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WBX crankcase dome nuts (the ones inside the waterjacket)
Posted: 09 Oct 2015, 16:39
by silverbullet
N 901 843 02 "dome nut" is now NLA/obsolete
4 required per engine, they are the ones that clamp the case together and can rust alarmingly if an engine has been stored with old coolant remnants inside.
10.9 grade, 14mm a/f, M10 x 1.5 thread. I could approach a fixings manufacturer to remake a batch to pattern but there will be a minimum commitment, I would guess 100 or 200 off, no idea of cost but they won't be pence.
If this is of interest, please start a list so that I can gauge numbers to see if it's viable to carry stock.
Re: WBX crankcase dome nuts (the ones inside the waterjacket)
Posted: 09 Oct 2015, 21:09
by 123-jn
Can you use quality stainless nuts instead with thread sealer and yellow gunk under them? Or would this not work?
Re: WBX crankcase dome nuts (the ones inside the waterjacket)
Posted: 10 Oct 2015, 07:41
by itchyfeet
123-jn wrote:Can you use quality stainless nuts instead with thread sealer and yellow gunk under them? Or would this not work?
Don't think that would work as it would likely leak down the thread, sealant would imo get sheared off in the thread.
Re: WBX crankcase dome nuts (the ones inside the waterjacket)
Posted: 10 Oct 2015, 07:59
by CJH
123-jn wrote:Can you use quality stainless nuts instead with thread sealer and yellow gunk under them? Or would this not work?
I can imagine there might be two reasons to use dome nuts - Silverbullet can probably say what's what though.
1) Because they sit inside the water jacket, so covering the threads completely with a dome nut prevents corrosion of the threads. The use of the proper coolant, and a stainless nut, would seem to deal with that problem though.
2) The stud comes from the 'oil' side and the nut sits in the 'water' side, so the dome nut is what stops oil or water seeping past and mixing. I think this is why sealant is specified for the head (dome) nut faces - one side (the stud) is in water and the other is in either air or oil. For the case dome nuts though, the oil side is already separated from the water side by the mating faces of the bearing webs where the studs sit. Maybe this is why there doesn't seem to be any mention in Bentley (that I can find) of using sealant on the case dome nut faces.
So both of these arguments would suggest that a dome nut isn't really required if you can use a high tensile stainless full nut.
Ian?
Re: WBX crankcase dome nuts (the ones inside the waterjacket)
Posted: 10 Oct 2015, 15:53
by silverbullet
I wouldnt chance it.
Looks like Heritage have some stock, at least for now.
Re: WBX crankcase dome nuts (the ones inside the waterjacket)
Posted: 10 Oct 2015, 19:35
by itchyfeet
silverbullet wrote:I wouldnt chance it.
so basically I agree, VW were frugal in their engineering, if they could have used a standard nut they would.