Mechanical temperature gauge installed

[hawkaleuge]

"Equus model 6242, 2" dial"
I'm on my second Equus temp gauge they both hang up on the cold start eventuallly so bad that the needle doesn't move until the engine reaches op temp.  Any body have a better brand that have put in. 

[DaveVA78Chieftain]

Is the tubing kinked or crushed between the expansion bulb and the gauge?  I believe the liquid in the bulb expands with heat resulting in a fluid pressure change to move the needle.  A kink or crush point in the line would cause an incorrect reading.

BTW - I always just use electric gauges that use a sender.

[tmsnyder]

I put this one in mine, it's an Autometer gauge, on the economy side of their stuff at $60 but I like the way it looks in the dash.  I put in a matching tranny temperature gauge too.


https://www.summitracing.com/parts/atm-2635


IMO the water temperature is important enough that it justifies a good quality gauge. 

[LJ-TJ]

This works for me.

[stanDman111]

i like the dash lamp= nice option

[Winnebago Warrior 94]

Pretty  fancy ...we still haven't checked  and traced down the problem  with my temp gauge , .but need to get back on it ,.we did have to change the foam sponge gasket on the roof of the ac unit ..clean coils front and rear  ..change out rotten water holding tank hose ..subbed down roof ..put one coat of elastomeric  roof  coating and need to pick up some  more and do me coats ..clean my running  lights on top of rv and caulked   them ..but really need to get back to the temp gauge..that's a must do

[LJ-TJ]

 Hm? Well if push comes to shove. You could always take a small garden tractor 12volt battery the gauge hook it up to the battery and put the sending unit in a bowl of boiling water and see if it works. As far as my gauges there all autometer purchased off Craig's list for a third the price of new. Everything I've read on gauges say's Stewart Warner are the best. Autometer were second best, MADE IN the U.S.A. and their customer service is fantastic.

[Winnebago Warrior 94]

my husband followed yalls advice and help on the temperature gauge not working ..he located the temperature sending unit on the engine with the helpful diagrams you posted and the temperature sending unit was not working properly..we used the testing methods that yall had posted ..so thanks so much for your help  ...we went to the auto parts and we installed a new temperature sending unit ..we started the engine and the temperature gauge started working immediatly ..we was very happy and thankful for the help we received from the members on here ..well we though all was working properly and then the temperature gauge kept climbing on the temperature gauge inside to the red zone ..YIKES!!! my hubby figured the thermostat was messing up so he went and got a fail safe thermostat they are the type that if the thermostat messes up they are suppose to stay open to keep engine from overheating .. and he installed it ..he turned on the engine and the temperature gauge started rising yet again to the red danger zone ..we stuck a temperature probe in the radiator and it is showing normal range and not overheating in the radiator ..we dont know why we are getting seperate readings ,,do yall have any idea why the temperature gauge inside the motorhome would show it was over heating but the temperature readings taking   on the radiator by removing the cap and taking water temp would show in normal range ? My husband said the engine doesnt appear like it is getting overheated ..im scared to drive it now ..not sure what its doing ..we see the water in the radiator drop and then go up off and on like the thermostat is working and we did install a new one 

[Rickf1985]

There are usually two temperature senders in the fuel injected engines, one for the computer and one for the gauge. The one for the gauge will have one wire and the computer will have two wires. One is in the thermostat housing and the other is in the side of the engine. For the life of me I can't remember which is which right off.  If the plug fit you probably got the right sender since it did affect the gauge but it sounds like it may be the wrong sender. There is a chart the give the Ohms readings for the normal temperatures on the senders and you can check the sender with a meter. I will look for the chart and post it if I find it. Dave may see this and he may have that chart, he has all kinds of charts and neat diagrams he teases me with all the time. Here is a thread that explains a little about how to check it. If you take the wire off of the sending unit does it just sit at around 100? And it is the one on the side of the block.


