HDJ80 Exhaust Manifold Leak? - How to fix? How does this joint work? Ok to drive?

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Annapolis, MD and Uvita, Costa Rica
So I have a '93 HDJ80 in Costa Rica. I was on a long journey over last 3 days way down in the Southern Pacific area (Zancudo, Pavones, etc.) Ran a bunch of back roads and trails. All unpaved and many with a rocky surface that jiggles the car endlessly. After I got back to pavement I noted a new noise that was tied to engine RPM and go louder with load/boost. It sounded like a classic exhaust leak so I just ran the 2+ hours back to my house.

Now looking under rig I see no leaks in exhaust system but after backtracking all the way to the exhaust manifold I now see that it looks like it is leaking at a joint in the exhaust manifold. I can't see the manifold very well due to the turbo but I'm thinking this is definitely the leak even though I can't detect it at idle with my fingers near it just trying to feel for exhaust escaping.

So I was wondering if the forum had experience (searches didn't get me much) on the 1HDT exhaust manifold leaking and how to fix? It looks like there is joint but I can't imagine why it would be separate pieces?

And I may have to drive the truck several hundred km before I can get this fixed. I don't think a bit of leaking exhaust is too big of a deal but this is before the turbo and maybe will get worse quickly due to high pressure?

Any thoughts from the braintrust. Thank you!

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And one glamor shot from the trip just for fun.

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Joined
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Annapolis, MD and Uvita, Costa Rica
So I just found these pictures for a manifold on ebay but it only covers 4 cylinders and I see the joint. I guess it is a two part manifold. Some kind of seal between these and I guess that is what has failed.
OEMmanifold.png
 
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Well, I'm answering my own questions with more digging. Funny thing is I started using google instead of forum search but ended up finding links back in the forum!

I think I see how this works now. Looks like I will need several rings/seals.

1HD-T Ex manifold diagram.jpg
 
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It comes apart but be prepared to hammer it and curse at it for several hours.

I'd order manifold/turbo gaskets, studs and nuts while you're in there. It's under $100 for everything.

Edit: You're fine driving it for a while. Turbo might not have all the chooch it did before depending on the size of the leak though.
 
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Well lets take a step back. I can't hear or feel a leak there when at idle but of course no pressure. I was keyed in on this due to the fresh looking black "soot" on this joint. Would you assume this is the leak that is loud and clear at load/boost when driving?

And then do you think it is OK to put several hundred km on it as is before it gets fixed?
 
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So just FYI the inner rubber o rings are designed to push the metal rings out to give a good seal, but they do wear out/break down due to heat. I would suggest taking the new rubber orings to a industrial seal type shop and getting them to supply some special viton style seals which will handle the heat a lot better. I can’t remember exactly what I used, but they were very special industrial seals with a much higher heat rating that will last a lot longer than the Toyota orings.

I would be ok with driving with a leaky header for a while…
 
Joined
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Messages
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Annapolis, MD and Uvita, Costa Rica
I would suggest taking the new rubber orings to a industrial seal type shop and getting them to supply some special viton style seals which will handle the heat a lot better. I can’t remember exactly what I used, but they were very special industrial seals with a much higher heat rating that will last a lot longer than the Toyota orings.
Thank you for info. I can't even imagine how hard/impossible it would be to get custom high temp seals made in Costa Rica. At least Toyota OEM parts are attainable. I assume OEM seals have been working OK for almost 30 years so I'm probably going to stick with that.
 

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