Will the real temp please stand up...

[shaunroche]

Hi Chaps - as you may be aware, I've put a Davies Craig EWP80 onto my Sprint with a Saab rad, and have removed the original mechanical water pump.

It uses the digital controller which also controls the electric cooling fan.

I have set the fan to come on at 85 degrees. The original temp sender and position in the inlet manifold has been retained, which is new.

Coolant temp rises and when the digital readout shows a temp of about 60-65degrees, the temp gague in the car is showing 1/2: when the readout reaches 70-75 degrees the gauge is showing 3/4.

If I set the fan to come on at 65 degrees the dash temp stays around half way.

I am wondering then if, the car is genuinely running hot, or there is a fault with the temp guage or voltage regulator which is probably about 40 years old.

It's worth pointing out that this is with the car static, not on the road....not got around to that yet, but not far off.

I'm going to relocate the temp sender to the back of the head to see if that has any affect............

Any thoughts chaps?

[sprint95m]

Your temperature sender is probably at fault, it is the gauge that is reading too high at any rate.


The DC controller won't ever control the temperature properly anyhow…..

here is my experience
viewtopic.php?f=4&t=30938




Ian.

[shaunroche]

But it's a new sender.........

I'm well acquainted with that thread as I've read it with interest but what do you mean....'The DC controller won't ever control the temperature properly anyhow...'?

[Jon Tilson]

Many new senders read incorrectly.
The reading is also influenced by the dashboard earth quality and the instrument voltage stabiliser.


Jonners

[soe8m]

Once a while I adjust temp senders to the car when all is checked, renewed etc. and still no good reading. Buy some resistors and have it ok in your car. Just measure and try till the gauge matches the real temp.

Jeroen

[tony g]

When the car is cold turn on ign (and controller) and see what the digital temp says on the controller. If it reads ambient temp I'd trust that and either add resistors to the stock temp sender wiring or try another new one. Senders have been known to read high unless the resistance is correct. This of course is assuming the digital can read 16-20 degrees, can it?

Tony

[shaunroche]

When the car is cold turn on ign (and controller) and see what the digital temp says on the controller. If it reads ambient temp I'd trust that and either add resistors to the stock temp sender wiring or try another new one. Senders have been known to read high unless the resistance is correct. This of course is assuming the digital can read 16-20 degrees, can it?

Tony

The controller is wired into the Ignition circuit so comes on as soon as the ignition is turned on: the temp scale on the controller starts at 60 degrees.

I'll look into the resitor thing, thanks!

[soe8m]

Some average smiths data in celcius. There are two types of sensors for the voltage stabilizer and the without voltage stabilizer types. The gauges are the same.

25 = 850 Ohm
50 = 300 Ohm
70 = 175 Ohm
80 = 140 Ohm
90 = 105 Ohm
100 = 80 Ohm
110 = 55 Ohm

These are about and do varie. Using resistors will change the whole range. But when adjusted at normal operating temp it will stay pretty accurate and does rise when the engine is hot. Just buy a few little resistors from 5 Ohm - 22 Ohm and experiment. These resitors should cost 0,05 gbp a piece.

Jeroen

[GTS290N]

10Vdc
If you can't read a reliable 10 volts at the output of your voltage regulator wrt earth using a cheap meter, then fit a solid stae vr and all of your tests again.

[gmsclassics]

I have an EWC110 fitted to my race car with the latest type controller, mechanical pump and thermostat removed and the bypass tube blanked off etc. I have a Porsche 944T radiator. Controller also works the electric fan. So basically similar to your set up. I've found it all works well and the temperature measurement on the controller is pretty accurate. The sensor for that is in the top hose and is insulated so it is not affected by airflow. Given that ensuring you know with 100% certainty that the engine isn't getting too hot when on the track, I have fitted an aftermarket temperature gauge so I can tell the actual temperature. I have an electrical one in the race car (white face) but use a capillary type in the road cars (black face). I find this helps enormously. Location is in the thermostat housing in place of the standard one and is similarly insulated from airflow cooling.

temp gauge 2.jpg (80.46 KiB) Viewed 776 times

temp gauge 1.jpg (107.68 KiB) Viewed 776 times

I suggest you replace the basic original gauge with something that tells you the actual temperature.
Just out of interest, I run this white faced gauge in a pod of three on top of the dash - the others are oil temperature (measuring temp on the return from the oil cooler) so I can see temperature entering the engine, and also one rigged up to measure pressure in the cooling system to see if the cap is about to blow (15psi).

I've not had any issues with coolant temperature even in very high NZ summer temperatures. I run just rain water with a water wetter/ inhibitor (water of course has a much higher capacity to remove heat than glycol). The great thing is that the pump keeps circulating after the engine has stopped, until the temperature is stabilised at what you've set the controller to.

Another useful tool is one of those small and cheap infrared temperature guns that you just point at an area and it tells you the temperature. You can even use it to measure temperature across the head, radiator etc. Mine looks like this one
http://www.ebay.co.uk/itm/New-Digital-I ... Swp5JWVa-0


Geoff

[shaunroche]

Hi Geoff, thanks for your input – that’s all very interesting and timely as I decided last night to ditch the electric gauge and put a mechanical one in. Bit of a no brainer really but then I am not very bright!

The two things I find most interesting is the fact that you’ve left the temp sender in the original place as some suggest it is better off in the back of the head, and that you state the controller temp readout is pretty accurate.

On that note, I have the EWP sender in the top hose on the LHS (passenger side) and did have it sticking out of the underside of the hose so that it was always submersed in coolant.

However, as it was a pig to get at I now have it poking out of the upper side of the hose so I can get at it….how is your sender positioned up or down and do you think it matters?

Just found myself another job to add to the list for the weekend then!

[sprint95m]

what do you mean....'The DC controller won't ever control the temperature properly anyhow...'?

The controller is supposed to replace the thermostat's role maintaing a coolant temperature.
In the rather long email conversation I had, DC acknowledge that it doesn't do this in our temperate climate
and state that a thermostat is required instead.




The sender in the top hose needs to be on the underside, unless you have a header tank thereby ensuring that the top hose is always full of coolant.




Ian.

[shaunroche]

what do you mean....'The DC controller won't ever control the temperature properly anyhow...'?

The controller is supposed to replace the thermostat's role maintaing a coolant temperature.
In the rather long email conversation I had, DC acknowledge that it doesn't do this in our temperate climate
and state that a thermostat is required instead.

The sender in the top hose needs to be on the underside, unless you have a header tank thereby ensuring that the top hose is always full of coolant.

Ian.

Hi Ian, are you telling me I need a thermostat back in there?

[sprint95m]

Hi Ian, are you telling me I need a thermostat back in there?

Exactly that, it needs to be a remote type with an external radiator bypass…..
please see page 5
viewtopic.php?f=4&t=30938&start=60




Ian.

[soe8m]

I have a mechanical waterpump conversion. I could use the original thermostat hole for the thermostat.

Jeroen