Miatapower List Archive

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Mail From: Toby Weir-Jones <(email redacted)>

Greetings power mongers,

I've read a few odd reports of this happening, and indeed, it's happened
to me once before: after extending heated use, the turbo/manifold
flange starts to leak slightly owing to the nuts securing the turbo to
the manifold studs coming a bit loose.

Tightening the nuts solves the problem--that's easy enough--but i'm
wondering if any damage to the studs can result from this. I find it
hard to believe that the nuts themselves are actually unscrewing
slightly from the heat, so where is the gap coming from? are the studs
stretching? in which case, should they be replaced?

Or should I just double-nut them with lock washers and uber-loctite and
be done with it...

thanks for all wisdom,
twj

This read-only message was archived from a public mail list.
Mail From: "Jeremy Schuster" <(email redacted)>

> after extending heated use, the turbo/manifold
>flange starts to leak slightly owing to the nuts securing the turbo to
>the manifold studs coming a bit loose.
>
>Tightening the nuts solves the problem--that's easy enough--but i'm
>wondering if any damage to the studs can result from this

Are the studs torqued into the manifold properly? Even if you are able to
torque the nuts down, the studs may not be properly seated. This will make
it quite easy for a little vibration to cause the studs to back out, leading
to loose nuts. Then again, with all of the thermal expansion going on, you
may have to resort to interference lock nuts.

Jeremy L. Schuster

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Mail From: "Tom Burke" <(email redacted)>

Metals expand and contract with temperature changes. During extreme
temperature swings, coupled with vibration, threaded fasteners can
become loose if there are periods when tension on the bolt is
minimized.
Lock nuts, lock washers and adhesives are used to keep one's nuts
tight.

Tom

Toby Weir-Jones <(email redacted)> wrote on Thursday November 19, 1998
at 1:36pm:
>
>Greetings power mongers,
>
>I've read a few odd reports of this happening, and indeed, it's
happened
>to me once before: after extending heated use, the turbo/manifold
>flange starts to leak slightly owing to the nuts securing the turbo
to
>the manifold studs coming a bit loose.
>
>Tightening the nuts solves the problem--that's easy enough--but i'm
>wondering if any damage to the studs can result from this. I find it
>hard to believe that the nuts themselves are actually unscrewing
>slightly from the heat, so where is the gap coming from? are the
studs
>stretching? in which case, should they be replaced?
>
>Or should I just double-nut them with lock washers and uber-loctite
and
>be done with it...
>
>thanks for all wisdom,
>twj

....

This read-only message was archived from a public mail list.
Mail From: (email redacted)

In a message dated 98-11-19 17:55:08 EST, (email redacted) writes:

<<
Are the studs torqued into the manifold properly? Even if you are able to
torque the nuts down, the studs may not be properly seated. This will make
it quite easy for a little vibration to cause the studs to back out, leading
to loose nuts. Then again, with all of the thermal expansion going on, you
may have to resort to interference lock nuts. >>

The up-down vibration characteristics of the 4 cylinder engine give the
fasteners a rather hard time. With the stud bottomed out tight on its
shoulder and the second nut (jam nut), it should stay in place. The
environment is too hot for loctite to offer any assistance.
CB

This read-only message was archived from a public mail list.
Mail From: "Nico van Steen" <(email redacted)>

Another way is using self-locking nuts. Not the ones with the plastic
center, but those that are a bit eleptical shaped. Downside is that you
can't get them off if you want to or have to. This then results in the
breaking of the studs. BTDT.

Nico van Steen

>
>In a message dated 98-11-19 17:55:08 EST, (email redacted) writes:
>
><<
> Are the studs torqued into the manifold properly? Even if you are able to
> torque the nuts down, the studs may not be properly seated. This will
make
> it quite easy for a little vibration to cause the studs to back out,
leading
> to loose nuts. Then again, with all of the thermal expansion going on,
you
> may have to resort to interference lock nuts. >>
>
>The up-down vibration characteristics of the 4 cylinder engine give the
>fasteners a rather hard time. With the stud bottomed out tight on its
>shoulder and the second nut (jam nut), it should stay in place. The
>environment is too hot for loctite to offer any assistance.
>CB
>