How do exhaust horn rings go bad? (2 Viewers)

[DFXR]

'85 FJ60, smogged. I've got a nasty leak at the rear slip joint / horn on my manifold. Confirmed it with a blower up the pipe and some soapy water. It really sucks (blows) under load.

Here's the thing - I put this manifold on exactly 2 years and less than 2K miles ago, and at that time it was a zero-mile NOS unit that I was lucky to find. The rings on the horns looked good (to me) when I inspected them, and on it went. I had no reason to think the rings would go bad so soon. I did not use any copper sealant inside the horns because at the time I didn't know that was a thing, and even if I did I probably wouldn't have thought I needed to.

What do you think happened? Did the little wave springs give up their tension after sitting all those years, and now the rings won't seal? I can't see the rings themselves going "bad" or getting brittle given that they saw so few heat cycles. My previous manifold had close to 220K on it and while it had some issues, the rings weren't them.

There are so many ways to screw up a manifold removal/replacement, and I really expected something else to come back and bite me long before any problem with the rings.

I am moving from denial into acceptance of the fact that I need to do this job again. Current plan is to refurb the original manifold, including new rings of course, so the truck isn't dead in the driveway for too long.

 

[OSS]

Rust.
They maybe didn't seal well in the very beginning due to oxidation.

If you take them apart and clean/polish all the contact surfaces with 1000 grit wet dry emory paper wet sanded with WD-40 to get everything clean— I betcha they won't leak there again.
The springs & rings are probably fine. My bet is a ring got hung up in its groove- preventing it from expanding against the manifold inner wall.
Also make sure that the two ring gaps are opposed from each other.

 

[Spike Strip]

The Rings/Springs are a high-quality Stainless Steel. Unlikely they're bad. Before taking it apart, try banging (gently) on that horn with a mallet or CAREFULLY with a ball-peen, if you can get to it (underneath the truck?) and see if it frees up something. You can spray some aerokroil or equivalent and let it sit overnight then hit. Stuff will just burn off when you fire it up.

 

[DFXR]

The Rings/Springs are a high-quality Stainless Steel. Unlikely they're bad. Before taking it apart, try banging (gently) on that horn with a mallet or CAREFULLY with a ball-peen, if you can get to it (underneath the truck?) and see if it frees up something. You can spray some aerokroil or equivalent and let it sit overnight then hit. Stuff will just burn off when you fire it up.

Thanks - I have tried that with Kroil and a long aluminum drift, but I could definitely try harder. I'll keep at it. The hardest part is getting a good angle on the spray.

(Edit: if you lay under the truck, you can actually get a can of Kroil upright into the cavity next to the rear joint, and the spray tube on this can is skinny enough to jam into the gap there)

In the meantime I am taking apart my original manifold and getting my head around refurb'ing it. Turns out it has the block-off plate between the int/exh, and I never even knew. One less thing (trimming the flapper) to do, and the plate is still in good shape.

Do you run one or two of the plate? Cruiseroutfitters says buy 2 in the description on their website.

 

[Spike Strip]

Do you run one or two of the plate? Cruiseroutfitters says buy 2 in the description on their website.

One Plate

Edit: Read the description on COs website - It says "We recommend order (2) of the corresponding heat riser gasket (EGEX60031 or EGEX61011) as well as associated manifold, carb and exhaust flange gaskets".

So they're saying one plate, two gaskets

If you run the plate, you'll have to lock the butterfly in the open position so exhaust is directed to the downpipe. Or cut it. Or remove it entirely and weld the holes close with a plug.

@ToyotaMatt has posted pix of this, before.

