98 V70 Blower Motor Lubrication

[sleddriver]

I noticed recently that this blower wasn't putting out near the CFM it used to. At times, the fan speed would increase, but then decrease. As the sled is now in her "mature years", I figured the blower motor bushings needed a lube.

Extracting it was straight forward. The squirrel cage blower fits on the splined shaft and you'll need a 3-prong puller to remove it.

The motor would spin, but not easily, and it would no longer coast to a stop, but abruptly stop.

The rear motor cover is easily removed and four tabs hold the oil-wick cap + bushing in place. This was completely dry.

The front motor bushing is inaccessible. I began prying on whatever I could get ahold of, but little joy. Note the brushes are up front instead of the rear. There was A LOT of dark brown/black dust inside and covering the outside of the front. Not sure if this was from the brushes arching or what.

I sprayed in some alcohol brake cleaner to flush it out, then sprayed a bit of DeOxit red into the front when I could see the commutator. I did manage to open up a gap up front, so added some ND sewing machine oil in the crack.

I went to test the motor in the car. No joy. A resistance test between the two motor terminals indicated a short. Not sure how that happened. Perhaps I jarred the rotor out of the brushes and it shorted there?

Looks like I'll be QUICKLY obtaining a new one as it's baking in fajita flats here (104°F).

This motor has been in service since July 1997! 18yrs!! I'd say it's gone the distance as this motor is (very) rarely off here.

 

[Nick1994]

Does the car have a cabin filter? If so it might be plugged causing bad air flow. Also see if you can see the evaporator. Could be plugged up too. I got a new blower motor from O'Reilly Auto Parts when I had my Chevy truck, worked great.

 

[Quest]

You've made the royal mistake RE: introducing oily substance to where the commutator meets the brushes, and that pretty much spells the end of the service life IMO.

those graphite impregnated brushes cannot come into contact with any form of contact cleaner, period. When they are worn, they shall be replaced with same type and must be grease-free and dry.

Also: same applies to the commutator side.

Most of these brush type motors run on sintered bronze bushings, and given it's time, it reaches the end of finite service life when you start hearing squeaks (oil dries up and gummed up).

Also: because these motors run on bushings and not bearings, when mounted vertically (shaft vertical), the bushing may not spin smoothly like ball bearing type does (due to additional friction imposed on the nylon or graphite friction discs).

Bottomline: you need to get a new replacement units.

Q.

 

[Brad_C]

Originally Posted By: sleddriver

I went to test the motor in the car. No joy. A resistance test between the two motor terminals indicated a short. Not sure how that happened. Perhaps I jarred the rotor out of the brushes and it shorted there?


I hope I'm not teaching you to suck eggs, but the entire motor will have less resistance from terminal to terminal than one of your meter leads, let alone both. Unless you are using a good four wire milliohm meter, it's going to measure a short in any case.

Having re-built a number of Volvo blower motors, my guess is your attack of the front bell has damaged, dislodged or otherwise jammed one of the brushes. What you *should* have done worked plenty of light machine oil (I use a mix of Amsoil ISO46 & ISO100 compressor oil) into the bushes and re-saturated the felt-rings. You can do that with a syringe and patience without disassembling the motor, but it's a multi-day affair.

My experience has been periodic maintenance of the bushes by way of lubrication will make the bearings outlast the brushes, whereas most motors fail from hogging out the bushes due to the lubrication drying up.

I'm just finishing the re-build of a 740 blower where I've replaced the bushes with ball bearings. I have no idea how that'll turn out but I had the motor and bearings floating around, so it's been a bit of fun. The motor came out of a wreck and at 29 years old the bushes were shagged.

 

[sleddriver]

Originally Posted By: Quest
You've made the royal mistake RE: introducing oily substance to where the commutator meets the brushes, and that pretty much spells the end of the service life IMO.

those graphite impregnated brushes cannot come into contact with any form of contact cleaner, period. When they are worn, they shall be replaced with same type and must be grease-free and dry.

Also: same applies to the commutator side.

