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MG TD TF 1500 - Wiper Motor fusing

The MGTD wiper motor is on one of the two fused circuits in the car. However, as we all know, the fusing on the MG is minimal; and wiper motors are expensive to repair. What would you recommend for an inline fuse to protect just the wiper itself?
Geoffrey M Baker

I always go by this chart:

David Sheward

Thanks for the laugh Dave! :)
I do remember getting stopped once for a taillight and it was a blown fuse... the old tinfoil bubble gum wrapper worked a charm...
Geoffrey M Baker

Considering the size of the wire going to the wiper motor, I think that it would burn out long before the motor would. Cheers - Dave
David DuBois

This is totally off topic, but David Sheward's chart made me think about it. Back in the late 50's, a guy I worked with had a 48 chev for a work car. One bitter cold day when we got off work, he went out to find he had blown a fuse on his heater motor. Unable to find a fuse in his glove box, he found a 22 long rifle shell, being the same length as his blown fuse he put it in the inline fuse holder. He said it worked almost 1/2 way home, before it went off. Blew the fuse holder to pieces, and scared the s### out of him.
G Parker

G Parker, that guy almost qualified for a Darwin award!
Geoffrey M Baker

All I remember about the fuse block is when I lost my keys once - I put one of the fuses in the center.... between the two fuse holders and it make the ignition work. Fuse has to be a good one of cause, but it will get you home ... :)
Rod
R D Jones

Dave D. - Not necessarily so about burning up the wire before the wiper. The biggest cause of wiper failure is a stalled motor due to old hardened grease and too small a primary wire. The result is almost always an increase of current draw and a burned shunt winding on the armature. When that goes, the result is a tremendous loss of power by the motor.
Although the motor can draw a few amps, internally the armature windings are 30 gauge wire. It doesn't take much current to burn through those quickly.
I think the factory thinking on fusing was that if it is a circuit which isn't critical to the operation of the car, it doesn't need its own fuse. And if it IS absolutely essential (e.g. lights) it shouldn't be fused at all.
Lew Palmer

Dave D. - Not necessarily so about burning up the wire before the wiper. The biggest cause of wiper failure is a stalled motor due to old hardened grease and too small a primary wire. The result is almost always an increase of current draw and a burned shunt winding on the armature. When that goes, the result is a tremendous loss of power by the motor.
Although the motor can draw a few amps, internally the armature windings are 30 gauge wire. It doesn't take much current to burn through those quickly.
Lew Palmer

To return to the original question--although I've never measured the current, I'd expect 5 amps to be fine. If the fuse blows for no obvious reason, you can always increase it.

I don't think a fuse will protect the motor, though. If the fuse blows, there is either a short in the wiring to the motor, which won't hurt the motor, or the motor is already hosed. The purpose of the fuse is to protect the wiring and to prevent a fire if the motor dies. I guess you could say that a fuse could be used to prevent burning up the motor if it stalls. However, I'd suspect that it would be hard to find a fuse that won't blow when the motor is running normally but will blow if it stalls.

You might want to read my treatise on fusing:

http://www.nonlintec.com/sprite/electrical/
S Maas

This thread was discussed between 03/05/2014 and 06/05/2014

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