Hi everyone

I have a gauge that I got from Slits to use in my street car
I still have not installed it, and its been a few years now

my 1st question:
-what can you tell me about this gauge?
is it 1972 or 1973?

silver dot
so maybe a really early 73 appearance gauge?

I'm not selling this one, just curious and for my own use

2nd questions:
-how do I determine if my current senders, or which senders will be needed.


Currently I have a -6 fuel/oil temp gauge in the dash
its wired to the correct sender in the taco plate
it was 20 years ago... so I'll need to pull the sender to find out which model number it is.

any way I can tell from the numbers/model of gauge which sender is correct to use with this one ?


the fuel side of this "new to me gauge." Its a 914/4 gauge, with a stock 914 fuel tank and sender. I'm betting it is within the correct 90 -0 ohm range since it likely use the stock sender in the fuel tank. How can I verify that, or what do the experts and charts indicate as confirmation?


thank you in advance everyone!

brant

and

I can't answer your questions with certainty. Hopefully someone else jumps in.

Clearly a combo 914 combo gauge. I'd assume it works with the same sender as the center console gauge that came with the appearance package. Fuel gauge, again should work. I'm not aware of fuel sender ever varying by year.

If you haven't already seen this link, that is the closest info I've seen to answering the question with any certainty on the temp gauges. Your gauge seems to have a fatter red band than the picture of a 74' combo gague shown in the link below. Perhaps they changed the width of the combo gauge in 74' just as they did with the 74' center console due to people being nervous about the needle being close to or slightly into the red? I have a combo gauge in storage similar to yours but haven't gotten as far as hooking up anything to verify calibrations.

http://www.914world.com/bbs2/index.php?sho...17496&st=20

That looks like a stock 1973 914-4 combo gauge. You can tell the difference between 73 and the later years because the "red" zone is much wider, and of course the silver dot. It was slimmed down to a fraction of that in 1974 because people were getting alarmed that their engines were overheating when they weren't.

This is great info
thank you

"I copied this:
Alternatives include a 914/6 combination instrument or the similar 914/2.0 combination instrument that included an oil temperature gauge and was used on the two-liter cars that did not have the appearance group and console.

The 914/6 combination instrument (914.641.101.10) is shown in Figure 2. The oil temperature gauge portion of the instrument has five factory calibration marks. The marks are along the upper edge of the interior face and are not very easy to see without looking at a very small angle or removing the temperature gauge portion of the instrument by taking out the four screws in the back. The calibration points include 50 °C (1220F), 68 °C (154°F), 109.5°C (229°F) when the needle is vertical, 129 °C (2641F) at the beginning of the red-shaded zone and 144°C (291°F) at the beginning of the solid red zone. There is also a red oil temperature warning light at the high end of the scale that was planned for use with the sportomatic cars, but not connected to anything on the manual transmission cars.

The 914/6 oil temperature gauge uses a different sender than the 914/4, part number 901.641.632.00, which is a 150 °C unit. A calibration check of this gauge similar to that used for Figure 1 is indicated in Figure 2. The gauge readings were found to be within five to ten degrees of the factory calibration marks from 160°F upward.

The four-cylinder, two-liter cars without console used two different combination instruments with oil temperature gauges. The original gauge of this type (914.641.101.30) was used until the end of the 1973 model year and pictures of it show a wide red zone similar to the 1973 console gauge. In 1974 and later cars, an updated gauge, 914.641.101.50, was used with a smaller red zone. I was able to borrow one of the 1974 and later gauges and found, like the 914/6 and 911 gauges, it had factory calibration marks on the edge of the gauge face indicating that the bottom of the white scale was 30°C (86°F), the beginning of the red zone was 156.7°C (314°F), and the middle of the red zone was 170°C (338°F).

Figure 3 shows the 914/2.0 combination instrument and the oil temperature calibration using a 200°C sender and the same method as for the console gauges. The results were very close to the factory calibration marks: the calibration thermometer indicated 308 °F at the beginning of the red zone instead of 314, which seemed within the accuracy of the method and gave some confidence that the rest of the numbers weren't too far off. The overall calibration of the combination instrument was also reasonably close to that of the console instrument with the smaller red zone. In the gauges checked with the stock 200°C sender, the red zone starts at approximately 300°F. "


it sounds like my 914/6 combo gauge may/should be using the 150 degree sender for oil

and this gauge may require a 200 degree sender

where do I buy that sender at?
is it something Porsche or pelican would sell new?


thank you for the link!
I just did an oil change (have not even started the car yet)
so I may wait to pull the taco until the next oil change.. . see which sender I actually have and install the 200 one at that time.

