Exhaust manifold won't stay tight

[Lewis Hein]

Hey everyone,

I am trying to get my 22R exhaust manifold to stay tight. If I tighten the nuts to factory spec, they spontaneously loosen within 30 miles. If I re-bend the nuts to make them triangular again, that makes no difference -- they loosen up anyway. Lock washers and loctite are, of course, of no use at all. If I tighten the nuts more, it just strips out the stud threads in the head.

I am out of ideas. Do Toyota exhaust manifolds just do this? That seems hard to believe, but it seems that I've done everything possible to make it stay tight with no effect whatever. And retightening these nuts every time I drive the vehicle is going to get old, fast.

[Dingman.]

Have you tried new hardware?

[Lewis Hein]

Do you mean new nuts or new studs? I haven't tried new studs. Nor have I tried new nuts, but rather reshaped the old ones.

[OVRAROK]

do you have the exhaust bracket, block to pipe

[Lewis Hein]

do you have the exhaust bracket, block to pipe

I can't think of any part that connects the engine block to an exhaust pipe. Do you mean the exhaust manifold of the EGR system? I have both, and they are the only things I can think of that connects any part of the engine to any exhaust-related pipe. If you mean something else, would you mind describing it more?

Thanks.

[OVRAROK]

I can't think of any part that connects the engine block to an exhaust pipe. Do you mean the exhaust manifold of the EGR system? I have both, and they are the only things I can think of that connects any part of the engine to any exhaust-related pipe. If you mean something else, would you mind describing it more?

Thanks.

its right after downpipe. I'm trying to find a pic

[OVRAROK]

Here's a pic for you

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[Lewis Hein]

Nope, nothing of the sort.

[H8PVMNT]

Yeah that piece helps keep it from yanking on the manifold.  Fresh hardware is your friend though.

[Snowtoy]

No, loosening on their own isn't a normal Toyota thing, chances are the threads in the head are worn, preventing a correct torque value.  An easy fix is to get the next size larger "standard size" stud and retap the head. 

Can also look into stage 8 fasteners.

[emsvitil]

I tapped the head for threaded inserts and then used stainless 3/8 threaded rod and locking flanged nuts (cheaper than stock 10mm)




Also make sure your manifold is warped,  I had to resurface mine.


(It's possible to drill and tap the head in the engine bay......)

[Gnarly4X]

Hi Lewis,

Sorry to read that you have more painful issues with your truck. 

Using the factory stock nuts will cause the studs in the head to strip and spin – and it doesn't matter if they are new.

I've posted on this many times.

The steel studs in the alloy head corrodes the threads in the head.  The clamping of the factory nuts will give a false reading on a torque wrench... IF they threads in the head do not strip first.

What kind of exhaust manifold gasket are you using?

To properly get the gasket to seal, you will probably have to pull the exhaust manifold off and check for flatness, then install a new gasket with hex nuts and lock washers.  Here's a post on my thread: 

http://board.marlincrawler.com/index.php?action=search2

The only way I've found to keep the nuts tight is doing a 3 stage torque sequence.  1 – not to full torque, drive it for an hour - recheck for tightness,  2 - drive it for several hours and then recheck and  3 - drive for another day or so - recheck for tightness - make a final torque.  I have never torqued the nuts down to the factory manual spec of 33 lbs.

If the studs are spinning inside the head, you will need to drill, tap and install helicoils or Time Serts.  That is THE most difficult repair I have ever made on my trucks with the head installed.

That's just my experience... everyone's may be different.

Gnarls. 

[Gnarly4X]

I tapped the head for threaded inserts and then used stainless 3/8 threaded rod and locking flanged nuts (cheaper than stock 10mm)




Also make sure your manifold is warped,  I had to resurface mine.


(It's possible to drill and tap the head in the engine bay......)

Although this may be a perfect solution, some exhaust header manufacturers do NOT recommend using stainless steel studs or nuts. 

Gnarls. 

[jimbo74]

are you sure the head is not already stripped?

have you thought of using oversize studs for repair? or time serts?

[Gnarly4X]

....  An easy fix is to get the next size larger "standard size" stud and retap the head. 

This may be described as an "easy fix" for some, however in my experience drilling and tapping and inserting new studs or helicoils into a 30-year old 22 head while on the engine was extremely difficult to do correctly.

But... I am not a machinist, engine builder, nor auto mechanic. 

Gnarls.

[emsvitil]

I drilled the head out by constantly going to the next size bit (1/64 increments) until I got to the correct size for the insert.

Used a right angle drill adapter, and for the studs next to the master cylinder;   I literally did it by hand  (held drill bit in gloved hand).

Luckily aluminum isn't that hard to tap......

[Lewis Hein]

I am quite sure the head is not already stripped. I stripped a stud out of the head once, and it made its stripped condition extremely obvious.

The problem is with nuts not holding on to the studs. I checked the manifold for flatness, and just installed a new gasket. But still, the nuts cannot be made to stay put.

Here's a pic for you

Uh... On further inspection, this picture makes no sense. It looks like the bracket is bolted to the clutch bellhousing, but it shows only a single pipe. My exhaust pipe is double almost to where it turns to head straight back under the truck.

[emsvitil]

86 and later have a short Y merge after the manifold and merge quickly into single pipe.

[emsvitil]

If there's some thread left, just jam nut it................

[Lewis Hein]

If there's some thread left, just jam nut it................

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

[emsvitil]

Use thin nut as first nut.......

[OVRAROK]

Here's a couple more pics, maybe help you clarify things

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[Gnarly4X]

"Uh... On further inspection, this picture makes no sense. It looks like the bracket is bolted to the clutch bellhousing, but it shows only a single pipe. My exhaust pipe is double almost to where it turns to head straight back under the truck."


The stock exhaust bracket is mounted to keep the engine torque from flexing the exhaust pipe.  Where the bracket is mounted, the stock pipe is only a single on my trucks.

Gnarls.

[Snowtoy]

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

You can buy longer studs.

[Toybrota]

I actually don't think you need an exhaust manifold

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[YooperYota]

Agreed, adding that brace at the bellhousing will definitely help take stress off those manifold studs.

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[Lewis Hein]

I actually don't think you need an exhaust manifold

In fact, with my percheron swap kit, you don't even need an engine.

[Gnarly4X]

In fact, with my percheron swap kit, you don't even need an engine.

If you go full Percheron, you won't even need your truck!

Gnarls.

[Lewis Hein]

If you go full Percheron, you won't even need your truck!

The trouble is, percherons don't get very good grass mileage.

[Gnarly4X]

The trouble is, percherons don't get very good grass mileage.

Gnarls.