Pressure relief valve thread size

[rincewind23]

Hi all,

I've got a Rover v8 from a Disco 1 in my kit car. I have been having some oil leaks from the bolts in the oil pump housing so I replace all the washers and gaskets, and as I was torquing up the bolt holding the pressure relief valve in (according to the Haynes manual, 48 lbft) the bolt went slack - threads stripped

I measured the bolt and it seems to be *just under* 3/4" at 20tpi - Googling it, it seems to be a 'cycle thread'.

Can anyone confirm the thread size for this bolt? I'm thinking of trying a helicoil before I resort to something more expensive!

Cheers,
KEv.

[SuperV8]

Do you mean 3/4" long, not dia!
A 1/4" UNC bolt has 20 threads per inch.
So if that's the case you need 1/4 unc x 3/4 long bolt.

48LB/ft sounds way too high! Are you sure you have the correct units?

Has the bolt or the hole stripped?

Tom.

[SuperV8]

Aha you mean the pressure relief valve plug?
http://forum.lro.com/viewtopic.php?f=21&t=44839
In that case ignore my last post

Looking here
http://workshop-manuals.com/landrover/v ... gs/engine/
It says the pressure relief valve should be

Oil pressure relief valve plug - Engine numbers
without suffix B 45 Nm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 lbf.ft

Tom.

[DaveEFI]

Oil relief valve cap torque is 30lb.ft in my BL manual.

[rincewind23]

Thanks for the replies guys. Yes, it is the pressure relief valve plug. According to my Haynes manual, it should be 45 lb.ft



So I'll do it up to 30 next time, but the question is still - what's the thread size?
It's definitely about 3/4 inch wide and 20 tpi. It's the hole where the thread has stripped, not the plug.

[ged]

The thread is 3/4" UNEF.
Unless you have access to machinery so you can guarantee the squareness of the heli-coil (even then there still wont be a lot of material left for strength) plus the amount of messing about involved I personally would bite the bullet & get another cover.

[rincewind23]

Thanks Ged,

I thought that as well, just trying to decide whether to go with a straight replacement (which seem to be pretty hard to find) or replace that and the mocal takeoff I have (type H here):

http://www.mocal.co.uk/products.html#remotefilterheads


with the Mocal combination pump and take off:

https://www.merlinmotorsport.co.uk/p/ro ... m-v8-cover

Last option is to swap the crank for a long nose one and use the later timing cover I bought for a future upgrade

[Ian Anderson]

Think Auto
http://www.thinkauto.com/acatalog/On_li ... rs_40.html

Call them tell them what you want to achieve and they will put all the kit together to make it work!

Just a happy customer

Ian