NOHOME
NOHOME MegaDork
7/30/19 11:38 a.m.

Still need a Oil pressure sender for the Molvo. If anyone has one in their spares pile surplus to requirement, I need one to finish the gauges on the factory display.

Alternative is to try the Ford sending unit but I have no idea on how the calibration will work with the Miata gauge. Anyone know why the Miata one is so large?

 

 

Pete

AWSX1686
AWSX1686 SuperDork
7/30/19 12:01 p.m.

That sensor was only on the 94 1.8 engines. It's a real sensor vs. a "dummy" gauge on the later cars. 

Does your dash have actual numbers for the oil pressure or just blank marks? If actual numbers this is, in fact, the sensor you need, and it's pricey new. If the marks are blank, it uses a smaller, cheaper sender. 

 

Here you can see the smaller sender for the "dummy" gauge cars on the left, and an aftermarket sender on the right. 

 

Unfortunately I do not have one on hand, so all I have to offer is this information.

AWSX1686
AWSX1686 SuperDork
7/30/19 12:06 p.m.

Here's 1994 vs 1995 from RockAuto...

 

If you need the pricey one, I would either look into getting the "dummy" style sender, and gauge and I think you can swap it into the cluster. (Kinda silly) OR go for an aftermarket sensor/gauge combo. 

NOHOME
NOHOME MegaDork
7/30/19 1:26 p.m.

I dont think that the gauge has numbers, but now that you mention, I need to check.

Yeah, I went to Mazda and asked for the big sender and about passed out- figured they were scamming me, but if that is what they really coast!?

 

The budget for the big one aint there right now, so if I have to do a calibration of electrical gauge vs mechanical and used the smaller sender, then I will go that way.  All I really need is a single mark to tell me where the pressure is when it  runs hot and cold. Could care less about the actual numbers.

 

Pete

BoxheadTim
BoxheadTim MegaDork
7/30/19 2:39 p.m.

The "big" sensor was also used on the 90-93 engine, IIRC. They certainly fit, I've used one plus the OEM gauge to get proper oil pressure readings. And yes, the sensor is expensive and the OEM gauge in unobtanium other than used.

I vaguely recall some articles on how someone turned the "idiot gauge" - the one without the oil pressure numbers that's essentially a glorified oil pressure light - into a real one after pairing it with a different sensor.

Unless you're wedded to using the OEM cluster (which would normally also require sourcing a gauge) I'd just try to find a nice aftermarket gauge.

AWSX1686
AWSX1686 SuperDork
7/30/19 2:52 p.m.
BoxheadTim said:

The "big" sensor was also used on the 90-93 engine, IIRC.

I do believe you are correct there, I was just pretty sure he had a 1.8. Definitely worth mentioning though.

BoxheadTim
BoxheadTim MegaDork
7/30/19 2:58 p.m.

In reply to AWSX1686 :

Unfortunatelty it doesn't make the sensor/gauge combo any cheaper. A lot of people with a 95-97 Miatas want that sensor and gauge to upgrade their own clusters.

wvumtnbkr
wvumtnbkr UberDork
7/30/19 3:02 p.m.

I wonder if the 86 through 88 rx7 pressure sender would work?  Looks similar with a different wire connection.  As far as I know it was actually pretty accurate in the 86 through 88 cars.

therieldeal
therieldeal Reader
7/30/19 3:06 p.m.

My ’99 miata came with the “dummy” style gauge/sender from the factory.  The sender was leaking, I replaced it with a 1/8 BSP X 1/8 NPT adapter and one of these inexpensive universal sending units:

https://www.ebay.com/itm/Oil-Pressure-Sensor-Transducer-0-80-psi-input-10-180-ohms-output-Pressure-Sensor/132334835497?hash=item1ecfc55729:g:hRcAAOSwiwZb85DD

My gauge doesn’t have any numbers on it so the exact needle position doesn’t matter much… but it DOES function like a real live pressure gauge now.  For example I can tell by needle position at idle when the oil has warmed up, which is very helpful.

Doesn't entirely solve your problem but i thought you might find this info helpful.

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