Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Rad fan not coming on

1987 4/4.
My rad fan is not kicking in. I’ve checked the fan and it works. I think it’s probably the relay but I’ve looked under the dash and dont see it. Can anyone tell me exactly where it should be.

On my 1991 4/4 the relay is under the bonnet on the bulkhead.

Thanks Brownbaker. Not there on mine.

My 4/4 with the Ford CVH does not have a relay for the radiator fan and the wiring plan doesn't include one.
I spent a good amount of time this year rebuilding my loom and I am certain that neither the 1984 nor the 1988/1989 are completely correct.That being said - maybe a relay has been added at some point - maybe not.

The BSAU7 color code for the radiator fan is Black/Orange but in the 1984 loom Morgan used Black/Green as cable from the temperature switch to the raditator (located at the rear for the engine just below the distributor). On the picture below you will see a Black/Yellow cable (as the AutoSpark replacement loom I got was based on the 1988/1989 version and Morgan used Black/Yellow in this version.

Wiring Plan 1984
Wiring Plan 1988/1989

Also not in the diagram but found both in the orginial loom as well as the replacement is an inline fuse - close to the alternator. In the old loom this was coming as a brown cable from the starter - and was continued purple (which is correct according to the BSAU 7 color code) to the radiator.

I would try the following:
1) Double check in inline fuse of the radiator (you might have done this already as you write the radiator is working)
2) Check that the temperature sensor is cabled correctly and that the earth cable has good contact
3) Measure the connection on the Black/Green (or Black/yellow) cable from the temperature switch to the radiator.

If all if this is working - chances are that the temperature switch is not working correctly anymore.

Hope this helps.
Regards
Tim

Here a better picture off the switch in the Thermostat housing

When you say the fan is working I am assuming you connected it directly to battery source using both + & - connections? Have you tested the Earth/Positive connections to the fan separately for loose connections/faulty fuse relay? Start simple and build up.

Are you sure that the engine is really hot?
My temperature gauge shows 20 deg too high.
I also wondered why the fan is not kicking in and mounted a manual switch.
Last year I got me a thermo camera and now I know better;-)

Miklos

New switch fitted. Working fine although temp gauge shows it kicks in at about 120c.

Fans can draw quite a bit of current, but I guess the Otter switch is appropriately sized to operate well enough, however if it fails as they sometimes do, it can be handy to wire in a manual override switch...

The idea of the switch is that if the Otter switch fails at some inconvenient moment and the engine begins to overheat, you can flick the switch and cool things down a tad.

Pretty sure that instructions/diagram may be found on GoMoG in the workshop manual should you be interested in fitting an override switch..?

My mid 80`s +8 Otter switch maintains the water temp at circa 90deg C, though perhaps in general lean burn technology may have been introduced around the mid 80`s which required engines to run hotter to clean up on their emissions thus 120 deg may be entirely normal for your engine..?

Treat the temp gauge as an indicator, rather than a direct reading instrument