88Fox correct position needle for watertemp.Gauge

Runs well, doesn't overheat, and the radiator fan comes on?

Don't worry... be happy!

My 90 Fox always ran very close to the last line when it was hot outside.

I have an '88 Fox. With the stock, proper temperature, and working thermostat the temp needle hovers around the hotter side of the warning light, which is a little higher than the middle.

I put in a slightly cooler thermostat and now it hovers around the cooler side of the warning light, a little lower than the middle.

IIRC standard operating temp is 212*F, if you were inclined to measure it with a thermometer at the little jet of coolant that circulates in the overflow resevoir.

"Lambert Moonen" wrote

I have a pair of 1987 Scirocco 16 valves. They have the temperature gauge similar (may be identical, I haven't been inside a Fox in a long time) you're talking about, but they also have an oil temperature gauge. Both normally run around 100 centigrade on the oil temperature gauge. One of them hovers it's water temperature gauge on the high side of the warning light in that gauge. The other one about the width of the needle below the top end.

When I commented on this at the shop I go to they said there's a loading resistor somewhere in the instrument cluster which influences how the water temperature gauge works. When I crack the thing open to fix the odometer, I plan to replace the resistor with a variable one so I can put normal back near the light, where I'm used to it being.

- Bill

Just about anywhere between hot and cold.

The important think is for the drive to know what is normal for their car and to notice if it starts changing.

"I plan to replace the resistor with a variable one so I can put normal back near the light, where I'm used to it being." Why re-engineer the car... it just doesn't make sense?

Short answer, yes it does.

Long answer:

The point of re-engineering is to obtain different behavior of some sort. Cheaper to manufacture, more reliable, better operation, and so on. Whether or not reengineering makes sense or not would depend on what you're trying to accomplish and whether it's worth the effort or not.

I want the gauge to behave correctly, which requires replacing the resistor. This isn't re-engineering, it's a repair, replacing a faulty part. Being a bit of a lazy sort, I hate to do things like this twice, or more. And being an engineer, I like to make things work better, if it's not too much work to accomplish. So rather than just dropping in a new fixed value resistor, I'll put in one I can adjust and position it so I can reach it from under the dashboard. Thus, I don't have to take the console out and replace it again if I get the wrong value the first time. This will give me the added benefit of being able to tune it precisely. This last, is a bit of re-engineering, since the original design did not provide for this feature. Having taken consoles out of these things numerous times, the added effort to put in a variable as opposed to a fixed value is small and the potential benefit worth it. The final bit is that I have to take the console out anyway to fix the odometer. Adding this bit to that effort is trivial and the benefits, both cosmetic and functional, are well worth it.

Someone else mentioned that the important thing is to know what's normal for your car and to notice that you're seeing a difference. This is entirely correct. But if you've got center as normal, it's going to be a lot easier to observe a trend to hot than if near the top is normal.

Consider that with a gauge which shows normal near the center, you've still got about 45 percent of the gauge travel to show measurements above normal. You can easily observe when it's running as little as 10% hotter than normal because the difference between normal and normal + 10% will be clearly visible. But, on the gauge where normal is near the top, there's less than 10% of the gauge left to show variations above normal. A 10% increase is unobservable. So, rather than get a advance warning, perhaps days in advance, your first indication will probably be the warning light coming on. Me, I like to be able to see problems coming.

As to whether near the center is normal or not, four factors.

1. Of the three of these that I've got or had running, "normal" was always on the upper edge of the warning light. I've also driven several other VW's with the same temperature gauge. Their "normal" was always near center. With a reading just above center, that's about 55% up from minimum, 45% down from maximum. This one shows "normal" at 90% up and 10% down. I know it's normal, but other than that, it's useless.

1. Bentley mentions in the cooling troubleshooting section the readings "high," "normal," and "low." They're pretty complete. If the range of "normal" as counterintuitive as being as high up on the gauge as 90%, I think they'd have mentioned it.

