How do exhaust horn rings go bad? (1 Viewer)

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Dex43 said:
Ok, do you know If my theory is correct though?

Well generally testing for exhaust leaks is done while it's cold so you dont spray cold soapy water on hot metal and cause it to warp or crack, but I have seen some info on the net suggesting that small leaks from these fittings go away when the metal gets to operating temps. Just wondering if this theory is correct
Click to expand...

Ok, now your question makes more sense.

I did a smoke test on mine (cold), pressurized through the tail pipe... There was some minor seeping from the horns and the entire manifold had been rebuilt (all new rings/springs) about 10 years ago but only had about 5K miles on it. Leak was a J-tube gasket

There's no detectable leakage at operating temp.

 
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Spike Strip said:
Ok, now your question makes more sense.

I did a smoke test on mine (cold), pressurized through the tail pipe... There was some minor seeping from the horns and the entire manifold had been rebuilt (all new rings/springs) about 10 years ago but only had about 5K miles on it. Leak was a J-tube gasket

Click to expand...


succesfully fixed the manifold to head leak, all the egr vacum/exhaust leaks, pipe flanges and welds and cracks, and exhaust to intake leaks, and the heat riser leaks. I can now confirm the horns are the only thing that leaks and I have not replaced the rings because I have seen some mixed info like people even saying brand new out of box manifolds will leak at these horn fittings while cold. I guess I'll just button her up and go for a drive and hope I dont have to pull the horns again. What's a small ring leak compared to all that crap I just listed above though
 
Those rings/springs are high-grade SS. Unless they are visibly damaged you can just remove them, clean the grooves with a wire brush, clean the springs and rings (I tried stretching them out a bit but that probably did nothing), reinstall and you should be good. I've done that on a couple other cruisers with no issue. No horn leaks. You can usually see some exhaust soot trails if there is.

Do you still have the original CAT converter ?
 
Spike Strip said:
Those rings/springs are high-grade SS. Unless they are visibly damaged you can just remove them, clean the grooves with a wire brush, clean the springs and rings (I tried stretching them out a bit but that probably did nothing), reinstall and you should be good. I've done that on a couple other cruisers with no issue. No horn leaks. You can usually see some exhaust soot trails if there is.

Do you still have the original CAT converter ?
Click to expand...
Thank you, yes I did not notice and soot traces at the horn joints despite the leaks when they are cold so It made sense what i read about the expansion theory. I did pull them out and clean a bit with the wire brush but I didnt pop the rings out lest I cause one to break or bend. I'm thinking it might work to put the shop vac on suction through the tail pipe and caulk the gaps with some copper rtv. I know these cant be welded but rtv would still allow them to expand and it would be easy to clean off if it doesnt work. I really dont want to pull the manifold off again. Any thoughts on this are also welcomed. Yes I do still have the OE cat to my knowledge. It's the flat one that looks like a panini press and its rusted to s***. The exhaust still leaks cat back for now but I dont think that will affect my back pressure so I havent tended to it yet
 
Those original CATs are VERY restrictive, even more so after 35 years of clogging up -- prolly creating a lot of back pressure.

You might want to delete or replace if you're in a smog state. You can get a universal CAT for $100. Hi-Flow Magnaflow 48-State bolt in are usually around $250ish ?

In 10 years I've had to take my int/exh manifold off 3 times because that MFing J-tube gasket kept blowing out. Each time using the OE Toyota gasket.. I used a remflex last time with the correct exhaust nuts and so far so good.

Good luck with yours.
 
Spike Strip said:
Those original CATs are VERY restrictive, even more so after 35 years of clogging up -- prolly creating a lot of back pressure.

You might want to delete or replace if you're in a smog state. You can get a universal CAT for $100. Hi-Flow Magnaflow 48-State bolt in are usually around $250ish ?

In 10 years I've had to take my int/exh manifold off 3 times because that MFing J-tube gasket kept blowing out. Each time using the OE Toyota gasket.. I used a remflex last time with the correct exhaust nuts and so far so good.

