cooler t-stat . . .

[audio_file]

i decided that i should spend some quality time with the wagon today, i'm sure she's been feeling a bit neglected with my various projects lately (but hey, she just keeps going and going and going . . . )

 

i've had my wagon since last halloween ('87 EA82 w 3AT, p.b. 4wd, and carbed), and even though i replaced the t-stat and refreshed the entire coolant system, she's always run a little too warm for my liking . . . somewhere around the 1/2 to 2/3 mark on the ol' temp meter. i did not replace the radiator, so i always thought that because i just had the OEM single core rad, that the rad was the cause of the temp.

 

just for kicks i went to napa and purchased a few of the lower temp t-stats (180 degrees vs. 192), one for each of my soobies. i dropped one into my wagon today and it made a huge difference! now the temp stays well below half always . . .

 

so a few questions. why is the t-stat listed as the direct replacement set at such a high temp? might there be something else working in combination with the OEM t-stat that was causing the high temps that i still need to address? is there any drawback/harm in running the lower temp t-stat?

 

thanks, as always . . .

chris

[GeneralDisorder]

It's probably a negligable difference, but the higher temp thermostat is what the engine was designed for. Likely if you take temp readings with a more reliable gauge you will see that it's just the guage or sender that is reporting high - they are notorious for being incorrect. The temp guage on my Brat reads 3/4 to right below red when the fan cycles on. It's right on the money according to both the NEW fan themo-switch, and my DMM using a k-type thermo-couple. Just the nature of old guages.

 

Also, non-OEM thermostat's don't flow as well. I only buy mine at the dealer now. Take a look (OEM on left):

 

 

GD

[audio_file]

It's probably a negligable difference, but the higher temp thermostat is what the engine was designed for. Likely if you take temp readings with a more reliable gauge you will see that it's just the guage or sender that is reporting high - they are notorious for being incorrect. The temp guage on my Brat reads 3/4 to right below red when the fan cycles on. It's right on the money according to both the NEW fan themo-switch, and my DMM using a k-type thermo-couple. Just the nature of old guages.

 

Also, non-OEM thermostat's don't flow as well. I only buy mine at the dealer now.

GD

 

yeah, i've been buying a lot higher percentage of my parts from the dealership, the price is so comparable . . . on this day, i just happened to be at napa . . .

[GeneralDisorder]

yeah, i've been buying a lot higher percentage of my parts from the dealership, the price is so comparable . . . on this day, i just happened to be at napa . . .

 

You and me both. I rarely set foot in an aftermarket store. I buy from a local place called Discount Import Parts that is VERY good (mosly OEM parts - catering to a lot of VW stuff - EMPI, ect.), and online places.... besides my dealer of course.

 

GD

[NoahDL88]

Just an FYI, the cooler T-stat will not allow your car to reach its maximum operating efficiency, expect a fuel mileage drop, and an increase in buildup on your valves.

 

 

The FHI guys knew what they were doing when they called for a 192 degree T-stat. :cool:

[audio_file]

Just an FYI, the cooler T-stat will not allow your car to reach its maximum operating efficiency, expect a fuel mileage drop, and an increase in buildup on your valves.

 

 

The FHI guys knew what they were doing when they called for a 192 degree T-stat. :cool:

 

that's what i was looking for . . .

so, assuming that as GD said, it's the temp gauge that is a little off, it would be better to go back to the 192 degree t-stat for the long term results (?)

 

where should the coolant temp be at full operating temperature, so that i can check it manually? 192 degrees?

 

thank you

chris

[GeneralDisorder]

A few degrees won't matter much overall. 160 would definately cause a noticeable decrease in fuel economy. 180 is a tough call. If your setup was well tuned you might notice it.... but I tend to doubt it.

 

At any rate you NEED to know why things aren't staying cool (according to the stock gauge) with the OEM stat. IE: you first have to verify the gauge accuracy.

 

GD

[Durania]

IE: you first have to verify the gauge accuracy.

 

GD

 

Good point. I borrowed a friends laser temperature checker. Great tool.

[3eyedwagon]

Just an FYI, the cooler T-stat will not allow your car to reach its maximum operating efficiency, expect a fuel mileage drop, and an increase in buildup on your valves.

 

 

The FHI guys knew what they were doing when they called for a 192 degree T-stat. :cool:

 

It all depends on what you mean by efficiency. In the sense of the car not efficiently burning all supplied fuels; yes that may be true. But in the sense of performance; it will actually run better cooler, to a certain extent of course. I realize this is a negligable difference on a car making 120 hp, but it greatly increases with displacement.

 

The reason for 192* thermostats is a compromise between necessitys. The oem's need the car to be reliable, user friendly (heaters), and perform. As technology increases, so does the temperature cars run at. Many newer cars run hotter than ever before, mostly due to better engine materials, and the ability of higher pressures in the cooling systems. My Camaro has a stock thermostat of 205. Try that in an EA81!

 

I used to think that the thermostat temperature would make a huge difference in fuel mileage. That hasn't been my experience. I've tried quite a few different temps in alot of my v8 cars with little difference. Many drag racers run no thermostats at all. I removed the thermostat from my ea81 wagon, because I intended to do alot of slow wheeling, and idling. The aftermarket gauge rarely moves above 130, and my temp gun shows this to be accurate. I recorded my gas mileage before, and after the removal; there was NO change. This is a car that is driven on the street regularly. That is just my experience anyway.

[audio_file]

I realize this is a negligible difference on a car making 120 hp, but it greatly increases with displacement.

 

The reason for 192* thermostats is a compromise between necessities.

 

I recorded my gas mileage before, and after the removal; there was NO change. This is a car that is driven on the street regularly. That is just my experience anyway.

 

thanks, that's what i'm seeing too so far, wagon runs better, the "buttdyno" says i might be up a few ponies ( i don't think ea82 carbed wagons even made 100hp off the assembly line ) and the fuel economy is still just as bad :-\ as ever (so far)

 

gotta love the buttdyno gains though

 

chris

[audio_file]

At any rate you NEED to know why things aren't staying cool (according to the stock gauge) with the OEM stat. IE: you first have to verify the gauge accuracy.

 

GD

 

Good point. I borrowed a friends laser temperature checker. Great tool.

 

will do, this is one of those tools i'm not familiar with using, but i'm sure i'll figure it out

chris

[presslab]

Your gauge is probably off. With the engine idling, turn on your headlights, interior fan, etc. Measure the voltage of your engine ground near the temp sender vs the chassis ground. Anything more than 10mV or so will cause the gauge to read higher than it really is.

 

I had that problem, when I'd turn on the interior fan the engine would instantly "overheat". I checked and cleaned the original ground and it seemed ok and didn't fix it, but then I added a big heavy ground at the thermostat and the problem is gone.