Temperature Problems

[barnett468]

The previous dash with the autometer gauge was in fahrenheit and it used to read high as well. When I was driving on a highway it used to read about 150F. If the car was idling in one spot like it was today for the test it would get as high as 200F with the thermo on. Or is it more than likely that this gauge was reading correctly?

So do you guys thinks its the sender?

an autometer gauge is not going to be inaccurate, plus it matches what your stock gauge reads perfectly . . your infra red results sound unrealistically low to me.

did they take the temp from around 6 inches away but

[Speed Demon]

Thanks barnett468 for your input.

Busy day today working on the car all afternoon. The dramas continue.

I changed the thermostat today for the new one I got. The old thermostat was a 160F thermostat which probably explains the low temperatures. After I done the thermostat 180F I then changed the sender. I put the thick one in I got yesterday which looked to be the same as the one recommended earlier in the thread.

So after starting the car up so I could fill the radiator full of coolant/water I noticed the temp gauge rocket up to full. I thought it may have something to do with an air lock in the housing but after filling the whole radiator and getting the coolant to circulate the gauge continued to read at the maximum.

I am now stuffed if I know what to do. I guess the only option is to get another sender??

[shaunp]

Get the correct sender from Big Al to start with, If the Autometer gauge said it was 150 at speed that is not hot, 200 at Idle good be lower, I suspect the issue with higher idle temp is fan issues.

[Speed Demon]

Yeah I think you're right Shaun.

Is it possible that my dash may be out of a 65 Mustang? Did the GT dashes only come out in the 66?

[scollist]

Get the correct sender from Big Al to start with, If the Autometer gauge said it was 150 at speed that is not hot, 200 at Idle good be lower, I suspect the issue with higher idle temp is fan issues.

From the link picture he posted I think he has the correct sender for the 66 gauge (purchased from Harry's classics).

So the choice is either faulty new sender (possible) or the gauge is the problem.

Speed - I suggest the following to trouble shoot the cause:
- go back to the old sender unit. What does that read with the 66 gauge?
       - if that gives a reading on the 66 gauge between high and low while at normal idling temp, then the new sender is faulty in my opinion (you can take that up with Harry's Classics)
       - if you want to be doubly sure use the sender testing process using a multi-meter set out in the Mustang Monthly article http://www.mustang.org.au/forum/index.php/topic,12082.0.html
- If possible go back to the Autometer gauge with the old sender and confirm that that combination is working by using the Infrared Thermometer (i.e. do they both give a consistent reading). This really just gives you your baseline to support the previous test of the new sender.
- If the new sender proves to be okay, and you know your temp is okay, then it is the gauge. I'm not sure how to fix it, but you can buy a new one (not cheap) from the likes of CJPony.

[Speed Demon]

I actually tested the new sender with my multimeter today before I put it in the engine. I boiled the water, poured it into a shallow dish, placed the sender into it and tested the sender with the multimeter. Reading that other thread I think it was supposed to read about 40 when the water was at about 192F.

The sender read 68 on the multimeter about 1 minute after the boiling water was poured into the dish. Unfortunately the IR gun wouldnt read the temp of the water, not sure why.

So does that mean the sender is faulty?

[GLENN 70]

Correct me if I am wrong but your engine should run around 80 -85 deg c and that's about 180 -190 F  ,my 347 runs around 85c most of the time .

[barnett468]

Thanks barnett468 for your input.

I changed the thermostat today for the new one I got. The old thermostat was a 160F thermostat which probably explains the low temperatures. After I done the thermostat 180F I then changed the sender. I put the thick one in I got yesterday which looked to be the same as the one recommended earlier in the thread.

So after starting the car up so I could fill the radiator full of coolant/water I noticed the temp gauge rocket up to full. I thought it may have something to do with an air lock in the housing but after filling the whole radiator and getting the coolant to circulate the gauge continued to read at the maximum.

I am now stuffed if I know what to do. I guess the only option is to get another sender??

no prob, you're welcome . . lots of other good info here by others too.

the senders are calibrated internally for different apps . . that one is the correct size but it will likely not read correctly . . i can pretty much guarantee it.

forget what the gauge says, you should have a good infra red or autometer gauge connected until this is resolved.

you may have just had air in the system . . this is common when draining and refilling the system . . look at your water level it may be low now . . if so fill it up leaving 1" of airspace then see whsat the gauge reads then remove the sender and put the previous one in and see what it reads.

post all the numbers on both senders . . the new one you have is likely a standard motors products one or possibly a scott drake . . both of those read incorrectly.

if you want the correct sender buy a used original one.

do you still have the bypass hose connected?
.

[barnett468]

Correct me if I am wrong but your engine should run around 80 -85 deg c and that's about 180 -190 F  ,my 347 runs around 85c most of the time .

with a proprely sized cooling system in good working order, it will run a few degrees either side of the thermostat and never more than around 7 degrees higher than a thermostat . . the only time it should run lower than the thernostat is if you are in antartica . . ethe stock thermostat is 192.

