Motometer reading

[Ten1nis]

How do you read/interpret a Motometer? I see the "mercury" move up and down based upon temperature:, but there is no calibration to relate it to. Thanks!

[daveymc29]

There is a simple way to guesstimate the temperature by looking at the mercury rising in the car. Get a near thermometer, or some other cheap thermometer with the range of 0-4-- degrees and pull over while driving normally and measure the temperature of the radiator water. Note where the mercury is. Then do it when it is a hot day and the mercury is quite a bit higher. You will have some base points. Use caution and a rag, don't get scalded. If the car is steaming, wait a spell. Most motometers have some type of scale on one face, turn that one to be visible from the drivers seat.

[Will N]

When my As are in motion and air is being drawn through by the fan and the motion of the car, I rarely ever see any mercury on the motometer- maybe 1/8 inch on really hot days. When idling, it might go up 1/2" or so.

[Fred K-OR]

If I remember correctly, I thought the motometer, at least mine does, noted what was going on as far as the temp of the car. The mercury would go up and as it goes up I thought you could read what was happening with the motor-like run temp, boil temp, etc..

[mass A man]

You're right Fred, Also in the little circle hole near the top, it would read "summer average".
Ten1is; do you have the inner plate that's supposed to face the driver in behind the thermometer glass? This is where your info is printed in the Motometer.

[pooch]

Sponsored Links (Register now to hide all advertisements)

Don't fret too much on reading a new motometer.

When new, they hardly ever read, except when near boiling .

After a few months, you will get the inevitable gaps of air in the red fluid.

This has worked great for me.

Both of my motometers now work in a visible area of sight.

The air seems to have settled down the bottom out of sight and just pushes the red up higher .

No, I am not going to freeze them or swing them around my head to get the red back down .

[Y-Blockhead]

Originally Posted by Will N

When my As are in motion and air is being drawn through by the fan and the motion of the car, I rarely ever see any mercury on the motometer- maybe 1/8 inch on really hot days. When idling, it might go up 1/2" or so.

Mine is the same. I look at a motometer as more of a indication when the water is boiling because it can't possibly read an accurate temperature since the bulb doesn't even reach the water level (until the water is boiling out the top of the radiator... ).

[Kurt in NJ]

I have both old original, 60s repro and old "aftermarket'---i think messco or something like that ---they all read accuratly, and only will get the "air bubbles" if laid on the side with the top lower than the bottom, i have compared top tank temps to the reading and they are close even with the coolant level at the bottom of the baffle, there is a line just below the opening --cold motor, use radiator cover ---this is 140-150,just above the top of the open circle is boiling---that is when I get steam out the overflow

years ago my father bought and sold many motormeters, unless the glass tube was broken they worked, and were accurate

[mass A man]

What exactly is the red fluid? I can't see it being Mercury since that is silver metal and I don't think one can dye it red. I've had old Motometers that seem pretty accurate but I got a new one for the A, and doesn't work very well. I went back to just the plain cap. Maybe the old type fluid had something to do with the accuracy back in the day.

[pooch]

100 % method to not have any air gaps in your motometer......

[BILL WILLIAMSON]

If you have gaps in the RED CRAP, let it idle, with the radiator mostly covered with cardboard, until the lower red goes up & touches the "other" reds & remove said cardboard, & all the red will come down together! COMPRENDE' ?
And DON'T swing thet thing around on a rope, might break yo' head ur yo' windshield!! ur hit yo' po' Dog ur yo' Mother-in-Law ---Your wife is smart enuff to stay in the HOUSE, while she calls the "FUNNY-FARM"
Bill W.
(OH! and while cruising along with a Moto-Meter, if the temp goes UP & Down in regular 2 to 3 minute intervals, YOU ARE LOW ON WATER!! And don't forget the roofing nail trick, like, jist drop it in the top of the overflow tube & give sum nails to your friends!)

[nickair]

With a good balanced cooling system the motometer is great.

[bikejunk]

you can also tap the air pockets out of the motometer by firmly banging the lower end on a tire or a soft piece of wood, kind of the way you shake down a thermometer .

[Hoogah]

My motometer seems to have TWO different liquids. A clear/silver liquid column is visible most times (which I thought might have been mercury?). When the car reaches operating temperature, a red column just starts to poke up into the visible zone. I'm confused because the clear/silver liquid appears to have breaks in the column. You can see this in the photo, taken after a 20 min run in the car. The red is just visible at the bottom, but there is a definite second column with what appears to be two air bubbles in it, one large and one small.

What's going on here?

I confess to laying the motometer sideways while topping up the radiator before I knew better.

[oldwoodsman]

I open the cap and heat the brass bulb on the bottom with a heat gun till the red reaches the top when it comes back down it is connected.

[Tom Wesenberg]

I had a small antique thermometer laying on the dash of my car. The interior of the car got so hot that the bulb was broken and the red alcohol spilled out.