testing temp gauge

[JC-jetro]

HERE WE GO: Got up this morning with a new look at life out side temp was a lot cooler and the tractor was in the shade my friend came over with his meter so here's a new report: Using his meter and starting with a cold eng. the sender read around 185 should have read between 6&700 ohm's right? removed raid.cap started eng no action in the raid used wife's meat t-meter to check eng water temp, after running 15 min at 1000 RPM.temp it only showed a little over 120 degree's with no action in the raid. and steady. I think the t-stat's is stuck open and not letting the eng warm up enough to actuate the sensor to show any temp we think maybe his ohm meter might be off as well? but the temp sensor is telling us it's the t-stat??. What do you think? as for the battery's the meter's would not work with bad battery's one is an analog the other a digital. the idea of the meat thermometer came from traveler see another post.

Paul,

Temperature and resistance in this application is "inversely proportional", meaning one goes up and the other comes down. if you have two point say hi or low then you can calculate the missing number in the middle, the fancy word for it is "interpolation". If I take the number I have below from my reading and combine it with your reading the temp I come up with should be around 100 degrees at your radiator. I think your resistance reading might be off some. Now pressure and temp is directly proportional meaning as the pressure goes up so does the temp. The fact that you radiator cap was open does not allow the temp to go up very quickly. The fact that you saw no action in the radiator after 15 minutes is more indicative of stuck closed vs stuck open. if I were you , I'd inspect the t-stat. drain enough below t-stat and save in a bucket so you can reuse the antifreeze. You will for sure need a gasket or you can make one if you have to. inspect the t-stat to see if it is closed or open. if closed then submerge it in a pot of boiling water to see if it opens up. if you find the t-stat open when you take it out of a cold engine then you know t-stat needs changing. I think even with stuck t-stat after 15 minute of operation the temp reading should be between 150-160 rather than low 120.

JC,




Ford 1700 oerating temps:

Cold: sender=690 ohms, T housing = 98 , Radiator= 98 , Head=98 , Exh Man=98

Operating temp: sender=140 ohms, T housing = 172 , Radiator=170 , Head=174 , Exh Man=192


1/8" , right of middle: sender=92 ohms, T housing = 196 , Radiator= 196 , Head= 197 , Exh Man=210

Hot
1/8" left of H: sender=66 ohms, T housing = 210 , Radiator= 210 , Head=212 , Exh Man=250

 

[twoone]

JC/JIM, I don't think the water temp ever gets hot enough to tell the temp sender to to give a temp reading to the gauge and that's why the gauge always remains on cold, even if the t-start bypass plug jammed the t-start partly open it would not be held open enough to keep it from getting hot enough because the t-stat is always wide open in this case. I think that's the problem? of course there is away's the chance there is a dual problem and the temp sensor is at fault also.?Am going to start by first replacing the t-stat $37+ dollars and see if that fixes it first if you agree with me. I can't thank you and Jim for helping me get my head on straight and hanging in with me on this problem I sure understand the system a lot better.INFO: By the way one of the things I found that their wasn't any information on that I could find was the location of the low water sender to the dash board warning light. it's on the bottom of the water overflow tank. Will keep in touch, Paul

 

[JC-jetro]

JC/JIM, I don't think the water temp ever gets hot enough to tell the temp sender to to give a temp reading to the gauge and that's why the gauge always remains on cold, even if the t-start bypass plug jammed the t-start partly open it would not be held open enough to keep it from getting hot enough because the t-stat is always wide open in this case. I think that's the problem? of course there is away's the chance there is a dual problem and the temp sensor is at fault also.?Am going to start by first replacing the t-stat $37+ dollars and see if that fixes it first if you agree with me. I can't thank you and Jim for helping me get my head on straight and hanging in with me on this problem I sure understand the system a lot better.INFO: By the way one of the things I found that their wasn't any information on that I could find was the location of the low water sender to the dash board warning light. it's on the bottom of the water overflow tank. Will keep in touch, Paul

