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Stripped Thermostat On The Head


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#1 Adge456

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Posted 12 May 2019 - 02:28 PM

I’ve had a few problems lately with the radiator. I’ve managed to get it sorted but it is now leaking out of the thermostat housing (I’ve ordered a replacement gasket.)
However, when I removed the bolts, they came with parts of the head still attached onto the bolt that could easily be screwed off and it now will not bit to bolt back in.

I’m guessing that the head has stripped.
What are my options for fixing this. I feel like I will need to tap the holes but that will require larger bolts.
Does anybody know what size to tap it/what bolts to replace the original ones with or can I tap it larger and put in a reducer?

Any help is appreciated.

Thanks
Adge

#2 mini13

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Posted 12 May 2019 - 02:34 PM

Helicoil kit,

 

IIRC they are 5/16" unc into the head, 

 

https://www.ebay.co....tAAAOSwrW5cwF0n



#3 alex-95

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Posted 12 May 2019 - 02:35 PM

You could heli coil it back to 5/16 UNC, you would need to be able to drill out the hole square to the head and tap it to the heli coil size and fit the heli coil.



#4 Adge456

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Posted 12 May 2019 - 03:01 PM

Never used on before. Is it like a spring that you insert after you tap it larger?

Could I not just tap the hole larger and drill the thermostat housing a little larger and put different bolts in?

#5 ChrisRuffell

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Posted 12 May 2019 - 03:03 PM

Never used on before. Is it like a spring that you insert after you tap it larger?

Could I not just tap the hole larger and drill the thermostat housing a little larger and put different bolts in?


They are quite simple to use and worth having a kit and getting the hang of it.
If you’re feeling rich you can get a timesert kit which is a solid insert rather than a springy coil.

#6 mini13

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Posted 12 May 2019 - 03:17 PM

If youve got an pold thermostat housing lurking you could drill i the hole out larger on a pilar drill to keep it square and use it as a guide for drilling& maybe tapping the head,

 

essentially yeah the helicoil "spring" screws in with a slutted tool and then you break off the tang at the end that you screwed it in with.

 

Its worth getting a genuine helicoil kit as the coils seem to be better material in my experience, so fit better, interestingly theres a video on youtube where a guy does pull out tests on the helicoil, and timesert, and theres litteraly nothing in it, in fact iirc the helicoil was stronger.



#7 RedRuby

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Posted 12 May 2019 - 03:22 PM

From your description it is possible that it has previously been heli coiled and the thread insert has come out still attached to the stud in which case it may not need drilling out just a new thread insert fitting. If that is the case this time when fitting the thread insert I would use locktite to secure it.

Edited by RedRuby, 12 May 2019 - 03:23 PM.


#8 spannerboy

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Posted 12 May 2019 - 03:47 PM

 

Never used on before. Is it like a spring that you insert after you tap it larger?

Could I not just tap the hole larger and drill the thermostat housing a little larger and put different bolts in?


They are quite simple to use and worth having a kit and getting the hang of it.
If you’re feeling rich you can get a timesert kit which is a solid insert rather than a springy coil.

 

 

 

I would go with a timesert kit myself, they are much better than a helicoil.

But a cheaper method would be to drill out and retap to a different size and put a different sized stud in it. You would need to widen the thermostat housing a little as well.



#9 ukcooper

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Posted 12 May 2019 - 04:19 PM

Get a new stage 3 head thats what i do,,,, dont think you can tap it bigger as not enough room m8 or 8mm is same size as 5/16's ,Helicoil threadset never had a problem with iver of em..



#10 Adge456

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Posted 12 May 2019 - 04:55 PM

I’m the opposite of feeling rich! Ha.
I’ll have to look at the sizes. They all seem to be ‘m10 or m something..

#11 ChrisRuffell

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Posted 12 May 2019 - 05:00 PM

I’m the opposite of feeling rich! Ha.
I’ll have to look at the sizes. They all seem to be ‘m10 or m something..


Recoil 34048 UNF 1/4-28 Kit, Multi https://www.amazon.c...i_Tcf2Cb5DW621E

This is the kit I purchased and done my heater valve with... I think I also did the thermostat housing as well...

If someone else can confirm that’s the right size? It’s what I have on my amazon orders from 2017 and I’ve definitely used it

#12 Adge456

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Posted 12 May 2019 - 05:52 PM

Thanks guys. Ordered the M8.
I will see if it fits without tapping to see if it’s been done before.
If not and I have to tap, would wd40 be ok to disperse the heat or is there something else I would need?

#13 Moke Spider

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Posted 12 May 2019 - 06:03 PM

The size of these threads is 5/16" UNC.



#14 alex-95

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Posted 12 May 2019 - 06:30 PM

 

I’m the opposite of feeling rich! Ha.
I’ll have to look at the sizes. They all seem to be ‘m10 or m something..


Recoil 34048 UNF 1/4-28 Kit, Multi https://www.amazon.c...i_Tcf2Cb5DW621E

This is the kit I purchased and done my heater valve with... I think I also did the thermostat housing as well...

If someone else can confirm that’s the right size? It’s what I have on my amazon orders from 2017 and I’ve definitely used it

 

Heater valve/take off threads are 1/4 UNF, as said previously thermostat housing is 5/16 UNC in the head and then 5/16 UNF for the nuts to tighten it down.



#15 Adge456

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Posted 12 May 2019 - 06:39 PM


I’m the opposite of feeling rich! Ha.
I’ll have to look at the sizes. They all seem to be ‘m10 or m something..

Recoil 34048 UNF 1/4-28 Kit, Multi https://www.amazon.c...i_Tcf2Cb5DW621E

This is the kit I purchased and done my heater valve with... I think I also did the thermostat housing as well...

If someone else can confirm that’s the right size? It’s what I have on my amazon orders from 2017 and I’ve definitely used it
Heater valve/take off threads are 1/4 UNF, as said previously thermostat housing is 5/16 UNC in the head and then 5/16 UNF for the nuts to tighten it down.





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