http://nastyz28.com/threads/how-to-check-temp-gauge.222226/

[Winnebago Warrior 94]

thanks rick we replaced the temperature sending unit that is mounted on the engine ..i believe dave had posted a diagram on one of the post and i showed it to my husband ..he followed the directions and he checked the original sending unit that is mounted on the engine  and it was bad so he replaced it with a new one ..and the temperature gauge started working as soon as he installed it ..he hasnt replaced a temperature sending unit on the thermaostat ..we didnt know there was one there too ..but the temperature on the temperature gauge went in the red zone after the engine ran for awhile it climbed up ..we put a regular temperature gauge in the radiator to check that and it is showed normal range ..we just took off the radiator cap and put a thermometor in it ..my husband changed the thermostat with the fail safe brand thermostat that opens at 190 degrees..he thought it might be bad and not opening properly for the high temp reading inside the vehicle on temp gauge  ..but the temperature gauge inside the vehicle still climbed up to over heated on the gauge ..so do you think he needs to change out the other temp unit on the thermostat too ? do they both work together to make a proper reading on the temperature gauge inside the vehicle ? and im thinking the one that we changed out on the left side on the engine that had a green wire going to it must be the gauge on the dash and the one in the thermostat or by the thermostate must run to the computor or both..maybe they both work together .. we appreciate the help !

[Rickf1985]

The one you changed was the right one, You have either a bad gauge or a bad sender. You need to run the engine until it is up to normal operating temperature, which you can tell when the thermostat opens and hot air starts blowing back from the radiator. Then shut the engine off and check the ohms reading from the terminal on the sender to a good ground on the engine. In that video I think it mentioned what the reading should be. If it is right then the gauge is probably the culprit. Make sure there are no bare spots on the wire since a grounded sensor wire would cause the gauge to go full scale also but it sounds like it is at the bottom of the scale until it starts to warm up and then goes full scale. If you have a laser thermometer you can point it at the block right next to the sender and see what it reads. This is very close to the exhaust manifolds so it will not be the exact temperature of the water but it will be close. If the water is at 180-200 and the gauge is reading off the scale then a laser temp gun should be in the 190-220 range I would guess at that spot on the block, maybe even cooler. If that is the case then the sender is bad.

[DaveVA78Chieftain]

OK, Dave's little bag of tricks:   

The single dark green wire sending unit located on the Drivers side head is for the dash gauge
1365 ohms = 100 degrees.
200 ohms = 180 deg
96 ohms = 220 deg
62.5 ohms = 250 deg.
28 ohms = 320 deg.

Sender check: Disconnect green wire from sender unit.  Use a multimeter on ohm scale with black to ground and red lead to sender center post.  Resistance should change as engine warms up per the chart above.

Gauge: Various size resistors (radio shack) in the sizes above (approximate) can be used to check the gauge. Connect one resistor lead to the dark green wire and ground the other lead and the temp gauge should read close to the values above.
---------------------------------------------------------------------------------------------

The 2 wire (yellow and black leads) sending unit located by the thermostat is for the ECM.


Sending unit: disconnect cable from sending unit. Resistance is measured across the two posts as the engine warms up.
You would need a ODB1 ECM data reader to see temp changes by using resistors.

Please note that you should never open the radiator cap with the engine hot.  Like a pressure cooker on a stove, as engine temperature increases, the system pressure increases.  This is to allow the water to reach temperatures above 212 degrees without boiling.   Opening the radiator cap at operational temperature can result in severe scallding by the super heated water. Like Rick recommended, use an inexpensive laser thermometer to read block temperature at the thermostat housing.