[Speed Demon]

Correct me if I am wrong but your engine should run around 80 -85 deg c and that's about 180 -190 F  ,my 347 runs around 85c most of the time .

Like i said I changed the thermostat today to a 180F one. Water was circulating in the radiator once the engine heated up. I tested the thermostat before I put it in and it opened right on 180F. I used the IR gun pointing it on the thermostat while it was in the pot.

I also put in a Davies Craig thermo kit today and that is also working nicely, got it set to around 90C.

I'll put the other sender it after dinner and report back the result.

[barnett468]

Like i said I changed the thermostat today to a 180F one. Water was circulating in the radiator once the engine heated up. I tested the thermostat before I put it in and it opened right on 180F. I used the IR gun pointing it on the thermostat while it was in the pot.

I also put in a Davies Craig thermo kit today and that is also working nicely, got it set to around 90C.

I'll put the other sender it after dinner and report back the result.

ok then you did not have an air bubble since you saw water circulating . . this also means your water and engine temp were above the thermostat rating.

need the numbers off of the senders

[Speed Demon]

No problem and yes the bypass hose is connected.

BTW the new sender is a Scott Drake job C6DZ-10884-B.

[StephenSLR]

double post

You have the option to remove posts Barnett, look in the top right of your posts.

s

[scollist]

I actually tested the new sender with my multimeter today before I put it in the engine. I boiled the water, poured it into a shallow dish, placed the sender into it and tested the sender with the multimeter. Reading that other thread I think it was supposed to read about 40 when the water was at about 192F.

The sender read 68 on the multimeter about 1 minute after the boiling water was poured into the dish. Unfortunately the IR gun wouldnt read the temp of the water, not sure why.

So does that mean the sender is faulty?

Not really sure unless you can identify what the impedence is at a particular water temperature.  The bowl of water will cool down quickly, so after 1 minute it will be well below boiling. The higher impendence reading is correct - it gets higher as the temperature gets lower.  At room temperature the impedence reading should be even higher - letting less voltage through and therefore a lower reading on the gauge.

I'm not sure why your infrared thermometer couldn't read the temp. In the article they use a cheap probe thermometer - http://www.dx.com/p/digital-lcd-food-probe-thermometer-50-300-c-1-lr44-52209?tc=AUD&gclid=COOPvMP8uMMCFVUsvQodV2gA4A#.VMoINpUcSUk. Maybe you could try again or get one of these.

[Speed Demon]

Ok here's where we're at.

Went in the garage, car had cooled down a bit from earlier. Thermostat housing temp was 45C. New sender was still in and after turning the ignition on the gauge went to Max straight away. Off to take the sender out and put the other one in.

After removing the new sender and putting the new one in(correction old sender in) something strange happened. I turned the ignition on and the temp gauge didnt move at all initially, then it too went to Max which I thought was unusual as the engine was only warm including the water in the radiator. So I thought I would play with the wire connection.

Removed the wire and the eyelet on the end of the wire feels like its only being held on by a few strands. Anyway put it back on the old sender and turned the ignition on again. Well the gauge didnt go to Max this time and only moved a little bit. So I started up the car and let it idle for about 10 minutes. The gauge slowly moved up and from about 1/2 went up pretty quickly over about 1 minute to H (Hot). Was checking the temp on the bypass on the thermostat housing the whole time and it reached 68C.

So it sounds like the wire connection might be dodgy. When its done up the wire can tend to turn while your tightening the nut on the sender. I think this has happened many times before I got the car. I'll wait until it cools down and then i'll change the new sender back in. I'll put a new eyelet on the wire also and see how that goes.

Tomorrow I will set the davies craig thermo to come on at about 85C and see how that compares with the gauge if its working of course. But so far the Davies Craig automatic thermo kit is working perfectly.

[barnett468]

your wire is not the prob now that you have fixed it . . both your senders read inaccurately hoh did i know that lol . . they shoud read aroiund 40 ohms in 200 degree water and the gauge should be just past the center . . you can not read water with infra red it will be inaccurate you need a candy thermometer

[Speed Demon]

Done another test on the new sender tonight, its looks like its actually working ok. I threw the old thermostat in a pot and heated it up until the thermostat was fully open. Turns out my IR gun is inaccurate, at boiling point it was ready 85C. So after the water boiled I let it cool to around 67C on the gun. Multimeter reading was reading around 33 ohms of resistance. So even though the reading was a little lower than it should be its not that much out.

I am sure I have a wiring issue.

[Speed Demon]

your wire is not the prob now that you have fixed it . . both your senders read inaccurately hoh did i know that lol . . they shoud read aroiund 40 ohms in 200 degree water and the gauge should be just past the center . . you can not read water with infra red it will be inaccurate you need a candy thermometer

While the sender is definitely inaccurate its not that much out. An inaccurate gauge thats out by a little bit wouldn't cause the gauge to go to maximum while the engine is cool, it has to be a wiring issue surely.

