Oiling a bearing.

[Dave Plowman (News)]

The rear wiper motor on the old car failed in a cloud of smoke the other day. The motor had been replaced a few years ago with a NOS one, so not had that much use.

It's a very easy thing to strip down being an oldish design, and on doing so obvious the motor had seized. And seemed to be the bearing on the far end of the motor from the brushes. It is a self aligning plain bearing - with a single ball the middle of the shaft to take the thrust.

A new motor isn't a vast price, but since it will be from the same NOS source, may well have dried out in storage of some 30 years.

So to the question. Is there a best oil to use for this, and how to soak the bearing bush? I'm assuming it is a porous type which soaks up oil.

The other end of the motor goes into the gearbox. Which has grease in it. Perhaps some of that finds its way into the front motor bearing, as that seemed OK.

[The Other Mike]

IIRC the original 1960's BMC and maybe Haynes manuals had the instructions for reimpregnating the end bearings in Lucas starter motors / dynamos and maybe wiper motors

Plain oil maybe 30 weight, drop in the bearing heat for a few hours at maybe 100 deg C and maybe leave overnight. But i'll admit most of that is a guess on what i'd do :)

[Peter Parry]

Generally any light oil should do. ISO VG (SAE 30) is the oil used to impregnate Oilite bearings during manufacture.

The best way is to get a discarded fridge compressor in working order and a fairly robust glass jar with a tin lid. Jam jar is usually OK.

Connect up the compressor and find which pipe is out and which in. To the jam jar lid solder (soft solder is fine) a piece of metal tube of same/similar OD as the fridge compressor inlet tube. Use some reinforced plastic tube to connect the jar lid to the compressor.

Try to clean as much old oil out by baking the bearing at 200degC (domestic oven) for half an hour or so.

Part fill the jam jar with warm light oil, place the bearing in the oils so it is fully submerged, fit lid to jar and turn on compressor to extract air. You will see bubbles rising from the bearing material. Hold vacuum until bubbles stop, release, wait 5 mins and repeat cycle several times. On the last cycle leave the bearing in the oil for an hour after finally releasing the vacuum.

Glass jars are fine under vacuum but (obviously) not pressure. The fridge compressor makes a fine vacuum pumps and no pressure switch is required as the high pressure outlet is simply open to air.

[Harry Bloomfield]

The Other Mike presented the following explanation :

I would add to that, soaking the bearing in petrol overnight, to dissolve out the existing lub, before allowing to dry and then re-lubing..

[The Natural Philosopher]

Lot of experienc ogf this on model motors: It its phosphor bronze plain bearing really any light machine oil will do

3 in 1

You can do the 'heat it and soak it' and it will last longer that way, but just OILING it is good for a year usually

[harry]

[tabbypurr]

the oil used in modern fridges seizes the compressor if exposed to the air. The first thing you need to do is flush it out. Also be aware that release of some refrigerants is a offence.

The oil to use is ATF. It's the best unseizing stuff there is. If you need something thinner it could be mixed with light mineral oil etc.

NT

[Rob Morley]

Did you clean and re-grease the gearbox when you fitted the motor? I've had wipers completely seize from hardened grease in the gearbox, wonder if that might have contributed to your motor failure.

[FMurtz]

We used to put the bearing between thumb and forefinger full of oil and squeeze, you can see the oil coming out of the pores of the bearing.