Hi,

For me, I would be concerned if I didn't run a needle straight across to its almost level.
In fact as it warms up it should actually shoot just a bit higher and then drop back about the width of the needle.
This is called over shoot.
All devices that heat, cool or regulate something have some of that built in to them!
It what would should call it is, a tolerance factor, as nothing is absolutely perfect in this world!

A thermostat disc should start to crack open at the set temperature stated on the device.
When it just starts to crack, that when it starts the cooling. In all respects it should just close but it won't! That's because when it's starting to open it brings on more hot coolant.
I can watch, in detail, my thermostats, in my oil bath and have seen differences in stats!
A low reading doesn't surprise me, at all! A lot of stats are junk because who checks them, a fanatic? Whoops!

One has to remember that the gauge sensor in in the engines head and it's the top of combustion chamber with the least surface area.
Heated water rises and therefore it will have the hottest water!
Especially, since the material up there is aluminum! That's the temperature we want to watch, not down below in the blocks cooling jackets.
The other heated object is the piston and it needs the benefit from oil from underneath.
Guess what temperature the oil runs?
Does oil have moisture in it?
Do we like it there?
What range thermostat do you want?

In my earlier post I referenced that running the combustion chamber, in its entirety, is best for efficiency if it's at least 200 degrees.
The outlet that the hose hooks onto should be really close to that 200 and thats another reason why I like 92C stats.
Most of the time I can only get about 190 degrees with an infrared thermometer.
But I know it's hotter by as much as 5 to 10 degrees because of the material thickness rule used in refrigeration work. We allow the temperature difference between suction pressure temperature and actual coil temperature to be different right on the coil.

There is an energy transfer loss and the infrared "Ray" doesn't even get through in a timely manner. You know how them Rays peoples can be! (:)-(:)
Air temperature efficiency "change" usually can not be more than 30 degrees, IN one pass!
Same goes for almost all heat exchangers in a refrigerated world.
That's Another, rule of thumb, I use!
It helps simplifies things, without a bunch of those "college boys" calculations!
It boils down to the greater the temperature differences, the greater the movement of energy or BTU's.
The greater the tilt of the see-saw, the faster it turns into a slide, for one kid!

A thermostats job is to modulate that see-saw angle!
I just think, that the brass Wahler stat housing is built right and I'm bias about my material selections.
I have been impressed with their past performance over the years because I have seen many other failures on our domestically designed engines.
Getting introduced to the Swedish Red Blocks outstanding longevity, says out loud, it's the materials first and then the craftsmanship!

I can't remember when I found it in my 1978 Green Books but the gauge doesn't even read on the lower end of the blank zone, until it reaches 140 degrees. So if the whole "blank" band took in 100 degrees, the red zone starts at 240.
Cars of the late 70's, Chevrolet's Vega all aluminum wonder, would run 210 degree thermostats! Even V-8's in pickups!
This was when they were first fooling around with government emissions and throttle body injection.
Not exactly ideal mixture control yet! So,the higher temperatures help them clean up their act!
The highly siliconized aluminum design, from Germany, didn't fair all that well!
I was told that the block was casted for $90 or was it the whole engine. I didn't know what to believe back then?
But later, Saturn engines used styrofoam blocks for their casting cores! If you look closely, you can see on the outside, the tiny circles from bubbles on the surface, just like an ice chest!
I don't know who made their engines?
The Ideas of Technology, crosses the ponds even more easily, nowadays!


I want to believe, that since Bosch bought Bendix's fuel injection ideas, for a song in the sixties and
reduced the temperatures somewhat? This was due to a sincere program of determination and some more sophisticated thinking on their part, with a working idea! This was only the mono/K-jet era too!
Bendix's equipment filled the back seat and the trunk of a car!

I feel that the 92C thermostat is better for all things involved with the computerized electronic injectors. They have better sensors, in more places and can have the temperatures of combustion chamber, dialed in! The O2 sensor requires it!
If the temperature is not hot enough the O2 sensor suffers with contaminations.

If the ECU's are sensing a colder engine it will run an adjustment accordingly.
So it wins on emissions, up to a limit and who knows what that's really doing to things!

A person on here said to check the plugs! Good idea ... When and how often and after what driving conditions?
Yep, That's what those lab coat wearing guys do for us!

I think the true arena of these injection systems want the more elevated temperatures!
I see the temperature gauge setup to have the scale to read halfway up as normal.
Many things are made to compromise or work within compromises all the time.
Halfway is good or best as I try to explain in many of my previous posts, of which, I share my "so called" enlightenment! (:) truly kidding here!

This is why the Check Engine Light was invented, to help deal with failing sensors, that might be caused by a simple failing thermostat!
That by the way, the thermostat is not electronic, as of yet!
Because the mechanical way is still the best thing going. In the realms of simplicity and being inexpensive to fabricate it's hard to beat!
I can only imagine how inexpensive they are, from my perspective, so why must they scrimp on the materials, unless it's only "greed" for a profit market dilemma?

I respect products made to perform at reasonable prices!
Probably, why I still shove my carcass around, in a 30-40 year old Volvo!
Some people use even older ones, but they started out long before I did!

Phil

88C = 190F. Your temperature gauge appears to be correct if the housing and top radiator hose is 160F.

Do NOT run the cabin blower, that will lower the temperature of the coolant.
--
Keeping it running is better than buying new

Hi,

My 91 240's temp gauge reads low no matter what thermostat is in it. My daughter's reads high. Neither has a comp board. I don't worry about it.

A rich mixture should show up on your plugs.

Peter

What is your actual coolant temp ? Sure your temp gauge sensor is good ?

I'm vindicated. Today, I brought the thermostat in question to class. The instructor put it in a metal cup and heated the cup and water with a torch. We got a slow and steady temperature rise documented to 215'F. The thermostat would not open up.

I'm not buying any more Wahlers.

I boiled only the water and waterbowl in the microwave, removed the water bowl from the microwve, then put the thermostat in the water on my kitchen table.