Big bolts and rubber bushings

[jonathan909]

This has to be one of the most consistent problems I've experienced working on these old(er) cars.

(Unsurprisingly,) the manual is right and the rear suspension has to be dropped in order to change the tank in this '01 OBW.  It looked a lot like there would be clearance to slide it forward and down to clear the floor pan without doing so, but the tank wedges on something above.  So I'm proceeding conservatively - loosen/lower/unbolt without entirely removing suspension, diff, etc., if possible.

The big bolts passing through rubber bushings up into the body are the problem.  The threads are loose and they're unscrewing, but dragging the bushing around with it, adding a lot of effort.

Is there a trick, something in a can, or other magic that helps with this - anything short of destroying the bushing?

[1 Lucky Texan]

If possible, make sure any vents built into the top of the tank are not stuck. I THINK there aren't any until later models but, just in case....don't wanna find out on the first fill that it only takes fuel at a glacial pace.

[jonathan909]

Huh?  Not a plumbing issue - damage (discussed in another thread) that requires replacing the tank.  It's loose, but I just don't have the clearance to slide it out.

[idosubaru]

3 hours ago, jonathan909 said:

This has to be one of the most consistent problems I've experienced working on these old(er) cars.

(Unsurprisingly,) the manual is right and the rear suspension has to be dropped in order to change the tank in this '01 OBW.  It looked a lot like there would be clearance to slide it forward and down to clear the floor pan without doing so, but the tank wedges on something above.  So I'm proceeding conservatively - loosen/lower/unbolt without entirely removing suspension, diff, etc., if possible.

The big bolts passing through rubber bushings up into the body are the problem.  The threads are loose and they're unscrewing, but dragging the bushing around with it, adding a lot of effort.

Is there a trick, something in a can, or other magic that helps with this - anything short of destroying the bushing?

Any non bushing damaging lubricant would help. 

Heat...oh wait you dont want to damage it. 

If the bushing is seized to the shaft snd turning it seems nearly impossible to get them to separate. Anything that lubricates will make the bushing also spin easier inside the housing so there’s no net gain and:

”turning bolt and bushing inside housing” < “turn bolt inside bushing” will always be true.  Reduce one will probably reduce both?

I like to torch the !$@!& out of them or just buy rust free Subarus from Georgia. I’ve wasted too much life with rust. 

[jonathan909]

Yeah, I was thinking about something like a silicone lube, but when it's a big bolt passing through a big bushing, it's almost certain that there's also a big cap or other piece of metal at both ends, making it hard to get it in where it's needed.

[Numbchux]

The spacer between the subframe and body is aluminum, I found this extremely effective at transferring heat without damaging things when I removed the subframe in my '00.

Interesting test of penetrating oil. I keep Deep Creep around since watching this

https://www.youtube.com/watch?v=st8dkGzJWtg

 

Although, if I'm picturing what's happening correctly. If that sleeve is spinning inside the bushing, the bushing is wrecked anyway.

[jonathan909]

Well, I don't actually know what the construction of the bushing is, since I haven't gotten one out (yet), so I'm not at all certain there's a sleeve in there, or just the bolt.

[1 Lucky Texan]

If you are gonna install a different used tank, make sure all the evap stuff is clear/working - that's what that was about above.

and, OT but, this guy might have some parts you could use; https://www.subaruoutback.org/threads/gen2-parts-rotors-inner-tie-rods-spring-seats-exhaust-gaskets-wiper-tank-airbag-etc.532082/

 

Edited April 16, 2021 by 1 Lucky Texan

[jonathan909]

Ah, okay, thanks.  At the moment the focus is a little tight, though.

[el_freddo]

The bush will certainly have a steel tube through it to which the bolt is grabbing. 

The use of an impact wrench/gun would be my weapon of choice, it might allow the bolt to move independently to the bush with all the hammering that hung does. 

Another good penetrant is 50/50 acetone and auto fluid. But as stated, getting it in the desired location will be the PITA. 

Cheers 

Bennie

[jonathan909]

This is what's so maddening about this problem:  Impact wrench does nothing.  The impact energy gets absorbed and returned by the rubber, so you can hold the gun on there for an hour and it just gets a nice massage out of it.  For penetrant I use "Yield" (now "Free") - another of GD's recommendations.  Expensive and a real hassle to get, but it's good stuff.

[idosubaru]

Is the bolt not moving or whizzing around not loosening when under an impact gun?

Is it free from the captive side it threads into?

[Numbchux]

Yea, sounds like it is not binding in the threads, but seized into the steel sleeve that's bonded to the bushing in the crossmember. So yea, the rubber will absorb a lot of the motion from the impact wrench. You can kind of see it here:

20191012_175953 by Numbchux, on Flickr

 

I just spent some time with the catalogs, and it looks like that bushing is not available separately (from Subaru, a quick google search didn't turn up anything, but I didn't do a deep dive).

Does the sleeve stick out enough at the bottom that you might be able to grab it with a pliers/vice-grip?

 

I don't know what else to tell you. Keep it soaked in penetrating oil. And heating that spacer made a considerable difference with mine, and it was the bolt seized into the captive nut, so it transfers quite a bit of heat into adjacent parts.

