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On my 1973 Spider Junior (1600cc engine) the oil pressure gauge goes off the scale (high) whilst driving. It sits at 4.0 bar when idling. Reading the various topics on here it points to the sender,as earthing it makes the gauge show maximum. So I need to order a new sender I guess. Problem is the current sender has 2 spade connectors (only one connected) whilst the replacements shown on the Alfaholics site shows only 1 connection. This makes sense as I believe the gauge is always live so only need one connection to the sender. The gauge is Veglia. Can anybody help with replacement sender I need to order as I understand fitting wrong/incompatible sender can cause problems. I guess as the existing sender has the 2 connectors this points to it being the wrong type.
 

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You may consider a mechanical gauge in addition to the factory gauge. A simple "T" fitting and mounting the gauge are the most difficult parts of the job.
 

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In the US, I have only ever seen a one connector pressure sender. I agree, the problem is usually the sender. While you are replacing the sender, while it is off, I advise temporarily installing a hand held mechanical gauge, and see what it reads. I always do this. I write down the oil pressure indicated for cold idle, cold 2k rpm, hot idle, hot 2k, hot 4k, etc. Then compare this to the instrument panel gauge readings. All for peace of mind... Please report your findings.
 

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Discussion Starter #4
Many thanks and good advice. Need to get the parts so might wait until lock-down over in Portugal as I can't drive the car at present.
 

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I’ve been fiddling with both my Spider, Jaeger, and Alfetta, Veglia, gauges this week.

First important point.

The hole in the block should be 10mm X1 straight threads that use a coppper sealing washer. I’ve never seen a two-connector sender on an Alfa, so predict you’ve got a non-original sender with a 1/8” NPT tapered pipe thread. If so, it remains to be seen if the sender installation has irretrievably damaged the threads in your block.

Others on the BB have attempted to define all of the sender options. I’ve not yet been able to absorb the important points. Need to reread earlier in the day.

I’ve got a sender sold by OKP for Veglia gauges. Unfortunately, it is not correct for the Veglia gauges in my Alfetta. Research continues. It is possible it works with your gauges. Where are you located?
 

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Discussion Starter #6
Hi DP!
I am in the Algarve, Portugal as is the car. The sender already installed looks non standard and based on the 2 connector issue I guess was fitted by the previous owner during an engine rebuild. You are worrying me now that they may have b**ggered up the thread in the engine. So now debating whether to fit a new one or leave well alone. As many have said on this forum the gauge is only a guide at best!
 

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I think all the gauge senders are the correct M10 threads. I think sometimes the oil light sender unit is mistakenly a 1/8 NPT tapered one. Mine was but the block threads are definitely M10.

I suggest removing both senders and verifying they are correct M10 threads. If not, get the right senders.

Male 1/8NPT seems to "work" in an M10 hole without too much "damage" as long as they didn't over-tighten the sender and used plenty of Teflon tape to just snug it up. Just put the correct one back in.

But M10 male doesn't fit a female 1/8NPT without really jamming it hard, and it will not go in enough for the washer to seal. But this problem does not apply to your car since there are no NPT holes.

I believe this is because 1/8 NPT tapper starts smaller than M10.
 

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the current sender has 2 spade connectors (only one connected) whilst the replacements shown on the Alfaholics site shows only 1 connection. This makes sense as I believe the gauge is always live so only need one connection to the sender.
Other makes of car use a single sender for both the gauge and warning light. So those senders need two connectors. I guess some PO used just the gauge side of one of those dual purpose senders. What sort of threads those senders use - straight vs. tapered - is an unknown to me.

The gauge is Veglia. Can anybody help with replacement sender I need to order as I understand fitting wrong/incompatible sender can cause problems.
Yes, different Alfa gauges use different sending units whose electrical characteristics vary. Classic Alfa sells three types of senders, which they describe as:

p/n EN054 for early model Veglia gauges
p/n EN055 for series 3 and 4 spiders with electronic fuel injection (clearly this one isn't right for your '73)
p/n EN056 for all Jaeger and some Veglia gauges

So you probably want an EN054 or EN056, but I'm not sure which. You might just contact Classic Alfa to ask.
 

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In my last exchange with Christian Ondrak at OKP, he remarked that he was confused about the senders as well. The one he sold me for my 78 Alfetta with Veglia gauges did not operate correctly. For a German parts guy of high repute to admit confusion....

So...

We in the US never officially received the “Junior” versions of cars. LandC’s car has Veglia where most, or all, of our US, non-Junior, Spiders have Jaeger.

