Strange Electric Fan Answers...(Fans ..Off & On..)

[Viet Nam Vett]

Here's the Poop Bob. Installed a Robert Shaw Thermostat Sold under Mr Gasket #4364..180 Degrees.

Try this link..
http://store.summitracing.com/partdetail.asp?part=MRG%2D4364&N=400330+115&autoview=sku.

This is a high Performance Thermostat...Cool Huh..?? Won't fight the water pump for opening and closing operation.

Also Moved the temp senser to the driver side Cyl Head. Should also work the same in the passenger side head. Just remove the plug and install.

The fans come on at 195 * and shut down at 175*. The motor runs around 180 * -190* while cruzen. Fans stay off. After a stop at the traffic light they come on and run about 2 min and shut down.

Now..so far this has been with a max outside temp of around 70*. As the weather get's hotter I expect that the fan run time will be longer due to the higher outside temps..but I do expect tham to shut down. So will see what happens from here.

It is nice to have the fans shut down while your cruzen. I think even with the higher outside temps the radiator will manage to keep the temps below 195.

Will ..see...

 

[richscorvettes]

We used the same thermostat and also installed the temp sender in the head but on the passenger side. Both worked fine.

I see that you've installed a heat shield around the steering box. Things getting a little hot in that area?

Rich Lagasse

 

[elints]

The electric fan(s) temp sensors should be mounted on the incoming side of the radiator. The fan(s) cool the radiator, the radiator cools the coolant and the coolant cools the engine. The engine temp should be controlled by the thermostat if the radiator can provide sufficient heat removal from the coolant stream.
In hot climates the "on" setpoint should be at or just above the thermostat opening temp. The "off" setpoint is determined by the deadband of the control switch.

Example, Your car comes with a 195F thermostat. That indicates the temperature where the thermo starts to open and allows coolant to flow to and from the radiator.The mixing of the two coolant streams is supposed reduce the engine temp.
Now your fans "on" and "off" setpoints were provided at 195/175F. The thermostat should cycle and maintain a fairly stable coolant temp around the opening setpoint of the thermostat (provided the radiator has the capacity to remove the excess heat).

If you change you thermo to a lower setpoint, say 180F, then the fan(s) on/off setpoints should be lowered to 180/160F the keep the controllers from fighting each other.

You may get by with engine temp swings in cooler ambient air but as the season change the swings between cruising and traffic will become more pronounced.

It would be nice to have a variable fan controller where the on/off settings and deadband can be set according to the application. Even better would be a real time model running in the ECM to control both the thermostat(valve) opening and the fan/radiator performance based upon ambient condition and load demands.

JMO


VN vette - Welcome home

 

[JL66REDCPE]

Mark -- good to see that you solved the fan challenge. Motor really looks great. Generally speaking, are you expecting an overheating problem in the summer.

 

[Viet Nam Vett]

The electric fan(s) temp sensors should be mounted on the incoming side of the radiator. The fan(s) cool the radiator, the radiator cools the coolant and the coolant cools the engine. The engine temp should be controlled by the thermostat if the radiator can provide sufficient heat removal from the coolant stream.
In hot climates the "on" setpoint should be at or just above the thermostat opening temp. The "off" setpoint is determined by the deadband of the control switch.

Example, Your car comes with a 195F thermostat. That indicates the temperature where the thermo starts to open and allows coolant to flow to and from the radiator.The mixing of the two coolant streams is supposed reduce the engine temp.
Now your fans "on" and "off" setpoints were provided at 195/175F. The thermostat should cycle and maintain a fairly stable coolant temp around the opening setpoint of the thermostat (provided the radiator has the capacity to remove the excess heat).

If you change you thermo to a lower setpoint, say 180F, then the fan(s) on/off setpoints should be lowered to 180/160F the keep the controllers from fighting each other.

You may get by with engine temp swings in cooler ambient air but as the season change the swings between cruising and traffic will become more pronounced.

It would be nice to have a variable fan controller where the on/off settings and deadband can be set according to the application. Even better would be a real time model running in the ECM to control both the thermostat(valve) opening and the fan/radiator performance based upon ambient condition and load demands.

JMO


VN vette - Welcome home

Thanks Elints for the reply,..and the Welcome Home...
This topic has been covered in many many posts. Some feel as you do ...and some place the sensor where I have it now.....recomended by the fan Mfg.
Some place it in the intake manifold. I think both have had success in all the different loctions.

I feel safer monitoring the the temp in the Cyl Head where the heat is generated. It's six and one half of this and that . As of now the fans are running perfect. Will see what happens as it gets a little hotter out.

It would be nice to have a variable fan controller where the on/off settings and deadband can be set according to the application.

Go here and check this out... I have one standing by just in case...
http://www.spal-usa.com/site_start/features_and_specials/PWM_page_images/FAN-PWM2.html

 

[Viet Nam Vett]

We used the same thermostat and also installed the temp sender in the head but on the passenger side. Both worked fine.

I see that you've installed a heat shield around the steering box. Things getting a little hot in that area?

Rich Lagasse

Yeah...Just a little but it's not a major problem. I had the heat shield laying around and one day at the end of working on the vette...I looked over and saw it on the shelf.

The next thing I new..I had it around the steering box. It does help keep the Lub cool.. Did yours get hot...??

 

[Viet Nam Vett]

Mark -- good to see that you solved the fan challenge. Motor really looks great. Generally speaking, are you expecting an overheating problem in the summer.

