exhaust manifold leak at the heat riser bushings (1 Viewer)

[Fast Eddy]

Fel-Pro work fine.

Compared to OEM? Why waste your time and money. OEM. I have nothing against Remflex, but I used OEM the two times I took off an exhaust manifold.

 

[roadstr6]

I have found that the metal sealing rings on the OEM gasket are a tad stiffer and less compliant than the Fel-Pro. The Fel-Pro is a fine manifold gasket...perhaps just as good as OEM for longevity and maybe a little easier to seal over irregular surfaces. You can get them at the local NAPA for $13.

 

[itsalltlc]

I had the same issue when I tore down to resurface and reseal the intake/exhaust. I pulled apart and drilled and tapped for a pipe plugs. I plugged with a brass plug and red loctite. I live in AZ so I dont moss the heat riser.View attachment 1029789

I had the same issue when I tore down to resurface and reseal the intake/exhaust. I pulled apart and drilled and tapped for a pipe plugs. I plugged with a brass plug and red loctite. I live in AZ so I dont moss the heat riser.View attachment 1029789

What size tap and plug did you use ?

 

[Oregon LC]

What size tap and plug did you use ?

I've had good success drilling and taping for 1/2" npt. Then I installed a 1/2" NPT plug brass pipe fitting countersunk thread Internal hex head.

 

[firestopper]

I used a 1/2” NPT.

 

[LandoNick]

I had the same issue when I tore down to resurface and reseal the intake/exhaust. I pulled apart and drilled and tapped for a pipe plugs. I plugged with a brass plug and red loctite. I live in AZ so I dont moss the heat riser.View attachment 1029789

I know tris has been a bit of time. did you have to drill the holes more to tap the hole?

 

[firestopper]

I know tris has been a bit of time. did you have to drill the holes more to tap the hole?

It’s been a minute for sure, however looking at the drill/tap chart, it looks like would have opened it up to 27/32 (.8437”). The cast iron drills and taps nicely. If you decide to use the 1/2” NPT plugs you should drill to correct possible size because the threads are tapered and you’ll want good thread engagement. Also by drilling you will have an easier time tapping without the possibility of breaking the tap or worse cracking the casting. The 1/2” NPT has 14 threads per inch. I also used brass to prevent corrosion. I trust you’ll be doing this with the manifold removed so you can remove all swarf.
The two plugs I installed are still in place without issue.
You can see the amount of material that allows for good threading.

 

[LandoNick]

It’s been a minute for sure, however looking at the drill/tap chart, it looks like would have opened it up to 27/32 (.8437”). The cast iron drills and taps nicely. If you decide to use the 1/2” NPT plugs you should drill to correct possible size because the threads are tapered and you’ll want good thread engagement. Also by drilling you will have an easier time tapping without the possibility of breaking the tap or worse cracking the casting. The 1/2” NPT has 14 threads per inch. I also used brass to prevent corrosion. I trust you’ll be doing this with the manifold removed so you can remove all swarf.
The two plugs I installed are still in place without issue.
You can see the amount of material that allows for good threading.
View attachment 3315905

Thanks for the response! yes it will be out of the truck. and brass. When you removed the flap shaft. Did you remove the flap first then have to hammer out the shaft? and which direction did you hammer?

 

[LandoNick]

It’s been a minute for sure, however looking at the drill/tap chart, it looks like would have opened it up to 27/32 (.8437”). The cast iron drills and taps nicely. If you decide to use the 1/2” NPT plugs you should drill to correct possible size because the threads are tapered and you’ll want good thread engagement. Also by drilling you will have an easier time tapping without the possibility of breaking the tap or worse cracking the casting. The 1/2” NPT has 14 threads per inch. I also used brass to prevent corrosion. I trust you’ll be doing this with the manifold removed so you can remove all swarf.
The two plugs I installed are still in place without issue.
You can see the amount of material that allows for good threading.
View attachment 3315905

I see a 23/32's drill bit?

 

[firestopper]

45/64 or 23/32 will work for a 1/2” NPT tap.
I quoted the incorrect size this morning. Perhaps
I should drink my coffee first before quoting….

 

[LandoNick]

So I drilled out the hole, threaded it. installed the plugs with High temp RTV. Im having an issue with the plugs backing out after I drive for a bit. Did you experience this?

 

[Caribou]

I actually made some plugs from 5/16" or 3/8" thick steel, a little tapered, and threaded them for a bolt. Then I bolted them in from the inside, cranked'em down tight, and welded the end of the bolts to the plugs. That way the manifold can be put back to original if desired.

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Great article and work around!! Wanted to ask you about the plugs. They look like threaded bolts with the bolt head on the inside where the butterfly valve used to be. How did you install them? Did they slide in with the threads? or did you tap new threads to match in the exhaust manifold?

 

[spotcruiser]

Great article and work around!! Wanted to ask you about the plugs. They look like threaded bolts with the bolt head on the inside where the butterfly valve used to be. How did you install them? Did they slide in with the threads? or did you tap new threads to match in the exhaust manifold?

The plugs are tapered a little with the larger diameter on the outside. I drilled and tapped them for the bolts and used the bolts on the inside to pull the plugs in tight from the outside.