testing temp gauge
- Thread starter twoone
- Start date
- Views: 30920
jinman
Rest in Peace
- Joined
- Feb 23, 2001
- Messages
- 20,387
- Location
- Texas - Wise County - Sunset
- Tractor
- NHTC45D, NH LB75B, Ford Jubilee
Okay Paul, I was really having trouble understanding your numbers in the previous post. If I understand correctly now, your radiator never got above 120 degrees and the lowest ohms read was 164 ohms just before you quit. That tells me the sensor is responding in the general area of correct (these things are not perfect and certainly not linear). However, I don't know if it was a typo, but you said your thermostat was set for 88 degrees. If it is 88 degrees, that is Celsius instead of Fahrenheit. 88 C is equal to 190 F. That is exactly the temperature I'd expect, but your readings of temperature in the radiator only produced 120 F. That is why I still suspect the thermostat is malfunctioning. What do you think?
JC-jetro
Elite Member
Good morning paul,
had a bit of problem reading your numbers till I understood second # was actual time. If I understand it right you ran your engine sum total of 1/2 hr for your test. It appears to me even at idle you should achive around 180 degrees Fahrenheit. The conversion factor from going Cecilius to Fahrenheit is like below.
F= (C x 9/5)=32 or simpler F= 1.8 C +32
So let's plug some numbers in
initial reading:
F= (1.8x98)+32= 208 Fahrenheit which does not sound right at all as your started with cold engine.
Final number:
F= (1.8x 120)+32= 248 Fahrenheit which again does not make sense as you would have had an overheated engine.. most likely dead.
So I think you had the setting right on your gauge and the numbers you read in Fahrenheit is just fine.
You said you also bought new meter. Did you take resistance reading with your meter from cold all the way to the end of your test.? that might give us some clue. from what you reported so far I agree with Jim that it appears your sending unit is working half way decent and your problem lies with your Thermostat. You told us you already bought the t-stat. Did you not get a chance to put it in? Why don't you try to replace the thermostat to see how things go. I'm fairly confident a new t-stat will fix your problem.
Report back and we'll try to help.
JC
Good morning: I Checked the call out for the t-stat and you were correct as always, it is in Celsius not Fahrenheit I did not read it correctly in my hurry so we are dealing with a 190 degree Fahrenheit t-stat. As for the the time of day it is correct the starting ambient starting temp was aprox.80 degrees F. (and climbing) starting with a cold eng. I started test, the temp sensor was disconnected and reading from sensor to ground and the meter showed 464 ohm's,-the temp at the raid,read 80.4 degrees Fahrenheit on the gun.What I was trying to show you was the rate of temp climb.in 7 min. the eng.temp climbed to 112 degree's f. with a sensor reading drop to 168 ohm's. At 11:15 it was aprox. a 1/2 hour run and the eng, temp was 120 f degrees and the temp.sensor read 164 ohms. this was done at idle and the raid. cap off and no sign of action within the raid. except for the slight rise of fluid in the neck. I hooked up the sensor and noticed a slight rise in the gauge ,the needle was off the cold peg and about a 3ed toward the normal marker. I have not purchased the t- stat seems the dealers I checked with did not have one in stock. ? what about sensor Resistance you said about 700 ohms . Paul
JC-jetro
Elite Member
Paul,
It is very plausible that your sender probably is okay. You might have a bit of error in reading due to the meter but they can calibrate the gauge between 460 to say 80 ohms to show full range of temp. The sender and the gauge are a matching unit. I have not done this myself but there is nothing magical about a thermostat. I bit ya if you take the t-sat off and take it to NAPA auto store they might be able to match up one for 190 less then $15.
Again you might be able to nip off the "thingamagic" that opens the bypass hole. That might have kept the thermostat opened. Then you just need to cut it off and put the old -t-stat back again.
Now one thing you have not done is to take a t-stat housing temp reading at the end of you 1/2 hr test. I wondered what the difference would be between that and the radiator temp of 120.
JC,
Last edited:
jinman
Rest in Peace
- Joined
- Feb 23, 2001
- Messages
- 20,387
- Location
- Texas - Wise County - Sunset
- Tractor
- NHTC45D, NH LB75B, Ford Jubilee
I agree completely with JC. Pull that thermostat and look at it. You may be able to cut off the "dangle" and get it working. If not, take it to NAPA and save yourself some money. I betcha they have an exact replacement that may work better than the original for about 1/2 the cost or less.
