Exhaust flange and gasket problems.

[BadDog]

Machining content is relatively small, but it is there...

In my copious spare time (heh) I'm working on a new desert truck. This one's an '85 Suburban outfitted for long range camping trips and totally focused on expedition style trips without the gratuitous rock crawling and such. As such, I'm building a Turbo Diesel to put in it for reliability and fuel efficiency for resulting longer range. And right now it's the final turbo (Holset "Baby H1C" if anyone cares) fitment that's causing issues.

This is a 6.2 with Banks turbo exhaust manifold, which appears to use a proprietary 3 bolt trigon flange. The flange is very close to a Walker 31305 gasket (link to specs), But the hole is at least roughly 1/4" too large (pipe is 2"), and the bolt holes are about 1/16 too far out. I've got that gasket and modified the bolt holes to fit, but that leaves very little (less than 1/8" between the bolt hole and the gasket hole.

The OEM Banks crossover flange was removed from the old tube on the lathe and the old weld beard turned down to more or less what it looked like when first used. It was warped pretty good, so I stabilized/averaged the flange face to surface grind the back side flat, then flipped it using the now flat back side as a reference to grind the face with minimal removal. It took about 0.008 to clean the seating area, leaving the ears just a bit low (which I think is good). But then I welded it on to the new cross over taking pains to minimize warp, which certainly warped it again to some degree, though I doubt near as badly.

FYI: The Banks gasket I got with the manifold and crossover was clearly leaking pretty badly between the flange ears on one side. Hard to say if warped by being installed by gorillas with impacts, or welding, possibly both.

So I have 2 question:

1) I know lots of you guys work in different industries. And while I can't find an automotive number that matches the Banks flange, I'm betting that Banks didn't actually have short runs made JUST to lock customer into their "only way to get it is a kit that will cost over $55 shipped" (kit only contains 2 non-common/cheap gaskets). So if any of you have suggestions for other sources where I can look I would much appreciate it.

2) Given that the flange has certainly warped to some degree, and it's utterly impractical to resurface grind after welding, it really needs a good crush gasket. The banks unit appears to have a crush ring in the ID of the main gasket, but the Walker gasket is just a steel/fiber flat gasket with no ring. I don't have great hopes for it holding, and it's not an easy gasket to replace. I've got ultra copper high temp RTV, but given that Turbo EGT's routinely hit 1000+ *F, I don't have much hope of that holding up. What would you guys suggest to help that gasket hold?

[warmstrong1955]

You might try making your own from stainless steel sheet metal, if you have nice flat surfaces, or can machine them flat.

Had a fleet of equipment with 3304 PCTA Cat engines, and they had a habit of failing the gasket between the turbo & 90 degree adapter to the manifold.
A 4-hole type, hi-temp paper with stainless laminated on one side, and both sides around the exhaust ports.
Anyway, we ran out. The local Cat dealer ran out. So I made one from a piece of stainless chimney tubing. I ran a file over both the mating surfaces to make sure there were no burrs or high spots.
My homemade one never did fail, but was replaced with another one I built just like it. I built several, and that's what we replaced them all with.

Bill

[warmstrong1955]

Oh....and to add....Cat did change the gaasket a year or three later. Gaskets that came with new turbos were just stainless steel sheetmetel, with a small bead rolled around the ID around the exhaust port. They held up fine.

Bill

[BadDog]

I've pondered a few DIY options. My favorite was an annealed copper ring, perhaps made of #10 solid wire I have on hand. The flange would be cut like a o-ring face groove, and the soft soldered ring placed in the groove before install. But the location and angle of the flange at fit-up made that seem impractical in-frame, and difficult even on engine stand, so that got ejected.

How would you make that flat gasket? I considered copper sheet as well, but not stainless. I would guess that the process would be sandwich between to pieces of sacrificial material to drill and bore the ID, then cut the outer profile with hand shears. I wonder if I could rig up and embossing press die to make a crush ring too. But lots of work for a single gasket.

[warmstrong1955]

I didn't have anything fancy. I cut them to rough dims using tin snips and a sabre saw, and cleaned them up with a die grinder to final dims. The holes were drilled, and hit all the edges with a deburring tool. Kind of a pain in the butt, but you can't make any money with a piece of equipment down.
Besides patience, clamping, and working close to the vise jaws is important. Die grinders can grab things when the work piece starts vibrating.