2. My mechanic agreed that it's off, and knows how to fix it.

1. Referencing Bentley, I see where the resistor is and note that it controls the voltage stabilizer (a.k.a. "regulator") which feeds both the temperature and fuel gauges. The fuel gauge on this car acts oddly too. Well, more so than on every other VW I've owned anyway. They all seem to go from full to 1/2 a lot faster than they go from 1/2 to empty.

Even with all of the above, if I didn't have to take the instrument cluster out anyway to fix the odometer, I'm not sure I'd bother.

- Bill

The down side, is if you adjust the gauge to read lower you may never know when the engine is really overheating?

Read lower at normal temperature. It'll still run up the scale as it gets warmer. The sensor puts out a certain number of volts per degree. The shop determined that the sensor is working correctly. The gauge is scaling it incorrectly. After installation, I'll set the variable resistor to match the value of the fixed one, then put it all back together. Fire the car up and wait until the oil temperature reads normal. At that point, I'll set the temperature gauge to normal.

Then, as a check, leave the car running and wait until the fan comes on and see that the gauge went up the correct amount. And I can know that because I'll actually run both cars and compare the oil and coolant temps as they both rise to see that the adjusted one tracks correctly.

- Bill

Boy I sure dit not know taht i created such a discussion about temp gauges .but I stil think it isdumb engineering for not using at lest a colorcode green ok .red your having problems simple as that ein ninkepoop verstande das,moony.Thanks for al the info.never to old to learn.

Touched a nerve with the phrase "re-engineer."

I agree, though I never really thought much about it before.

Considering that the damn fuel gauge has a red zone, you'd think putting one on the temperature gauge would be obvious.

Did they think that running out of gas was more important than destroying the engine?

- Bill

On my VW Fox wagon, with a 180F thermostat (important), runs at or just over the little mark past midtravel of the gauge. Had it since '92, always the same after warming up. What you're looking at is what my dad called an "idiot gauge" with no reference to any numbering system on the gauge. These are not uncommon as you seem to imply. Have an indash voltmeter gauge on a 94 Blazer S-10, says just under 18 V when running. Don't think that's accurate either.

I think they figured that since they installed a warning light that flashes when the temperature is too high, marking a red zone on the gauge would be redundant. The oil temperature gauges, which has no light, *does* have a red mark (at 150C.)

The manual for my old Vanagon said anything below the solid white line at the top of the gauge was 'normal'! The Bentley's instructions for checking the gauge allowed +/- one needle width of variation. These gauges are not really calibrated in any absolute sense; they give you only a relative indication. (Is it higher or lower than your car usually runs, in other words.)

My '89 Cabriolet seems to run anywhere from just below the LED when driving downhill in cool weather, to just above the LED while sitting in traffic. The cooling fan comes on about halfway between the LED and the solid white line. This seems pretty consistent with other 1980s VWs I've driven.

Ford used to put gauges in their trucks that just had an L for Low (or a C for Cold), an H for High (or Hot), and the word 'NORMAL' in between.

The real "idiot gauges" are the ones with circuitry that causes them to read in a few fixed positions, like an idiot light. Some Volvos are like this -- they have a "temperature stabilizer" board that causes the water temperature gauge to read cold until the engine reaches a certain temperature, then exactly midscale unless it exceeds a certain threshold, at which point the gauge is driven to the high peg. Apparently they were getting too many warranty complaints about cars that ran towards the upper side of the gauge, but still within normal limits, so they rigged the gauge to give more stable (but fake) readings.

Two of my Scirocco's (an 8V and a 16V) do the same for the fan. "Normal" is just at the upper edge of the LED to just above the LED for the cases you note. The other one is at the lower of the two white dots at the top of the gauge or at the white line at the top for the same two cases.

Yes. All the late 80's VW's I drove worked the same, except for this other 16V (my daily driver now).

- Bill

My personal advice is to never use any of those leak stop products. The problem is they tend to stop more than just the leaks.

Yes you need antifreeze. Pure water will boil and flash to steam, the steam will not allow the remaining water to circulate properly, and your engine will overheat.