How long should my stag’s electric fan run

[RobinLegin]

I was delighted to get my toy back yesterday and drive it home 12 miles . An issue is that the electric fan ran for a good 10 minutes or more after I had stopped the engine. It near flattened the battery. I can adjust the point at which the fan cuts in and out. I was wondering how long is the ideal run on? I think cooling the engine after switching off is good - both my BMW and spouse’ Golf do so but for no more than a minute or so after stopping.

[tvrgeek]

Depends entirely on the controller the shop put in , where and how they mounted the sensor. I agree, 10 minuets is way too long. Most cheap fan controllers only all you to set the turn on temp. The hysteresis is built in. Without seeing your specific setup, it is hard to give a exact solution. I suggest you look at the module and go to their WEB, read their install instructions and look at how yours was done. You then can discuss it with the controller maker and the shop. A wild guess is where they put the probe. If they used the engine sensor, it won't be getting water circulated and would take forever to cool. It is the standard upper hose, location, it should be quicker. It depends.

[barkerwilliams]

My fan usually runs 30 secs to 1 min. However after MOT emissions test when the engine is rev'd up for some time the fan ran for about five minutes. I presumed being in the MOT garage the air being drawn into the fan had recirculated within the garage and was already warm and had less cooling effect, the moisture in the air was low and had less cooling affect and the engine was rather hot.

So you question of the ideal time is simple, it runs until the coolant reaches a temperature set by the sensor and the engine is protected from high temperature surges in the coolant as the heat in the metal dissipates. If you decide that you would like a higher "parking" coolant temperature than a running coolant temperature it would be fairly easy to add a second, higher rated, sensor into the plumbing and a little wiring change.

I once blew a mini rad top hose on the M1, blasting down the motorway, parked and walked away, now when I park I always let the engine idle for a minute to circulate the coolant and cool before turning the engine off.

In spite of all that I do not think a fan running on a fully charged battery for even 20 minutes would reduce the battery to a point it could not restart the car.

As a fan will spin at the speed determined by the battery voltage and become less efficient at moving air as the voltage drops, perhaps your battery is reaching the end of the road and a new battery might be a good investment. And perhaps checking the radiator for blockages on the radiator care caused by litter, dead leaves, and impaled insects etc., better airflow = better cooling.

Alan

[dasadrew]

I was delighted to get my toy back yesterday and drive it home 12 miles . An issue is that the electric fan ran for a good 10 minutes or more after I had stopped the engine. It near flattened the battery. I can adjust the point at which the fan cuts in and out. I was wondering how long is the ideal run on? I think cooling the engine after switching off is good - both my BMW and spouse’ Golf do so but for no more than a minute or so after stopping.

Been there, got the T-Shirt.

I've got a Revotec and have gradually increased the temperature at which it kicks in as it flattened the battery twice already when I was doing short shopping runs and it was always switching on at each stop when the soak temperature went up.

I couldn't believe the power that it was taking just to spin some plastic blades. On one occasion, there was enough juice left to start the car when I pulled the Revotec fuse, but not enough for both.

I've now fitted an IR remote switch so I can override the fan completely. I've also got a capillary water temp gauge which continues to show temperature even when the ignition is off, and I noticed that the Revotec does sweet all to lower the temperature when the engine goes into heat soak mode. Switching the fan on and off with the remote whilst idling in traffic made no difference whatsoever visibly to the needles on both temperature gauges (one in LH ater transfer housing, one in the right hand)

Furthermore, I have the impression that the thing is doing more harm than good as it certainly blocks off quite a lot of the radiator surface for cooling when driving.

All-in-all, I've been de-convinced of the merits of an electric fan.

Drew

[Matt Cook]

This is the problem of controlling the electric fan with a temperature sensor in the top hose when the engine and therefore water pump is stopped. Fan is cooling the water very nicely in the radiator and it's not going anywhere. Convection currents are being relied upon to circulate the water.

I have an electric water pump and the fact that the controller puts the pump and fan on when the engine stops is one of the best features (that along with pump speed being independent of engine speed), they run until a temperature 10 degC below normal operating temperature, I have this set at 88. This process take about 5 minutes. I have a Kenlow 2 speed fan, the water pump controller works on one of the fan speeds and I have a revotec controller in the top hose, set at a slightly higher cut in temperature ~95, though this never comes on.

Matt

[tvrgeek]

One can put a timer on it to limit it to a couple of minutes. This is not an issue on modern cars, so one should look a little closer at the install and the product used. I am looking at the Hayden controller.

I noticed one of the PWM controllers used a sensor you attach to the radiator tank. A sensor in the top hose if closer to the engine will not respond to cool down as one installed close to the rad. As we have brass rads, one can consider putting in a bug and use the good old reliable K-car switches. ( THe don't blow out like an MG switch does!)

