Stags in the heat

[MikeParker]

You wouldn’t get flow in the bottom hose either until the thermostat opens. Top hose is temperature of coolant coming out of the engine isn’t that more important? Maybe that’s why they put the thermostat on the top hose?

Terry,
I think my point is that normally you only want the fan to come on when the natural air flow through the rad is not sufficient to cool the water. That can only be tested by measuring the output flow temperature. The input temperature to the rad (top hose) should, ideally be constant and be at the opening temperature of the thermostat. So you can't know by measuring the top hose temp. whether the fan should be on or not.

[trunt]

Terry,
I think my point is that normally you only want the fan to come on when the natural air flow through the rad is not sufficient to cool the water. That can only be tested by measuring the output flow temperature. The input temperature to the rad (top hose) should, ideally be constant and be at the opening temperature of the thermostat. So you can't know by measuring the top hose temp. whether the fan should be on or not.

I see what you are thinking but as I feel that the fan is there to maintain the engine temperature rather than the radiator temperature I’ll leave mine in the conventional top hose position.

[MikeParker]

I see what you are thinking but as I feel that the fan is there to maintain the engine temperature rather than the radiator temperature I’ll leave mine in the conventional top hose position.

I am sure it won't do any harm. You could set the temperature some way above the thermostat opening temperature, so that it only comes on when the engine starts to over-heat. I was just being a bit theorist about it!

[RobinLegin]

I’ve been playing around with the setting for the Revotek fan. I now have it coming on at about 75 / 80 degrees. The concern though is that the temperature gauge is now moving towards the red - but not in the red. This is noticeable after a dash down our local duel carriageway. At that speed I don’t think the fan is doing much good. Like sailing with a spinning propeller, it actually slows you down.
will wash daily drivers after lunch before a blanket housepipe ban comes. Than will do further road testing. I suspect I might be looking at Dave’s auxiliary cooling system.

[Wheelz]

The only concern is my Revotec fan which comes on at about 58 degrees C and then takes ages to switch off after engine is shut down. I keep adjusting the sensor on the top hose, and so far the fan now runs for 4 - 5 minutes after shut off. Temperature reading at top hose is 60 degreesC.
what should be thee right temp for the Revotec to kick in? I don’t wish to flatten the battery keeping cool.

If the fan kicks in before the thermostat opens, you would be just wasting battery power because there would be no coolant flow, hence no cooling effect. Also overcooling the engine leads to poor fuel efficiency, increased wear etc. Ideally the fan should come on at the same temp as the thermostat, ie 88C.

[richardthestag]

I’ve been playing around with the setting for the Revotek fan. I now have it coming on at about 75 / 80 degrees. The concern though is that the temperature gauge is now moving towards the red - but not in the red. This is noticeable after a dash down our local duel carriageway. At that speed I don’t think the fan is doing much good. Like sailing with a spinning propeller, it actually slows you down.
will wash daily drivers after lunch before a blanket housepipe ban comes. Than will do further road testing. I suspect I might be looking at Dave’s auxiliary cooling system.

First thing that I would do would be to check that the Gauge is actually reading correctly. common fault on the stag is that the voltage stabiliser is not earthed and as a result the Gauge will over read.

Next up check you've got the correct thermostat fitted, if you have a mark 2 stag or mk2 inlet manifold it needs thermostat with the foot. The wrong thermostat will cause the engine to run hot.

If you have no thermostat fitted and a standard stag v8 cooling system it will run hot.

Depending on thermostat that you have fitted I would adjust your fan control to start a higher temperature.

They always run on, so for instance if you start your fan to run at 80ﾟ it will run until the cooling system is back down to 75

[Tdm]

Living in Texas, the temp fluctuates from 10°F to 110+°F. It's looking like we will have 24 days this July over 100°F. The record is 30 days.

I have no issues driving the Stag in the summer time. Having StagDad's belt driven water pump brings a little piece of mind, but on days like today (it's 111°F in the shade!, 43.8°C in your money) it's just too hot for anything. Even my pool water will be getting up to 90°F (32°C) this afternoon. It's just nasty.

I have no problems with the outside Temperature in Tenerife when it can get up to 50 degrees Centrigrade in high Summer.
Doesn't stop me driving the car, it is just me that is sweating, whilst the engine temperature remains normal.

[flying farmer]

I have just returned from a week in the Annecy region of France, 1936 miles in the Stag over a 10 day period, 865 miles of that was done yesterday (19 hours door to door, just as well it has comfy seats)!

While we were there the temp was in the 34-38 degree C region. Didn't trouble the Stag in the slightest, though the occupants were wilting a little!

The cooling set up is electric fan only, TR6 front spoiler, Tony Hart Supergill radiator and Davies Craig EWP80 Electric water pump.

I use a Mk1 ceramic ignition ballast resistor in the pump feed so it runs constantly on 8V and an 82 degree thermostat. I did actually fit a booster circuit before I went so I could bypass the resistor and give the pump full voltage.

Some observations over the past week. Until the temp gets well into the 30's the temp needle sits a few degrees to the cool side of central, well into the high 30's it is slightly above central. Stuck in traffic and it goes about a needle width higher then the cooling fan comes on (1st speed on the 2 speed Kenlowe).
Climbing up to the Col de la Forclaz to go Paragliding is all 2nd and 3rd gear stuff round the hairpin bends, not much forward speed for airflow so the temp rises to the fan cut in point but no higher. Since I had fitted the booster switch to the electric pump I tried it out. No difference whatsoever.

What this shows is that airflow through the rad is the crucial matter here, pumping the water round faster doesn't help. This doesn't entirely surprise me. Last time we did this trip it had the old leaky rad and a cooling system full of radweld and no booster on the pump. In the same conditions it used to get 3/4 of the way up the gauge and the second speed of the Kenlowe would come on. The new radiator works better, no surprises there then!

With an original pump the pump output will obviously depend on engine rpm, the electric pump output is the same regardless of rpm. It is not possible to operate the engine at a high enough power output on the road to challenge the pumping capacity of the electric pump (if you want to keep your licence). Even towing my half ton trailer tent at 70mph in those temperatures will not get the coolant to the fan switch on temperature. Can't say I ever had any problems with a well set up original pump (6 or 12 vane) back in the days before I got fed up with their reliability

I must point out that having the engine set up correctly is going to make a big difference to the heat output of the engine, if you burn the fuel inefficiently you will use more and generate more heat. Someone on here mentioned this earlier. My Stag was achieving 30mpg on E10 petrol (despite being fitted with fast road cams) towing my trailer tent at a steady 60mph but it does have the advantage of full engine management.
Neil