1997 FJ80 Exhaust Manifold Replacement

[SFSurfer]

I just failed my smog test on my 97 FJ80 and after talking with the tech it looks like I have a pretty major exhaust leak at the manifold and most likely needs replacement. Question is how difficult is it to replace myself? I’m a weekend warrior mechanic at best, but the 80 is used as our weekend camping vehicle and with winter coming I don’t see us using it anytime soon, thus I have some time to learn via trial by fire. But just want to get an idea of what kind of fires I may lead myself into replacing a manifold for the first time?

 

[nukegoat]

Not bad at all. The bolts can suck to remove but it's basically an unbolt and bolt on thing. My opinion may vary from othera

 

[jfz80]

Manifold crack or blown gasket?
Id make sure its not the manifold to Y-pipe union first. More common and easier fix.

 

[SFSurfer]

Manifold crack or blown gasket?
Id make sure its not the manifold to Y-pipe union first. More common and easier fix.

I’m not sure. The tech only told me I failed due to a leak before the cat and most likely the manifold needed replacement. Is there a way to dive in and pin point the problem?

 

[Ronny Grady]

Weird - post the report

manifolds don’t usually fail - maybe gaskets

 

[inkpot]

Weird - post the report

manifolds don’t usually fail - maybe gaskets

Agree. Could be the gasket between the manifold and the head, but more likely the gaskets at the bottom of the manifold to the down pipes.

 

[jonheld]

I’m not sure. The tech only told me I failed due to a leak before the cat and most likely the manifold needed replacement. Is there a way to dive in and pin point the problem?

He is likely referring to the Y-pipe as the manifold. That is what typically rots and cracks. In any case, it should be fairly easy to tell just be running the truck at idle and looking and listening and feeling.

 

[SFSurfer]

You guys are right on the spot. Found the leak via the picture. It looks like it’s just the seal from the bottom of the manifold and pretty straight forward to fix. Any tips?

 

[Spdstr280Z]

Agreed based on my limited experience. These manifolds are beefy, and made in two banks of three which I assume was wisely done to even further reduce the chance of cracking a single long manifold. My down pipes were OK, but the cats themselves were rusted through in places. Like others, I would start there. PB Blaster, Kroil, etc. is your friend...

Good luck,

Jason

 

[Spdstr280Z]

LOL, you beat me by seconds. Glad you found it.

Jason

 

[jonheld]

You guys are right on the spot. Found the leak via the picture. It looks like it’s just the seal from the bottom of the manifold and pretty straight forward to fix. Any tips?

Purchase new OEM studs, nuts and donuts to seal it up properly.
Part numbers are in post #34 in this thread:

Magnaflow now owns Bosal

Ordered a non carb compliant off Amazon and this showed up (even with prime shipping) straight from magnaflow. Wonder if they either pulled the regular after complaints of the bosal or are out of them.

forum.ih8mud.com

 

[jfz80]

Yep ^^^ new studs and nuts make it a nice easy install and chances are a stud or two will back out anyways. A 3/8” 18” extension + 3-6” with wobble end and deep socket make it a lil easier. Wear glasses.

 

[SFSurfer]

Last question what is the part # for the flange called? I can’t seem to track the part down online or at least doesn’t seem like the right part.

 

[SFSurfer]

Just saw your previous post, sweet! Thanks for all the advice!

 

[Cruiser804]

Exhaust Manifold Downpipe Kit Or buy the kit from witts end Temporary link to the kit Exhaust Manifold Downpipe Kit

 

[SFSurfer]

Just a quick update I dove into this evening and was able to remove the exhaust manifold, replace the seals so I “think” I should be good for the smog retest. We shall see??

 

[KenH]

good luck bud, if idle you not smelling strong odor from the tail pipe you should be good, rev up 2500 rpm and no smell you're good to retest.

 

[Heckraiser]

Like @jonheld said, get new studs while you're at it. This guy helps immensely with getting the old studs out. Put it on a long extension and go to town.

:edit: oops, late to the party!

 

[Dissent]

You guys are right on the spot. Found the leak via the picture. It looks like it’s just the seal from the bottom of the manifold and pretty straight forward to fix. Any tips? View attachment 2146741

Is this just pressurized with a shop vac and sprayed with soapy water?

 

[skhochay]

replacing manifold is very simple, unbolting can be an agony, use new parts especially new OEM gasket DO NOT use some aftermarket crap or you will be doing it again in 1-2 years speaking form experience