Oil temp gauge reading when cold

[Djdiplomat]

Trying to narrow my down my issue ( inaccurate reading). This is how mine looks when cold with just ignition on. When fully warm it shows 250 but Per my thermometer dipped in the oil it's more like 175. Sender and sensor look original.

[fintstone]

While the sender may be original, gauge sure is not. It clearly has an overlay that may or may not be correct for that gauge.

It helps to indicate what year your car is when you ask for help. Most list it in their sig area.

[Djdiplomat]

Originally Posted by fintstone

While the sender may be original, gauge sure is not. It clearly has an overlay that may or may not be correct for that gauge.

It helps to indicate what year your car is when you ask for help. Most list it in their sig area.

Thank you would do. It's a 77

[spuggy]

Originally Posted by Djdiplomat

Thank you would do. It's a 77

That isn't the correct gauge and/or overlay for a '77, which originally had a 0-340F temperature gauge for the US (some RoW markets used Centigrade scale).

It's important for the sender to match the gauge; otherwise it'll read 60F high (or low). 74-76 cars used the 0-300F gauge - but they take a different temperature sender to the '77.

[Djdiplomat]

Originally Posted by spuggy

That isn't the correct gauge and/or overlay for a '77, which originally had a 0-340F temperature gauge for the US (some RoW markets used Centigrade scale).

It's important for the sender to match the gauge; otherwise it'll read 60F high (or low). 74-76 cars used the 0-300F gauge - but they take a different temperature sender to the '77.

Thanks for that info! I just checked and build date is 6/76 could it be I still had the 0-300?

[Nditiz1]

99% sure 76 also had 340. Even still when my 77 is cold it does not jump that high even if you had the correct overlay.

[Djdiplomat]

Originally Posted by Nditiz1

99% sure 76 also had 340. Even still when my 77 is cold it does not jump that high even if you had the correct overlay.

Thanks! What can make it jump like that? I diconected the sensor and sender and it still jumps, however tad lower. I doubt the gauges were changed since everything on the car looks original but it's a possibility for sure.

[Nditiz1]

I would double check its wired correctly. You can test the gauge by grounding out the sensor wire.

[Djdiplomat]

Originally Posted by Nditiz1

I would double check its wired correctly. You can test the gauge by grounding out the sensor wire.

I did...it maxes out.

[spuggy]

Originally Posted by Nditiz1

99% sure 76 also had 340.

Really? I've also seen folks trying to tell me that my '77 didn't have a 0-340 gauge, that it had a 0-300 like their '76. When there's a picture of it right in the owners' handbook, lol.

PET seems pretty clear the cutoffs on the various "combination instrument #11" parts are the "chome dot" part up-to-74, the early middie up-to-76 and the 77-and-later (which of course, didn't include the SC in the end, because they dropped the numeric scale).

That said, no idea where the actual cutoff in production was; my build date is May '77. They would have started actually building 77 MY cars in '76 (after the August break, IIRC), and could have started fitting the new gauge towards the end of the '76 MY.

Or it could be the wrong gauge and/or overlay scale, which might explain it reading too high.

Originally Posted by Nditiz1

Even still when my 77 is cold it does not jump that high even if you had the correct overlay.

Agreed. I never really paid any attention to mine before the motor was running before, but just went and checked. It moves the needle off the bottom stop, and reads ambient - currently less than 80F, the first mark on my gauge. So, with power applied, "cold", it sits between the bottom stop and the first tick on the gauge.

Unless either the garage or the motor is 175F, it really shouldn't read that, I'm thinking..

[Nditiz1]

spuggy - I stand corrected 76 manual does show 0-300

Here is how my 77 does it:

[spuggy]

Originally Posted by Nditiz1

spuggy - I stand corrected 76 manual does show 0-300

LOL - I've never been wrong. Not once. Nuh-uh

PET is quite confusing in this section too (and the drawings aren't detailed enough, and the "descriptions" are all pretty terse)...

The SC's had separate instruments (or at least part #'s) for -81 versus 82-up - but they also had a separate instrument for Sporto-equipped cars, which also took a different temperature sender (same as the early middies, I think).

And, of course, at least some RoW were in Centigrade, and some had pressure in bar instead of PSI.

I /used/ to think the SCs took that same sender - but someone figured out on another thread that 'SPM' in the part listing meant 'Sportomatic'. So it looks like 74-76 and Sporto-equipped SCs take the same temp sender, whereas 3.0/3.3 930s, 77-up 911s through SCs up to the last 3.2s take the other one.