Most of these brush type motors run on sintered bronze bushings, and given it's time, it reaches the end of finite service life when you start hearing squeaks (oil dries up and gummed up).

Also: because these motors run on bushings and not bearings, when mounted vertically (shaft vertical), the bushing may not spin smoothly like ball bearing type does (due to additional friction imposed on the nylon or graphite friction discs).

Bottomline: you need to get a new replacement units.

Q.


I didn't get any of the bushing oil on the brushes. I've used DeOxit on brushes before with no issues.

This motor mounts horizontal.

 

[Quest]

deoxit cannot be used in commutator/motor brushes, period.

It will contaminate the contact and the brush, thus ruining them.

You should have used CRC QD contact cleaner instead.

Q.

 

[sleddriver]

Originally Posted By: Brad_C
Originally Posted By: sleddriver

I went to test the motor in the car. No joy. A resistance test between the two motor terminals indicated a short. Not sure how that happened. Perhaps I jarred the rotor out of the brushes and it shorted there?


I hope I'm not teaching you to suck eggs, but the entire motor will have less resistance from terminal to terminal than one of your meter leads, let alone both. Unless you are using a good four wire milliohm meter, it's going to measure a short in any case.
Good point. Didn't spin though. Might have blown an ECC fuse.

Quote:
Having re-built a number of Volvo blower motors, my guess is your attack of the front bell has damaged, dislodged or otherwise jammed one of the brushes. What you *should* have done worked plenty of light machine oil (I use a mix of Amsoil ISO46 & ISO100 compressor oil) into the bushes and re-saturated the felt-rings. You can do that with a syringe and patience without disassembling the motor, but it's a multi-day affair.

I've gone on and removed the cylindrical metal tube, holding the four magnets. I now have access to the four brushes. There's about 5/16" left. None of them are stuck. The commutator end closest to the front bushing has a reduced dia compared to the end closest to the coil! Quite odd that! Not sure how that could have worn away and still worked.

I was tempted to drill a very tiny hole in the front bushing wick housing so I could insert a syringe needle in there and inject some oil. I was concerned about introducing metal shavings though. This would have been a better idea than prying on it though. C'est la vie...



Quote:
I'm just finishing the re-build of a 740 blower where I've replaced the bushes with ball bearings.
Completely different animal. These don't even look like the motors in the 850. Those you could more easily get to the front bushings & brushes. This motor was made by Delco in the USA.

This one was soon to be Tango Uniform. Good thing I pulled it before it died in a whif of ozone, quit working and left me with no A/C on a trip when it's 104°F with a solar index of 124°F. I lost the A/C in another car while driving across the deserts of southern Utah and man was I glad to get up into the mountains of western Colorado! No fun at all.

G'day!

 

[Brad_C]

Originally Posted By: sleddriver

Quote:
I'm just finishing the re-build of a 740 blower where I've replaced the bushes with ball bearings.
Completely different animal. These don't even look like the motors in the 850. Those you could more easily get to the front bushings & brushes. This motor was made by Delco in the USA.


Oddly enough this is a Delco also. I acknowledge they are different. The 240 horizontal motor is different again, but a brushed DC motor with sleeved bushes is a brushed DC motor with sleeved bushes. Some are just harder to open than others. The wear on the commutator is pretty normal for a high miles unit. If they are a little worn or grooved and the brushes are still serviceable I chuck them up in the lathe and true them up but it sounds like yours was toast as the brushes are pretty short.

I don't mind drilling a tiny hole to put oil into the felt. I've got a Proxxon drill press with some 0.8mm (I think that's about 1/32") carbide drills that are ideal for that. Any swarf that makes it through the hole gets trapped in the felt, but at 8000RRM the drill bits tend to eject most of it.

I'm one of those guys that will re-build something until there is nothing left to re-build rather than toss and replace. I see it as a challenge rather than a practical saving. You need to know when to cut your losses though.

 

[sleddriver]

Just waiting to dinner (!) to heat up for a wee bite them off to sleep. Didn't realize the time had really gotten away from me. It happens when the Diver-Down flag is deployed...

