rfitzpatrick
Well-known member
Not yet do I know exactly where -- I have an "exhaust-tic'. And a great case of Carpal Tunnel in my right-hand. Until I can muster some assistance - how serious is the tic?
TKS
TKS
Exhaust-Tic
- Thread starter rfitzpatrick
- Start date
Synchro909
Well-known member
I am assuming you hear this tick when you press the accelerator. That would be a leaky manifold gasket. If you do that while holding your head under there, you might get an idea where it is - towards the front or the rear. Then, a careful examination of the manifold gasket in that area might show you where the leak is It will be black at the leak. A mirror on a stick will help get a peek at the under side of the manifold. Otherwise, you might have to take the manifolds off to find it but with your carpal tunnel issue, you may have to call on a Model A friend.
These things don't heal themselves but on one occasion when I had the problem, I drove nearly 3,000 miles before I could get a gasket to do a repair. I can tell you, that "chooffing" (severe ticking) became a part of the drive but when I was able to replace he gasket, the quiet was very welcome.
These things don't heal themselves but on one occasion when I had the problem, I drove nearly 3,000 miles before I could get a gasket to do a repair. I can tell you, that "chooffing" (severe ticking) became a part of the drive but when I was able to replace he gasket, the quiet was very welcome.
A logical first step would be to snug up all the manifold bolts. Don’t go overboard lest you break the little ears on the manifolds. 35 ft-lb max.
If that doesn’t work, you will need to pull the manifolds to replace the gasket. I’ve settled on the two-piece copper clad late ‘31 version.
And if you get the manifolds off, this is the time to check for two things:
1. Are the manifolds flat? Lay a straightedge across the combined manifold sealing surface. You should not see any gaps across all the sealing surfaces. If you have feeler gauges, consensus is that about 0.002”-0.003” is maximum. An automotive machine shop can deck those flat.
2. Is the exhaust manifold drooping? A weakness in the Model A is that the exhaust pipe hangs off the end of the manifold without a second manifold stud to support it, and over time that end sags. Take that same straightedge and lay it on the sealing surface at the bottoms of the openings. All four holes should line up. I’ve seen exhaust manifolds that were so sagged (>3/8”) that the #4 hole drooped so much that it would not cover the hole in the block, and there was no way to get it bolted up without an exhaust leak. 1/8” sag is probably ok if you don’t use gland rings, but much more may be an issue. There really is no cure, but good aftermarket new exhaust manifolds are available. You will need to deck the new exhaust to the old intake as above. Consider using gland rings if you get new exhaust manifold, and no, I’m not trying to open up that particular debate!
Good luck, and sorry about your CTS.
If that doesn’t work, you will need to pull the manifolds to replace the gasket. I’ve settled on the two-piece copper clad late ‘31 version.
And if you get the manifolds off, this is the time to check for two things:
1. Are the manifolds flat? Lay a straightedge across the combined manifold sealing surface. You should not see any gaps across all the sealing surfaces. If you have feeler gauges, consensus is that about 0.002”-0.003” is maximum. An automotive machine shop can deck those flat.
2. Is the exhaust manifold drooping? A weakness in the Model A is that the exhaust pipe hangs off the end of the manifold without a second manifold stud to support it, and over time that end sags. Take that same straightedge and lay it on the sealing surface at the bottoms of the openings. All four holes should line up. I’ve seen exhaust manifolds that were so sagged (>3/8”) that the #4 hole drooped so much that it would not cover the hole in the block, and there was no way to get it bolted up without an exhaust leak. 1/8” sag is probably ok if you don’t use gland rings, but much more may be an issue. There really is no cure, but good aftermarket new exhaust manifolds are available. You will need to deck the new exhaust to the old intake as above. Consider using gland rings if you get new exhaust manifold, and no, I’m not trying to open up that particular debate!
Good luck, and sorry about your CTS.
nkaminar
Well-known member
I take it that you have problems working on the engine because of your Carpal Tunnel and are worried that the exhaust leak can cause problems. An exhaust leak can get worse because the gasket gets eaten away. It can cause erosion of the exhaust manifold and can make you sick from exhaust fumes in the car, especially a closed car.
If you belong to a local club, bring this up at the next meeting. You can have a "technical day" at your house and invite your fellow club members over. Feed them and they will be happy to help you with your exhaust leak. Before hand buy the original style gaskets. See https://www.snydersantiqueauto.com/product.htm?pid=979402
If you belong to a local club, bring this up at the next meeting. You can have a "technical day" at your house and invite your fellow club members over. Feed them and they will be happy to help you with your exhaust leak. Before hand buy the original style gaskets. See https://www.snydersantiqueauto.com/product.htm?pid=979402