No more viscous fans

[TahoeFerrari]

Just ditched the viscous fan on my '87 d/r 5spd spfi 3-door in favor of a left side electric (from an '82 EA81). Up to now, I've gotten up to 34-36mpg at 70-75mph (w/o A/C) on long trips, so it should be interesting to see what ditching the viscous fan does - if anything.

 

I've done the same dual fan setup on my '89 d/r 5spd spfi wagon. It gets around 31-32 on long haul highway trips but I've only had it a few months and am working to improve it.

 

So I now have fan systems similar to my old EA81 hatches. Left fan is controlled by A/C and right fan by radiator thermoswitch. Both also have manual switches. I've also got indicator lights on both fans so I can see how ofter they come on as well as switches to manually turn them on if necessary (dead thermoswitch!)..

 

Once I get some more data, I'm planning to post something about how often the fans run, specifics on the cooling systems, what they might have done mpg-wise, etc. Maybe in a few months after I've run both of them a few thousand miles. So far it's pretty interesting that without A/C on, the right fan (thermoswitched) almost never runs if I'm steadily moving at over about 30mph - even on 90+F degree days! I'm planning an 800 mile+ 75mph trip next week and I expect the temps to be mid 90s and maybe 100s so A/C will be running - should be interesting to see what happens.

[Subi81]

That is interesting. Did you use the stock thermoswitch? I have a set of 2 spal fans. While driving on the Highway yesterday 105 Deg F they were on almost all the time unless I was going down a big downhill. I have the stock thermoswitch, I think it activates at 199-207. When I switched to electric I noticed a little less drag when reving the engine. But never really looked at the MPG issue. I also have lights monted inside to indicate when the fans are on. Nothing like piece of mind.

[TahoeFerrari]

Yes, still have stock thermoswitch in both. Thermostats are not stock 192s, however. I put in 180's instead - both new with the fan mod.

 

In addition, since I wanted to have a clean starting point - and almost everything was out of the way - I pulled both radiators (aluminum finned of unknown age in the wagon from a JY '92 loyale and several year old copper finned in the 3-door that really should be replaced) and back flushed them and really straightened and cleaned the fins with a vacuum and then by blowing air and water through from the back side (be careful if you do this - especially if you have a copper-finned radiator that is turning pink - you can do a lot of damage with too much air or water pressure).

 

There was quite a bit of crud in both of them - feathers, grass, dust, dirt, and small stones. I've backflushed before but never pulled a radiator out to clean the fins. I think I might start doing it as a routine everytime I replace timing belts (every 60K) since everything will already be out of the way.

 

Maybe you shoud take a look at the front of your radiator - pretty easy to do by pulling the grill.

 

You didn't say if you were driving your turbo or not - both of mine are spfi. I would expect a turbo engine to create more heat, but not much at a like cruising speed. It takes only so much power to move at a certain speed so heat load should be pretty similar. Under acceleration / full power, though, the turbo is going to create a lot more heat I would think.

 

Forget the last - I just re-read your post and see that the GL is an '81 and thus not EA82 so you must be talking turbo.