Hello all:
My oil pressure light has been blinking on and off for two years. I've verified that it's not the sender, or the actual oil pressure itself. The problem is in the wiring. The light acts normally when the key is switched on, and engine started. Light goes out, but then blinks on and off. Mostly randomly, but more often when car is accelerating. Light throttle on/off at cruise will make the light blink on and off.

Problem is in the wiring. Disconnecting the sender results in the light not coming on with the key. It still blinks on and off with motor movement back and forth (throttle on and off).

Obviously, there's been no engine failure or loud noises, etc. I'm thinking of just installing an aftermarket oil pressure gauge like this:

http://www.jegs.com/i/VDO/918/350-041/10002/-1

I'm thinking it would use a sending unit like this:

http://www.jegs.com/i/VDO/918/360-005/10002/-1

Can anyone verify that the stock oil pressure switch uses a 1/4" NPT thread?

What would be the best way to route the wiring for the sending unit into the passenger cabin?

Responses from those with actual experience/knowledge would be appreciated.

 

I doubt it as the engine is based on a Peugeot unit that would be entirely metric.

 

Thank you for your response, but you need to be better informed. First generation MINI's have a BMW/Chrysler engine made in Brazil. Furthermore, even metric engines/cars often use standard oil pressure senders with 1/8" pipe thread. It's a taper thread.

 

If you have a thread gauge, you could pull the Sending Unit (if you are referring to the one on the drivers side near the top of the cylinder head) you should be able to pull it and check the thread, then re-install it with little or no oil seepage.

Since the OEM unit has two leads, I would assume one is a ground, therefore the blinking light isn't due to a bad or faulty engine ground. It would point to a wiring problem with the stock wire harness. (I personally think troubleshooting electrical issues are the most time consuming in all maintenance tasks). I understand your desire to put in an ancillary pressure gauge. I would trace the OEM harness in the hopes of finding something obvious like an intermittent open located at a pass through (where the wire harness passes through the firewall).

If I have time when I get home tonight, I'll see if I can pull one of mine and gauge the threads for you if the thread question has not been answered by then.

Motor on!

 

I've installed an aftermarket Oil pressure gauge on my 2004 MCS and used this adapter http://www.promini.com/product-exec/...arch_model/100 . I purchased a AutoMeter gauge that has an 1/8" NPT thread. Check out www.egauges.com they have a wide selection of gauges that comes with the sender included. Also the max oil pressure will be around 50 so an 80-100 psi gauge would work well on a Mini.

 

From what I can tell from observation (and I removed and examined the plug to the sender) there is only one wire to the sender. The circuit uses the engine for the ground return path. Further, the circuit is normally open (the sender completes the path to ground.

Therefore, any abrasion on the one wire to the sender causing a path to ground would cause a false signal.

I have examined the wiring diagram closely, and believe I am correct about the foregoing.

 

That sure looks handy, but WOAH! $50 for 2 brass fittings? That's $6 in parts max.

That is how it is in my non-MINI. The one wire sender is the ground path for the idiot light in the dash. In it, oil pressure above 5psi breaks the contact thus turning off the dash light.

 

I've got a 2003 MC-S. Recently changed the oil filter housing, and the old one was still sitting around to inspect- the good news is that a 3/8-18 NPT tap fits _perfectly_ into the hole where the stock oil sender goes. The oil sender also threaded perfectly onto the 3/8 NPT die (all the way up, so it was cut pretty small).

One signal wire on mine.

I have read you have to be careful when installing them, as the sender needs to be sealed but still make good ground contact - perhaps too much tape would be a source of your intermittent signal - you are supposed to leave the first 3-4 threads without tape and just put tape on the threads closer to the body of the sender.

 

Actually: no PTFE tape on the thread. The taper gives the seal.

3/8" NPT it is.

 

The Bentley manual says replace the sealing washer on the oil pressure warning switch, which is clearly wrong.

The one I just pulled to measure clearly had teflon tape on the second half of its threads - I don't know if that was factory or the work of a previous owner/mechanic.

The version TIS I can see also refers to the non-existant sealing ring.

 

Where did you run the signal lead through the firewall? Can you post pics of where you ran the lead?

Thanks.