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cylinder head studs
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Miken



Joined: 24 Dec 2012
Posts: 543

PostPosted: Tue May 16, 2017 9:53 pm    Post subject: cylinder head studs Reply with quote

Thoughts please;
When fitting cylinder head studs to an iron cylinder block, some of the threaded holes in the block break into the water gallery.
So, something is required on the threads of the studs to both seal the water in and prevent the studs rusting to the block in case they ever have to be removed again.
Could use ordinary mineral grease, silicon grease, copper grease, Hylomar gasket goo (or similar), loctite hydraulic thread sealant (easily dismantles).
But maybe not silicone sealant as acetic acid can cause corrosion.
Discuss.
Mike
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billysugga



Joined: 01 Jan 2017
Posts: 55
Location: Carlisle

PostPosted: Wed May 17, 2017 6:54 am    Post subject: Reply with quote

I Went with loctite on mine but I haven't ran it more than in the garage. Loctite breaks down at high temperature but that is very high normally. We used to use it on steam pipes so I think it should be ok.
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Kenham



Joined: 12 Mar 2012
Posts: 209
Location: Kent

PostPosted: Wed May 17, 2017 9:10 am    Post subject: Reply with quote

Is it the bottom of the stud that goes into the gallery or down the side of the thread? Side valve or overhead?
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MikeG



Joined: 16 Sep 2013
Posts: 56
Location: Cheshire/Staffordshire Border

PostPosted: Wed May 17, 2017 9:35 am    Post subject: Reply with quote

My Engine restorer used PTFE tape on the studs.
Hope this helps
Mike
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Kleftiwallah



Joined: 27 Oct 2016
Posts: 222
Location: North Wiltshire

PostPosted: Wed May 17, 2017 12:51 pm    Post subject: Reply with quote

And to follow the P.T.F.E. idea, how about Boss white and hemp as used by plumbers of yore?

Cheers, Tony. Embarassed
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Miken



Joined: 24 Dec 2012
Posts: 543

PostPosted: Wed May 17, 2017 3:30 pm    Post subject: Reply with quote

Kenham wrote:
Is it the bottom of the stud that goes into the gallery or down the side of the thread? Side valve or overhead?

All interesting suggestions, thanks.
Kenham, it is the bottom end of the thread and a SV engine.
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colwyn500



Joined: 21 Oct 2012
Posts: 1745
Location: Nairn, Scotland

PostPosted: Wed May 17, 2017 4:07 pm    Post subject: Reply with quote

Clean the threads in the block and the stud really well with a good solvent such as panel-wipe and then use stud-grade Loctite or similar.
All the other suggestions may work for a time but aren't designed with that specific purpose in mind; and as far as I know, none of them have the added benefits of the Loctite in resisting the stud loosening and in helping to transfer the torque more evenly throughout the threads.
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alastairq



Joined: 14 Oct 2016
Posts: 1948
Location: East Yorkshire

PostPosted: Wed May 17, 2017 5:23 pm    Post subject: Reply with quote

What was used originally? {Assuming an ancient engine?] Smile
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colwyn500



Joined: 21 Oct 2012
Posts: 1745
Location: Nairn, Scotland

PostPosted: Wed May 17, 2017 6:42 pm    Post subject: Reply with quote

alastairq wrote:
What was used originally? {Assuming an ancient engine?] Smile

The original idea was that the studs had a slight tapered waist where the threads stopped. This "chamfer" would create an interference fit when the stud was torqued into the block. Therefore no precaution was taken to seal the threads against moisture. This creates the nightmare that many people face when the studs are eventually attemped to be removed.


Last edited by colwyn500 on Thu May 18, 2017 12:41 pm; edited 1 time in total
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Farmer John



Joined: 18 Feb 2010
Posts: 181
Location: Manawatu NZ

PostPosted: Thu May 18, 2017 2:29 am    Post subject: Head studs. Reply with quote

Hi Mike. You are right to be concerned, but the proper Loctite will take care of movement and sealing. There are makes of block where the top surface is swollen around the head studs from repeated or over tightening of the studs. (Some top plates are pretty thin in places.)
Get both threads perfectly clean and screw them in until only just tight, the Loctite will keep them there.
The matter of corrosion of the end of the stud should be taken care of by using coolant from somewhere they supply industrial or heavy vehicles. Buy the best they have, so many worries about classic engines just vanish when you use top quality coolant.
John
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MikeEdwards



Joined: 25 May 2011
Posts: 2459
Location: South Cheshire

PostPosted: Thu May 18, 2017 10:38 am    Post subject: Reply with quote

I'm sure you all know, but keep in mind there is Loctite and there is Loctite. I have a bottle of Loctite that I bought because I thought it was a bargain. Fortunately - and due to a conversation I was having with a mate who bought a Jaguar XK8 project car and found suspension bolts that are fixed using the same stuff - I noticed before I used it that the specific one I had bought is described as a "permanent" lock, not just the usual medium strength that I intended. I forget exactly what is required to undo it, but it's quite extreme.

Like I said, I'm sure that isn't news to you.
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Ray White



Joined: 02 Dec 2014
Posts: 6264
Location: Derby

PostPosted: Thu May 18, 2017 11:39 am    Post subject: Reply with quote

I am with Colwyn 500 on this; 100%. I was recently advised by the engineer who has been working on my Dodge engine that a couple of the studs in the block have pushed through into the water jacket. He recommended Loctite.

The PTFE tape also works. My Dad was the engineer who built the first PTFE tape making machines and used it extensively over the years but when Loctite began being used in industry he also went over to it.
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Miken



Joined: 24 Dec 2012
Posts: 543

PostPosted: Thu May 18, 2017 4:07 pm    Post subject: Reply with quote

OK, So i've done a bit of an experiment today.
I tapped a thread in a bit of cast iron bar .
Degreased a high tensile bolt and wound it in by hand with some Loctite 270 threadlocker which the manufacturer produce for "the securing AND sealing of bolts , nuts and studs".
Which sounds just the job.
After 8 hours I attempted to dismantle it with a socket spanner.
After fitting a long tube extension I merely succeeded in shearing the bolt off.
So I wont be using this as i may want to dismantle it again and i wont want to heat it up to 300deg.C to break the bond.



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Ray White



Joined: 02 Dec 2014
Posts: 6264
Location: Derby

PostPosted: Thu May 18, 2017 4:16 pm    Post subject: Reply with quote

If you want to be able to get it apart again then maybe PTFE tape would be your best option.
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Kenham



Joined: 12 Mar 2012
Posts: 209
Location: Kent

PostPosted: Thu May 18, 2017 6:22 pm    Post subject: Reply with quote

I think I would do what they did when they built the car, put a bit of grease on it. PTFE would be good, Its lasted many years without such stuff as Loctite and if it were mine it would do many more. No great pressure in the system so just a bit of copper grease so the studs will undo later.
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