Good luck with yours.
Click to expand...
I am a firm believer in rtv, I had the j pipe gasket disintegrate so I put copper rtv on it with new nuts and torqued it down real good so we will see how it holds. Now withthe cat I am not in a smog state so I can delete it no problem, thanks for the advice. If I delete it do I need to advance the timing or anything or can I just tune it at the carb?
 
You can advance timing slightly, usually about 10 BTDC is max, but it helps to have the distributor recurved to handle it. There are threads on where to get the springs etc, or there are a couple vendors here who will rebuild/Recurve the dissy for you.

Cut the flanges off the old CAT and use for the delete pipe.
 
Spike Strip said:
You can advance timing slightly, usually about 10 BTDC is max, but it helps to have the distributor recurved to handle it. There are threads on where to get the springs etc, or there are a couple vendors here who will rebuild/Recurve the dissy for you.

Cut the flanges off the old CAT and use for the delete pipe.
Click to expand...
For sure, and if I use a universal cat does it still need time?
 
No, timing change not necessary. You can replace the CAT and leave everything else as is.
 
I use Magnaflow, but whatever is listed on Rockauto should be fine and probably cheaper. Your local muffler shop (if not a chain) will probably be more help.
 
Spike Strip said:
I use Magnaflow, but whatever is listed on Rockauto should be fine and probably cheaper. Your local muffler shop (if not a chain) will probably be more help.
Click to expand...
Does your cat maintain the temp sensor?
How about the mufflers on these trucks, are they restricting too?
 
@OSS So are you saying remove the riser flapper, and plug the holes, no need for the block off plate? Thanks
 
@Dex43 At least it sounds like your manifold is not back on the truck!? Mine is on and running....and leaking..... :bang:
 
Dex43 said:
Thank you, yes I did not notice and soot traces at the horn joints despite the leaks when they are cold so It made sense what i read about the expansion theory. I did pull them out and clean a bit with the wire brush but I didnt pop the rings out lest I cause one to break or bend. I'm thinking it might work to put the shop vac on suction through the tail pipe and caulk the gaps with some copper rtv. I know these cant be welded but rtv would still allow them to expand and it would be easy to clean off if it doesnt work. I really dont want to pull the manifold off again. Any thoughts on this are also welcomed. Yes I do still have the OE cat to my knowledge. It's the flat one that looks like a panini press and its rusted to s***. The exhaust still leaks cat back for now but I dont think that will affect my back pressure so I havent tended to it yet
Click to expand...
Those rings are meant to have movement that’s why they’re made the way they are. Adding sealer will prohibit movement. I didn’t add any to mine when I replaced them. I simply cleaned the landings on the horns and reassembled.
 
Dex43 said:
Does your cat maintain the temp sensor?
How about the mufflers on these trucks, are they restricting too?
Click to expand...

My CAT has the port for it and I have the Sensor installed , but I'm in California... You don't really need the Temp sensor, particularly if you're going to desmog, at some point. I've seen quite a few trucks where the muffler shop has simply cut the sensor lead off at the chassis and the truck just runs along fine. It's an input for the Air Injection system when the CAT is running too hot, but that's on those old bricks. New ones are much more efficient and less restrictive. Also, it will allow the Muffler shop to just weld in a simple universal CAT (cheap) so your exhaust won't smell. That's all you really need. It also keeps the truck a little quieter.

DON'T let them CUT the sensor! Those of us who are stupid enough to still be living in Kalifornia or New York need these and will buy it from you :)

The Sensor has a connector under the carpet, under the E-brake handle. Just lift the carpet and disconnect it and pull the floor grommet and pull the cable through. You've just got yourself $50 for a working Thermosensor.

Mufflers can be restrictive if they're old and clogged. The shop will let you know if they think it's bad
 
NeverGiveUpYota said:
Those rings are meant to have movement that’s why they’re made the way they are. Adding sealer will prohibit movement. I didn’t add any to mine when I replaced them. I simply cleaned the landings on the horns and reassembled.
Click to expand...
Yea I do understand they are meant to move, but I would think rtv would break long before the metal
 
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