Exhaust(ing) leak(s) (4 Viewers)

[2mbb]

I have a systemic exhaust leak that occurs at the junction between the exhaust manifold and the. Two years ago, after my biannual smog check I replaced the gasket in positions 17410B abecause the smog tech commented he could have failed my test. Two years later (and maybe 2000 miles) and it's leaking again (still) pretty much out of the same space. I use a plastic tube to listen for the leak and it's coming from a space between two of the flange bolts. I have the gaskets and am ready to replace them again. I just wanted to check for some advice what to do different, it anything.

Two years ago, I dropped removed the pipe 17410 and replaced the studs in the exhaust manifold 17152 with the newer style that @ToyotaMatt offers. I must have replaced the pipe and gaskets at both ends, then tightened first the flange connection at the exhaust manifold, then the one at the catalytic convertor. I must have inspected the flange connections, but didn't notice any gross issues.

I have a two sets of new toyota gaskets as well as something I got from Rockauto (FelPro brand). Quite frankly they all look pretty similar.

Thanks.

 

[CruiserTrash]

Mine leaks from there about a month after I install a new gasket … every time. For a while I was changing that pretty regularly and then gave up. Maybe pop a new one in before the smog test and run it. At least you know the studs are new and the nuts will come off.

Oh, and remember to tighten the three nuts one at a time, little by little. Obviously this isn't a hyper critical component, but if you’re trying to eliminate the leak it couldn’t hurt.

 

[2mbb]

Mine leaks from there about a month after I install a new gasket … every time. For a while I was changing that pretty regularly and then gave up. Maybe pop a new one in before the smog test and run it. At least you know the studs are new and the nuts will come off.

Oh, and remember to tighten the three nuts one at a time, little by little. Obviously this isn't a hyper critical component, but if you’re trying to eliminate the leak it couldn’t hurt.

Thanks. Yes, my smog test is due again, so I'm getting prepared.

 

[Spike Strip]

It's very VERY common for the weld under the down-pipe flange to have a small crack. Warm up the engine and use a telescoping mirror to check the back of the pipe welds for a hairline crack. Also, check to make sure the pipe flange is not warped. Flatten with file if it is.

Also, it's 'Biennial' unless you are actually getting your smog check twice a year .... Sorry, I be a pedant.

 

[OSS]

Yeah a leak there isn’t necessarily a given. Mine never leaked and the exhaust pipe was on & off maybe 3 times in 30 years for something else.
Like Spike said, either something is cracked or warped.

 

[Spike Strip]

I found mine was cracked inadvertently when I used a smoke machine inserted through the tailpipe to see if the J-pipe was leaking (again). Saw smoke leaking from a small crack facing the block, it also was leaking where the pipe inserts into the flange (as above). I removed the pipe and took it to an exhaust shop and had it TIG welded. So far so good .... (fingers crossed).

 

[2mbb]

Also, it's 'Biennial' unless you are actually getting your smog check twice a year .... Sorry, I be a pedant.

Very important discussion...I had forgotten about Biennial, which I think is a "better" word. At work we schedule maintenance "semiannual" ( twice per year) but also "biannual" (once every two years) I thought, like you said they both mean twice a year. I found this one defintion, and that's what stuck in my head. Thanks!

 

[2mbb]

I will try and check for cracks. I was underneath for a few minutes earlier today. Two nuts came off easily; one of the studs came out (but couldn't get the nut off the stud). I remember now that the threads in the exhaust manifold for the one stud were a little messed up, so now I'm thinking how to chase them. I'm going to see if I can come in from the side or at move that little skid plate out of the way. Things are quickly snowballing.

I know I torqued the nuts when I installed them two years ago, but I probably never re-torqued them. They were somewhat loose. they don't "spin off" because they are oblong, but there was very little break loose torque needed.

Thanks. mbb.

 

[Spike Strip]

Either way, the every-two-year smog check is a giant PITA in Kalif.

FWIW, the Calif definition of an 'Historic Vehicle': "... is considered a classic in California if it's at least 25 years old, was manufactured after 1922, and is of historic interest. When a vehicle in California meets these requirements, the owner can register it as a historic vehicle, which will allow the car to use special license plates."

I think now with prices, and interest is old Land Cruisers, one could strongly argue its' 'Historic Interest'. I believe with Historic plates you're exempt from inspections.

Wanna try ?

 

[g-man]

The flange can get warped or pulled out of it's flatness by overtightening the stud nuts. I bought a new flange (ebay I think) and had it made to a pipe at an muffler shop to solve the problem. A fix that helped for a few years was to double up on gaskets. I tried grinding over the areas where the holes are on the flange but it still leaked. Also make sure the exhaust joint above that where the heat riser valve resides in NOT leaking. Those leaks can bounce off the manifold and run down the pipe and feel like a flange leak.

 

[g-man]

I just went through my entire exhaust dilemma and I feel for you. I took it to the muffler shop for the flange. They found one stud hole at the flange was 1/2 way stripped so they decided to drill and re-tap it with standard thread. And they did it at an angle because they were doing it upside down on the lift. so they put this giant stud in angled with wrong threads. Then they wallowed out one of the holes on my brand new flange to get it past their crooked stud to the point I have a very thin piece of metal left on the outside edge the flange. Then they threw out my stock toyota pipe and put the flange on a crappy piece of aluminized pipe that is about 1/2 the thickness. After all that it still leaked. I took it back and they said I have a leak at the heat riser. This was true. I took it home and pulled it apart, scrapped the manifold that they screwed up, got a block off plate for the riser, replaced the gaskets, had the intake and manifold re-surfaced, put it all back on then had a leak at the EGR pipe. Replaced that with an SOR stainless pipe and now .....
I'm leaking at the horn joint. Holy hell. I put new rings in too and turned them right. Can't win for losing! It's a real can of worms The only good thing is the leak at the horn joint is a small tick that goes away after warm up.

