Exh manifold leak

I recently started to get ticking under acceleration and suspected a leak at the exh manifold. Today I hooked up a shop vac to pressurize the exhaust and found leaks in the area of the welds connecting the pipes to the flange on both #4 & 6 tubes. Also found small leaks at the gaskets after the primary cats. I am considering trying to patch these up with tig welds, but fear that the corrosion has made the tubes too thin and will just blow through the remaining metal. Has anyone had this issue and successfully patched? Does anyone know what alloy this is? I am guessing something in the 400 series. I suppose that I could bend a piece of ss and weld it to the tube further away and then tie it into the flange.

Assuming I cannot repair it, any recommendations on an aftermarket manifold/cat? Unwilling to spend whatever insane price toyota asks for these on a truck with 180k miles. I know many aftermarket cats don’t last that long and hoping to get some wisdom from the group here. Don’t need carb compliance.

thanks in advance for your help.

 

Difficult to say without pics, but for the cat flange, could you simply change the gaskets? I just did it last weekend, about 100$ worth of parts. The 3 cat gaskets were completely gone, lotsa noise coming from em and lots of air. I Though it would be a quick job, but a few bolts broke off which made the whole thing take most of the day. I also needed to reinforce one of the cat support with a bit of welding and a small piece of angle iron, it was rusted through where it joined the flange. Now the engine is purring like it was new, well, almost . I'm at 150K miles, salted roads.

 

Well fuck.

what region are you in? Asking regarding rust.

I’d say decent aftermarket. Or upgraded. Question is if you need CARB or not.

there is headers. But I’ve heard from people who have them they’re too loud. I don’t know if there’s ways to quiet them to a nice level like if a resonator or something would do that.

you could technically try and find a decent used set.
I did exactly that on another car that was like $50 for a 4cyl.

from a less rusty environment. With lower miles. That doesn’t leak. That last part is the big one.
Plenty of junkyards lie about parts “it’s working” when it doesn’t. Many true stories.

 

Cat is working well so like to keep the assembly, due to cost. After more thinking on this, i am leaning toward covering the weak areas with silicon bronze. You use less heat, as no puddle is formed and may get away without blowing through the thin metal.

 

yea , not worried about the gasket leaks. That will all come apart when i pull the manifold and will replace all the gaskets.

 

will look for used but not optimistic. Around here thay are stealing cats left and right. Figure that wouldn’t be happening if you could find them for #50 in a junk yard. No need for carb compliance. What is a good aftermarket cat? Several brands out there.

 

if a person upgrades to something else, they may sell stock.

If a person steals cats, and they have a whopping 2 brain cells, they go for something well known to be high in precious metals like a Prius and little else.
If they have one brain cell, they steal a muffler.

Doesn't have much to do with anything. They do it to sell the precious metals.

 

Sadly many folks with 2 brain cells. Had one stolen from our 15 year old honda odyssey and my son had one stolen from a 20 yo cherokee. I assumed they were selling them to disreputable installers, but you are probably right aboutcutting them open and selling the guts as scrap.

 

Someone stole cats off some trucks at work. The report said they were worth $400

 

Thought I would post an update. Pulled the manifold this week and brazed thae area where tubes attach to the flange plate. Had a fair amount of pitting on the edges of the gasket sealing area on the flange, so brazed on new material and ground flat. Tick is gone and expect better mileage now that the ecu isn’t seeing a lean condition. Not a fun job, but surprisingly got the manifold off without breaking any studs. The #2 lower nut is a bear to get to and had no idea how i was going to heat it without removing the compressor and alternator. Surprisingly, that nut came off easily without heat. Luck was on my side.

 

Do you have a pics of what the manifold looked like and what you did? My 2010 is leaking a bit at the manifold and considering my options.

 

Sorry but did not take any pics. It was unclear if the tubes were pressed into the flange or welded in, but suspect the former as the tubes were a sandwich of three steel pieces and over time it either loosened a bit or corrosion caused the leakage. Once hte manifold is off, you have a good view from the head side of the flange and have clear access to fill in the area between the tubes and flange. I used silicone bronze and applied with Tig. Should be a one hour job for a welding shop.

You can connect your shop vac to the tailpipe and blow air into the exh. THen spray soappy water on to the manifold and see if the leaks appear from the tube/flange area or from the gasket area. You have good viewing through the wheel well. If it is the gasket, the welder can add the brazing onto the flange area and then grind it down flat for a better sealing interface. You grind and check with straight edge; RInse and repeat. I don't think mine was leaking in this area, but the amount of metal left to seal in a couple spots was pretty thin so did it as a precaution. I reinstalled with a fel pro gasket, as it was the thick style that compresses and thought it would do better at sealing an imperfect surface. Also used the ultra copper RTV to help. THe oem is thin SS and those don't do well with imperfect mating surfaces. Those only work well clean and flat surfaces.

 

Thanks. Do you think the manifold is stainless or mild steel?

 

based upon the rust I observed, I doubt it is stainless. The tubes may be SS, but not the flange.

 

Did you do anything yet?

Just had both manifolds replaced on my 2011. It had been noisy for a while (ticking). Nice and quiet now. FWIW I used Walker "Ultra" replacements p/n 16390 and 16391. Aftermarket pipe gaskets, toyota manifold gaskets, toyota studs & nuts. Saved a pile having a Toyota-knowledgeable friend of a friend do the work, and getting the manifolds myself from another parts supplier.
I still have the old manifolds sitting in my garage if pics would be of any use/interest to anyone.

 

Haven't done anything yet. Mine leak a little bit where they meet the cylinder head...the price of new ones is very high, espeically OEM.

Was yours leaking where manifold meets the cylinder head?

 

I'm not really sure where it was leaking. It doesn't look like the gasket was leaking, but it's not my area of expertise. I will post some pics.

 

Curious, do you live in the Rust Belt?

 

I sure do.
Also identified that the leaks were holes in these areas:

 

I hook a shop vac up and blow air into the exhaust (truck not running) .... then sprayed soapy water in the exhaust manifold.....I have small leaks in the same area.