[stag8manod]

My two speed Kenlowe never runs when the engine is switched off because the controlling relay is switched/feed from an ignition source. Engine off fan off, problem doesn't exist, works well. If the engine is restarted in a short time and the the heat soak is still up the fan runs and brings the temp down under the low set point and switches off.It has never caused any problems.
Cheers Ian A

[dasadrew]

.... Fan is cooling the water very nicely in the radiator and it's not going anywhere....
Matt

EXACTLY! And where are the worries about head warping etc., on a Stag engine? Rear RH head! You couldn't get much farther away from the radiator and fan!

Drew

[DJT]

No idea. My 2-speed Kenlowe never comes on. Standard radiator and quality viscous coupling keep the engine cool enough. If there was sufficient heat soak to raise the temperature enough, then the Kenlowe would kick in as it has a battery feed......

[tvrgeek]

Curious, the temp sensor is in the left rear head, yet here it suggests the problem is on the right. I still haven't found a way to get a wrench on it yet!

You are not going to circulate some water through the bypass port by convection, but hoping electric fans will prevent heat soak is probably wishful thinking. As I have AC, and am going to a lot of effort to make it work, I already have two fans that if set up correctly should eliminate the need for the engine fan. May need different fans if course and that condenser dies look a bit small.

Not going there yet, but a thicker core, moved foreward, pullers in shroud with relief flaps would be my choice. I hope I don't have to go that far, or even the electric pump.

[bullstarz]

This is the problem of controlling the electric fan with a temperature sensor in the top hose when the engine and therefore water pump is stopped. Fan is cooling the water very nicely in the radiator and it's not going anywhere. Convection currents are being relied upon to circulate the water.

I have an electric water pump and the fact that the controller puts the pump and fan on when the engine stops is one of the best features (that along with pump speed being independent of engine speed), they run until a temperature 10 degC below normal operating temperature, I have this set at 88. This process take about 5 minutes. I have a Kenlow 2 speed fan, the water pump controller works on one of the fan speeds and I have a revotec controller in the top hose, set at a slightly higher cut in temperature ~95, though this never comes on.

Matt

Your fan controller should be controllable as in the temp it switches on and off at, as mentioned above the hysteresis setting. This is where the fan will come on at 90 but switch off at 88. Also most of the temp senders will not always be accurate, as the system voltage may alter the reading as well as the actual temperature in the engine bay effecting it. Then theres all the issues with things like bad earths. I have 5 temperature senders in the cooling system and they all read different. I just trust the one the ECU uses.

Circulation pump is the way forward. All a very simple part to fit and will work better than the fan when the engine is switched off. I have one that was about £30 this works along with a heat controller to switch it on and off .I set it to come on/off at 79 degrees. The pump draws about 1 amp while the controller uses almost nothing and is always on.




https://www.ebay.co.uk/itm/NTC-10K-D...8AAOSwvDpbDd~D

I fitted mine into the heater coolant circuit. The only issue now is that when the pump come on it pump coolant through the heater matrix. So your driving and suddenly the car get hot. I'm going to fit a diverter valve in a vain attempt to reduce the in-car heat

[bullstarz]

Just took my mine out to get some ice cream the shop is about 2 miles a but theres a better route (20 mile round trip) which i took. I wasnt going silly but lets just say enjoyed the A368. When finished i thought the engine would be hot but no. Looking at the Log data from the ECU on the way back the engine temp started at 76 and went up to 83 degrees,. looking at the data the temp hovered around 81-82 and the electric coolant pump only went on twice (set to go on 83 deg @ 25% and 88 deg 100% power). I know my cooling system is slightly larger then standard but threres no thermostat fitted but it still has the original water pump.



Yesterday i did a similar journey along the A388, the engine was hotter with same sort of driving/distance/time. The only thing i had altered between the two trips was the acceleration enrichment mixture. Yesterday was a bit on the lean side but today a slight too rich in places but this has made a big difference to the engine temp.


So i think everyone may be missing the point you should be looking in to the reason the fan has come on in the first place.

* the speed is in KPH not MPH

[RobinLegin]

The engine and gearbox were rebuilt just over a year ago. In addition the rad is a new 4 core rad. Generally the needle stays in the middle. The fan cuts in when the needle nudges to the right, which happens after a run at legal cruising speed and slowing down in general urban areas.

and the coolant is flushed through each year. No water in the V and the h/g are new.

[Seaking]

Took mine for a test run yesterday . We covered 140 miles on all different types of roads lanes ect. Some very steep hills twisty roads well a lot of East Devon back roads . Through into Dorset into and around Weymouth . Back via cerne Abbas Sherborne and home .My temp needle stayed mostly in the middle my electric fan only switched on a couple of times for a very short time .( No other fan on my car). As a Key worker travelling lots of miles every day . It just seemed the right thing to do with my Stag. Now back in the garage to take out radiator to fix a small weep that has appeared. Other wise all ok and I have at last finally got rid of my vibration at 7I mph. Plus and a extra
bonus I now have my Stag drivers suntan back lol .

[tvrgeek]

Of course, Federal cars with their retarded ignitions will run a lot hotter at idle.