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Finding exhaust Leak

ksurfer2

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I have been chasing an exhaust leak since reinstalling my newly rebuilt motor (440) in my 69 RR. I am still running stock manifolds. What is the easiest way to chase the leak? I am thinking of using my leaf blower to push air into my exhaust pipe and then spray some soapy water around the mainfolds. Other than sealing up the other exhaust pipe, is there any thing else I would need to seal off? I am thinking of using some plastic bags and rubber bands around the carbs. Is that necessary? Is there any potential for harm from doing this? Effective? Any other suggestions?
 
I usually start it cold and move my hand around the manifolds. You have a minute or two before the extreme heat sets in.
Other wise if you've run it enough, take the manifold back off and you can see where it's leaking it will have some black carbon usually.
If you can find somewhere with a really large belt sander you can likely smooth out the manifold face.
They are not supposed to use gaskets against the head surface, but I have one on one side. You can cut the gasket up and glue it one if you don't want it to be visible.
 
Don's idea is usually what I do AFTER I just listen to get a "basic" location of the leak (front/back or left/right). I don't like the idea of putting a plastic bag anywhere near the carburetor for fear of somehow sucking it into the engine. I suppose a shop could use a "smoke generator" like you describe using a leaf blower for, but I've never done it that way.

Also, like Don says, if there's a leak where the pipes meet the manifolds or in the pipes somewhere, you can usually feel it "puff" when the exhaust is still cold and usually see some black soot where it leaks.
 
just pore a little transmission oil down the carb,your sure going to see where that leak is.
 
Dishwashing solution in a spray bottle with the engine running.
 
I always had someone else hold a rag over the tail pipes to make it a bit more exaggerated.
 
Sure it is a leak? Could not differentiate a leak from a bent rod recently.
 
The manifold faces should be Blanchard ground, not a belt sander. (really) Of course the heads exhaust side needs to be flat as well. There is a paste used to seal exhaust leaks. I don't recall the name, but shouldn't be hard to find. That is if you can't do it correctly.
 
I take the amplifying part off of my stethoscope just using the hose, trust you will know when you find it. I also use for finding vacuum leaks.
 
Hose or stethoscope will find it in seconds.
Doug
 
I would first check all bolts and nuts, all the leaks I have had with cast iron hp manifolds have been at the pipe flange. Buy some remflex gaskets will save you a lot of headaches.These sealed mine up even with a slightly bent pipe flange.
 
I ended up using a spray bottle with some soapy water water and instantly found several leaks between the head and manifold. I spent Saturday morning removing the manifolds, and cleaning up the mounting surfaces on both the head and the manifold. Installed new gaskets (some say they aren't needed, but I only wanted to do this once) and put everything back together. No more leaks. Wow, what a difference in sound....no more annoying "ticking" noise that got even more annoying (and embarrassing) under acceleration. Now its just the pleasant roar of horsepower!!!!!!
 
Be sure to retorque after some heat cycles. I would keep doing it until you find no loose ones

As a retired journeyman diesel mechanic, I’ve found exhaust/turbo leaks on a many, many diesel engines using the soapy spray over the years. Volvo engines are the worst for leaks.
 
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