Dunno. Pretty darned sure mine are matched & read correctly

It's a real shame, considering that you can remove/swap the temperature gauge itself between instruments, that there's no part #'s for that. Not that I've ever noticed one marked on it (might be one inside). Ho-hum.

Originally Posted by Nditiz1

Here is how my 77 does it:

Yeh - exactly the same - except that it was 75F earlier, so it didn't reach the 80F mark

I stare at the pressure gauge when cranking/starting and figure there's no point even looking at temperature until it's been running for quite a few minutes.. Like 3-4 miles at least.

[SCadaddle]

Originally Posted by spuggy

LOL - I've never been wrong. Not once. Nuh-uh

PET is quite confusing in this section too (and the drawings aren't detailed enough, and the "descriptions" are all pretty terse)...

The SC's had separate instruments (or at least part #'s) for -81 versus 82-up - but they also had a separate instrument for Sporto-equipped cars, which also took a different temperature sender (same as the early middies, I think).

And, of course, at least some RoW were in Centigrade, and some had pressure in bar instead of PSI.

I /used/ to think the SCs took that same sender - but someone figured out on another thread that 'SPM' in the part listing meant 'Sportomatic'. So it looks like 74-76 and Sporto-equipped SCs take the same temp sender, whereas 3.0/3.3 930s, 77-up 911s through SCs up to the last 3.2s take the other one.

Dunno. Pretty darned sure mine are matched & read correctly

It's a real shame, considering that you can remove/swap the temperature gauge itself between instruments, that there's no part #'s for that. Not that I've ever noticed one marked on it (might be one inside). Ho-hum.



Yeh - exactly the same - except that it was 75F earlier, so it didn't reach the 80F mark

I stare at the pressure gauge when cranking/starting and figure there's no point even looking at temperature until it's been running for quite a few minutes.. Like 3-4 miles at least.

That was me.

[Djdiplomat]

Quick video, at the end I plugged in the sender back and grounding the sensor. Should I start with the gauge since it's creeping up disconnected?

https://youtu.be/_K7lXydyv-Q

[917_Langheck]

Pull the sender out - put a plug into the case to minimize oil seep - and put it in a container of boiling water. With it wired to the car you can key on the car. It should read just above even with the 210° line.







If it doesn't make that reading then the either the sender doesn't match the gauge, or the dial face is incorrect.

[Nditiz1]

If you can, get a reading on what sender is in the block. The correct one should say 200Cmax 911.606.112.00. That is the correct for a 77. Now, if you want one that matches the overlay that would be 150C. Don't know the part number for that one. BUT with that overlay, it can't be determined if the gauge is a 340 or a 300. So you may need to figure that out or swap the correct one. Another thing is I don't like how you said the gauge is slowly moving up when disconnected. It shouldn't do that. Don't know if that's a grounding issue or gauge issue. Test it on the bench.

If it were my car, I would ditch all those white gauges. Your car looks too nice to have these bright white "ricey" overlays. Not meant to be offensive, just looking at what your car could transform into with a stock set. Your car though so you do you.

[Djdiplomat]

Originally Posted by Nditiz1

spuggy - I stand corrected 76 manual does show 0-300

Here is how my 77 does it:

Looking at your video and mine I think the needle may have been placed incorrectly when the face was swapped. Additionally, the oil pressure needle looks lower than the temp it seems.

[Djdiplomat]

Originally Posted by Nditiz1

If you can, get a reading on what sender is in the block. The correct one should say 200Cmax 911.606.112.00. That is the correct for a 77. Now, if you want one that matches the overlay that would be 150C. Don't know the part number for that one. BUT with that overlay, it can't be determined if the gauge is a 340 or a 300. So you may need to figure that out or swap the correct one. Another thing is I don't like how you said the gauge is slowly moving up when disconnected. It shouldn't do that. Don't know if that's a grounding issue or gauge issue. Test it on the bench.

If it were my car, I would ditch all those white gauges. Your car looks too nice to have these bright white "ricey" overlays. Not meant to be offensive, just looking at what your car could transform into with a stock set. Your car though so you do you.

Thanks I'll play with it tomorrow and see. I agree on the gauges...that's how I aquired it. Once I get everything working I'll do that as well.

[Djdiplomat]

Originally Posted by 917_Langheck

Pull the sender out - put a plug into the case to minimize oil seep - and put it in a container of boiling water. With it wired to the car you can key on the car. It should read just above even with the 210° line.







If it doesn't make that reading then the either the sender doesn't match the gage, or the dial face is incorrect.

Thanks will try this!

[917_Langheck]

Best of luck.

I did the procedure above to make sure the needle was "resting" at the correct spot on power up, since there was no way to know if it was still in the correct spot once I acquired it.