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TT_Vert · 01-04-2022, 03:43 PM

So on my particular 460 the tube pressed into a flange that is bolted to the exhaust manifold w/ 2 bolts. The flange/tube are stainless so they must be TIG'dAND they are hard to get to to even get a torch in there. I'd like to replace the entire piece however the only PN on it is JUST for the check valve. Why, i do not know. I'm pretty sure the bolts that hold this flange on are going to break which means I'm SOL anyway and would have to pull the manifold to get them extracted. If I did that I'd put long tubes on it but I don't want to spend any more money on this thing given it's not that valuable to begin with.

Ideally I'd be able to get a TIG torch in there and TIG it w/ flange in place but I don't know that's possible to get a good bead around the entire thing. I don't have a TIG so i'd have to take it somewhere to do. It has to be done from doghouse unless I drop the Y pipe as there is about 1/2" access between the frame/Y pipe to get access to it. Anyone ever do this or have a PN for this tube? Here is a sample of what the tube looks like. It has a tab which bolts to the back right intake manifold bolt to secure it up top. The side on the opposite side of the check valve is what presses into the stainless flange on the exhaust manifold.

Right now I just tapped the hole in the exhaust manifold and put a 3/4" bolt in it but I'd really like to get the SMOG stuff working again as I just sources and and installed an air pump. My OCD got the best of me and those thermactor codes were killing me.

153stars · 01-20-2022, 07:24 AM

We use some expensive silver solder rods that will solder/braze most anything use it on stainless parts and brazing things to buckets and paint type cans for the lab for odd thing they want to try out. It takes a lot less heat than brazing rods but the manifold will soak up a lot of heat you probably need oxy. acetylene or acetylene/ air HVAC brazing torch.

TT_Vert · 01-20-2022, 04:18 PM

The exhaust manifolds can reach in excess of 1000 degrees, I'm going to guess the melting point of this is not much higher than this no?

Dave

153stars · 01-20-2022, 07:15 PM

It flows at about 1250f but you can choose higher temp. Silver mixes. My guess if that thin pipe was getting 1200 f it would be in way worse shape.

TT_Vert · 01-20-2022, 10:00 PM

Quote:

Originally Posted by 153stars

It flows at about 1250f but you can choose higher temp. Silver mixes. My guess if that thin pipe was getting 1200 f it would be in way worse shape.

I would say the wall thickness of this thermactor tube in question is actually about as thick if not a bit thicker than any stainless headers I've had so I wouldn't be surprised to see these tubes get very hot at the point where I need to braze/solder this. There is a ton of thermal mass in these cast iron exhaust manifolds and the tube is part of a flange that is bolted to the back of the manifold right where the Y pipe connects to the manifold so it does get warm there. It's maybe 12" from the rear exhaust port. Just unsure of exact temp.

Dave

153stars · 01-23-2022, 05:51 PM

Could you make small one two hole flange out of heavy washer or flat stock, weld to tube and and drill and tap bolt/s with exhaust rated/type gasket. Similar to some EGR tubes/valves.
If it lost its press to fit tolerance could add some braze to one side reshape to decently round, heat manifold and dry ice tube for tighter than interference fit. Might take a couple tries more or less braze.

153stars · 01-23-2022, 05:59 PM

Could you make small one two hole flange out of heavy washer or flat stock, weld to tube and and drill and tap bolt/s with exhaust rated/type gasket. Similar to some EGR tubes/valves.
If it lost its press to fit tolerance could add some braze to one side reshape to decently round, heat manifold and dry ice tube for tighter than interference fit. Might take a couple tries more or less braze.
You could also try to expand tube at business end, tape end fill partial with water ,do several freeze and thaw cycles. put digital caliper on see if any progress. The try freeze and heat to fit.

TT_Vert · 01-24-2022, 09:11 AM

Quote:

Originally Posted by 153stars

Could you make small one two hole flange out of heavy washer or flat stock, weld to tube and and drill and tap bolt/s with exhaust rated/type gasket. Similar to some EGR tubes/valves.
If it lost its press to fit tolerance could add some braze to one side reshape to decently round, heat manifold and dry ice tube for tighter than interference fit. Might take a couple tries more or less braze.
You could also try to expand tube at business end, tape end fill partial with water ,do several freeze and thaw cycles. put digital caliper on see if any progress. The try freeze and heat to fit.

"If" I could get those flange bolts out I could just mark it and take it in to be TIG welded. The bolts have been in that cast iron manifold for nearly 25 years and the bolts are very hard to get at and impossible to get leverage on. I may take some MAP gas to the bolts and see if I get lucky but I usually have the bolts break off when they've been sitting in a cast iron manifold for that long. IF the bolt breaks then that manifold would have to come off to fix that. The 460 exhaust manifold bolts are notorious for breaking off in the head as well. You can see the downward spiral I'm on if i do try to remove this flange and break a bolt off. That's why I'm trying to fix this in place.

I did try to expand the tube and the wall thickness is quite thick and given there is only about 1" of curve before the press fit it'd be hard to hammer it back in. Plus there is pretty much no room to wield a hammer in there. I also don't want it popping out again while on the road with it so expanding and trying to hammer it back in is out of the question. I'm actually assuming it's press fit by how it popped up and that I do not see any mechanical bond or indication of such but i'm not 100% sure on this. Not that is matters.

Dave

TT_Vert · 04-03-2022, 03:12 PM

Well as suspected a bolt broke. The first one I was able to turn about 1/16th a turn, go back the other way and then repeat until it loosed up. The other one started to move as well but unfortunately broke. There wasn't even an indication is was about to yield either. It wasn't very corroded from what I can see either which i find strange. With that said, If i had room to get an easy out in there I could probably extract it but w/o dropping the exhaust it's not happening as the frame rail/Y pipe give me no access from bottom and there is no way I could do it from the top. Given the flange is some type of ferrous metal and the tube is stainless I have to assume this was press fit. Oddly there is no interference fit any longer and it slides in/out with easy. So I suppose would I could do is expand the ID of the tube, heat the tube and cool the flange. My issue is if it were to pop out again I have to do another roadside repair that I don't want to have to do on a hot engine.

If anyone has any source for this tube it'd be extremely helpful as I could probably use copper RTV and one bolt for a leak free setup. As of now I just have a 3/4" bolt in the hold to plug it. I know this would be fine forever but it just annoys me.

Thanks much,
Dave