 

[ToyotaMatt]

I have a systemic exhaust leak that occurs at the junction between the exhaust manifold and the. Two years ago, after my biannual smog check I replaced the gasket in positions 17410B abecause the smog tech commented he could have failed my test. Two years later (and maybe 2000 miles) and it's leaking again (still) pretty much out of the same space. I use a plastic tube to listen for the leak and it's coming from a space between two of the flange bolts. I have the gaskets and am ready to replace them again. I just wanted to check for some advice what to do different, it anything.

Two years ago, I dropped removed the pipe 17410 and replaced the studs in the exhaust manifold 17152 with the newer style that @ToyotaMatt offers. I must have replaced the pipe and gaskets at both ends, then tightened first the flange connection at the exhaust manifold, then the one at the catalytic convertor. I must have inspected the flange connections, but didn't notice any gross issues.

I have a two sets of new toyota gaskets as well as something I got from Rockauto (FelPro brand). Quite frankly they all look pretty similar.

Thanks.

View attachment 3017023

View attachment 3017024

It's very VERY common for the weld under the down-pipe flange to have a small crack. Warm up the engine and use a telescoping mirror to check the back of the pipe welds for a hairline crack. Also, check to make sure the pipe flange is not warped. Flatten with file if it is.

Also, it's 'Biennial' unless you are actually getting your smog check twice a year .... Sorry, I be a pedant.


View attachment 3017213

- i agree with Alf , you might just have a cracked weld at the front pipe flange ?


- another hard lesson is a double by mistake gaskets issue , i have done this more then once and it sucks to find out it was just that ?



- smoke test is the ONLY way here for certain ........



- this is out there now if need be , its Thicker then the oem original one by 1 SOLID size spec. too ...

Carbon Steel 2F Exhaust Manifold Flange Down PIPE KIT 1/75 -1987 FJ40 FJ60 FJ55 OEM TOYOTA Genuine Parts Updated Upgraded Special Unique Hardware TORX STuds and Locking Flange Nuts ( 3-BOLT FLANGE WATER JETTED IN-HOUSE ) - VintageTEqParts.com

OEM TOYOTA Genuine Parts FJ60 2F Engine Updated / Upgraded Exhaust Manifold to Front Down Pipe Gasket and Special...

vintageteqparts.com

 

[cps432]

If you keep blowing gaskets at that joint make sure all of your exhaust mounting brackets are tight and are not putting extra stress on the system. For years I didn’t have any support for the down pipe near the transmission. I didn’t know there was a mount there until I went to install headers and had a closer look. I suspect, in my case, there was too much sag on the down pipe which allowed for vibrations and eventual failure of the gasket. It happened 4-5 times in 4-5 years. I got really good at changing those things.

 

[g-man]

I'm not a fan of those oblong "torque to fit" nuts. If you tighten them down you can strip the stud. Or strip the stud when you try to remove them. Then you're really struggling to get the stud out. Especially if it's been in there a while with lots of heat cycles. They tend to freeze up in there. I prefer stock Toyota exhaust stud nuts.

 

[cwwfj60]

I'm not a fan of those oblong "torque to fit" nuts. If you tighten them down you can strip the stud. Or strip the stud when you try to remove them. Then you're really struggling to get the stud out. Especially if it's been in there a while with lots of heat cycles. They tend to freeze up in there. I prefer stock Toyota exhaust stud nuts.

Agreed, they lock….aggressively and ruin the stud often when removed, 1fz’s use these stock and always give me grief, 1 out of 4 guaranteed to strip.

 

[2mbb]

It's very VERY common for the weld under the down-pipe flange to have a small crack. Warm up the engine and use a telescoping mirror to check the back of the pipe welds for a hairline crack. Also, check to make sure the pipe flange is not warped. Flatten with file if it is.

Also, it's 'Biennial' unless you are actually getting your smog check twice a year .... Sorry, I be a pedant.


View attachment 3017213

Bingo. We have one winner! I took that exhaust pipe off and by carefully spraying wd40 on top of the flange where the pipe penetrates through, the fluid weeps through under the weld bead. I have a section of about 120 degrees where I can see leaking.

Otherwise the gasket looks fine, but I'll replace it when I put it all back together.

Can this be rewelded? Is there a DIY solution like a patch or tape I can use?

Thanks.

 

[Spike Strip]

The pipe is Stainless steel and the flange is carbon steel and I imagine that's what leads to the eventual cracks. If the pipe is off, I'd find a good welder to fix it, if you don't weld yourself. If it's still on the truck, a muffler shop should be able to get in there with a stick welder. You can have an O2 bung welded in too, if you don't already have one for an A/F meter.

As far as those muffler-tape wraps go, they're crap booty fab.

Good mom 'n pop muffler shop is your best bet, or a Hot Rod place that does exhaust.

Glad you found it.

 

[2mbb]

Went to a local muffler shop and had the leak welded up. Got it back installed and am now waiting in line for my biennial smog check. Wish me luck!

 

[Spike Strip]

Fingers

 

[2mbb]

Well I did pass smog (I'll post my results in another thread). Funny thing is, the tech warned me that I have an exhaust leak, and that he will let me slip by this time! I told him my story, but sure enough, when I got the truck back, I checked and the exhaust is leaking again or still. Not sure what I will do next, or how quickly...In some sense I have two more years.

I did not check that the new weld was actually sealing, but I suppose that is on the list. I'll also get under my truck with the stethoscope and see if I can pinpoint where the leaks is. I guess I could also try a smoke test--I'll have to research how to do that.

Thanks for the help and support!