Electric fan issues

[Karlos]

Those temperatures seem very high to me especially as you said you have no thermostat. Have you got a restrictor plate in place of the stat so that the coolant flow is correct?

It also sounds like the rad is not performing well.

[GrahamFountain]

No restrictor plate. The point of taking the thermostat out was to maximize flow and reduce the higher temperatures, though I acknowledge it does that mostly by evening them out. That may account for the relatively small drop across the rad. I agree that the eveidence suggests its the rad that limiting the system.

On the basis that you reckon these temperatures a bit high, as do I, how have you measured them yourself?

Graham

[Karlos]

The basis of my reckoning was your own figures and experience of running without a stat on a previously owned Dolomite. Back in the late 1980's access to measuring equipment was limited. When running without the stat the engine never got to "normal" running temp, but it seems yours does, different cars I know but the principle is the same. I view the cooling systems as pretty much the same configuration across a 16v and a 4v slant.

[sprint95m]

There is a lot wrong here I'm afraid.

With the thermostat removed the coolant won't ever be circulated properly
and on a moving car the temperature gauge won't register above the lowest mark.


Using an 88 degree thermostat I never did get the electric fan to come on (95 degree thermoswitch)….
the bottom hose should be noticeably cooler than the hot LH hose.


Does the heater work?


Ian.

[gmsclassics]

Maybe I've misunderstood but are you really running a Sprint engine with the thermostat removed? This will result in a lot of coolant being recirculated around the engine and only some passing through the radiator and the engine getting too hot as a result. No fan will compensate for that. The reading on the original gauge will also give an inaccurate reflection of what is going on. Leaving the thermostat out for an extended period (or using the incorrect type without the 'foot') will cause damage to the engine. The issues you mention about running rough may be a result of high internal engine temperatures. If you trying to determine temperatures, the IR temp reader is the only reliable source.

I stick to an 82 degree thermostat (check it if it is an old one). The theory is then that whatever sensor you are using to control the fan should come on at around 92-97 and go off at about 87. You should then be able to drive normally on the open road without the fan on, but it will come on quite soon after stopping or slowing right down in heavy traffic. Depending on ambient temperature it may stay on a while whilst stationary or cycle on and off until you get going and resume a natural flow of air through the radiator. As far as the fan is concerned, open the bonnet and put your hand between the fan and the engine. If you feel the flow of hot air, the fan is doing what it should.

On both my road cars, I now use a full flow fan controller that is infinitely adjustable and works extremely well. Maybe not the cheapest, but very good.
http://www.revotec.com/acatalog/Electro ... tting.html

I also have this and my fan wired through a NON ignition circuit so that the fan will continue to cool after the ignition is switched off.

The Sprint radiator is I believe a 3 core, whereas the 1850 and others are two core. I suspect over time some Sprints have been fitted with incorrectly re-cored radiators. On mine the Sprint core is as thick as the radiator frame, whereas a 'Dolomite' one I have is noticeably thinner. Otherwise there are various Saab, Porsche and other radiators that have successfully been used as substitutes and a search on this forum should bring those up for you.

Geoff

PS Photo of the correct thermostat, cold on the right and hot on the left - showing how the foot extends blocking off the re-circulation of the water in the engine

IMG_0224A.JPG (170.67 KiB) Viewed 560 times

[MIG Wielder]

No restrictor plate. The point of taking the thermostat out was to maximize flow and reduce the higher temperatures, though I acknowledge it does that mostly by evening them out. That may account for the relatively small drop across the rad. I agree that the eveidence suggests its the rad that limiting the system.

On the basis that you reckon these temperatures a bit high, as do I, how have you measured them yourself?

Graham

I have done some I.R. temp; measurements on my 1850 on the temperatures on the LHS, the RHS of the radiator and at the thermostat housing. There is a fair old drop in temperature across the rad; One difference though is that I'm using Evan's Waterless Coolant so I would expect the temperature drop with standard anti-freeze to be rather higher.
This is with the outside temp; at 15 deg C., the temp; gauge reading 1/2 = 82 deg C at idle with the engine running.
L.H.S. rad = 80.3 Deg C
R.H.S rad; = 56.4 degC
Thermostat housing = 74.2 deg C. The reason that this indicated lower than the gauge is due to the emissivity of the housing being bright aluminium rather than the black of the rad; side tanks.

[GrahamFountain]

There is a lot wrong here I'm afraid.
With the thermostat removed the coolant won't ever be circulated properly and on a moving car the temperature gauge won't register above the lowest mark.

I agree that's what should happen where the rad works and the system is able to easily dissipate the heat the engine is generating, i.e. can do so at a low temperature.

"Using an 88 degree thermostat I never did get the electric fan to come on (95 degree thermoswitch)…."

That seems surprising. With the car stopped for long enough and the fan off, the system temperature will go up to nearly the same level, whether there's a thermostat in or not. I take it you have a light in parallel with the fan?

"the bottom hose should be noticeably cooler than the hot LH hose"

Again, it should be, if the rad works. However, as the temperature difference across the rad increases for reducing coolant flow, too big a drop could be worrying given everything else is ok.

But remember that increased coolant flow reduces the temperature difference across the rad by bringing both the top and bottom temperatures closer to the average, i.e. it reduces the top temperature as well as raising the lower. Taking the thermostat out will give more flow than an open thermostat, and reduce the top temperature in that condition. That will increase the time before the fan comes on when I stop after driving, and reduce the time it takes for the fan to go off after I set off. Perhaps the effect is small, but it's all I can do until I sort the rad out.

"Does the heater work?"

Yes, the heater works very well and sustains a good heat output with the blower on. That also adds to the conclusion that it's not the pump that's the problem. And the warm-up test excludes the fan, and the thermometer shows the fan switch is switching at the right temperature. So, becasue the warm-up tests gives a bit of a short a time for the fan to come on, means the problem is squarely with the rad.

Graham