I don't understand how a commutator could wear like that...unless the constant sparking actually vaporizes bits of metal. Might work if they're made of solid copper. It would also appear that the brushes & commutator were not correctly lined up for some reason, but rather offset. Leading to this weird-wear appearance. Amazing it lasted this long, given that.

A tiny hole would have been preferrable to cranking on it. No doubt. My bad. I have a whole set of tiny carbide bits as well + a drill press.

Re: Rebuild/fix/modify/adjust/etc. Me too. I do have an inquisitive mind and restless hands. I've been taking things apart since I was 4 or so, when I began dissasembling my toys...

It IS quite a challenge! Indeed! I like a good challenge and diving into something unfamiliar. "Getting our heads into new and different things is what it's all about" says the card showing a woman with an empty cookie jar upside down on her head. I agree...

 

[HerrStig]

Originally Posted By: Quest
deoxit cannot be used in commutator/motor brushes, period.

It will contaminate the contact and the brush, thus ruining them.

You should have used CRC QD contact cleaner instead.

Q.
DeOxit is a very GOOD contact cleaner.

 

[Brad_C]

Originally Posted By: HerrStig
Originally Posted By: Quest
deoxit cannot be used in commutator/motor brushes, period.

It will contaminate the contact and the brush, thus ruining them.

You should have used CRC QD contact cleaner instead.

Q.
DeOxit is a very GOOD contact cleaner.


Yes it is. It's just a [censored] commutator/brushes cleaner because it leaves a residue. Brushes & commutators don't need de-oxidising, so it's the wrong tool for the job.

 

[sleddriver]

UPDATE:

S U C C E S S ! I was misled by another connector that needed connecting in order to power the ECC & blower. After this, I drilled a small oil hole in the bushing wick cover and used a wood glue syringe to squeeze in some oil.

I also pulled the speed control xnstr and cleaned up the l o n g heatsink. Removed a bit of fuzz from the evaporator, then sprayed it with a healthy coat of TuffStuff. I'll let the condesation rinse it off.

The blower was coated in a very, very fine gray/black dirt and persisted despite spraying it with TS and allowing it to work for 10min. So I had to swab each blade fore and aft to clean it.

Reinstalled everything and fired her up. Amazing amount of CFM now! I actually have a top end now. It blows even more forceful on RECIRC. This was definitely worth the time as a new motor is about $225.

Sure is a lot of hate here re: Deoxit. No worries here. It worked fine.

 

[Brad_C]

Congratulations. A win is always a real score.

No hate for Deoxit at all. I have 3 of their products in various concentrations and containers. It's a great product for what it is designed to do, it's just not the right tool for cleaning a commutator and brushes. You'll probably get away with it, but in future using a cleaner like CRC CO Cleaner that does not leave a film is a better product to use.

I get old carby cleaner cans, load them with absolute isopropyl alcohol and gas them up with butane as a propellant. That makes a great cleaner/washer.

 

[sleddriver]

Thanks! Blows air like it was new!

You two were pounding on me pretty hard about Deoxit! Caig even recommends soaking motor brushes in it overnight! Look it up.

How do you load up an empty carby can? Never thought of that. I could do this with my airbrush though...

 

[Brad_C]

Originally Posted By: sleddriver

How do you load up an empty carby can? Never thought of that. I could do this with my airbrush though...


I made a little brass adapter. I suck it dry with a pneumatic vacuum pump and then it just draws the isopropyl in with the vacuum. Dump in a hundred or so grams of Butane and it's done. Rather than vacuum you can force it in using compressed air, but I had the vacuum setup anyway for something else.

You don't want to suck on the cans too hard as I've had some collapse, but about 12-14" Hg does the job. Makes sure the remaining carby cleaner is out also as most of the residue boils off.

I've got all the components to make my own carby cleaner too (Toluene, Acetone & Methanol mainly) but it eats the rubber in my home made adapter, so I've not got around to coming up with a way of getting it back in the can. Makes a good paint stripper too.