Paul,

I forgot to ask you previously. when your buddy help you with the meter. did you take a reading cold as well? I'd probably would keep the meter hooked on, read it cold and then start and let the engine warm up. It would have been a good information to see the resistance going down as the engine warmed up. Well, T-stat is a bit pricey.. isn't it?. About the low water level alarm. Although I'm not familiar with exactly what you have the concept that I'm going to explain is the same. There are several ways to tell the fluid level where you have contact or no contact variety. The most reliable that is used in auto industry is float level. It can be like a bobber (cork) that has a little magnet attached to it. This float can go up and down and make or break a sealed switch inside of glass capsule. it make or breaks the contact without contacts getting contaminated. What ever device you have in the over flow tank will have two wires coming out of it. if you get a test light or make one and hook it to the end of two wires, then a change of state has to either turn off or turn on the light. usually switch will make when the tank is empty. You simply might have a dead light. check the light first. You can use any flash light to make a test light out of.There are other technologies that actually tell you the actual height at any level but it is not used in your case. If you can take digital pics and post it here might give us a little better clue.

Good luck and keep us posted.

JC,

 

[twoone]

JC: meter did move lower but on his meter it was reading i84 or so to start but dropped that check when it showed movement in order to get on with the rest of the ck with the meat t-meter and to ck for flow with increased water temp and ck to see if the t-stat appeared to show a movement which it did not as I said temp went up and showed aprox 120 degrees and stayed there with a slight rise but you could away's put your finger in the water during the time we ran the eng. . RC I did not have a problem with the low water temp warning light at least one that am aware of. it was just something I came across and found as I could find no info on it in the ford 1720 manual or owners manual other there is one on the dash as well as the gauge I came across the sw and wiring while we doing the overheat problem and thought I just put that in as possible info. Paul'















.

 

[JC-jetro]

JC: meter did move lower but on his meter it was reading i84 or so to start but dropped that check when it showed movement in order to get on with the rest of the ck with the meat t-meter and to ck for flow with increased water temp and ck to see if the t-stat appeared to show a movement which it did not as I said temp went up and showed aprox 120 degrees and stayed there with a slight rise but you could away's put your finger in the water during the time we ran the eng. . RC I did not have a problem with the low water temp warning light at least one that am aware of. it was just something I came across and found as I could find no info on it in the ford 1720 manual or owners manual other there is one on the dash as well as the gauge I came across the sw and wiring while we doing the overheat problem and thought I just put that in as possible info. Paul'

.

Paul,

Dropping ohms reading is a good indication that sending device is doing something like it should. I just cant trust that ohms reading. Like Jim said, reading low ohms is more difficult specially with some cheesy meter. You have to chose the lowest scale of ohms to read it more effectively. I have a file attached here that is in PDF format. click on it and open it, it shows the radiator diagrams for 1720. Your coolant recovery plastic tank is there but they don't show a part # for the low level. You might have to purchase the whole thing. As long as you keep it at the specified level don;t need to fiddle with it much. just keep an eye on it.

JC,

 

[twoone]

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[twoone]

The pdf files are good but as you said they do not show the wiring however they are coming out the bottom of the fiberglass tank that is shown they extend about 9in to a disconnect plug that you can disconnect for troubleshooting purposes if need be as I said I have NO problem with it just thought some one reading our bodgs might and could not find out where it is Tks, Paul:thumbsup:

 

[EE_Bota]

Gentleman, one possible help or aid would be, if access is adequate, perhaps put cardboard in front of the radiator to block half the air flow. Then monitor the temperature carefully with any hand thermometer, while also looking sometimes at the gauge to see if there is any movement.

If a thermometer is not available, if it is safe to do so, monitor the hoses by hand touching.

It may be a less complicated approach than the meter approach. But I know nothing of the tractor, so it could be difficult.

I did this on a machine once with the same symptoms..no gauge reading, but no obvious cooling problem. The thermostat was bad, and all else was good, and the engine began down the path of running much better after the thermostat was changed.

 

[jinman]

Yep, cardboard in front of the radiator should cause it to heat up,:thumbsup: but you'd still have the problem of why it isn't heating properly without it. If it never gets over 120, I gotta believe the t-stat is defective or jammed open. If Paul takes out the thermostat and the little dangle is holding it open, he can just cut the dangle off with a set of diagonal pliers and put the thermostat back into his tractor without spending the big bucks for a new one. Once he gets the coolant to the proper temperature, then he can analyze the proper function of the sending unit and gage.

 

[twoone]

Your idea is worth noting however it does not test the complete system. We wanted to do this as the t-stat is priced like gold and the sensor is not cheap either. Also it was a great learning experience and i had some excellent teachers and now understand my tractor a little better(and how other vehicels system work) Thanks for the input. twoone:licking: