Topic: Exhaust manifold won't stay tight

[Lewis Hein]

This explains the mystery of that loose clamp on my exhaust pipe. Unfortunately, it was so rusty that the bolt twisted off rather than loosening.

The exhaust pipe is now hooked to the bracket with a U bolt.

[Lewis Hein [OP]]

Well, the bracket helped, but I still need new hardware. Can I get by with new nuts only, or had I better do new studs as well?

My personal instinct is new studs and nuts. But if I'm wrong, I'll happily save the trouble and expense of replacing them....

[Gnarly4X]

Well, the bracket helped, but I still need new hardware. Can I get by with new nuts only, or had I better do new studs as well?

My personal instinct is new studs and nuts. But if I'm wrong, I'll happily save the trouble and expense of replacing them....

Hey Lewis,

Unless the stud threads are buggered or they are spinning inside the head…I highly recommend that you DO NOT remove them.

Are the nuts coming lose or are the nuts loose because the exhaust gasket/manifold is leaking?

For what its worth, I already posted my solution on this below. 

Gnarls. 

[Gnarly4X]

Unfortunately, I don't think there's enough thread left to hold a jam nut.

If the stud has tight thread space you can use 2 5mm jam nuts.  They should be grade 5 or 8, or case hardened. And you'd have to be careful with torquing the first one. The jam nut doesn't need to be torqued to spec.

Just my thoughts and experience.

Gnarls.

[Lewis Hein [OP]]

The studs appear to be solidly in the head, with a few nuts religiously backing off every trip to town. Some nuts are much worse than others; There is a motley collection of hardware attaching the manifold, including quite a few aftermarket nuts and at least one or two aftermarket studs I re-bent some of the Toyota nuts to their proper triangular shape at the tip -- the one that I got most aggressive with the hammer on is holding fine. A couple of aftermarket nuts don't hold worth anything, the rest loosen up a little.

I am nervous about a jam nut -- It seems to me that if one nut backs off so fast, two will back off equally fast. I'm also trying to get this problem under control before I burn up my manifold gasket with blow-by or warp the manifold beyond repair.

[THK Matt]

The studs appear to be solidly in the head, with a few nuts religiously backing off every trip to town. Some nuts are much worse than others; There is a motley collection of hardware attaching the manifold, including quite a few aftermarket nuts and at least one or two aftermarket studs I re-bent some of the Toyota nuts to their proper triangular shape at the tip -- the one that I got most aggressive with the hammer on is holding fine. A couple of aftermarket nuts don't hold worth anything, the rest loosen up a little.

I am nervous about a jam nut -- It seems to me that if one nut backs off so fast, two will back off equally fast. I'm also trying to get this problem under control before I burn up my manifold gasket with blow-by or warp the manifold beyond repair.

nut - split washer - nut

[Gnarly4X]

I am nervous about a jam nut -- It seems to me that if one nut backs off so fast, two will back off equally fast. I'm also trying to get this problem under control before I burn up my manifold gasket with blow-by or warp the manifold beyond repair.

Hey Lewis,

Something doesn't make sense to me.  Torquing down exhaust manifold nuts or header nuts is not rocket science.  You torque them down, recheck, retorque if necessary, recheck... if the nuts are coming loose, they are not properly torqued, or the gasket is failing or burning.

Jam nuts work, that's why they are called "jam nuts".

There are millions of header and exhaust manifolds torqued down and never come loose!

Gnarls.

[Lewis Hein [OP]]

nut - split washer - nut

I wish. People have tried split washers on this manifold before, but they lose their temper and become useless within a few miles.

Something doesn't make sense to me.  Torquing down exhaust manifold nuts or header nuts is not rocket science.  You torque them down, recheck, retorque if necessary, recheck... if the nuts are coming loose, they are not properly torqued, or the gasket is failing or burning.

No, it's not rocket science, but you omitted to mention new hardware. Based on the discussion in this thread, and my experience with "new-ifying" some of my nuts, the evidence is pretty conclusive at this point that I need to get new hardware or it won't stay tight. Everybody says to replace those nuts after each use, and they are least on use #4 (not counting numerous retightenings)

The only remaining question is: will new nuts be sufficient, or do the studs wear out as well? I want to fix this once and fix it right, but I don't want to fix things that don't need it.

[Snowtoy]

I am nervous about a jam nut -- It seems to me that if one nut backs off so fast, two will back off equally fast. I'm also trying to get this problem under control before I burn up my manifold gasket with blow-by or warp the manifold beyond repair.

Jam nuts do not back off, that is the purpose of them, they have been in use for 100-150yrs. 

The first nut is torqued to spec, the second nut is then tightened down to the first. IIRC,  two nuts having a different rotation on the threads is what keeps them from loosening.

[THK Matt]

I wish. People have tried split washers on this manifold before, but they lose their temper and become useless within a few miles.

No, it's not rocket science, but you omitted to mention new hardware. Based on the discussion in this thread, and my experience with "new-ifying" some of my nuts, the evidence is pretty conclusive at this point that I need to get new hardware or it won't stay tight. Everybody says to replace those nuts after each use, and they are least on use #4 (not counting numerous retightenings)

The only remaining question is: will new nuts be sufficient, or do the studs wear out as well? I want to fix this once and fix it right, but I don't want to fix things that don't need it.

Id pull the studs, chase them with a tap to clean them up, replace with new studs and hardware.

[Lewis Hein [OP]]

Id pull the studs, chase them with a tap to clean them up, replace with new studs and hardware.

You mean chase the studs with a die, or chase the holes with a tap? I am confused... Besides, aren't the studs supposed to be out-of-round to hold the nuts on better? I would think chasing them would change that.

[THK Matt]

You mean chase the studs with a die, or chase the holes with a tap? I am confused... Besides, aren't the studs supposed to be out-of-round to hold the nuts on better? I would think chasing them would change that.

i meant what i said. get new studs. most oem studs/bolts are TTY, meaning one time use. and why would a stud be out of round. thatd mean 2 points of contact opposed to the whole surface. they hold by pressue (torque)

[Gnarly4X]

i meant what i said. get new studs. most oem studs/bolts are TTY, meaning one time use. and why would a stud be out of round. thatd mean 2 points of contact opposed to the whole surface. they hold by pressue (torque)

The nuts are not one-time use.  The studs are not out of round.  DO NOT remove the studs unless you are prepared for probable drilling,  tapping the head, and inserting heli-coils!!  If the studs are tight in the head and the threads are good - LEAVE THEM ALONE!! 

Did I get transported to some other planet!!

Gnarls.

[helipilot77]

I’m going to have to agree with Gnarls on this one. If you try to remove a steel stud in an aluminum head you risk the aluminum threads galling and turning into cheese. At that point your only option would be to thread-sert, heli-coil, or replace the head. If the studs are tight I would also recommend leaving them alone. Get some new Toyota nuts and make sure the pipe clamp to the bellhousing is secure and see if it holds. I had the same problem on my 22R. New OEM nuts solved it. Also there are two different styles of nuts. One has a split section o the end. The other looks more like a standard flange nut that has been squished to be a lock nut. You want the one with the split section on the tail.

[Slabzilla]

I agree 100% with Gnarls and helipilot,  DO NOT REMOVE THE STUDS, new nuts as described by helipilot and clamp that down pipe and you'll be good to go. Don't strip out the threads in the head removing the studs unless one or all of them are loose to start with.   

[Lewis Hein [OP]]

I never particularly wanted to remove the studs... I just wanted to make sure of exactly what I need to replace.

Thanks guys for telling me. One heli-coil on my head is enough, and I have no desire whatever to put in 7 more.

[Lewis Hein [OP]]

Also there are two different styles of nuts. One has a split section o the end. The other looks more like a standard flange nut that has been squished to be a lock nut. You want the one with the split section on the tail.

All the ones I can find for sale look like this:


Except for the ones that come with a super-bling stud and nut kit from 22RE performance. I don't want to pay super-bling prices and 22RE performance shipping rates just to get 8 nuts... That would end up like $70, or nearly $9/nut!

[THK Matt]

MY bad, i thought you meant both the studs and nuts were loose. on that note.


Exactly what Gnarls and Helipilot said.

[Gnarly4X]

.......... super-bling stud and nut kit from 22RE performance. I don't want to pay super-bling prices and 22RE performance shipping rates just to get 8 nuts... That would end up like $70, or nearly $9/nut!

Holy crapity...!!  $70.00  .... geezz that's 2 jugs of Barcardi lite, 1 case of Cherry Coke, and 12 limes!!!.... that's nuts!!


Gnarls. 

[Prismo]

Here is a set for 40 bucks  https://www.toyotatruckengine.com/22re-oem-exhaust-nuts/