O2 sensor stud thread pitch doublecheck - is it M8x1.25 ? (1 Viewer)

[LINUS]

Had a weird thing happen - primary O2 sensor blew its’ nuts (joke there somewhere) & I came out to a raspy sounding 80 today.

I found a universal gasket & bought some temp cheap nuts in M8x1.25 - was judging from under the 80 at dusk w/o a flashlight.

When I go to chase the stud threads tomorrow, am I using the right die going at it with a M8x1.25?

Will sensor safe RTV hold up in that primary O2 location?
I’m betting there’s some pitting on the flange & I can only expect using either copper or aluminum Never-Sieze on that flange will booger my O2 sensor itself. Right?

The gasket isn’t the metal compression ring like before, it’s that tan ceramic with a metal core, so hoping it’ll deform enough to seal, with or without whatever RTV/ Never-Sieze you guys think I can skate by with on this semi-experimental / hopefully permanent fix.

 

[Tools R Us]

You have rust pitting, likely buggered hardware, could half ass it, or the opportunity to do it correctly by getting new dealer parts.

 

[ToyotaMatt]

Had a weird thing happen - primary O2 sensor blew its’ nuts (joke there somewhere) & I came out to a raspy sounding 80 today.

I found a universal gasket & bought some temp cheap nuts in M8x1.25 - was judging from under the 80 at dusk w/o a flashlight.

When I go to chase the stud threads tomorrow, am I using the right die going at it with a M8x1.25?

Will sensor safe RTV hold up in that primary O2 location?
I’m betting there’s some pitting on the flange & I can only expect using either copper or aluminum Never-Sieze on that flange will booger my O2 sensor itself. Right?

The gasket isn’t the metal compression ring like before, it’s that tan ceramic with a metal core, so hoping it’ll deform enough to seal, with or without whatever RTV/ Never-Sieze you guys think I can skate by with on this semi-experimental / hopefully permanent fix.

The " Toyota Phenomenon " u experienced I call O2 Sensor Flange Blow Out , Its real and has happened to dozens of toyota

vehicals I saw come into the dealership service dept. & Now my own shop

I just repaired a 2004 tundra 4.7 with this exact problem

what happens is after age & time , the Two 8 x 1.25 Hex nuts rust away leaving only the studs with trace elements of the nuts stuck on the threads , which are made of a metal with a

higher alloy content that Don't rust as easy , that why your studs stayed in place

the 2 nuts are a high carbon steel Locking Flange style


U need to approach this repair correctly in order for it to last long term :

- Don't use universal aftermarket parts like the gasket and nuts from the auto parts store

- Only Use gasket 89466-20020-83

- Nuts 90179-08059

- Permitex Copper High Heat Gasket Sealer Repair # 81878


- Yes , Chase your studs with a Die , using oil as a cutting fluid , remember the nuts were a Grade #8 or greater carbon steel metal , the studs are also a like a grade #5 or greater

- brake clean off the oil good when finished

- use a wire brush to prep clean the metal of the exhaust pipe mating flange surface and the studs below the threads

- apply MED. skim coats of copper sealer to both sides of the gasket and both metal surfaces , the flange and pipe ( wet them down ) with the sealer so to speak

- tighten nuts / Torque by hand firmly

- let sealer sit overnight before starting engine like directions suggest

- have some


btw,

the 2 OEM nuts & gasket at the dealer will run u under $10

 

[LINUS]

You have rust pitting, likely buggered hardware, could half ass it, or the opportunity to do it correctly by getting new dealer parts.

To start with - I’m just looking to solve the issue.

You’re right - my gasket was amazingly still there (or a 2/3 artifact that still was hanging to 1 stud). Funny thing was I only got the ‘check engine’ light during the drive home with some “fudge fix” parts at the moment I clearly heard the O2 sensor blow off the studs after mocking back in place in the parts store parking lot.

The last 1.5 days driving around it sounded louder, but I chalked it up to being “Tundra spoiled” of late - it took driving under an overpass with the PS window down for me to say “nope, I really have an exhaust leak” - no CE light though (seemed odd IMO).

@RAGINGMATT - thanks for the pics, having the real PN#’s to make the correct fix is huge - esp the shouldered nuts since the O2 gasket itself is the same for most ‘Yotas from most models of the era.

I’ll use your fix - band-aid it with my Vatozone parts tomorrow & get real new parts on the brown truck to get it nailed down permanently

Thx Matt!

 

[ToyotaMatt]

To start with - I’m just looking to solve the issue.

You’re right - my gasket was amazingly still there (or a 2/3 artifact that still was hanging to 1 stud). Funny thing was I only got the ‘check engine’ light during the drive home with some “fudge fix” parts at the moment I clearly heard the O2 sensor blow off the studs after mocking back in place in the parts store parking lot.

The last 1.5 days driving around it sounded louder, but I chalked it up to being “Tundra spoiled” of late - it took driving under an overpass with the PS window down for me to say “nope, I really have an exhaust leak” - no CE light though (seemed odd IMO).

@RAGINGMATT - thanks for the pics, having the real PN#’s to make the correct fix is huge - esp the shouldered nuts since the O2 gasket itself is the same for most ‘Yotas from most models of the era.

I’ll use your fix - band-aid it with my Vatozone parts tomorrow & get real new parts on the brown truck to get it nailed down permanently

Thx Matt!