[Mgs] Fan Relay fried...

PaulHunt73 paulhunt73 at virginmedia.com
Tue May 21 05:16:51 MDT 2013


Yes it's a bad connection, but highly unlikely to be a bad ground.

Any bad connection reduces the amount of current that can flow, and in the 
process a voltage is developed across the bad connection, and hence heat is 
developed where heat would not normally exist.  That heat can cause damage, 
but it would have to be in a high-current circuit to do so.  The only earth 
connection in the vicinity of the relay is for its winding, which only takes 
a very small current, so any bad connection in the winding circuit is only 
likely to affect whether the relay operates or not, not cause heat damage.

The bad connection is likely to be in the fan circuit, i.e. the 12v supply 
spade at the relay, the relay contact itself, or the relay spade that then 
supplies the fan motor.  If it is the insulation board that carries the 
spade that shows heat damage then almost certainly it is the relay contact 
that has gone high-resistance, I've replaced one myself (on a UK V8) for 
that reason.  The relay needs to be replaced, but you should check the 
condition of the wiring to the relay spades.  If that is showing heat damage 
it may have been from a bad connection between wiring connector and spade, 
in which case the spade will need to be replaced and maybe the wiring cut 
back and pieced out.

But you have a non-standard setup anyway.  From September 76 North American 
MGBs had twin cooling fans as standard, operated directly from a 
thermostatic switch in the header tank of the radiator and no relay, unlike 
the UK V8 which did use a relay.

PaulH.

----- Original Message ----- 
> I have discovered that the relay controlling the fan fried.  It still 
> functions, but the wire coming out of the bottom is nearly burned off.


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