2019-10-14_08-20-28 by Numbchux, on Flickr

[jonathan909]

It's certainly seized into the bushing sleeve - that's the characteristic failure mode.  So the bolt is turning - with a great deal of manual effort, a few degrees at a time.  But anything more aggressive (like the impact gun) just makes a lot of noise, thanks to the rubber.

Those pictures illustrate the problem.  Main thing is that I'm trying to do a nondestructive removal in order to get to the tank, then bolt the suspension back up again, so the torch just turns one problem into another one.  Also, as can be seen in the torchy photo, the bolt passes through a big washer before going up into the bushing, so there's no access for getting penetrant into the bottom.  It's a little better on top now that I've unscrewed the bolt and opened a ~1mm gap above, but no change yet.

[1 Lucky Texan]

runt he impact in the TIGHTEN direction a little, then loosen, maybe alternate a few times - just to see if that helps bust it loose.

A little heat, followed by carefully (no fires please) spraying with penetrant could work. as it cools, the penetrant may get pulled in deeper.

just a coupla ideas.

 

[1 Lucky Texan]

oops, slow typing

[idosubaru]

1 hour ago, jonathan909 said:

It's certainly seized into the bushing sleeve - that's the characteristic failure mode.  So the bolt is turning - with a great deal of manual effort, a few degrees at a time.  But anything more aggressive (like the impact gun) just makes a lot of nois

Is this the case - If the bolt is turning - keep turning them all a little at a time and they have to come free of their captive nuts and it would drop out?  Then extract the bolt off the vehicle.

You surely know this but to be clear - the tighter they are the less degrees they can be turned and more time to let them cool due to localized heating at the source of the tightness.

Turn one bolt 360 degrees, go work on another one, turn it 360 degrees...wash rinse repeat, give sufficient time for them to cool down and avoid that localized heating issue  

There are times lubricant can’t get to areas it needs too. 

[jonathan909]

7 hours ago, Numbchux said:

Yea, sounds like it is not binding in the threads, but seized into the steel sleeve that's bonded to the bushing in the crossmember. So yea, the rubber will absorb a lot of the motion from the impact wrench. You can kind of see it here:

20191012_175953 by Numbchux, on Flickr

I just spent some time with the catalogs, and it looks like that bushing is not available separately (from Subaru, a quick google search didn't turn up anything, but I didn't do a deep dive).

Does the sleeve stick out enough at the bottom that you might be able to grab it with a pliers/vice-grip?

Looking at the photos of the suspension frame (thank you, these are really helpful), it's clear why those bushings aren't listed as a separate part - they're moulded into the frame, with the inner sleeve moulded into the rubber.  So it's all or nothing with this assembly - a bushing tears away inside or out and the whole thing's getting replaced.  With the big washer between the bolt head and the underside of the bushing, it's a Chinese puzzle.  Can't grab the sleeve to try to hold it still while turning out the bolt because the washer's in the way.  Can't remove the washer because...

[idosubaru]

Unbolt it and drop it out. People refresh diff bushings with some kind of urethane or window weld or something.  Use that to refresh the bushings here as well?

[jonathan909]

Well, the SMU (Small Matter of Unbolting) is the whole point of this thread, no?

I was hoping for some serious magic, but obviously none exists.  This one's about judicious use of heat, less judicious use of penetrants, 3/4" drive breaker bars, and a healthy dose of...

 

Edited April 18, 2021 by jonathan909

[Numbchux]

On 4/17/2021 at 2:29 PM, jonathan909 said:

so the torch just turns one problem into another one. 

Everything was reusable after heating that up. And it made a HUGE difference.

 

 

[jonathan909]

I see now that the spacer you're torching is metal - I thought that part up there was rubber.

[Numbchux]

Aluminum, to be specific. It transfers a lot of heat energy into the adjacent parts, without burning things. Extremely helpful.

[jonathan909]

On 4/16/2021 at 1:15 PM, 1 Lucky Texan said:

If possible, make sure any vents built into the top of the tank are not stuck. I THINK there aren't any until later models but, just in case....don't wanna find out on the first fill that it only takes fuel at a glacial pace.

Well, I finally got the miserable sumbitch out of there... in the end it was the predicted "brute force and ignorance"

So I've been busy today transplanting the necessary bits between old and new tank, repairing hacked wiring, and finally checking those two valves:  The fuel cut valve and the vent valve.  They're in the top rear of the tank, behind the seats and without access panels.  So nothing's happening to them without dropping the tank, and I'd better get it right this time.

The cut valve is easy to check:  It's just a float, so poking from beneath or just inverting it closes it.  Simple enough.

The vent valve is harder.  To quote the FSM:

When the fuel vapor pressure becomes higher than the atmospheric pressure and overcomes the
spring force which is applied to the back side of the diaphragm, the port toward the canister is
opened . The vent valve also has a float which blocks the fuel vapor passage when the tank is filled
up. Increasing fuel level raises the float to close the port toward the canister.

So it responds to both tank pressure and fluid level.  How the &@!! do I check this?  I've got two of them, and they seem to behave the same ways when I suck+blow the external ports (not tryin' with the in-the-tank portion), so do I call that "good enough" and put it together?

[1 Lucky Texan]

I think you want to KNOW, that with 'slight differential' gas pressure, there is flow OUT of the tank thru the vent valves. So, suck out of it, or blow a little pressure into the tank.

Maybe borrow a WRX driver's vape pipe and use that smoke to confirm? lol