I've used copper on motorcycles, but they don't get as hot as a turbo on a diesel, that's for sure. My YZ's had copper head gaskets....back in the days of 2-strokes.
With higher temps, copper may tend to erode, but I'm not sure. Might be worth a try.

Do you have flat mating surfaces to seal, or a groove?

[BadDog]

Yes, I wasn't sure about the copper resiliency either. But I found some internet references to using them, so it must be true.

The manifold is as provided by Banks. I didn't check it before install, but it's cast iron, so surface should still be flat.

The crossover flange was warped (apparently from Banks welding, but possibly from impact past install) when I got it, and appeared likely to have contributed to the blown gasket I found (no erosion visible on manifold). The gasket ID ring was intact, but the fiber outer was blown, likely indicating that the ring didn't seal due to warp of the flange and gasses blew out the surrounding fiber. Anyway, after welding on the flange I'm sure it warped to some degree, it's just a matter of how much.

[warmstrong1955]

Can you mill it?
If it's not flat, you will have problems that a new gasket will not fix, at least permanently.
Been there. Most often on home made ells & tubes with flanges welded on.
I've done some, again in a pinch, with a disc grinder, and successfully enough where the gaskets stayed intact. You do what you have to when you are days away from a new part.

[BadDog]

This is what it looks like. The speckles are overspray from the VHT I sprayed the pipe with, it was surface ground before welding.

My current soft plan is to make the flat piece I mentioned (with 2"+ hole to fit over protrusion) to do a blue transfer and check for flatness, potentially quantifying with feeler gauges to determine if size/location will hinder sealing, and potentially provide a flat reference for flattening the flange if required (sandpaper etc).

And don't look too close at the welds. Two not quite the same shape of round butt welded 16 ga mandrel bent tubes don't make for pretty welds using MIG, at least not with my skill level. But I did leak test it under low pressure. Found and fixed one pin hole out of 5 butt welds, so I counted it a win...

[warmstrong1955]

If you can mill that flat, I bet life would be a lot better. I can't tell how flat it is, but I know the problem.
The problem is common to exhaust headers. Besides warping, the welds stick out, and they generally make things flat with a grinder, and a the guy is running it in the dark...

So..... Another possible option, would be to find some of that high temperature Garlock gasket paper. They have some grey graphite stuff, that was good to 1000 degrees or more. Looks like header gaskets, and I assume the same stuff. I have bought some that was around 3/32" thick. Fact is, I had some here, but gave it to the kid who bought my old CJ5 a few years ago. (I moved up to a Rubicon) Even 1/16" thick might do it, but flatter is better.
I've used it between the flanges and the inlet/outlet cones on PTX catalytic purifiers, which get up to 1000 F and above, and the exhaust manifold to the pipe on HJ65 Land Cruisers with diesel engines. Looks similar to your pipe, but with a two bolt flange.
I've always picked it up at auto parts stores. Summit may have it....not sure.

[BadDog]

Exactly right on header flanges. I hate the things, both at the head, and at the collector.

Not familiar with that stuff. Good to know, thanks. Do you think that a full surface gasket of that stuff would be better than the narrow width remaining of the steel/fiber resulting from the 9/32 over size diameter hole in the gasket I modified to fit? Call it roughly 1/8" wide where about 1/4" wide sealing width would be possible with a (just over) 2" ID hole in the gasket material in question? Not sure how much the steel inner will offset the loss of sealing width...

[warmstrong1955]

Something like this:

https://www.summitracing.com/parts/rfl- ... /overview/

Or with steel:

https://www.summitracing.com/parts/mrg-5960/overview/

They have other flavors.

Last stuff I bought, was NAPA....or Carquest....I forget.....

[BadDog]

That Remflex looks interesting at 0.140 (according to Q/A) thickness. But the steel core Mr Gasket at 0.063 looks more interesting, haven't seen any like that before. And my surface ground (pre-weld) flange should easily be flat enough for 0.063 to seal up, AND unlike the 31305, give me full a width seal.

If I can't find a ready made gasket, I may just get that and make 2. One to install now, and another while I'm setup to put on the shelf to make sure that the first never blows...