rusting together in the future?

What is torque spec on these; 30 ft/lbs?

Any other good tips on servicing this part of the engine? Looks like it has the heat-riser setup on the pass side; anything there to watch for?

Thanks,

Joe

Pretty sure the factory put a gasket there, the 73 FSM says to remove and discard the old one and use a new one..

Use brass nuts where you can, especially on the pipe to manifold connection. Makes R&R easy.

Some people use tape, others dope, some use RTV and some put them in dry. They all have worked. The FSM says to use sealant, but I haven't seen where it spells out what sealant.

for the manifold to head, 20 ft/lbs on the nuts, 120 in/lbs for the bolts.

Pipe to manifold 35 ft/lbs.

As for warpage, the FSM says "Test mating surfaces of manifolds for flatness with a straightedge. Surfaces should be flat within
.008 inch per foot of manifold length."

i have never seen gaskets used at the manifold to head junction, with the exception of motor home big block setups using the valve cover gasket "protector" gaskets. make sure your manifold is flat.
if you want gaskets, use a thin smear of hi-temp RTV, or possibly those graphite [silver, multi layer] gaskets.
as for what to do about the bolt threads, i use hi-temp, copper anti-seize on blind holes, and loctite #567 [part #56765] high temp pipe/thread sealant on wet holes. i've used this stuff for over 40yrs with zero problems. [which also includes fastener removal]
when possible, use studs in the heads.
hope this helps some.


on fastener torque values, tighten up until it strips or breaks, then back it off 1/2 a turn. [JK !!! ]

Gaskets are cheap and there is no reason not to use them.

I always use anti-sieze on exhaust fasteners, and a couple good dabs of sealant on the threads of anything that fastens into a water jacket.
I'd certainly check the manifolds for straight/flat surface, and I'll bet you they need attention. Unless it's a restoration, I like studs on the exhaust as well. Same with gaskets, but if no gasket a smear of the copper hi-temp stuff works.

R/T Specialties appears to have the original fastener hardware:

http://www.rtspecialties.net/proddetail.asp?prod=1000028B

Thanks for the information, especially torque values.

anything to be wary of on the heat riser for the intake, on the pass side?

Just clean it of any carbon buildup. The FSM has the details, any FSM.

http://www.mymopar.com/index.php?pid=109

I don't like the OE nuts, they rust on and you are back in the same boat you're in now. I replace them with brass.

10-4, thanks! I will source brass nuts for the studs then.