[Winnebago Warrior 94]

thanks guys yall are the best ..im gonna show this too my hubby ..the sending unit we just installed was a nrw sending unit ..we wasn't getting any type of temperature readings at all and when we installed the new sending unit that is when the temperature guage started working ..but then when it started working it started at the bottom temp and kept on climbing up to the red zone as the engine slowly warmed up ..are the new sending units prone to not working ..that would be our luck that we got a bad new sending unit ..and we didn't take the cap off the radiator after it got hot ..what we did is we let it cool down then we took the cap off after we started it again before the engine got hot to compare the temperature reading in the radiator with a thermometer  to see if it was hot like the dash temperature guage was reading and it wasn't showing the same temperature ..I think one of yall on here told me to check my radiator like that a while back to make sure the  engine wasn't overheating since my temperature guage wasn't working  ..im going to get a a lazer temp gun like yall told me and check the temperature that way . with yalls help we will get this ..thanks  im also going to make sure the wires don't have any worn spots to make it ground

[Rickf1985]

Two words, Chinese Junk! Most aftermarket parts nowadays come from China and the failure rate out of the box is quite high. Run the tests using the charts that Dave provided and you will probably find that the sender is bad. He didn't use teflon tape on the threads did he? That will cause problems sometimes since it affects the grounding of the sender.

[LJ-TJ]

Well I've been following this exercises and feeling your pain. I have to agree with Rick. Back in the day when I was trying to get a working fuel gauge. Being frugal as I am I went to Princess Auto (Harbor Freight) in the States to get their fuel gauge and sending unit. I ended up going through 10 yes 10 gauges or sending units until I got one combonation that worked. Remember that's taking the tank out, putting it in, taking it out, putting it in. Finally I ended up stepping up to the plate and buying a Autometer gauge and sending unit and have never looked back. They work like a dream and I finally built a complete instrument panel out of Autometer.Don't get me wrong here but the moral of the story is you get what you pay for. AND Autometer is made in the U.S.A.

[Winnebago Warrior 94]

I checked with him and he didn't use any Teflon tape ..and that would be terrible to have to keep dropping a fuel tank ..lets hope mine keeps on working ..hes going to test the sending unit and get a lazer temp gun ..he will probably test it today ..we are going to check the wires too and make sure they aren't any skinned places ..we would like to have a working temperature gauge I will report back to yall on my findings ..thanks

[tmsnyder]

If you installed a new temperature sensor and the gauge went from not working at all, to sort of working but reading too high, then I would suspect you have found the problem; a bad sensor.   The trick now is to install the correct sensor for the rest of the gauge circuit, they have to match.  It must be the wrong part or a defective part, or a problem in the rest of the circuit.


Put the thermostat back in the engine. Start the engine and let it warm up. 



Once it is up to temperature, what is the resistance of the sensor?  Read the ohms between the pin on the sensor and ground on its base.  Compare it to the table for the sensor above, is it close to correct resistance at that temperature?  Something in the neighborhood of 100 ohms? 

[Rickf1985]

260-325 ohms, See Daves chart and write up above.

[tmsnyder]

Dave's info says those numbers for the air and water sensor for the fuel injection system, but ~100 ohms for the dash gauge.  I was just taking his word for it.

[DaveVA78Chieftain]

For reference, the ECM info is from the 1992 Chevy Emissions manual.  The same manual set just says 1400 ohms cold, 55 ohms hot.  I found the more detailed information on the web.  So, I am fairly comfortable that the temp gauge information I provided is reliable.

[Winnebago Warrior 94]

Yall are the Best in the north ,south,east and west ! We did what yall said the hubby checked the ohms reading and he could not get a reading on the post like yall said..so we think the sending unit was bad or the wrong one since it would not show a reading  ..he went back to the auto parts place they was out of the temp sending unit ..my hubby also got a lazer temperature gun and the reading was not high like the temperature gauge said it was reading normal  ..the next day the new temperature sending unit came in ..it was a different brand ..he installed it and it started working..and he could pick up a ohms reading with this one like yall said  he compared the temp on the gauge to the temp reading on the lazer temp gun and they was both spot on ..same temp ..this time the new temperature sending unit worked ..and it showed the temperature in normal range on the gauge and it matched with the temp lazer gun ..YIPPIE !! so we are happy campers again now ...thanks for all the helpful advice and charts and knowledge and for taking your time to help us ..greatly appreciated ..hip hip hooray !!! and we will be taking the bad sending unit or wrong one whichever it is back to the auto parts for a refund  

[DaveVA78Chieftain]

Your welcome.   

[Rickf1985]