Water Pump Pulley Damage. WTF? w/ Pictures!

[Corvid]

The car is a 1991 Loyale, EA82 SPFI with AC, and the AC compressor is mounted inbetween the Alt and the PS Pump. 3 weeks ago, the bearings in the water pump gave up the ghost and it was flopping the clutch fan around and puking coolant. I replaced the Water Pump, Gasket, and Water Pipe O-ring with factory parts. Water pump was Subaru #21110aa026.

That water pump came without studs, but I've seen that before on correct water pumps, so I picked up some bolts and snugged it down.

 

Ran great for 3 weeks, then started making terrible noises. I opened it up today, and found 4 tight fan bolts, which have huge grooves worn through them now, and a water pump pulley that has beat its holes into ovals. FML.

 

I search quite a bit, and I'm tired and sick. Can someone please tell me why this would happen?

 

[WoodsWagon]

Bolts were too long and bottomed out in the threads, and felt tight, but weren't actually clamping the pulley. More washers, shorter bolts, or the correct stud and nut combo are your options. Why didn't you reuse the studs from the old pump?

[Corvid]

I'm not too proud to say I didn't know how to remove them without damage.

 

I thought the threaded holes on the water pumps go all the way through?

That sounds like a good answer given the witness marks and damage, but how would they bottom out?

Edited September 18, 2013 by Corvid

[Crazyeights]

Put two nuts on the end of each stud and jam them together with 2 wrenches to turn them out. I usually use a tiny amount of blue Loctite on the end of the stud that threads in to the hub on the new water pump. You may want to spring for a new pack of studs (they used to come with most water pumps). After they get used over and over several times they can stretch and fail.

[Corvid]

Also not too proud to admit that i have done that before to force other things out of threaded holes.

That's what I get for working on cars instead of sleeping.

 

Thanks Crazyeights.

 

I'm still curious as to how these bolts failed, or if WoodsWagon is correct, what they bottomed out on?

Edited September 18, 2013 by Corvid

[Crazyeights]

Also not too proud to admit that i have done that before to force other things out of threaded holes.

That's what I get for working on cars instead of sleeping.

 

Thanks Crazyeights.

 

I'm still curious as to how these bolts failed, or if WoodsWagon is correct, what they bottomed out on?

I'm not sure on the specifics of this situation. When you removed the studs and changed the design to bolts it entered in new variables for failure. The original design works and works for many years. Make your changes carefully and your method will too. Just make sure everything is new, tight, correct thread pitch, length, ect. Last of all use some Loctite on the studs or bolts.

[Loyale 2.7 Turbo]

If you replace the Studs with Screws (In example, when doing an electric fan retrofitting, removing the Clutch Fan) The Right Replacement Screws for the pulley are: M 6 X 12 mm with 1.0 Pitch. You Shall Use Lockin' Washers because they not only Lock the Screws in Place, they also reduce the 12 mm screw's Lenght to a safer 10 mm to avoid contact on the Waterpump's shaft.

 

Maybe you used different Meausurement Screws?

 

Kind Regards.

Edited September 20, 2013 by Loyale 2.7 Turbo

[86 Wonder Wedge]

IIRC, the studs have a bulge that separates the two halves of the threads. that bulge also acts as a bit of a centering ring in the pulley hole. The pulley should have near zero rotational play when fitted (mine did at least and I used an OEM Atsugi pump) because when the engine slows down and speeds up suddenly, it causes a shock load on the belts and pulleys, and if that pulley is able to "shift" since there is a gap in the stud hole, it will. Over and over and over again...

[Gloyale]

I don't think they bottomed out, the holes ussually go all the way through. 

 

I think you didn't crush the spring washers nearly enough.  They were compressed, pinning the pulley somewhat tight against the flange, but not enough.  May not be able to get enough force on them to really crush the washer to a "zero" point against the flange.

 

No lockwashers are used on the original nuts.  I would suggest not using any when you reassemble.

Edited September 18, 2013 by Gloyale

[BEECHBM69]

IIRC, the studs have a bulge that separates the two halves of the threads. that bulge also acts as a bit of a centering ring in the pulley hole. The pulley should have near zero rotational play when fitted (mine did at least and I used an OEM Atsugi pump) because when the engine slows down and speeds up suddenly, it causes a shock load on the belts and pulleys, and if that pulley is able to "shift" since there is a gap in the stud hole, it will. Over and over and over again...

This ^^^^^^^^^^^^^^^^^^

 

Dan

[Corvid]

Ok, I hit the yard and came home with an undamaged pulley and 4 studs.

