My 56 Victoria with a 312 has an exhaust leak I cannot find. It is under the hood and only makes noise when the engine has a load on it. Idling in park you cannot hear it, but put it in gear and step on the gas and it sounds like an old truck! I have replaced the manifold gaskets and exhaust pipe gaskets. I have replaced the manifold to pipe studs; everything is tight. A friend says the noise is coming from the fuel pump but it sure sounds like exhaust to me (I can sometimes smell it in the car. The manifolds have been inspected for cracks and none found. I put Felpro gaskets on it, the metal/composite type. Now I am thinking of doubling up on all the gaskets. We even checked the flatness of the manifolds where they attach to the head and that was fine. I just ordered a mechanics stethoscope and maybe can pinpoint where the noise is coming from. You cannot hear it from under the car. This is driving me nuts... am I missing something???
Strange Noise
- Thread starter Ricks56
- Start date
Hmm, that sounds interesting 40cpe. We were using a piece of hose and it did sound like it was possibly in the intake manifold. I'm not sure how that tube works. I have a Holley 2 bbl replacement carb with an electric choke that does not a heat tube. There appears to be a bolt in the side of the intake on the drivers side that may has been where there was a tube that ran to the old teapot choke. If the tube in the intake has a hole in it would that leak exhaust into the intake manifold? If so, what would be the fix?
I believe it is the stock manifold with an adapter plate for the 2bbl. Is it possible that the exhaust leak could be coming from the center portion of the intake?
Is the center section of the intake only used for an exhaust crossover? If so, possibly a bad intake manifold gasket could be leaking? My buddy listening with a hose did say he could hear something in that area. Sorry for my ignorance here!
Thanks!
I believe it is the stock manifold with an adapter plate for the 2bbl. Is it possible that the exhaust leak could be coming from the center portion of the intake?
Is the center section of the intake only used for an exhaust crossover? If so, possibly a bad intake manifold gasket could be leaking? My buddy listening with a hose did say he could hear something in that area. Sorry for my ignorance here!
Thanks!
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dmsfrr
Well-known member
Yes the center section of the intake manifold is an exhaust crossover.
It may have a small heat tube inside it for the choke thermostat. If it leaks or was removed & not plugged carefully there will be exhaust leaks to the outside at either end.
Does the car have dual exhaust with a heat riser valve at the rear of the right side exhaust manifold?
If it isn't opening fully it forces the right side exhaust thru the intake manifold to get out thru the left side exhaust pipe. Resulting in lots of exhaust pressure thru the intake manif.
It may have a small heat tube inside it for the choke thermostat. If it leaks or was removed & not plugged carefully there will be exhaust leaks to the outside at either end.
Does the car have dual exhaust with a heat riser valve at the rear of the right side exhaust manifold?
If it isn't opening fully it forces the right side exhaust thru the intake manifold to get out thru the left side exhaust pipe. Resulting in lots of exhaust pressure thru the intake manif.
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Yes, the car has dual exhaust but has had the heat riser valve removed. This is starting to make sense to me now, thanks for the pictures! The hole for the tube to the carb has been plugged with a bolt. I will check that area tomorrow but suspect it is a leaking intake manifold gasket. I never realized the center portion of the intake was for the exhaust crossover! Pretty embarrassing... I should have asked my questions a week ago LOL!
dmsfrr
Well-known member
There are two basic kinds of replacement intake gasket for 272 thru 312.
If you don't want the exhaust crossover runners of the intake manif to burn their paint off so easily get the type with smaller center holes. (photo)
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dmsfrr
Well-known member
A choke heat tube hole that got plugged(?) with an unknown object, and a cheesy choke heat tube substitute.What is it I am looking at here ...
The original photo came to me from a fellow in Germany who was sold what was supposed to be a relatively nice driveable car, that was something more like a basket case. It had multiple other problems as well.
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40cpe
Well-known member
The steel tube runs through the center of the intake, open on both ends. It is heated by the exhaust crossover. The hot air choke is connected to the tube and heated air drawn through the tube and into the choke serves to weaken the choke spring and allow the choke to open. If the tube rusts, exhaust will exit the manifold where the tube enters/exits.
Grumpy Rick
Senior Member
If that is not the problem, you might check to see if you have a loose spark plug.
Don't ask how I know this.
Don't ask how I know this.
KULTULZ
Well-known member
Isn't that something?
It looks and sounds like a bad gasket on the passengers side. Gaskets ordered! Thanks again for all the advice. I still can't believe that is my 62 years of life and cars I never suspected that an exhaust leak may be coming from the INTAKE manifold! Just goes to show me that I need to think a little bit more outside of the box.
