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MG MGB Technical - Windshield Wipers Died

I have a 1977 MGB with the two speed wiper motor. I never drive the car in the rain but living in Florida once in awhile you get caught in a shower. The wipers had been working no problem but half way through a sudden rain storm they quit. After they stopped working if you tried the wiper switch they would work once in awhile and then stop, work for a few minutes then stop until they are now completely dead. Same scenario with the windshield washer. Worked, then stopped. I have checked fuses and connections which all seem to be ok with no success. Can someone please walk me through a step by step process on determining what is wrong. I have done a lot of work on this car but I am by no means the mechanical gurus that many of you are so please explain how to go about the proper way to identify and fix this problem. Thanks.
JCH Hibbard

If the washers and wipers come and go together it is an intermittent connection in the green circuit. Normally one would expect this to be in the fusebox, but if the tachometer still works this won't be the case. However there are two green wires leading out from the fusebox, one feeds the washer motor, brake light switch, reverse light switch, manifold heater and the other feeds all the circuits inside the cabin including the wipers and tachometer, which tends to point back to the fusebox again as the only common link. Of course if the washers and wipers come and go independantly, you have two problems. Unfortunately the green circuits are a veritable tree of 4-way bullet connectors, any one of which could be making a bad connection. Short of the fault remaining on long enough to determine which other circuits have also failed, you can either go through every one of the dozens of conenctions checking they are clean and tight, or start driving around with a voltmeter connected to first one conenctor, then another, and so on until you track it down.
Paul Hunt 2

Thanks Paul. Most definitely not at the fuse box. The wipers are still not working and have not done so since the last time they quite. Today I was out for a ride and tried both the wipers and washer. The wipers remained dead but the washer motor did spray the windscreen so the peoblem seems to be independent from one another. I will start tracing the green wiring more closely and checking the bullet connections. Any further thoughts would be appreciated. Thanks again.
John Hibbard

Have you tested the electrical connections to the wiper motor? To the wiper switch? Loose and corroded connections can cause an intermittant failure. The switch itself may need to be disassembled, cleaned, and lubed with dielectric grease.
Time to get out the multimeter and a copy of the wiring diagram. You can make an enlarged copy of just the wiper circuit or the whole diagram at http://www.advanceautowire.com click on stock schematics.
Kimberly

Thanks Kimberly. Have tested at the switch but am having trouble getting to the motor connection itself. Looks like I have to remove the glove box to do so. Time allowed I will get to it later in the week and keep you posted. In the meantime I took advantage of your wiring schematic link, very useful thanks.
JCH Hibbard

On a 77 the green circuit chains from the fuse-box to a 6-way connector. Here one branch goes direct to the motor for parking. Another branch goes to a 4-way connector, and from there to the multi-way plug by the steering column for the wiper switch. Other branches from the 4-way go to the turn signals and the handbrake warning circuit, so if those are still working power must be *reaching* that 4-way at least. When the wipers quit did they stop in the middle of the glass, and did they park when you turned the switch off but then move no more? If so the supply to the motor itself is OK, and 4 out of the 5 conenctions in its connector, so I doubt the problem is there. But if they stopped, and didn't park, and are still stuck across the glass it could be the wiper motor connector or the ground brush.
Paul Hunt 2

Thanks again Paul. Each time they quit up until the final time when they would start no more they parked, They are now in the parked position and quite still.
JCH Hibbard

Tested all connections today and checked for corrosion, seems to be ok. While I was moving the motor around to get to the connection the wipers moved a bit then died again. I'm guessing maybe it's the motor itself. Anyone had any experience getting the motor out and back in on a 1977 B. I was able to see where the motor comes away from under the dash and bracket but what about the cable that feeds to the wipers? In short how the heck do you get it out of there!
John Hibbard

It's enough of a fiddle on a RHD tin-dash, I'd expect more problems on a LHD.

I've done this several times but can't quite remember the exact sequence of operations. Basically you remove the flat(ish) cover over the gears and crank from the motor, and you should be able to get the crank off (there may be a circlip somewhere) and that should allow you to slide the end of the rack tube out of the end of the gearbox housing.
Paul Hunt 2

This thread was discussed between 02/09/2007 and 09/09/2007

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