 

When visually comparing everything, it seems like the math on the bolts was pretty right on. They don't look long and the wear mark is spaced pretty close to the bulge on the stud, which lends to the idea that the bolts were the size desired.

 

The bulge is interesting, and the idea that the bulge centers and takes up slack on the pulley holes sounded promising to me. Upon examination, the bulged area on the stud is still smaller than the diameter of the pulley bolt holes. Maybe the bulge is better able to hold up to contact with the pulley than the bolts, but if you go up to the OP, the picture of the damaged pulley shows that the pulley can't handle it either.

 

This makes me think of EJ22 crankbolts, where if they are improperly torqued, the woodruff key becomes exposed to rotational forces and annihilates itself, the harmonic balancer, and the crank pulley. This never happens normally, because the clamping force of the bolt pinches everything together with the end of the crank snout, and everything turns together.

 

So, at this moment, I think Gloyale nailed it. I think that I didn't crank down on the bolts hard enough. The split ring lock washers I think were a decent idea, and even made the spacing desirable. Unfortunately, I couldn't get a torque wrench in there, so I cranked them down by hand, and I think the lockwashers made them feel done prematurely. That doesn't even take into account a possible difference in the correct torque for studs vs. bolts.

 

I'm gonna go put fresh batteries in the headlamp and try to slap this thing together tonight, so my friend doesn't have to take the bus to work tomorrow. If there are more ideas or info, keep 'em coming. I'm going to see if this takes care of it.

[ivans imports]

Pitch that clutch fan away junk nothing but problems riuned rads water pumps ect the berring in pump is to weak for the load of fan and electric fan can cool it just fine on its own

[Loyale 2.7 Turbo]

I Agree, the Clutch Fan is not a good Idea at all, I removed it and retrofitted Twin Electric Fans, also I posted a Complete Writeup with Photos, explaining such retrofitting procedure in five easy steps.  The Writeup is Here:

 

~►  http://www.ultimatesubaru.org/forum/topic/125754-easy-guide-on-five-steps-to-twin-electric-fans-swap/

 

Kind Regards.

Edited September 20, 2013 by Loyale 2.7 Turbo

[Flowmastered87GL]

No one mentioned it, its likely not the issue but at least something to look at.  There is a long style water pump and a short style.  I forget which goes to which model but if you had the wrong style on there your pully may be in the wrong spot which would cause your belts to be out of line... again likely NOT the issue as you would probably notice that the belts were way out of line.   Regarding your fan, are all the blades still intact?? (I'm thinking if it was off balance maybe I would eat up the pully)  If you still have your old water pump I would also double nut the studs out of there and move them to the new one. (if that makes sense)

[ivans imports]

I had one of those fans try to kill me split in half at 5500 rpms missed my face by mms was a sobering exp it had a small crak that we never noticed no warning just split in half

[Corvid]

Repair finished, as of 4am last night.

 

My final analysis is that this damage was the intersection of 2 events. The first was the short water pump (factory part number 21110aa026) was installed, when the longer one was needed. Somehow, I missed the visible 5mm offset on the pulleys the first time around. The second event was that when I replaced the studs with bolts, as I had seen work successfully in other threads here, I kept the torque on the bolts and lockwashers equivalent to the FSM torque for the nuts. This didn't completely engage the lockwashers, and when the pulley had additional side forces put on it by being out of position, I imagine that they walked out quickly and destroyed themselves.

 

Solving this without replacing the water pump with the long factory unit, as a time and money issue, was a matter of installing longer studs, placing a stack of three 1.5mm thick washers on the studs beneath the new pulley, then reassembling. The annoyance was finding the correct automotive studs and trimming them to fit. I went through 3 sets of studs before I got the ones that would engage correctly.

 

M6x1.00x30mm with the unthreaded shoulder in the center, are 1mm too short overall after being trimmed to fit the pump side, and cant fully engage the nuts.

M6x1.00x40mm with the wide, offset, unthreaded shoulder look perfect after trimming to fit, but the unthreaded should sticks out above the surface of the fan clutch by .5mm, preventing nuts from clamping parts.

M6x1.00x37.5mm is the answer, with a much shorter offset unthreaded shoulder. Fit is correct for WP side, and after trimming the long side to fit, they allow firm torque on both ends, and don't hit anything. You can get them from Tacoma Screw.

 

I'll give it another couple weeks to make sure stuff holds the way it should, but I think this one is done.

[Flowmastered87GL]

Well I at least hit one of the issues right.