hi, i have cross threaded my heater valve thread where the stud goes, i was looking at a helicoil kit but these seem expensive so i was thinking of tapping it slightly bigger size. Any ideas of what size of new thread to use?
Thanks
Adam
heater valve thread
Started by
mini mad adam
, Dec 30 2005 11:38 PM
6 replies to this topic
#2
dklawson
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Posted 31 December 2005 - 04:18 AM
The heater valve studs are 1/4". If the HeliCoil isn't for you, you should start by seeing what size bolts you can get. If you want to keep it "inch" your next size would be either 5/16-18 or 5/16-24. At this point in time it's probably easier for you to get metric fasteners so the "standard" M8x1.25 fastener would be your best choice. However, it's quite likely that you'll need to drill out the hole(s) in the heater valve foot if you go to this larger size fastener.
#3
Bluemini
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Posted 31 December 2005 - 10:09 AM
M6 would be the best metric size to use wouldn't it? Its only slightly bigger than 1/4".
But if you've only cross threaded it and not stripped it then you should be able to get away with running a tap down the hole to clear the threads. If you get stuck finding a tap then PM me and I will sort one out for you as we use them all the time in work.
But if you've only cross threaded it and not stripped it then you should be able to get away with running a tap down the hole to clear the threads. If you get stuck finding a tap then PM me and I will sort one out for you as we use them all the time in work.
#4
dklawson
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Posted 31 December 2005 - 11:46 PM
Er... 1/4" is bigger than 6mm. 1/4" = 6.35mm
#5
Bluemini
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Posted 01 January 2006 - 02:08 PM
Yup your right I got them mixed up...Er... 1/4" is bigger than 6mm. 1/4" = 6.35mm
5/16 would be too big tho like you say and I recon so would mate too.
#6
Bungle
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Posted 01 January 2006 - 02:12 PM
could you just retap it and use some P.T.F.E tape to make sure it tightens up 
#7
dklawson
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Posted 02 January 2006 - 04:09 AM
You could chase the threads in the head with a 1/4-28 tap to clean them up and put epoxy on a stainless steel stud to permanently mount it to the head. The Teflon tape would fill the gaps but it won't account for the lost material from cross-threading and re-tapping.
There are other types of thread inserts you could consider. I don't know what they're called in the U.K. By description... the other type of insert looks like a grub screw with a tapped hole down the middle and a machined slot across its nose. These use standard size tapped holes so you wouldn't need to buy the HeliCoil kit. All you'd need to do is tap for (probably) 3/8-16 and insert... the insert. Again, I can't help with brand names.
For an image, go to www.mcmaster.com and type "3060" into the search field. It will take you to page 3060. Look at the bottom of the page an you'll see one variant of that type of insert that uses keys to secure the insert in place. There are other types out there
There are other types of thread inserts you could consider. I don't know what they're called in the U.K. By description... the other type of insert looks like a grub screw with a tapped hole down the middle and a machined slot across its nose. These use standard size tapped holes so you wouldn't need to buy the HeliCoil kit. All you'd need to do is tap for (probably) 3/8-16 and insert... the insert. Again, I can't help with brand names.
For an image, go to www.mcmaster.com and type "3060" into the search field. It will take you to page 3060. Look at the bottom of the page an you'll see one variant of that type of insert that uses keys to secure the insert in place. There are other types out there
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