Jump to content
Click here if you are having website access problems ×

Crossflow - Oil Pressure Sender Thread size?


Tazio

Recommended Posts

Based on "normal" threads on a X/flow I would have expected it to be 1/4" NPT.

However the VDO one fitted to my Caterham supplied X/flow in 1990 was 1/4" BSP (parrallel).

The markings on the Hex are:-

0-5 bar

5.90 (I think that is the date)

29/39 (I think a model / thread reference)

Ian

Link to comment
Share on other sites

1/4 NPT and BSP are close enough in thread form/angle to go together reasonably well - certainly brass into iron.  I've managed to hold 25 Bar inside a system with such a combination.

Above that things start to get a little more abusive.

Link to comment
Share on other sites

  • 2 weeks later...

Tazio, just come across your post, you're probably sorted by now but just in case:

I have recently replaced my oil pressure sender with this:

https://www.merlinmotorsport.co.uk/p/vdo-pressure-sender-5-bar-with-1-4npt-thread-360081029008

My original one was marked:

0-5 bar

12.85 (date? Car is a 1987)

29/39

The new one is marked:

0-5 bar

5.16

29/8

No idea what these numbers mean but it fitted my crossflow and I now have oil pressure!

Neil.

Link to comment
Share on other sites

Just as an aside, the oil gallery threads in a Crossflow are indeed  NPT of either 1/8" or 1/4". So obviously I always used 1/8" or 1/4" BSPT plugs - which leak!

No, I'm not insane. The two threads are a reasonable(ish) match for each other, but the BSPT plugs normally have a much deeper and tighter fitting socket for your allen keys. You can almost guarantee that an NTP plug will strip its allen key socket if you try to remove it, thus necessitating drilling the plug out. This is not too much of a problem if you are stripping the engine down, but if you merely want to remove a plug in order to fit a sender it can be a disaster.

The trick is to degrease and then smear the BSPT plug threads with a little Loctite thread sealant before assembly. I never had one leak once this was done, and the plugs would nearly always come out easily with an allen key, saving a lot of work and potential heartbreak.

Just occasionally, a bodge is better than doing it properly! 

Of course, this won't apply to senders and other devices that have spanner flats.

Link to comment
Share on other sites

That has some merit, but in one case at least, it won't work. The oil gallery that runs across the Crossflow block between cylinders 2 and 3 has a plug in one end, but the engine mounting fits over it when bolted in position. The Hex head would prevent the mounting from seating onto the block properly.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...