Generally Speaking.....:L ....Not with the Dewitts Radiator and those Spal Fans. I don't like the idea of the fans running all the time when not needed such as cruzen down the highway. They suck some major amperage. About 20 Amps for both.

No sense in loading up the Alternator when the ram air can cool the rad down at speed. Last weekend when I had the Vette out they never came on while moving....of course it was only 70*.

Will see what gives when the temp jumps up..

 

[elints]

Keep the mind that monitoring the temp of the engine is fine. As long as you have excess capacity in the radiator, the engine will behave. When the ambient temps get hot the cooling capacity of the radiator diminishes sometimes to a point where the thermostat is full open. If you set up the control point on the radiator temp you will have feed forward control and keep the engine from exceeding the thermostat setpoint. At highway speeds the fans will be controlled by the radiator temp and the high air flow should allow the fans to turn off very shortly.

Honestly, fan manufacturers make suggestions from what they have heard was "successful" not from any control engineering. I have in the past had a few discussions with Dewitts about this. Hopefully I will have the opportunity to have them make a radiator for me with the features I think wouuld be helpful. At least now they are using the term "setpoint".

BTW Porsche has their fan control switch mounted in the radiator and the results are stable temp operation even when the ambient temp is high.

Just give it some thought and if you start having swings in engine temp in traffic keep the sensor location in mind.

I am going to raise on to you in a little bit.

 

[Viet Nam Vett]

Keep the mind that monitoring the temp of the engine is fine. As long as you have excess capacity in the radiator, the engine will behave. When the ambient temps get hot the cooling capacity of the radiator diminishes sometimes to a point where the thermostat is full open. If you set up the control point on the radiator temp you will have feed forward control and keep the engine from exceeding the thermostat setpoint. At highway speeds the fans will be controlled by the radiator temp and the high air flow should allow the fans to turn off very shortly.

Honestly, fan manufacturers make suggestions from what they have heard was "successful" not from any control engineering. I have in the past had a few discussions with Dewitts about this. Hopefully I will have the opportunity to have them make a radiator for me with the features I think wouuld be helpful. At least now they are using the term "setpoint".

BTW Porsche has their fan control switch mounted in the radiator and the results are stable temp operation even when the ambient temp is high.

Just give it some thought and if you start having swings in engine temp in traffic keep the sensor location in mind.

I am going to raise on to you in a little bit.

Just give it some thought and if you start having swings in engine temp in traffic keep the sensor location in mind.

Will do...

 

[studiog]

If all else fails just hard wire this switch to the fans and you'll be all set.

 

[IH2LOSE]

My story in a nut shell
Fan censor in the head, tempature censor in the intake water passage


Saturday I take the 62 out. 20 minute ride to work, fans are on in about 7 minutes temperature gauge never over 160 degrees. Go in the building and leave in about 2 hours. Turn the key on the fans come on right away temperature gauge is not even reading

feel the radiator its cool but the motor is hot

So it seams my heads are at least 175 degrees even though the water that the gauge reads is cool.

it seams I am dealing with a heat soak of the motor

 

[elints]

My story in a nut shell
Fan censor in the head, tempature censor in the intake water passage


Saturday I take the 62 out. 20 minute ride to work, fans are on in about 7 minutes temperature gauge never over 160 degrees. Go in the building and leave in about 2 hours. Turn the key on the fans come on right away temperature gauge is not even reading

feel the radiator its cool but the motor is hot

So it seams my heads are at least 175 degrees even though the water that the gauge reads is cool.

it seams I am dealing with a heat soak of the motor

Ever think about reversing them?

 

[magicv8]

Keep the mind that monitoring the temp of the engine is fine. As long as you have excess capacity in the radiator, the engine will behave.

BTW Porsche has their fan control switch mounted in the radiator and the results are stable temp operation even when the ambient temp is high.

Just give it some thought and if you start having swings in engine temp in traffic keep the sensor location in mind.

I have always questioned why people tie the fan settings to the engine temperature, since engine temp is controlled by the thermostat - by design.

The Derale fan controller monitors radiator temp and is adjustable to allow fans to run when you set the controller to cool the radiator. It does not require radiator mods - the external temp probe sits between the cooling fins below the inlet to monitor radiator temps. That way you don't have ugly wires hanging all over your engine, and the radiator is cooled to provide engine coolant when the engine tstat demands it.

Works for me.

 

[Viet Nam Vett]

My story in a nut shell
Fan censor in the head, tempature censor in the intake water passage


Saturday I take the 62 out. 20 minute ride to work, fans are on in about 7 minutes temperature gauge never over 160 degrees. Go in the building and leave in about 2 hours. Turn the key on the fans come on right away temperature gauge is not even reading

feel the radiator its cool but the motor is hot

So it seams my heads are at least 175 degrees even though the water that the gauge reads is cool.

it seams I am dealing with a heat soak of the motor

Have you checked to make sure your temp gauge is accurate?? And what is the "T"stat temp ? Is it a 160..180 ..190..?? Have you taken any readings around the motor with an IR gun....(For Reference Only not for accuracy..to see what's what as far as temp differential?

 

[Viet Nam Vett]

If all else fails just hard wire this switch to the fans and you'll be all set.

Got me one of them there switches...I can turn em off..or turn em on..

 

[magicv8]

So it seams my heads are at least 175 degrees even though the water that the gauge reads is cool.

and if the probe was on the radiator, the fan wouldn't be running on a cold rad.