The old gauge was around 8 years old I think but it might have been a secondhand unit I found in a box so could have been a lot older. The new one I fitted from SNG is only a couple of weeks old so not the same batch.
The wiring has not been altered and apart from pulling the wires out of the wiring loom there is no way of detecting an intermittent fault with it if that is what this is.
The gauge is original other than having been cleaned 8 years ago and I can see nothing wrong with the connections on the back.
Will have to see where I go with the new sender unit when it arrives and if SNG find fault with the unit I will be sending back. At nearly £90 a pop you would expect quality and reliability from the sender.

 

Thomas Rochelle ~ my go to man for the whole project that Mr Barratt assigned to me said that the new senders were vastly improved, with no comeback rate. Mine has been faultless. Thomas has subsequently been promoted up the chain. Well deserved. His standard of service was excellent.

 

https://forum.etypeuk.com/viewtopic.php?t=18515

Reading the link above, especially the comments indicating the modern replacements to the original design aren't to the original design, can make you abandon all hope in anything other than opening up an old sender and old gauge and doing some surgery to make them work or swapping to a Bourdon gauge. I keep changing my mind on the latter.

 

My pressure always reads a little high but I did Plastigauge every bearing in my engine & use the original oil pump which measured very healthy. I've checked the reading with a calibrated gauge at the filter housing/sender point and it is correct.

As far as I'm concerned as long as there is extremely good flow at the cams all is OK.

 

https://www.jaguarforums.com/forum/m...cation-209831/

 

Just to continue this thread. I have the new sender from Barretts but have not fitted it yet. The oil gauge with this sender in is still running wild ie one minute zero then up to 60 then back to normal on a run. Not too bothered regarding oil pressure as I think it is either the gauge or the sender unit that are faulty. Before I fit the new sender I thought I would buy an oil pressure testing gauge. Arrived a couple of days ago and in the advert it states it has adapters to fit most applications. My question for now though is which adapter fits our oil sender unit. Comparing the thread patterns against the new unit going in it looks like 1/2" X 20 UNF is the closest thread on the adapters but is this the correct thread?

I have to wonder about the design of this tester though as it has a quick release system like you would find on an air line. Problem is the quick release system seal is on the end of the gauge hose not on the adapter? So if you release the gauge from the adapter that is screwed into the oil filter there is nothing to stop the oil (if the engine was running) from shooting out of the adapter all over the engine. Surely common sense would say that the end you want to seal is the end where the oil comes out under pressure not the dribble of oil that might be in the gauge. Can you imagine disconnecting an air line from a compressor with this same set up and having all the air from the compressor jetting out of the fitting whilst the hose you have disconnected is sealed. Does not make sense to me.

 

I think the sender thread will be BSP, probably 1/8 inch parallel. Unfortunately, BSP isn't in the list on your box. It's possible one of the ones in the box will be near enough. The best thing to do is compare the diameters and distance between threads on a sender with the fittings in the box to see if one matches. NPT is sometimes close. In case you don't know and to avoid (?) confusion, the size of a pipe thread relates to the nominal bore of the pipe the thread would be on the outside of. So a 1/8 inch BSP thread has a diameter of approximately 1/8 + 2 x wall thickness.

 

....however, as you mentioned 1/2 inch UNF looks close, then it's probably 1/4 inch BSP. Still check the threads per inch before forcing the UNF adapter into the hole. Sorry, for giving the wrong size before. My memory of what I'd used years ago must be failing.

 

Would this be of help:
https://www.ebay.co.uk/itm/113182077...3ABFBM4piar-Fi
Richard

 

Thanks for the suggestion Richard but the threads on the female side of that adapter do not equate to any of the adapters in the set I have. 3/8 UNF is fine but I have 20 TPI where as the EBay adapter is 24TPI.
I also need someone to confirm what thread is on the oil sender. Don't mind jamming 20 TPI in to 24TPI on the adapter but don't want to do that on the oil filter housing as it will bodge the thread up and I will not get the Oil pressure sender back in to sit tight. I see there are a lot of these adapters and they are relatively cheap so if I can get confirmation of the thread on the sender I could possibly find one to fit.

 

Cass, sorry my info is a bit confused, but it was shortly after my Dad bought the car that he and I were trying to attach a second pressure gauge to investigate the mystery of the disappearing oil pressure. I was still at school and the Beatles were still together and someone had lent us an industrial size bourdon gauge. The threads on the sender connection tappings were definitely BSP. The bolts on the side of the block that close the oil gallery, being bolts, will almost certainly be UNF and might well match one of the nipples of your test gauge. Using one of those will also allow simultaneous measurements from the car gauge and the test gauge.

 

Thanks Pete as that is what I want to do. Have the test gauge running at the same time as the oil gauge on the dash so I can compare them. Are these the bolts you are talking about on the oil gallery. There are Six of the them.
​​​​​​​

 

Yes, those are the ones. If they are brass as in your photo, apart from access, it shouldn't be too difficult to remove one. I think these are where the block is drilled to take oil from the gallery to the main bearings. In view of that, it may be a good idea to clean the area before taking one of them out as it's not a good place to mainline some dirt. With a bit of luck, they will be half inch UNF.

 

Peter how dare you think I have a dirty engine. Clean as a whistle and no oil leaks. Not even from the gear box or the power steering.

Access might be a problem but no worse than getting to the Oil pressure sensor itself.

 

Well, you know a tiny speck of dried Brasso might just have been caught on the ledge above the gallery. And I didn't intend to judge you by my low standards. I had thought of looking at my engine to check the size of the bolt heads, but realised how much oily mud I'd have to shift ... .

 

Perfect timing on this thread. My engine has been completely rebuilt and I was thinking it would be wise to attach a mechanical gauge in place of the electric sender to eliminate the sender, gauge and wiring as potential problems for the first start up. I also have a mechanical gauge kit that does not include the correct adapter. Best I can tell, the sender is a 1/2-18 thread and not a pipe thread. The sender very easily thread into the block and the copper washer creates the seal in place of a pipe thread arrangement.
I did some looking around for a 1/2-18 male adapter on Ebay and a general Google search and came up with nothing except one with a ridiculous price. I was hoping someone could point me to an adapter or some other temporary, inexpensive mechanical arrangement since I do plan on switching to the electric sender once I have some confidence in the oil pressure.

 

Are you sure the threads per inch are 18 and not 19?

 

Hi Peter, I'm pretty sure it is 18. My thread gauge is plastic but it fit in there very nicely and 1/2-18 does seem to be real but not very popular. My search of adaptors and fittings did not turn up any 1/2-19 parts. I did find a 1/2-18 brake line fitting that I may be able to modify to work with my mechanical test gauge. I think I will take a $15 gamble on that.

 

Thank you for the reply. 1/2 inch by 18 tpi is 1/4 inch NPT. If it were 19 tpi, it would be BSP. Both parallel of course; the seal being made by the copper washer under the flange. I'm a little surprised that it's NPT as the US standard wasn't common in the UK or anywhere outside North America until Ford and GM subsidiaries adopted it. If the threads are properly made, you can also feel the difference: the American thread has sharp edges, while the British is smooth. It is possible to 'bodge' fittings of the two different sizes to gether, if there aren't many threads on one (or if you grind them off). Apologies for any nerdism - my father spent his life as an engineer in the steel tube industry and my first job was as an apprentice there.

 

NPT is a taper thread, so I'm sure it isn't that. I would suspect it is British Parallel Pipe thread.