Temperature Sensor Location

[07cob]

All

As part of the recent MassFlo conversion, my temperature gauge sensor is now located at the rear of the intake manifold, with the ECT sensor at the front. While mostly everything else is going well, my gauge is not reading full temperature. It was previously located at the front left of the inlet manifold and would generally read 85-95*C. Now (same thermostat) it is reading only 45-55*C when the engine is hot.

So the question is (for anyone with a 302 or similar variant), where is your gauge temperature sensor located?

Cheers


Geof

[Rog246]

This might be a silly question Geof, but have you checked the temp gauge ?
I mean with another gauge or a thermometer to make sure that the reading is correct ?

[Merv and Sharon]

Mine is on the front left of the new manifold Geof. There is another spot at the rear but I was told it should go on the front position



Reads 82 degrees (180F) most of the time or a little lower.

[sideshow]

only thing i cam think of is if u have air lock
maybe when cold remove sensor fill radiator with water
till it comes out of the sensor hole and while u r filling radiator
start to screw sensor back in
u might have done that already
there should not be thst much temp difference between the 2 positions
maybe u have too much thread tape and sensor has bad earth to block
try earthing sensor wire for split second to see if dash gauge goes to full
only for short period

[CHANMADD]

The temp at the top front is the Hottest and that is where the reading should be taken. The coolant at the back of the engine is the coolest because it was just cooled by the radiator. The fan switch is or should be located as close to the radiator intake hose.

[07cob]

Thanks Gents

Rog, not silly at all! Any advice gratefully accepted. I did remove the offending sensor and tested it against a kitchen thermometer in a cup of just boiled water and it was comparable.

Merv, mine was originally at the front (same as yours) but I put the ECT sensor in that location. Hence the move to the rear. Thanks for the photo, too. I also am looking at around 85-90*C as an actual temp.

Jim (welcome to Queensland!), the sensor was originally heavily wound in thread tape but this has now almost all been removed. When the engine was hot, I also tried earthing the body of the sensor to the chassis directly - no change. I might try re installing it without tape just for laughs. I have also removed the sensor to check there is no air and the water level looks OK. Just to be sure, I completely filled the void left by removing the sensor and left it for a few hours to see if it was dribbling down somewhere - then screwed the sensor back in.

CHANMADD, I will probably end up with the sensor at the front but before I move it I would like to know why it is so much different at the back.

I am thinking along the air pocket lines at this stage since the gauge is reading but just well below actual coolant temp.

Thanks again all.

Geof

[Gaz64]

Geof,

It's cooler at the back, because most engines run the coolant through the block from front to rear (cooled from the radiator), then through the heads from rear to front.
Although the bulk of the flow goes this way, there is small flow through steam holes etc between block and heads.

This is generally true for engines with the thermostat, the water pump and the hoses to and from the radiator at one end of the engine.

The hottest point is leaving the front the heads where the thermostat is located, which logically controls the temp of the engine.

Is a bit strange you see such a difference, but shows you must have a good radiator.

The block gets nowhere near as hot as the heads do, after all the combustion happens in the heads.

I'd be moving your temp sender to a similar location as your ECT sensor.

What does your ECT temp show in data?

[07cob]

Gary

I will certainly be moving the sensor. I just want to be sure everything is OK before I do.

I can't actually dump data from the ECU but I have spliced into the signal and ground for the ECT sensor - on pins 7 and 46 on the EEC IV respectively. Right, wrong or indifferent, I have used the following mapping for the voltage to temperature. (source: ECT Pin Dead on EEC-IV? - Ford Mustang Forums : Corral.net Mustang Forum)

volt / temp (*C)
4.5 -40
4.4 -23
4.1 -7
3.6 8
1.4 57
0.7 82
0.4 106
0.3 123

The voltage starts at around 2.5V (cold - 28*C) and when hot drops to just under 0.7V (85*C - thermostat rating). It stays very close to this mark during all types of driving. Stationary idling will drop the signal further to just over 5V (about 90*C) when the thermo fan kicks in.

So as far at the ECT sensor goes the engine is doing exactly what I would like it to be doing.

The question is - would there really be 30* difference between the front and the back? Or is there something else that is causing the difference.

Geof

[sideshow]

u need to borrow a laser temp gun
ive got one and came down yr way yesterday as we went to cabaretta beach
but maybe get it hot and just use yr fingers as a guide
i recon 45 to 55 degrees wont be too hot on yr fingers
and then touch the front ect sensor and that should be hot to touch

[Merv and Sharon]

Good advice Jim. Or Geof, get two eggs out of the fridge and crack one ... Seriously though 30 (C) degrees difference is a hell of difference.

[Merv and Sharon]

How did you go Geof? I could lend you my code reader if that helps

[Mando]

Geof, why don't you install the temp sensor in the front of the head? I don't have a normal manifold so the head was one of the few options. It was easy and quick and was done after the engine was installed into the car.

Regards.

[Mando]

Geof, why don't you install the temp sensor in the front of the head? I don't have a normal manifold so the head was one of the few options. It was easy and quick and was done after the engine was installed into the car. You should be able to see it at the front of the head in the following pictures.





Regards.

[leroy17]

Looking at that enging bay never gets old!

[07cob]

Update so far...

I eMailed Chris Richards from MassFlo and he suggested that he would expect around a 20degree difference between the front and the rear. Mine appears to be a bit more than this but I think it will have to be attributed to a variety of factors.

The feel test (thanks, Jim) reveals little discernable difference between front and rear. However this may be affected by the coating on the manifold which is designed to dissipate heat.

Merv, I have just been counting sweeps on the voltmeter for the codes. I am only getting 15 (bad power to ECU) and 95 (poor or no earth on Fuel Pump). Since the engine is running well I am not too concerned about either of these although I will still chase them up.

Mando, that is a very neat solution in a sensational engine bay. I will look at this but think I will end up making a fitting for the opening in the RHS of the inlet manifold. Won't be a big job.

Cheers


Geof

[Merv and Sharon]

Good news Geof. Code 15 is worth checking, 95 is expected

[07cob]

Originally Posted by Merv and Sharon

95 is expected

Intersting, Merv. Do you know why?

Geof

[Merv and Sharon]

From what I understand Geof, it is because most builders wire the fuel pump separately from the original main harness (Warwick even suggested that; mine would not work at all from the harness connection) and that the pumps we use are different in terms of resistance from the original Mustang pumps. Code 15 is more important as you know, with is KOEO memory function. Peter or Jim would have more detail.