'59 Mystery Exhaust Leak

I'm hoping you guys can help me find an exhaust leak on my 59 f134. It shows up under load and it leaks so much that I can't drive without having the doors off and the rear window rolled up. It makes a strong popping noise and is only present when accelerating. So far I've replaced the exhaust manifold and all of the gaskets. The oil is clean, not milky. It sounds like it is right in front of the dash. The only thing I can think is a blown head gasket. Any other ideas?
Thanks for the help!

 

So then do a compression test. Or try pulling plug wire off #4, see if the sound abates.
But that would be an unusual place for an F-head head gasket leak, usually they blow between cylinders.
Sure it's not the manifold gasket at the rear of the block?

A piece of flexible tubing to your ear can be used to locate the source of an exhaust leak sound.



Welcome to the Forums.

 

Thanks PeteL. I'll try pulling the plug wire tomorrow. I replaced the manifold gasket last week but I'll double check the rear gasket to make sure it's not leaking. Thanks again for the help!

 

That connector between the exhaust pipe and the bottom of the manifold. That would place the sound right at the firewall. Or any of the connectors between there and the muffler.

 

Thanks for the feedback guys. I replaced the gasket between the manifold and the exhaust pipe when I did the manifold gaskets, but I will double check and make sure it is tightened evenly. I have to drive with the doors off because of the exhaust that is coming into the cab, otherwise I would pass out. I'll post what I find after I've dug into it some more today. Thanks again.

 

Thanks Glenn. Yes, it does do a stationwagon effect with everything open, but if the doors are on it is unbearable. I only drove it once since the leak developed and that was to get it to the shop where I work. The tailpipe ends at the back right corner like original.

 

Your popping noise you describe usually indicates an individual gasket leaking. I would be looking again at the 3 individual manifold-to-head gaskets. Yes, if one of these is leaking, it will be much more noticable under accelleration. If your engine is clean, you can usually see soot or burning of the paint where the leaking gasket is.
-Donny

 

Mmm... That would be Block to Manifold, would it not?

 

Oops! Yes
-Donny

 

I think you have something else besides an exhaust leak going on.
but, then I have nothing to go on. I run a Bikini top all year.
You might consider a complete replacement from the joint between the exhaust manifold to the left rear corner.

 

Thanks for your help guys. Did a compression test and the last cylinder is low (90 vs 120). There is also black soot on the firewall right behind that cylinder. At this point I am taking it to the local shop for repair so I can hopefully drive it a little before the snow flies! I will let u know what they find... One more question; I have the original steel top with doors. Glass and gaskets are in perfect shape. I am going to sell it but I have no idea of value or where to post it. Any ideas?

 

Thanks Focker. Dumb question but where is the off topic section?

 

Well it turned out to be a blown head gasket at the rear center head bolt. It was blowing exhaust out against the firewall. We replaced the head gasket, rocker cover gasket, carb base gasket, thermostat, and all head bolts. Glad the head wasn't cracked!

 

I like when they get fixed.

 

Score one for the Good Guys.