I’ve got a hunch there are far more than three types of senders for Alfas between 1965-1995. It seems possible the PO made a stab at a replacement with no success, and possibly some hopefully minor damage.
 

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Discussion Starter #10
Thanks to all who have responded. I fitted an oil pressure gauge to my Mini Moke which was a doddle compared to this as only one sender was listed plus I bought the sender and gauge as one so no confusion! I guess it is a case of removing the existing one, talking to the suppliers, getting hold of replacement and hope for the best!
Is it easy to determine the thread on the existing one once it is off the engine?
For the dumb amongst us (me!!) how can I tell if the current sender has the correct M10 thread.
Cheers
 

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You can look at the threads and if they are straight they are M10. If they are tapered they are 1/8. Kinda hard to tell without both side by side, then it would be obvious.

If you have a caliper you can measure the threads. M10 is the same at the end and the base. 1/8 will be smaller at the end and wider at the base.

Or if you have a size M10 sealing washer it will fit all the way down but will get stuck half way on the 1/8NPT.

If your sender you remove has the washer, then it's probably the correct threads...unless someone put a larger washer on a 1/8NPT sender to "make it fit" but that is unlikely, but also not impossible.

But either way...the correct sender will have M10x1.0 threads
 

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for a few euros you can buy a thread pitch gauge......very useful little tool that you will use forever:)

thread pitch gauge.jpg
 

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Discussion Starter #13
Cheers all. I guess the first task is to remove the current sender and check it. Doesn't look that easy based on its position deep down by the starter. Will remember to disconnect the battery to avoid shorting out across the starter terminals.
 

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As to the damage done to the 10 x 1 mm female threads by the 1/8” NPT tapered pipe thread. (At least in my case.) I just installed a new sender sold by Centerline with the 10 x 1 mm size. The old 1/8" only went in a few threads. No tape, no leaks. The new one went all the way in enough to seat the aluminum washer.

The new sender reads 269 ohms before install. Reads reasonably well, when tested, but it will be a few weeks before I get to take it out for a run.

BTW: A 17mm crow foot wrench works really good installing the sender.
 

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Discussion Starter #15
Cheers and thanks for the tip regarding removal of existing sender. Looks a real pig of a job. I guess it's easy in manufacture with the engine on a bench!
 

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its not that bad a job.....
if it's the original one on there, you might need a 14mm thin wrench to take it off and a 17mm thin wrench to put the new one back on...once you crack it a quarter turn loose, it will spin off easily
 

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you can cut down an old wrench if needed or try a stubby wrench (they do make those). The gauge sender by the starter is likely M10 male when you remove it. I don't think I've seen an NPT gauge sender in the last 40 years on any car. unless someone try installed one from an old 1970's American car??? I could be wrong but most American cars went metric in the 80s.

The light sender on the left side it would not be uncommon to find an NPT sender incorrectly installed. I think a lot of domestic cars might still use NPT on the light sender.

I suddenly feel the need to check my 2005 Dodge Neon. I recently replaced the light sender and it had thread sealant and no washer??? I didn't think anything of it because that's what the part counter sold me. And yes, I'm stupid for not looking closer at the old one :(
 

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On my 1973 Spider Junior (1600cc engine) the oil pressure gauge goes off the scale (high) whilst driving. It sits at 4.0 bar when idling. Reading the various topics on here it points to the sender,as earthing it makes the gauge show maximum. So I need to order a new sender I guess. Problem is the current sender has 2 spade connectors (only one connected) whilst the replacements shown on the Alfaholics site shows only 1 connection. This makes sense as I believe the gauge is always live so only need one connection to the sender. The gauge is Veglia. Can anybody help with replacement sender I need to order as I understand fitting wrong/incompatible sender can cause problems. I guess as the existing sender has the 2 connectors this points to it being the wrong type.
First- do you have a low pressure warning light?
Second - where is the sending unit on the block?
3rd- I presume this is a Kamm tail Euro spider with carbs.
4th check wires for voltage- if no voltage ground each wire one at a time. One should max gauge the other might turn on low pressure light ( some have mistaken the light for alternator light to drastic results )
You might have to make a T fitting and acquire a “ground with no pressure switch”
for the second wire. A long time ago when converting from FI to Weber and/race car
I setup relays and sensor/switches for low oil pressure warning light and fuel pump cut-off with pump on momentary with starter.
Took some time but well worth it.
 
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