radiator fan

[califkid_66]

what could cause my radiator fan to runs slow
was running fine when first started tested it with the switch inside the car then after 20 miles i stopped motor was hot and fan was really slow turned the switch on still was slow
i have a otter switch on the rad and manuel switch in the car i suspect maybe the relay come hot or when fan motor gets hot looses power i did run the fan directly on battery was running fine but was cold
any suggestions thanks

[jbcollier]

Original rad fan?

[jbcollier]

Jump it with a separate ground and power.

Still runs poor?

- it's the fan motor itself.  Original S2 cooling fans are Renault 16 rad fans wired backwards.  This means the fan blade runs backwards and does not blow as much air as it could suck.  I would not repair an original S1/2 rad fan.  Just replace it with something better.


- runs great?  Try running with the factory power or ground and jump the other.  Now you know whether you have a ground or power issue.  Trace the circuit back to resolve the issue.

[califkid_66]

yes it is original fan and it’s the negative that is controling the fan but it used to run fast and now it’s really slow  im just trying to figure out why
i know there’s been discussions on different fans but i don’t know the specs like cfm if i decide to change i would probably put a slim fan
but i want to find what the problem is on this one

[califkid_66]

ok just figured out part of the problem tested the motor yesterday was running good when i put it back in the two wires from motor a black and a red well black goes on positive and red on negative to make it push instead of pull by mixing the wires when it was hot the fan was running pull
now it’s cooling the car but i was turning on and off the switch one time it didn’t run i turned the fan a little by hand and it started ok it seems to have a spot where when it stops the power doesn’t get through

[jbcollier]

Nice diagnosing.

In your initial post you say "motor was hot".  Do you mean the rad fan motor?  Or, the engine was running hot?

[califkid_66]

both were hot the rad motor was pulling heat toward it preventing air to flow through when driving so the engine was running a little hotter than usual my next step is im going open the fan motor to see the condition inside and what causes the dead spot maybe brushes are pretty worn ill find out when i open it

[jbcollier]

Repair by all means but, given the stock fan blade runs "backwards", it is well worth replacing with a proper hi-flow pusher fan.

[califkid_66]

little update put a new 160 thermostat the temperature was always 90 and less engine runs great
the fan doesn’t really need to turn on it’s getting cooler up north i was in my garage decided to turn on the fan manually to make sure it was ok it didn’t work put power directly to it didn’t move so i took it apart found broken rusted springs so the brush was not touching the parts were dirty and rusted i cleaned it up just need a new spring and it’s gonna be all good

[JNS]

Hi,
My fan stopped working (see earlier post), I took it to bits and had the same problem- the springs had rusted to nothing so the bushes weren't pressed against the motor windings. I took the springs from an old Black & Decker powerfile and popped them in. Seems to work fine now.
These motors are easily acessable and it was an easy fix. They don't seem particularly watertight though so I've assembled with a smear of silicone around the joins.
Jeff

[SilverBeast]

Have you got the fan motor weather protection shield fitted as per Lotus bulletin #73/13 here
 http://www.lotus-europa.com/manuals/index.htm#sbulletins

EDIT: typos - 3 times!

[Sandyman]

Great link! Thanks

[califkid_66]

just found another source for the spring i always keep the old parts
there’s a spring in the voltage regulator mine was not working anymore got a new one and found this in the old one