 

[Spike Strip]

exhaust manifold leak at the heat riser bushings

After replacing my carb and dizzy, I finally got my 82 FJ40 (2F) up and running. Unfortunately, I found a leak in my exhaust manifold. Seems the manifold is leaking out the sides where the heat riser bushings pass from the inside to the outside. Any ideas on how to repair or permanently seal...

forum.ih8mud.com

 

[DFXR]

exhaust manifold leak at the heat riser bushings

After replacing my carb and dizzy, I finally got my 82 FJ40 (2F) up and running. Unfortunately, I found a leak in my exhaust manifold. Seems the manifold is leaking out the sides where the heat riser bushings pass from the inside to the outside. Any ideas on how to repair or permanently seal...

forum.ih8mud.com

I've been wondering about these bushings. I can pick up a tiny leak there on my currently installed manifold (on the side opposite the coil).

On my old manifold, now apart on the bench, the bushings are definitely a weak point, on both sides.

Can I pass the CA visual with no heat riser? I would tap and plug, and be using the block off plate inside. I'm not worried about warm up time.

From the link you sent, it sounds like @Fast Eddy has a CA-smogged cruiser with no heat riser. (I bought some 33x9.5s from him a while ago.... maybe he'll chime in)

If I have to keep it for the visual, the flapper on the old manifold is already trimmed and it seems like I could back out the mounting stud a little and then use it to lock the flapper in the Hot position. Is that how you lock it out? See pic below.

Or does it even matter with the block off plate in place?

But I'll still have to deal with the bushings.

 

[OSS]

Can I pass the CA visual with no heat riser? I would tap and plug, and be using the block off plate inside

I did. Never a problem at my smog shop in SoCA. There's so much other vacuum crap going on inside the engine bay that I'm sure the heat riser is the last thing on a smog tech's mind since it's not something anyone usually tampers with.
Also there's no visual check box for it on the smog report.
A machine shop removed the heat control flapper for me (I didn't ask them) and they tapped & plugged the hole. They said they remove every heat control valve on every FJ60 manifold that comes into their shop - cuz it can stick open and overheat the intake.

When the heat control valve is completely removed, like mine was, the exhaust sounds much different when driving. It's louder and can resonate at certain RPMs. Not annoying but noticeable.

I brought one of those block off plates (from SOR) for them to install between the manifolds and the owner of the machine shop talked me out of it (even in SoCal). He said he doesn't install them (and was familiar with them) and insisted I shouldn't use it - so I didn't.

I think once the heat control flapper is gutted out of the manifold, the manifold won't overheat. The whole purpose of the flapper was to quickly heat up the manifold for emissions purposes - then get out of the way when it got up to temp.

 

[Spike Strip]

I've been wondering about these bushings. I can pick up a tiny leak there on my currently installed manifold (on the side opposite the coil).

On my old manifold, now apart on the bench, the bushings are definitely a weak point, on both sides.

Can I pass the CA visual with no heat riser? I would tap and plug, and be using the block off plate inside. I'm not worried about warm up time.

From the link you sent, it sounds like @Fast Eddy has a CA-smogged cruiser with no heat riser. (I bought some 33x9.5s from him a while ago.... maybe he'll chime in)

If I have to keep it for the visual, the flapper on the old manifold is already trimmed and it seems like I could back out the mounting stud a little and then use it to lock the flapper in the Hot position. Is that how you lock it out? See pic below.

Or does it even matter with the block off plate in place?

But I'll still have to deal with the bushings.


View attachment 2362586

Technically, you can not pass smog with the heat-riser removed, but like OSS sez, it's difficult to see, with the insulator in place over the intake, and the tech would have to get under the the truck and look up and KNOW what they're looking for to see it.

If I had known about that technique I would have done mine that way instead of just locking the butterfly open. It's just a further restriction on an already restrictive exhaust.

 

[DFXR]

Thank you both. I'm going to keep working on freeing up my horn rings but Plan B will be refurbing the old manifold without a heat riser.

Speaking of which - the heat sink lower section inside of my intake manifold is coated in this white stuff. Some kind of spray-on thermal paste? Feels like white lithium grease but I did not think something that mild could handle manifold temps. Whatever it is looks pretty good after 15 years of use.

 

[Fast Eddy]

Mine both have functioning flapper valves. Also both have detectable amounts of leak right at the flapper rod, but I don't think at the place you have circled. (?)

