Manafold Leak

[Tom Cavallaro]

I guess it's because this car hasn't run in fourty years...LOL. I have the car running quite well now, but have developed an exhaust leak, and it's on the end close to the firewall. Is this common? Can I just replace the gasket or do I need to have it sanded down like I've read, because of the possibility of being warped?? Is this something I can do myself..or should I take it to a garage with all the parts needed?? This is a late 1930 model a, and some say to buy a new intake and exhaust manifold...if I can use the old...I'd like to keep things as original as possible.

 

[85930tudor]

Have you tryed to tighten the bolts?

 

[AKsportcoupe]

If tightening the bolts doesn't help, you should take the manifold off and check that it is perfectly flat. Also check for droop. Over time sthey tend to droop down on the outlet nearest the firewall above where the manifold attaches to the muffler (where all the heat accumulates) and will never seal correctly if not perfectly level.

 

[Bruce in southern OH]

I have replaced several, different cars, AA trucks you name it, I have found that the exhaust manifold port near the fire wall was always thinner, about the thickness of a dime and blown through, the other ports about and 1/8". Remove the carb, exhaust connector and the four nuts and washers to block. Take the two manifolds to a machine shop and have them deck " plane" and get a new one piece exhaust/intake gasket, replace every thing. I left out to inspect the manifold for cracks, oval ports and warped ports that do not line up. Use a straight edge to check for warped ports that do not line up. Ask a local model A friend to look at your job, not hard at all, Bruce

 

[Marco Tahtaras]

They can be a LITTLE forgiving on the flat surfacing but should be checked with the intake installed as a pair. As mentioned they usually droop at the rear port causing a misalignment that won't easily seal if at all. You'll likely see black on the gasket just over the rear port from the leak. It's easy to understand once you've seen a Model A exhaust glow BRIGHT red at night. This is more common than you may think due to running lean and/or retarded timing at higher speeds.

You can see the droop with it off the car placing a straight edge along the bottom of the exhaust ports and you are doing good if you find even three ports aligning! With said, You can often buy yourself a little overlap at the top of the rear port by lifting the rear of the manifold while snugging it down.

 

[Tom Cavallaro]

Thanks, I didn't try to tighen anything for fear of braking the studs. You can see the black soot at the top now that I took it out for a drive. That's when I heard some noise that sounded like something floping..lol. It was also mentioned that the heat there could be caused by being too lean. I'm pretty sure the valve was only 1/4 turn out while driving and my top speed was 35 mph. This could have been blown before I got it running, because you don't notice it a idle. I'm still learning how to drive it using the advance throttle...never sure just were the best feel is while driving. Doesn't seem to get very good mileage...went through a 1/4 tank pretty fast.