I agree.. the fuel seems like a no brainer as I too believe all of the fuel tank senders should interchange.

brant

Chris, do you concur or know if the 4 cylinder combo uses the 200 degree sensor?

Brant - minor word of caution here: this size and style of gauges was used over several models and over a number of years; also, it is relatively simple to pull the mechanisms from the back and swap them out, but to compound that, it also easy to swap around the fascias too. In other words, the gauge mechanism you think may be inside MIGHT NOT not be what you're expecting...

So looking at the shots you posted, the variation in corrosion of the two gauge halves MAY be an indicator that one of them has been swapped out? Usually the pattern of corrosion tends to be uniform, as all metal components are exposed equally. Another clue is that when new, VDO (usually) put some green gunk (technical term) on each of the fastener screws to thread lock them; on untouched, pristine units you can usually still see remnants of this in place - again, the shots of yours indicate the securing screws have been removed at some point.

Again, comments are cautionary. Please don't take this as negative or critical intent!

- Tony

If you tip the gauge up and look at the area just above it, you will see a part number. A good parts guy can cross reference that gauge part number with the correct sender.

@partsguy22 can help if you give him the part number. It's not really clear in the picture.

this is good insight.
I have no way of knowing if its stock inside
hmmm... If I opened it, would I be able to identify the individual components to make the right match...

or a boiling water test for reference.

I'll tip it, get a picture and part number in a few minutes

thanks again
brant

Tony,

I just got the thing from the garage and took another look
I can see that the screws on the back have all been molested... driver marks from a poor fitting screw driver.

how do you recommend I tackle this?
to find the correct range oil sender to match my gauge

brant

picture of the part number for the gauge

@partsguy22 , can you help here?

Sorry I don't, but I'm sure someone will chime in. Make sure you get the right sensor, the wrong one will read too hot which will freak you out unnecessarily.

Does this help?

Bowlsby Tech Page

keep scrolling....keep scrolling....and.....scroll...then...check the oil temp calibrations pics on that page

Looks like 200 is probably what you want.

what a great resource
I haven't been on it in so long... and it has so much
thank you

yeah.. it looks like a 200 sensor is the most likely

One approach is to get the sender you think is right, hook it up with the gauge on a bench and do a temp check - room temp and boiling water at a minimum. All of these sensors work by changing their electrical resistance as temp varies; I have access to a programmable resistance box, so I can use that as a "dummy" sender to see what any target gauge is ideally expecting as a sender, so - for instance - a 911 combo gauge expecting a 901.641.632.00 sender would look like this:

Click to view attachment

..where the horizontal axis is indicated temperature (degC), the vertical scale is "ideal" sender resistance (ohms). Data for 2 different gauges plotted. Note the two "identical" gauges differ a bit at low temps, but are consistent where it matters.

So I can characterize a gauge: The REAL trick is uncovering the specs of the various senders we know and love to match the above type of plot. VDO publish some data, but it would be great to find a comprehensive source of part number vs. transfer function over temp. Anyone...?

- Tony

nice

and wow...

I'm going to source the 300 degree sensor that I "think" is right
and can test it

do you have a go to for buying sensors?

Brant - the Usual Suspects apply; though you might want to try calling either North Hollywood Speedometer or Palo Alto Speedometer - They have a lot of accumulated knowledge around the VDO components, and I've found the former shop helpful in identifying and shipping sensors in the past.

- Tony

Interesting thread and timely for me - I just picked up a 914 641 101 50 and am wondering if I'll need to change my sender. I currently have the "wide-red-band" 914 641 118 20 in the console.

In a perfect world, I'd love to just be able to plug in the new gauge and be good to go - can I be that lucky?

also - @brant - Notice there is the "B" symbol under the top section - this tells me this was originally a standard combo gauge and the brake warning section has been replaced with a temp gauge....right?

I think so?
after looking closer at the screw heads, broken green Loctite, different amounts of tarnish... I'm pretty sure the "B" brake warning light is different from a 914 combo gauge. it might have been made out of parts? dunno

so It looks like there are really only 2 different oil temp sensors
I don't want to drain my fresh oil.
so I'm going to get the 300 degree... test it with the gauge in boiling water
before install at the next oil change.

Hmmm - "B" and other markings look the same as a standard gauge to me. Here's my non-silver-dot version...

Click to view attachment