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OK tried that. Hot engine fan spun fairly freely when stopped. That is consistent with correct operation. The fan will only lock semisolid if the engine is hot enough to get the thermocouple at the front to engage and so lock the two plates inside.
Mine spins fairly freely after a run and engine up to full operating temp. I stopped the engine and gave it a flick with my hands. It turns over reasonably easily. I start the engine and get full blast of air coming back. Rolled up the newspaper ( Murdoch press has its uses ) and I cannot slow the fan down. So advice from another thread re the news paper seems sound.
After all is said and done I am now reasonably sure my issue was a thermostat from the start. I can think of no reason to re-install one. I will wait 'til winter and see if I get an over-cooling problem and re-asses. I will here swear never ever ever not ever to use Barr's leaks again. I will use pure de-ionized water without any treatment ( Glycol water soluble oil ) as my friend who runs a Merlin in his P-51 mustang does, in an effort to limit galvanic corrosion. ( I may even try a sacrificial anode) .
so far as lubrication of the water pump is concerned it does not rely on coolant for lubrication so far as I can see.
I will now overhaul my spare 4 litre as a standby given the ol 3.9 is a bit long in the tooth.
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I just got my New Aluminum radiator and Viscous fan coupling put in on my over heating 3.5 v8 on gas, WHAT A DIFFERENCE! had trouble putting the fan shroud back on so left off (yeah yeah I know bad bad bad) but I do mainly highway k's all country, its gone from sitting 3/4s the gauge to sitting between 1/4 to 1/2, The new coupling does not roar when cold, but the fan is audible when on the just hot side and the temp quickly drops.
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Finally pressured up the coolant system and put a boreoscope into numbers 1,7 2 and eight cylinders.
If the head is leaking into the coolant system these are the only cylinders water can get into. No water not even a slight sign of it. I know it is easier for gas to get out than for water to get in but a fully pressured system should produce at least a damp spot. :-/
hey :) Flemo do you think its the new radiator or the coupling?? did your coupling have any signs of unhappiness....weeping etc.
Ok run out of head gasket checks.
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Gina
As the thermostat provides flow regulation as well as temperature control, running fine without a thermostat fitted could be an indicator of a blockage somewhere in the system
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Shouldn't you replace the thermostat?
Sent from my GT-P5210 using AULRO mobile app
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Hmmm
Flow regulation??? the Tridon thermostats are more along the line of flow disruption and turbulence creators with the built in loveliness that failure means catastrophic overheating .
I can find no evidence of a blockage of any kind. The radiator inspects well using a boroscope internally and a torch and mirror externally. what goes in the top comes out the bottom very quickly and with apparent full flow.
The heads and block flow very well as does the return lines through the inlet manifold , heater and etc.
There is evidence of active corrosion that I will trial resolution using sacrificial anodes.
In Sydney the ambient temp this time of year is around 20C , The Disco comes up to temp in around eight minutes and stays put no ups no downs nailed just below the little wavy water thing on the gauge that's around four needle widths below half.
I will stick in a temp sensor and give a reading of what that is in deg C .
Thermostats are only required if the engine is overcool. Overheat and they open as far as they will and do no more. My engine is not overcool. I suppose that the thermo gets the engine up to temp a lot quicker...say three minutes instead of eight . If I was in very cold climate , snow and ice etc etc and overcooling was a problem ...well I would find a hi flo low turbulence thermostat and install it.
The viscous coupled fan acts as a thermostatic control as do the twin electric fans on the front of the radiator . -
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Yes after the coupling was off (was seized on badly) there looks to be some leakage from it, its spun up and roared when the car was cold, but could never hear the fan even when it was over 3/4's hot.
Had put a new water pump in and thermostat early last year to no effect, took the rover for a big run last night, Flogging it up hills and a 110km/h highway and some steep off road that used to get it up 3/4's in less then 2 minutes, the gauge did not go off half way AT ALL, in fact when running on the highway it went closer to a quarter. I noticed im getting better fuel economy too for some reason, so win all round.
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I can hear a "roar" (fan) at different times when engine is supposedly at running temp, usually when putting more load on i.e. going up a hill, accelerating, even worse when towing. Have turned motor off after driving for 1/2 an hour or more & can hand spin fan with 1 finger, is this right?
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check the vally cover for leaks.
try this.
drain the coolant, remove one of the small hoses, blank the fitting it came from and using regulated pressurised air run about 17psi of air into the system.
remove all the plugs and check for air coming out the pots. remove the inlet plenum and check for air coming out the trumpets.
put your bore-o-scope down under the inlet manifold you may have done the jacket there.
The reason you cant find the coolant is its a slow leak and is being "burnt" in the cylinders when the engine is running. It may also be the heater matrix inside the cab and you cant find the leak because its running out the AC drain where you're not looking for it. (and in the right positions the AC box can hold what seems like about 2l of liquid.
A leak down test on each cylinder on a warmed up engine is also more likely to help you find the leak if its a liner or head gasket.
