What adapter is required to convert to wet oil pressure gauge?

(old jag man) #1

Hi all, I want to convert my Daimler 250 V8 electric oil pressure sensor to a capillary / wet line for greater reliability.
Can someone please tell me what are the required threads I need for the adapter at the engine end.
I have already purchased a capillary feed AC gauge which is very similar to the original and has a 0 to 80 psi reading.
Thanks in advance.

(Paul Breen pay palled it) #2

I remember pondering this very matter having bought an aftermarket gauge. Pleasently surprised to discover the correct tapered thread adaptor - for fitting at the oil filter block - came with the kit. No further action beyond fitting. I think mine is the Spaco brand. I disconnected the original gauge. I you want both, you will need a tee. Paul

(old jag man) #3

Thanks very much Paul for your reply. Hopefully someone will come in and tell me the actual threads on the the all important adapter to insert in the filter block to take the copper pipe to gauge.
I intend fitting an ‘AC’ brand gauge which male thread differs to the more common Smiths gauge, as I found out when I bought a new copper link pipe.

(Robert Wilkinson) #4

I’m not familiar with the 250 V8 in particular, but if your Smiths OP sender is the same as that on other saloons (you can google for photos) the thread is 1/4 BSPP. You would have a crush washer which confirms that it is parallel, not tapered (BSPT) thread. I/4 BSP is very close to the pitch and diameter of the more common 1/4 NPT and 1/4 NPS. But neither is the same.

(old jag man) #5

Robert many thanks for your info.


(old jag man) #6

Hi Paul, many thanks for your reply.
I had a look today to check approx what length of capillary piping I need to buy. Started off from underneath ( I have an inspection pit in my garage) as the V formation blocks any view of the engine block sidewalls. No way could I find the sender or any sighting of the W/B tracer wire going to the sender. Went up top to look for the said wire and found it above the front engine mount on the driver side. Then I found the sender which is well beyond reach with my big broad hand. Nothing seems to be handy to do on this car. How did you cope with removing your old electric sender unit from your car ?
I did a search on ebay for an electric sender to see if it mentioned the thread pitch/type which it did not but I was surprised to see a connection attached to one which was horizontal to the unit base, can you explain this to me Paul, does the sender unit unscrew from this connector pipe affair or does everything have to come out which I believe would be very difficult with engine in the car, calling on your experience.

(Paul Breen pay palled it) #7

Hi Eugene. Should have made clear that my car is a 3.4 Jaguar six. Perhaps less difficult than your V8. Paul

(old jag man) #8

Hi Paul, I got the sender out which had been a relatively new unit, probably made in China.
Currently changing over the system as I type ( I am waiting for some boiling water to soften the PVC tubing so I can push on the male end to it… The V8 sender is situated almost above the right hand side engine mounting.

(old jag man) #9

Hi Paul, for the benefit of yourself and others reading this post job is successful.

With the electric oil pressure sender I had no more than 20 Ibs pressure dropping to zero on tick over when warm.
Now with the wet line I have a reading of 45 Ibs when cold with only a slight drop to approx 42Ibs pressure at tickover with engine at normal ( 70C ) operating temperature.

Lesson learned, before fearing the worst if your oil pressure stays low change to a wet line.

(Paul Breen pay palled it) #10

Hi Eugene, that’s a great outcome. As for the sixes it seems the aftermarket V8 senders are also poor. I my cars I pulled out the operating English made originals and replaced with wet gauges, for posterity. Paul