My '76 has the same manifold as you are showing, I think. My '78 has a Thermal Reactor. I would have removed the flapper if I had any way to do so. It's way the f-bomb down in the pipe and that rod is very hard steel. I was not about to attempt to saw or drill on it.

FWIW, I have the intake manifold block-off plate installed in my '78. I have never had the manifolds on my '76 apart. The 2f short block is from a 60-series or perhaps later '40 with all the other parts from the earlier motor.

I don't see how a smog tech could check if it was functioning since it's always hot when you run the test, but they could visually verify that it had the spring. It would be pretty easy to make it look like it was functional, but have the actual manifold brazed solid.

I'm getting my carby worked on again, and I suspect I will have the honor of begging some shops to run a test for me and paying the DMV about a grand in back fees soon. Woo hoo. The guy I bring my Audi to doesn't test anything older than 2000 or so. He won't even test my 80-series.

 

[DFXR]

Mine both have functioning flapper valves. Also both have detectable amounts of leak right at the flapper rod, but I don't think at the place you have circled. (?)

My '76 has the same manifold as you are showing, I think. My '78 has a Thermal Reactor. I would have removed the flapper if I had any way to do so. It's way the f-bomb down in the pipe and that rod is very hard steel. I was not about to attempt to saw or drill on it.

FWIW, I have the intake manifold block-off plate installed in my '78. I have never had the manifolds on my '76 apart. The 2f short block is from a 60-series or perhaps later '40 with all the other parts from the earlier motor.

I don't see how a smog tech could check if it was functioning since it's always hot when you run the test, but they could visually verify that it had the spring. It would be pretty easy to make it look like it was functional, but have the actual manifold brazed solid.

I'm getting my carby worked on again, and I suspect I will have the honor of begging some shops to run a test for me and paying the DMV about a grand in back fees soon. Woo hoo. The guy I bring my Audi to doesn't test anything older than 2000 or so. He won't even test my 80-series.

Thanks for the info. I circled the rod there to show that it could maybe be used to hold the flapper in the hot position if you were using the block off plate. My leak is not there.

My little leaks (not my big one) are prob the same as yours - from the bushings on either side of the flapper. I just don't know how bad those leaks actually are because there is always some other bigger leak somewhere nearby masking their noise.

If I can get away with plugging the bushings I will. I just want to know what it's like to live without an exhaust leak. Must be nice!

 

[Fast Eddy]

I know my leak is there and about how much it leaks by having a stool set up when it's cold, starting and quickly jumping up there and feeling around right when it's running fast with the choke on but still cold enough to feel around the manifold.

 

[calvinator]

77 FJ40 - Thanks for all the info, guys - I just replaced the rings and springs on my manifold horns and was wondering if you would recommend applying some sort of non-hardening paste(?) that could withstand the heat, assist with sealing, and prevent rust?? The horns feel a little loose and I'm worried they might leak. Also, do you know if you can replace the bushings on the flapper rod? Any suggestions would be appreciated.

 

[Dex43]

Hey yall I'm wondering are the horns on these exhaust manifolds meant to seal 100% all the time or only when the exhaust gets hot and the joints expand?

 

[OSS]

Hey yall I'm wondering are the horns on these exhaust manifolds meant to seal 100% all the time or only when the exhaust gets hot and the joints expand?

When I replaced all the rings & springs on my exhaust manifold and burnished up the contact surfaces inside the socket – my exhaust never leaked again - when freezing cold or blazing hot

 

[Spike Strip]

Usually when the exh manifold is cold, the engine is not running, so does it even matter ?

 

[Dex43]

When I replaced all the rings & springs on my exhaust manifold and burnished up the contact surfaces inside the socket – my exhaust never leaked again - when freezing cold or blazing hot

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

Usually when the exh manifold is cold, the engine is not running, so does it even matter

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

 

[OSS]

If you can't hear it or smell it, that's all that matters

 

[Dex43]

If you can't hear it or smell it, that's all that matters

Yea I guess that's a point, just hoping to get an answer before putting her back together