Nordlock Washer vs Locking Plate

[fjmuurling]

Any opinions / experiences with using Nordlock washers for locking of the aerotight nuts for mounting the exhaust manifold to the Head?

Freek 

[Vulcan Grey]

Mine has the aerotight nuts and I was losing studs (still attached to the nuts...) all the time until I got the locking clips correctly applied..  Lotus hadn't bent very many of the clips, and they weren't close enough to the nuts to prevent them spinning.

[fjmuurling]

"Double" locking is required in order to prevent the nuts coming loose from the studs and to prevent the stuts coming out of the head with the nut still on.

think I will go for the Nordlock Washers (easier mounting, no fiddling with tabs), If they fail I always can switch back to the tabs.

[Vulcan Grey]

Let us know how they work.  FYI, there is not even enough room for a socket on some of those nuts, so make sure the Nord-Locks aren't larger diameter than the nut!

[ragingfool35]

old school lesson of always tightening exhaust manifold bolts/nuts while hot, due to thermal expansion causing them to come loose.  i would think that would hold true most especially for Nordlock.

let us know how you fare

[Chillidoggy]

I used K-nuts when I replaced my old manifold with the Alunox one. I fitted them cold and haven't had any of them coming loose.

[naasaa]

I used nordlock washers on my. Havent had any issues.

Used them on my Volvo T5 in the past. They had a notorious problem with studs coming loose.

Nordlock are standards on large turbocharger nozzle rings. These you cant tightening when hot.

Lars

[lotus4s]

I've used the Nordlock washers on the exhaust manifold in several Esprits and never had an issue with them coming loose. Sure beats bending and unbending the locking tabs. 

[ragingfool35]

good to know

[glynherron]

What is the best adhesive available in the UK to fix the studs to the head or is it not required?

[fjmuurling]

AFAIK it is not required, aerotight nuts with locking plates / Nordlock washers do the job.

I will be using Nordlock washers

[sailorbob]

The workshop manual states Permabond A025 High Temperature Sealant is to used on the exhaust manifold studs. Loctite 272 is similar.

[glynherron]

Thanks Guys

[Chillidoggy]

I know one thing: I tried unwinding my cylinder head exhaust studs, and gave in when I was sure they would shear. Whatever they're in with, it must be damn good stuff.

[sailorbob]

There are high temperature threadlockers with much higher shear strengths than the Permabond A025 and. Loctite 272, maybe someone's used one of those in the past.

[Loose Cannon]

Is it recommended to replace the studs when fitting the new stainless manifold? Would differential corrosion be a problem if the existing ones are left on?

And worst case scenario is it an engine out job if one shears?

[Chillidoggy]

The original Lotus studs are stainless. Therefore no corrosion issues.

If studs shear in situ, the cylinder head has to come off to fix it. I recall Sparky had to do that when he fitted his new Alunox manifold.

[Gasman GT3]

Funny this should come up.  My 2 year old Alunox manifold developed a blow last week, and i feared the worse, that a weld had gone.  jacked the car up yesterday and crawled under for a look.  Hey presto front port has one stud missing and one with the stud still in but the nut gone.  I used the Nordlock type nuts that came with the manifold but obviously didnt fasten them up tight enough.  Lesson leanred

[fjmuurling]

The (mine) Alunox Manifold came with Flange Nuts and no Nordlock Washers.

Flange Nut example:

Nordlock Washer (1 washer is made of 2 parts) example:

[Loose Cannon]

Which is better?

[fjmuurling]

You need "double" locking, so special locking (aerotight) nuts in combination with tabs or locking (nordlock) washers. 

[Gasman GT3]

The (mine) Alunox Manifold came with Flange Nuts and no Nordlock Washers.

Flange Nut example:

Nordlock Washer (1 washer is made of 2 parts) example:

Ahh, I thought the flange nuts were nordlock, but now I see what you mean, might put nordlock washers on and see how I go.