Engine Manifold Repair
5-9-2009 to 6-8-2009
  There
are two obvious exhaust leaks. One is on the heat
riser and the other is at the exhaust pipe flange. The
flange leak was caused by the studs rusting away to the
point where the nuts moved. Then the hot exhaust
played hell with the brass nuts. So the studs will
have to be replaced. |
 The
heat riser is another story. The heat riser's job is
to redirect warm exhaust around the intake manifold and
carburetor base to help the engine warm up faster. It
is automatic and controlled by a bimetallic spring and
counterweight. You can see how it works in the
pictures. Mine works but it looks like the cast-iron plate split right in half. Looks like
it has been that way for a while. the good news is the
moving parts are all intact and in good shape. Let's
go take a look at the spare engine... |
  This
looks promising. But the lower bolt is broken off and
the shaft is frozen. I eventually had to use a hacksaw
blade and cut out the broken bolt to get this off. The
shaft is rusted into the plate and I am afraid to use
drastic measures to get it out. I am likely to break
this plate just like the the other one. So far I have
heated it with a torch twice and tapped on it from all
angles. I am hoping time, patience, and penetrating oil
will get it off. |
So
much for patience. The shaft is mild steel and slotted down the
middle. My tapping and heating distorted it badly so I broke down
and just cut the damn thing off. After that a few minutes with a
chisel and a punch was enough to get the it apart. I then mounted
the plate in my drill press and chased the hole out. Good as new!
Got
the manifold back from the machine shop. For $60 they removed the
rusted studs and media blasted the manifold. That saved a
ton of time. I cleaned it with acetone then applied
Eastwood's high-temp coating. It looks pretty good. This
needs to dry for 48 hours then I can install the manifold. I also
coated the heat riser parts.
I
could not find stainless studs but the old ones lasted almost 70 years
so I probably should not worry about it. Here I am installing the
new studs in the exhaust manifold. The silver goop is a
high-temperature anti-seize. I use it on anything that might rust
in place or get really hot.
Time
to assemble the heat riser. The only tricky part is installing
that fragile and impossible to replace bimetallic spring. I put
anti-seize from that blue can on everything to lubricate and protect.
Then I used a new gasket and stainless hardware to install the heat
riser. I scored a whole bag of these gaskets on e-Bay.
The manifold is now officially done! I am a little concerned though. The heat riser plate I scored off my spare engine is not very flat. If I see any leakage I will have to rip this all apart again and get the plate machined flat. For now I will just wait and see what happens..