[barnett468]

While the sender is definitely inaccurate its not that much out. An inaccurate gauge thats out by a little bit wouldn't cause the gauge to go to maximum while the engine is cool, it has to be a wiring issue surely.

Your wire has basically four choices and no more.

1. work properly.

2. have a bad connection so you get no reading.

3. have a corroded connection which causes higher resistance which will cause the gauge to read lower than it should.

4. be grounded so it causes the gauge to read full hot around 4 seconds after the key is on.

unless it is grounded, it is 110% impossible for it to cause the gauge to read higher than it should . . this would defy ever law of physics . . it simply will never, ever, happen...ever.

i told you that your ir gun would not read water temp accurately . . this is one of their flaws but this does not mean it is reading other things inaccurately.

if your gauge is reading full hot with the sender reading 38 ohms, you have a gauge problem providing the wire is not grounded somewhere.

as someone else mentioned, the gauges are adjustable to some degree but the problem is that if you can set the gauge so it is to the left of the T in temp but if your sender is inaccurate, it might only go to the P in temp when your engine is boiling over . . in other words you can narrow the operating range of the needle which is something you do not want to do because your gauge will tell you your temp is still acceptable when your pistons are actually melting.

the gauges are designed to operate from around 11 ohms on full hot to 78 ohms on full cold . . this means that your sender should read around 60 ohms or more in around 60 degree water and around 30 at near boiling.

again, the correct place to read the engine temp is behind the thermostat, not on the thermostat because water does not flow thru the thermostat if it is closed . . if you don't read it there you will not get an accurate reading . . this is all really very simple.

if you want to determine if your wore is grounded, simply remove it from the sender and the gauge and check it for continuity with the body anywhere like the engine on a carburetor stud or something unpainted.

also check it against a location on the body like a fender bolt etc.

your engine should have a ground strap on the back of it grounding it to the body.

[Speed Demon]

I put a some teflon tape on the new sender yesterday before I put it in the manifold. So hopefully its wasn't grounding properly. Your number 4 option is what was happening yesterday with the new sender. I will put the new sender back in shortly with a bit less teflon tape this time and see what happens. If the gauge goes to full hot again I will ground it with a separate wire and see if that makes any difference. I will report my findings back in about 1 hour. If this doesn't work I will order another sender.

[barnett468]

I put a some teflon tape on the new sender yesterday before I put it in the manifold. So hopefully its wasn't grounding properly. Your number 4 option is what was happening yesterday with the new sender. I will put the new sender back in shortly with a bit less teflon tape this time and see what happens. If the gauge goes to full hot again I will ground it with a separate wire and see if that makes any difference. I will report my findings back in about 1 hour. If this doesn't work I will order another sender.

what are you going to ground with a separate wire?

the sender will often cut thru the teflon tape and ground as it should amyway . . i use a very thin layer if black permatex gasket maker.

you sender actually should not leak if there is no sealer but that is in a perfect world.

your sender body should ground itself to the engine when you instsall it.

your sender wire should never, ever be grounded.

remove your wire from your sender and do not let the wore end cointact anything.

turn the key on.

if your gauge does not move, the wire is not grounded which means it is fine.
.
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[Speed Demon]

So I put the new Scott Drake sender back in and the same thing happened. After about 4 seconds the gauge moved to the Max position which is just past the Hot.

Then I grounded the body of the sender to the body of the car with a wire to make sure the sender was grounded properly, it did not make any difference. The gauge still went to Max after about 4 seconds of turning the ignition on.

So then I put the old sender back in to test if the same thing was happening. Bear in mind the car hasn't been started up today so is cold. After putting th old sender back in I turned the ignition on, the temp gauge didnt move and stayed in the cold position.

Has to be the sender then.

[Speed Demon]

Ok new temp sender from Big Al's has been purchased and should arrive early next week.

[barnett468]

So I put the new Scott Drake sender back in and the same thing happened. After about 4 seconds the gauge moved to the Max position which is just past the Hot.

Then I grounded the body of the sender to the body of the car with a wire to make sure the sender was grounded properly, it did not make any difference. The gauge still went to Max after about 4 seconds of turning the ignition on.

So then I put the old sender back in to test if the same thing was happening. Bear in mind the car hasn't been started up today so is cold. After putting th old sender back in I turned the ignition on, the temp gauge didnt move and stayed in the cold position.

Has to be the sender then.

ok the drake sender has to read around 60 ohms or higher then in cold water.

what do both senders read in cold water?

check continuity between the drake sender post and sender body . . if there is none, the sender is not broken but might be out of range.


.

[barnett468]

Are you talking normal cold water out of the tap?

Yes.

Just checked the Scott Drake sender with the multimeter in normal cold tap water, the reading was 209.

might have been pretty cold water