Fiat Coupe Club UK

Where to measure oil temperature.

Posted By: dante giacosa

Where to measure oil temperature. - 28/10/2015 12:40

I am interested in oil temperature. I'd like a gauge.

Where would be a terrific place for a probe?

I probably won't go for a screw-in FIAT/Lancia pickup, and will use something more electronic which I'll attach somehow.

On the oil pump? Can we see that- low down- externally?
Posted By: Anonymous

Re: Where to measure oil temperature. - 28/10/2015 13:25

Drill and tap sump or swap sump for the earlier style with the oil temp sensor? Neither would be a fun job though.

Only other obvious spot would be where the oil pressure and low pressure warning sensors are fitted on the back of the block. There's a threaded hole there into an oilway, with a "Y-piece" adapter screwed in for the 2 existing sensors. Maybe some kind of 3 way adapter is available that could be used there.

Or you could put a sensor under the oil return pipe at the turbo and measure the temp of the usual drips of oil there. tongue
Posted By: Countrycruising

Re: Where to measure oil temperature. - 28/10/2015 13:54

It's also possible to fit an oil temp sensor in the end of the head by the thermostat.
Posted By: dante giacosa

Re: Where to measure oil temperature. - 30/10/2015 10:21

Thanks for this-

Oh yes, of course- the blanked off measurement point on the thermostat.

(I don't have the turbo)

I'm really just interested in how warm the engine oil is getting, aside from coolant temperature. Just a sort of 'mechanical sympathy' thing you know?

I'll have a look at the rear of the sump then...
Posted By: Countrycruising

Re: Where to measure oil temperature. - 30/10/2015 11:00

The blank on the thermostat is water.

The one I meant is small blank on the end of the head so I'll get you a picture of it's position later.
Posted By: Jopa_zgd

Re: Where to measure oil temperature. - 31/10/2015 18:49

Would sensor readings from head have unreliable data's? As I know, oil flow in head is at minimum (there is a restrictor at top of the block). Also that oil "chamber" in head will never be full of oil (if I remember correctly this "chamber" is for oil return). So you will read head and oil temp, depends which one will have more influence on sensor.
Posted By: Countrycruising

Re: Where to measure oil temperature. - 31/10/2015 20:23

The oil galleries are always full on the head of a 20v, if they weren't the cams would be staved leading to wear issues, and there's no restriction between the block and head.
These galleries are under pressure feeding the buckets/cams, from there they gravity drain back to the sump so if a sensor was fitted in one of the gallery blanks it would read the same temp as if fitted to the sump or 'T'ed off the pressure sensor fitting on the rear of the block.
Posted By: Countrycruising

Re: Where to measure oil temperature. - 31/10/2015 20:24

Originally Posted By: dante giacosa
Thanks for this-

Oh yes, of course- the blanked off measurement point on the thermostat.

(I don't have the turbo)

I'm really just interested in how warm the engine oil is getting, aside from coolant temperature. Just a sort of 'mechanical sympathy' thing you know?

I'll have a look at the rear of the sump then...


Been busy but I will get a picture for you.
Posted By: dante giacosa

Re: Where to measure oil temperature. - 01/11/2015 19:33

Thank you for your help...

No rush...
Posted By: Jopa_zgd

Re: Where to measure oil temperature. - 02/11/2015 12:42

Originally Posted By: Countrycruising
The oil galleries are always full on the head of a 20v, if they weren't the cams would be staved leading to wear issues, and there's no restriction between the block and head.
These galleries are under pressure feeding the buckets/cams, from there they gravity drain back to the sump so if a sensor was fitted in one of the gallery blanks it would read the same temp as if fitted to the sump or 'T'ed off the pressure sensor fitting on the rear of the block.


You're right smile
Just looked at my head, these galleries are pressurized. Don't know how I had in my mind that these are for return.

2 Dante, this is the place what Countrycruising talks about. smile
lower big hole is for thermostat, two upper thin holes are oil galleries, closed with allen bolt in original
click to enlarge
Posted By: Countrycruising

Re: Where to measure oil temperature. - 03/11/2015 15:19

Thanks, you've saved me a job thumb

Yes as Jopa's pictures shows there's two small ports which are the ends of the oil galleries, feeding the buckets/cams, it's a 1/4 bsp thread from memory so you should be able to find a generic sensor to fit, I would however double check that thread/size first.
Posted By: dante giacosa

Re: Where to measure oil temperature. - 03/11/2015 21:39

That is pretty terrific!

Couldn't ask for more than that- thank you jopa, thank you Joe...

Thinking cap on...
Posted By: gturcic20vT

Re: Where to measure oil temperature. - 12/03/2018 20:51

I have a '99 20vT Plus, with voltmeter in the dials, and would like to put an aftermarket oil temp and boost gauge.
As I understand, my car has sump without oil temperature sensor hole, so the sensor would have to go in the blanked hole on the head, as on Jopa's picture?

What do I need to buy?
I've been looking at gauges with simple white faces and font (as on stock Plus dials), but couldn't find any other than cheap china ones, eg. Aliexpress https://www.aliexpress.com/item/Car-Gaug...2770695250.html
From the product description I can't see sensor thread dimater, do I need to buy some other sensor (what diameter?) to fit into existing holes in the head? Are generally sensors interchangeable / same voltage output range?
Posted By: Countrycruising

Re: Where to measure oil temperature. - 13/03/2018 12:46

Originally Posted By gturcic20vT
I have a '99 20vT Plus, with voltmeter in the dials, and would like to put an aftermarket oil temp and boost gauge.
As I understand, my car has sump without oil temperature sensor hole, so the sensor would have to go in the blanked hole on the head, as on Jopa's picture?

What do I need to buy?
I've been looking at gauges with simple white faces and font (as on stock Plus dials), but couldn't find any other than cheap china ones, eg. Aliexpress https://www.aliexpress.com/item/Car-Gaug...2770695250.html
From the product description I can't see sensor thread dimater, do I need to buy some other sensor (what diameter?) to fit into existing holes in the head? Are generally sensors interchangeable / same voltage output range?


I've found the sump more suited for a temp sensor, yes it fits in the end of the head which is where I've fitted them in the past but I've found it's not reliable so over the past couple of years I've changed there position and fitted them in the sump so the sensor is constantly submerged in oil.
Posted By: gturcic20vT

Re: Where to measure oil temperature. - 14/03/2018 22:00

Originally Posted By Countrycruising

I've found the sump more suited for a temp sensor, yes it fits in the end of the head which is where I've fitted them in the past but I've found it's not reliable so over the past couple of years I've changed there position and fitted them in the sump so the sensor is constantly submerged in oil.


It's not realiable as in temperture reading, or starts leaking as the gallery's under pressure?
To mount it in the sump, sump must be drilled and right threaded hole made?
What about using oil filter sandwich plate with hole for sensor? Is that a potential leak?
I don't drive the car hard, I'd like the gauge as a source of information against Coupe paranoia - is everything ok, when has the car warmed itself up properly, why sometimes pressure reads 1,5 on idle and sometimes 2,0bar... and I've always hated the voltmeter gauge, it's not very accurate and the same info can be had with 10€ multimeter or lighter usb charger with a display.
Posted By: carmine

Re: Where to measure oil temperature. - 28/05/2018 22:39

Hi, I wanted to know if someone could show me a picture of the hole on the head, (I can not visualize it), to attack the oil temperature, my car had the engine replaced with a new one without the hole in the oil pan. I have the speedometer with the built-in meter could I use that?
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