Exhaust Manifold Leak

[My1stHemi]

I spoke with an independent shop owner the other day that has replaced many cast iron manifolds from different manufacturers. He was well aware of our struggle and he recommended NOT installing the heat shield. Apparently the Ford 460’s in RV applications would commonly smoke their manifolds too. He found that it was all temperature related and that a fix was to remove heat shields and also add a duct system of dryer vent hose aiming outside air at the manifolds.

Obviously I am not going to do the dryer vent trick, but I can attest that these trucks run HOT exhaust temps. I’ve shared photos of my exhaust valves when I removed my manifolds and they are clean and gray. I’ve burned the ceramic coating off of three sets of headers and I don’t race or tow crazy loads. I’m sure it has to do with emissions.

 

[KMach]

Did VOR two weeks ago for my manifolds so I didn’t wait as long as most. 29,000mi. My passenger side was broke in half. Doing both sides. With any luck, can squeeze them in again one more time before 60k.

 

[theblet]

I spoke with an independent shop owner the other day that has replaced many cast iron manifolds from different manufacturers. He was well aware of our struggle and he recommended NOT installing the heat shield. Apparently the Ford 460’s in RV applications would commonly smoke their manifolds too. He found that it was all temperature related and that a fix was to remove heat shields and also add a duct system of dryer vent hose aiming outside air at the manifolds.

Obviously I am not going to do the dryer vent trick, but I can attest that these trucks run HOT exhaust temps. I’ve shared photos of my exhaust valves when I removed my manifolds and they are clean and gray. I’ve burned the ceramic coating off of three sets of headers and I don’t race or tow crazy loads. I’m sure it has to do with emissions.

I would like to see if removing the heat shield would help, or if it will melt anything around there.

 

[Rick3478]

I would like to see if removing the heat shield would help, or if it will melt anything around there.

My knee jerk is that there is a lot of plastic on wire insulation and other stuff under the hood, and even if it doesn't outright melt anything, the heat is likely to make plastics age fast and become brittle, possibly leading to premature failure.

 

[Rick3478]

My knee jerk is that there is a lot of plastic on wire insulation and other stuff under the hood, and even if it doesn't outright melt anything, the heat is likely to make plastics age fast and become brittle, possibly leading to premature failure.

A random afterthought from a skew angle: Do they make marine exhaust manifolds for the hemi, like with a water jacket around the exhaust? Or would they be too big to fit the truck engine bay. Hmmm.

 

[6of36]

A random afterthought from a skew angle: Do they make marine exhaust manifolds for the hemi, like with a water jacket around the exhaust? Or would they be too big to fit the truck engine bay. Hmmm.

I've never heard of any boat with a gen3 Hemi.

 

[My1stHemi]

People run bare stainless headers on the Hemi without heat shields. On my ceramic coated shorties I don’t have heat shields(besides the tabs on the gaskets) and don’t see any issues with the other items in the engine compartment.

 

[My1stHemi]

A random afterthought from a skew angle: Do they make marine exhaust manifolds for the hemi, like with a water jacket around the exhaust? Or would they be too big to fit the truck engine bay. Hmmm.

If FCA made them, I bet they would fail too.

 

[Cbty2050]

If FCA made them, I bet they would fail too.

You know who makes the manifolds?

 

[theblet]

You know who makes the manifolds?

Probably phizer

 

[6of36]

You know who makes the manifolds?

Not being sarcastic, but do you? Not that it really matters, but curious. I understand some GMs have the same issue.

 

[Cbty2050]

Not being sarcastic, but do you? Not that it really matters, but curious. I understand some GMs have the same issue.

I do not know that. FCA makes very little parts and outsource most parts. There are alot of parts in backorder waiting on vendors to fill orders.

 

[Vulpes]

Here to add even more confusion and chaos, with a highly super scientific test of stainless non-coated header temperatures on 5th gen 1500 Hemi. Engine was at it's normal operating temperature, meaning, hot.

 

[theblet]

Here to add even more confusion and chaos, with a highly super scientific test of stainless non-coated header temperatures on 5th gen 1500 Hemi. Engine was at it's normal operating temperature, meaning, hot.

That is pretty hot. Is that a cat converter or a resonator directly downstream of the header?

 

[Vulpes]

That is pretty hot. Is that a cat converter or a resonator directly downstream of the header?

Directly downstream (right below the flange) is indeed the catalytic converter, hence the significant increase in temperature from the header tube measurement to the collector measurement. Those cats like to get nice and toasty, or maybe "burny" is a better description.

 

[theblet]

Directly downstream (right below the flange) is indeed the catalytic converter, hence the significant increase in temperature from the header tube measurement to the collector measurement. Those cats like to get nice and toasty, or maybe "burny" is a better description.

That’s what I figured from the temp change.

 

[kapinallinen2]

Here to add even more confusion and chaos, with a highly super scientific test of stainless non-coated header temperatures on 5th gen 1500 Hemi. Engine was at it's normal operating temperature, meaning, hot.

ce of 0.95 is the defacto.
That manifold might have been running hotter than what was measured, due to it`s reflectivity. edit "emissitivity"
Needs to be black for more accurate reading. Or adjust emissivity to the type of stainless used in the header.

 

[My1stHemi]

Not being sarcastic, but do you? Not that it really matters, but curious. I understand some GMs have the same issue.

No Clue. I tried for an hour one time to look that up. I’d bet a dollar they outsource them and do not make them in their own foundry.

 

[Vulpes]

ce of 0.95 is the defacto.
That manifold might have been running hotter than what was measured, due to it`s reflectivity. edit "emissitivity"
Needs to be black for more accurate reading. Or adjust emissivity to the type of stainless used in the header.

I definitely did not correct for emissivity on those readings. I'll be pulling the fender liners for something else soon, and if I remember, will try to get some readings with adjusted emissivity. What do you think, stainless, dulled, and a tad grimey, say, 0.30?

 

[kapinallinen2]

I definitely did not correct for emissivity on those readings. I'll be pulling the fender liners for something else soon, and if I remember, will try to get some readings with adjusted emissivity. What do you think, stainless, dulled, and a tad grimey, say, 0.30?

0.35 to 0.50 possibly, depending on the condition of the surface.
I would put a spot of high temp black paint on it and run with 0.95.