EXHAUST MANIFOLD

[mccammonds]

On my 1975  821F  with a 360 I keep having problems with an exhaust gasket leaking on the right bank.  After replacing a gasket and driving about 10k miles I found a crack in the manifold.   Had it brazed but it is leaking again after driving about 500 miles. 

Has anyone experienced a like problem and what was the remedy to fix it?

[Horst]

Brazing? sometimes works - depends on where and how bad the crack is etc.
Alternatives:
1) New manifold - expensive, might be hard to get in some areas
2) Used manifold - (wrecking yard) - cheaper - don't really know what you're getting (do a good visual inspection, check for mileage on vehicle in came out of if you can, pay to have it re-surfaced)
3) switch to headers all the way around

good luck - I did the junkyard deal and have been lucky so far.........

[mccammonds]

Thanks,

I've got the word out on Craiglist right now for another  manifold.

[LARRY RAY]

Although our Clipper has a 440, you might try what I did when my right side was cracked. I found one on E-Bay. It was new yet redsigned (aftermarket) because the 440 right side was bad about that. It has been holding up just great now for three years. Hope this helps.

[des48]

Hi I am buying a 1976 that had a cracked manifold. The best solution is to install headers just like the owner prervious to the present owner. These manifolds reach extreamely hot temps. and when they cool they crack.Headers help to dissipate this heat.With headers the carbs have to be rebuilt but it will solve the problem. Watch out, keep the spark plug wires away from the headers if you don't want to replace burnt wires. DR. Dan

[tomfridley]

it is very common to have the right side exhaust manifold crack on dodge 360 and 440 engines due to the heat riser valve sticking in the closed position. the butterfly valve is inside the exhaust manifold.
the purpose of the valve is to direct heat from the exhaust gas back to the lower portion of the intake manifold to aid in pre-heating the carburetor for better cold performance. once the engine is warm, the valve opens via the thermostatic spring that is found just inboard of the large round counterweight on the right exhaust manifold.
be sure to check the valve is in proper working order by gently twisting the counterweight one direction and see if the counterweight returns by itself. if it does not move, the valve is stuck shut most likely in the closed position. they usually stick in the closed position since that is where it returns to when the engine cools down.  try some rust penetrant to free-up the valve shaft. also, it is not uncommon for the thermostatic spring to rust through in two pieces.
there is a heat riser rebuild kit probably still available from any dodge dealer.
i did have the above problem with my 440 engine. mine was badly cracked, but found my local parts house could order an aftermarket replacement, and it fit perfectly.

[mccammonds]

Just ordered a new after market exhaust manifold  from E-Bay.

By the time I bought a used one and had it planed it would be cheaper to by a new one..  Will wait and see.!!!!!!

[LARRY RAY]

As to my earlier post about buying an aftermarket manifold. It has not given me any problems until on the trip home last week. I started to do this when I put it on a few years back but didn't. The heat valve bushing musthave gotten pretty hot while coming home and the one opposite the spring blew out. Sounds pretty bad right now. The nature of my engine is a little on the cold side anyway, so now I must drop the exhaust remove the flap and rod and put bolts thru each side to stop the leak. Should have done it then. My suggestion is do it now before installing. It will be a lot easier.

[mccammonds]

I ordered an after market one from e-bay.  When it arrived it was the wrong one.  Tried to talk to the senders.   No Phone Number.  Sent it back.   I finally found one from about an 1980 vintage. It has holes in the front for a smog pump.   Any suggestions on how I can plug those holes.

[tomfridley]

exhaust manifold smog pump block off plates are [or were] available from a dodge dealer.

[mccammonds]

Thanks for the info on the smog pump plates.  Now, all I have to do is hurry and get to a Dealer before their gone!

[bush2]

Do  a good visual inspection, check for mileage on vehicle in came out of if you can, pay to have it re-surfaced

[John Eversoll]

Take the manifold to a real welder and have it Heliarced or tig welded " It is one of the two"

Brazzing is only a bandaid... and you know what happens when you pull off a Band Aid-----

[Khyron]

Take the manifold to a real welder and have it Heliarced or tig welded " It is one of the two"

Brazzing is only a bandaid... and you know what happens when you pull off a Band Aid-----

A lot of clipper arm hair comes off? 

[John Eversoll]

Why does everybody have things Brazzed???

Brazzing is only a Band Aid.

Take the manifold to a REAL Welder and have the thing Heili arced

they should have a surfacer if it is a reputable shop You wont be able to tell wghere it was welded