How would you press this shaft out?

Taymar · Apr 30, 2020

Hi all,

I'm struggling with how to proceed on a repair to this automotive electric cooling fan. (bearing replacement).

The fan itself is molded plastic, and has a steel sleeve embedded into it.

The motor shaft passes through the front housing & bearing, then is press fit into this sleeve.

I need to press the shaft out of the fan, but can't figure out any good way to support the motor side, except on the plastic ring outside the motor housing. I'm concerned that it'll deform or crack the plastic fan before the shaft comes out though.

If I try and press the front housing against the fan, it doesn't want to sit flat, and rocks slightly.

Totally get that this is meant to be a non-serviceable part. It's horrifically expensive to replace so I'd like to at least try - the bearings seem to be a standard size.

I have access to a small lathe/mill, a press, various pullers and standard mechanic's tools.

Thanks very much for any ideas or suggestions.

I've tried to draw out the problem, and attached a couple of photos:

Approximate drawing:

rear of fan motor unit

face of fan showing shaft and sleeve

Scottl · Apr 30, 2020

I think I would rig up something like a three jaw puller attached to the stator housing with screws AND nuts on the back side and see if I could pull the housing clear of the shaft. A partial turn of the center screw against the shaft would give you a feel as to whether it could be pulled without excessive force.

The nuts on the back side of the housing "ears" are to prevent pulling the threads from the thin metal.

I wouldn't attempt to touch the plastic fan for fear of warping it.

carlherrnstein · Apr 30, 2020

I think that is what is called a non-serviceable component. If the bearing is bad the whole thing is bad.

Terry Keeley · Apr 30, 2020

Turn up/find something (outer bearing race) the same diameter as that steel housing part where the screws are?

Curious, what car's it for?

Peter from Holland · Apr 30, 2020

Drill and tap 2 holes in that steel sleeve (M3- M4 whatever size is possible )
Then take a piece of flat bar and drill 3 holes in it and tap the centre hole (M5 perhaps)
Bolt it on the sleeve and use a bolt in the middle to pull the sleeve with fan off
Classic way of doing it

Peter

dana gear · Apr 30, 2020

carlherrnstein said:
I think that is what is called a non-serviceable component. If the bearing is bad the whole thing is bad.

You can give it a try, worst case you end up replacing the motor/fan. That said most automotive electric fan units are not serviceable and are changed as a unit.....

muckalee · May 1, 2020

If your have equipment and skills. Drill out the shaft from fan end, use bit that is 0.200 inches or so . make new shaft.

crazygoat · May 1, 2020

Easiest way to do this is go to the junkyard and spend $15 for one. Problem solved.

timvercoe · May 1, 2020

Consider the possibility of removing the stator from the housing, and then see f that gives you any different access.

Taymar · May 1, 2020

Thank you all,

Was able to press it out undamaged by supporting the stator housing.

To answer a couple of the questions - it's from a WK2 jeep grand cherokee 5.7 w/HD cooling package. I'd planned to simply buy a new fan but they're $550+. Auto parts store brand ones are still in the $400 range, and I didn't find many used for much under $300. I couldn't believe how much these things cost.

Quick question though - since it's been removed and reinstalled it'll presumably be slightly less snug of a fit. Should I consider tapping a LH thread and installing a small bolt and washer in the front of the shaft, or peening it with a punch to lock it in position?

The fan sleeve is only about 10mm long and the shaft it presses onto is 7mm diameter.

Thanks again so much for the help here, I'm jazzed to have got it pressed out without damage since it is indeed a non serviceable part.

Erich · May 1, 2020

Loctite green

Taymar · May 1, 2020

Thank you - I've never seen the green before (only red and blue).

Just to make sure I'm following, I'd need the green wicking threadlocker, and use it on the two press fitted parts? Before or after assembly?

Thanks a ton for any clarification.

Erich said:
Loctite green

crrmeyer · May 1, 2020

Erich said:
Loctite green

You need to be cautious with loctite thread lockers near plastic. I had a case where loctite was being used on metal in the proximity of plastic and the plastic cleaved like obsidian while you watched. Our material guru referred to it as "molecular unzipping".

Scottl · May 1, 2020

carlherrnstein said:
I think that is what is called a non-serviceable component. If the bearing is bad the whole thing is bad.

No such thing as a non-serviceable component. Some require quite a bit more "service" but as this is a machinist forum there is very little that can't be repaired with the right approach.

I see the OP has indeed pressed it out, proving my point.

PS: I've serviced trickier things than that, including several in situ vehicle repairs that normally would require serious disassembly.

richard newman · May 1, 2020

Scottl said:
No such thing as a non-serviceable component. Some require quite a bit more "service" but as this is a machinist forum there is very little that can't be repaired with the right approach.

I see the OP has indeed pressed it out, proving my point.

PS: I've serviced trickier things than that, including several in situ vehicle repairs that normally would require serious disassembly.

Absolutely! Sure it's more efficient to just buy a replacement, but some of us have more time than money, or enjoy a challenge like this - using skill and ingenuity instead of a credit card. And then sometimes stuff breaks down friday afternoon and monday is too long to wait, or the parts just aren't available anymore.

Terry Keeley · May 1, 2020

How did it go back together? Was the fit still there? If so I wouldn't worry about it...

MattiJ · May 1, 2020

Taymar said:
Thank you - I've never seen the green before (only red and blue).

Just to make sure I'm following, I'd need the green wicking threadlocker, and use it on the two press fitted parts? Before or after assembly?

Thanks a ton for any clarification.

Erich was possibly referring to retaining compound. Almost same as thread locker but not.
"green" can be 603, 620, 638, 648 and few others. Most if not all of the green retaining compounds are high strength.
603 or 648 would be most suitable for this purpose(small gap or interference fit)

Taymar · May 1, 2020

Good question. I haven't reassembled it yet - waiting on the new bearings to arrive.

Terry Keeley said:
How did it go back together? Was the fit still there? If so I wouldn't worry about it...

Taymar · May 1, 2020

MattiJ said:
Erich was possibly referring to retaining compound. Almost same as thread locker but not.
"green" can be 603, 620, 638, 648 and few others. Most if not all of the green retaining compounds are high strength.
603 or 638 would be most suitable for this purpose(small gap or interference fit)

Ah, thank you very much!

Scottl · May 1, 2020

Be very sparing with the Loctite products on an electrical assembly. Odds are you won't need any anyway for something like that if nothing is scored or otherwise worn. Light press fit should be fine.

How would you press this shaft out?

Plastic

Diamond

Aluminum

Titanium

Diamond

Hot Rolled

Cast Iron

Stainless

Hot Rolled

Plastic

Hot Rolled

Plastic

Stainless

Diamond

Titanium

Titanium

Titanium

Plastic

Plastic

Diamond

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