On my 1986 F150, the heat riser valve started leaking (see picture below for hole location). The hole is big enough for me to stick my pinkie in and I can feel the valve rod end. The valve works fine and I like to keep my stuff stock so I don't plan on removing the valve. Plus that would require removing the exhaust, and, well, as rusted as it is, would require replacing a lot of the exhaust pipe.

What can I use to plug the hole so it stays? I've tried taking it to the local muffler shop but they refused to weld it until they could see inside the hole to make sure the valve was open. I've also tried a variety of methods including rubber hose, metal tape, some steel mesh with some exhaust glue (the stuff that turns into glass when it heats up). The best method so far was the mesh and glue that lasted almost 1 year.

The arrow indicates the hole location:



Thanks!

 

Not knowing the size of the hole maybe you can find a plug. Something like a casting plug also known as a freeze out plug and drive it into the hole.


Also how far in is the end of the shaft could you force in a short bolt in the hole?
Dave ----

 

It's not very deep, maybe 1/4 inch? The expansion plug (and rubber hose) just blew out of the hole due to exhaust pressure. The bolt won't screw in because there's no threads in the hole.

 

The expansion plug (and rubber hose) was this the type that you put in place of a steel plug and tighten a bolt to expand the rubber to hold it in?
If so that is the wrong type use the steel type and drive it in. May even try a little of the glue that came with the mesh around the plug before you drive it in. Then mesh & glue over that.


As for the screw can you tap the hole or find a self taping one.
If that does not work you will have to drop the pipe and valve for either a bench top fix or new valve. Get the nuts red hot before trying to remove them. If they start to get hard to remove stop and reheat to red hot and try again.


I have to drop my front pipe to replace the donut and will use the torch when I can find it in my garage or work shop.
Dave ----

 

So I've tried a few more methods and nothing seems to be working. Can I just remove the heat riser altogether? It looks like it's just sandwiched between the exhaust manifold and the exhaust pipe. Can I just take it out and hook the pipe directly to the manifold?

 

Braggs, sometime back, someone was blocking off a hole in the EGR adapter of a 4.9L six and found a suitable brass (?) plug @ Lowes in the plumbing section.

I will copy a link to the gasket for that application. The hole they were sealing off is the larger one on the lower side of this particular gasket.

Carburetor Mounting Gasket Victor G27289 Fits 78 86 Ford F 250 4 9L L6 | eBay

I couldn't find the plug on Lowes website, but it was something like this: http://www.ebay.com/itm/like/261742868100
I am sure other sizes are available.

 

So you're advocating for NOT removing the heat riser altogether? Does it not come out easily?

 

It only comes out easy if you can either loosen the bolts or cut them off and replace them. They do sell this at the local parts store, but I had a friend use that metal puddy stuff and sanded it to look decent. He has not said it has failed. Oh I just remembered. JB Weld. I have not used it before.

 

I have not tried to remove that valve and then bolt the pipe back up but from what I have seen for other makes you cannot.
The pipe is make to work with the valve in place. If you try it the pipe will not fit or seal right. If you can get a spacer to make up the valve space that would work.


If you go thru all that you might as well either replace it or make sure it was open and weld up the end holes.
Dave ----

 

The heat riser on my 84/302 leaked the same place. I ended up replacing the heat riser. RockAuto has them.


I also replaced the manifold. No way was I getting those exhaust studs to come out. Much easier replacing the works. If you remove the riser, the exhaust pipe won't reach the manifold, you will need that replaced.

 

You can get rid of the valve if you buy the proper exhaust manifold, they made two different ones.

On one like you have the manifold outlet is flat to accept the valve and uses a flat gasket inbetween the valve and the outlet.

The manifolds without the valve have the ball seat that receives the y-pipe made onto the outlet of the manifold, no gasket required.

P.S. I am assuming you are working on the 86 with a 5.8? I just looked a little bit, and don't see optional exhaust manifolds like they had for the 5.0, so you might not have the no-valve option.

 

I just looked on car-part and they do list a no-valve exhaust manifold. Not sure where you can buy a new one though.

8-351W (5.8L), LH AIR holes
8-351W (5.8L), LH w/o AIR holes; heat control valve
8-351W (5.8L), LH w/o AIR holes; w/o heat control valve
8-351W (5.8L), RH AIR holes
8-351W (5.8L), RH w/o AIR holes