I really think you are on the "home stretch" and leading the race. You're almost to the big payoff.:thumbsup:
I really think you are on the "home stretch" and leading the race. You're almost to the big payoff.:thumbsup:
Hi"
As a mater of fact I did read the T-stat housing just to see if there was a overheat while at 120f degrees but I did not write it down and I can't remember what it was however I recall it being some where close to the same temp. there was only a slight difference higher and remember the ga. did move. I hate to do the same job twice by opening the T-Stat housing with out parts the idea about Napa sounds like a good one, I guess the difference between $10.00+ and $52.00 +that the dealer wants is worth it. I checked the price at Messicks and they want $36.00+but neither had one in stock and i would still will need the proper gasket. I am thinking of waiting till i work the tractor and check it as opposed to now at only a idle check. Am not using it much now as were out of season but some jobs and work do come up? what about the seeing the water move , Even at idle shouldn't I see it moving if the T-stat is stuck open ? and if it were stuck closed shouldn't the temp rise to more than 120f degrees in a half hour at idle/1500 rpm.? this all blows my mind that's why I am thinking that the later test might be a good idea and to compare. . What about the temp sensor ohm reading at hot and cold is there a standard for this ga.2: Paul
As a mater of fact I did read the T-stat housing just to see if there was a overheat while at 120f degrees but I did not write it down and I can't remember what it was however I recall it being some where close to the same temp. there was only a slight difference higher and remember the ga. did move. I hate to do the same job twice by opening the T-Stat housing with out parts the idea about Napa sounds like a good one, I guess the difference between $10.00+ and $52.00 +that the dealer wants is worth it. I checked the price at Messicks and they want $36.00+but neither had one in stock and i would still will need the proper gasket. I am thinking of waiting till i work the tractor and check it as opposed to now at only a idle check. Am not using it much now as were out of season but some jobs and work do come up? what about the seeing the water move , Even at idle shouldn't I see it moving if the T-stat is stuck open ? and if it were stuck closed shouldn't the temp rise to more than 120f degrees in a half hour at idle/1500 rpm.? this all blows my mind that's why I am thinking that the later test might be a good idea and to compare. . What about the temp sensor ohm reading at hot and cold is there a standard for this ga.2: Paul
jinman
Rest in Peace
- Joined
- Feb 23, 2001
- Messages
- 20,387
- Location
- Texas - Wise County - Sunset
- Tractor
- NHTC45D, NH LB75B, Ford Jubilee
I think watching for water moving is very subjective. It's very hard to see water move unless you are watching something floating as it moves by.
On the thermostat. . . Your gasket is probably going to be easy to match at NAPA. Remove the neck that goes into the hose and take it with you for a perfect match. If they don't have one, they are easy to make from some gasket material. Just put the material over the opening and tap lightly with a hammer to make an impression. Then, use a cutter to cut out the center and a pair of scissors to trim the outside. You can carefully drill holes in the material with a sharp drill. I don't think you will have to do that because NAPA will surely have a size to match. Of course, it's your call. Once you've done it, it seems easy, but I can understand your point since you've never replaced a thermostat. Honestly, I've removed lots of thermostat necks and just used blue gasket making silicone to patch up any breaks in the gasket. It's your tractor and your job, so do what you are comfortable doing.
On the thermostat. . . Your gasket is probably going to be easy to match at NAPA. Remove the neck that goes into the hose and take it with you for a perfect match. If they don't have one, they are easy to make from some gasket material. Just put the material over the opening and tap lightly with a hammer to make an impression. Then, use a cutter to cut out the center and a pair of scissors to trim the outside. You can carefully drill holes in the material with a sharp drill. I don't think you will have to do that because NAPA will surely have a size to match. Of course, it's your call. Once you've done it, it seems easy, but I can understand your point since you've never replaced a thermostat. Honestly, I've removed lots of thermostat necks and just used blue gasket making silicone to patch up any breaks in the gasket. It's your tractor and your job, so do what you are comfortable doing.
JC-jetro
Elite Member
Paul,
ditto On what jim said about blue RTV gasket. Once I actually managed to damage a brand new gasket that I bought putting a water pump in. I was supposed to use if I can remember "Indian Head" red color high temp sealant. I had to get the vehicle moving and had no choice and no access to store. I actually used cereal box cardboard and made as close replica of the old gasket as I could using punch, razor blade and scissors. I then smeared blue RTV on both side and let it skin a bit, put a little extra on water pump housing to keep the gasket in place while putting in the water pump. My idea was this is just temporary till I get a new gasket. It never ever leaked a drop and I finally sold that old car with my temporary fix.
JC,
ditto On what jim said about blue RTV gasket. Once I actually managed to damage a brand new gasket that I bought putting a water pump in. I was supposed to use if I can remember "Indian Head" red color high temp sealant. I had to get the vehicle moving and had no choice and no access to store. I actually used cereal box cardboard and made as close replica of the old gasket as I could using punch, razor blade and scissors. I then smeared blue RTV on both side and let it skin a bit, put a little extra on water pump housing to keep the gasket in place while putting in the water pump. My idea was this is just temporary till I get a new gasket. It never ever leaked a drop and I finally sold that old car with my temporary fix.
JC,
barbqranch
Silver Member
If you make a gasket, there is a better way to make the bolt holes. If you have a large ball bearing, put it over the gasket on the housing and tap with a hammer. It will act as a hole punch and make a perfect hole.
