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 Power steering failing -- which is likeliest?
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Elliot
Senior Member

USA
54 Posts

Posted - 09/12/2016 :  6:54:43 PM  Show Profile  Reply with Quote
Long time no see, but time to check in again.

We continue to get great service out of our aging Blue Bird. Using TranSynd in Allison MT643 and full synthetic Rotella in Cummins 5.9.

Just had king pins, rod ends and front brakes done. Good for another 250,000 miles!

But the power steering is failing.

1992 TC2000, Forward Control, 84 pax (40 feet).

Steering works normally with engine revved up. But little or no assist at idle.

Power steering pump is bolted to engine below injection pump.

Which component is most likely to be at fault?

Any way a moderately skilled amateur can check?

As always, I sure appreciate the help!

JoeHEB1
Advanced Member

498 Posts

Posted - 09/13/2016 :  04:20:31 AM  Show Profile  Visit JoeHEB1's Homepage  Reply with Quote
Since it just had king pins replaced. I would check that the caps (caps are how you grease the king pins) on the steering knuckle are mounted flush. If the caps aren't sitting flush then they are hitting the king pin and would make the the steering very stiff. The caps have a lip that hold the O-ring on. If the caps aren't flush then you'll have to use the caps that came with the king pin kit or the king pin is in upside down (king pin is marked "top"). It's happened here before with one of my apprentice.

If that's not the case then I would think the pump is getting weak.
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RonF
Top Member

867 Posts

Posted - 09/13/2016 :  04:54:53 AM  Show Profile  Reply with Quote
Like Joe said, something that just had been replaced could be assembled incorrectly. Check the line from the reservoir to the pump. I had one on a TC2000 that was collapsing causing a hard steering issue.

US Army retired CMBT
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Elliot
Senior Member

USA
54 Posts

Posted - 09/13/2016 :  12:06:25 PM  Show Profile  Reply with Quote
Good thinking!
But the power steering was failing before the king pins were done.

Collapsing hose.... I have certainly seen various collapsed hoses in my day, so will check that.

(In my auto dealership days, I even saw a collapsed exhaust pipe on a car. Brand new high-end Chrysler. It was a double wall pipe (for noise reduction, I reckon), and the inner layer was mis-shaped, blocking flow. Manufacturing defect. Took some head-scratching to find why it wouldn't run right! LOL )

Elliot
1992 Bluebird TC2000 FE, 5.9, MT643
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KnuckleBuster76
Active Member

45 Posts

Posted - 09/19/2016 :  03:40:40 AM  Show Profile  Reply with Quote
Check/change your power steering filter? Found a lot of problems that can be fixed by that simple bit of maintenance. I'm assuming it has air brakes, but if not, hydraulic brakes and power steering are usually linked. Check into that, if applicable. Other than that, a collapsed line sounds plausible as well.

"Just... I dunno... Just fix it."
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Elliot
Senior Member

USA
54 Posts

Posted - 09/20/2016 :  10:29:52 AM  Show Profile  Reply with Quote
Haven't had a chance to look at it yet.

But the filter rings a bell -- loudly. Back in the mid-1980s, when I was driving 18-wheelers, there was a big and urgent recall of new tractors. It was one of those "Park it right now!" issues. A batch of filters had been manufactured incorrectly. The filter disintegrated, and the debris clogged the screen. No steering.
This had already happened on my truck, and I had diagnosed it and cleaned out the gunk. (In those days, drivers did that sort of thing. Now they just pick up a cell phone.)
So, yeah, I will check that.

A friend suggested that a pressure relief poppet valve (?) in the steering gear could be stuck. That sounds like a long shot, but I suppose it is possible?

But first, check the filter and check the hose. No reason not to replace both. I should get to it in a couple days.

Yes, air brakes.

Elliot
1992 Bluebird TC2000 FE, 5.9, MT643
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Elliot
Senior Member

USA
54 Posts

Posted - 09/28/2016 :  5:45:54 PM  Show Profile  Reply with Quote
Well, it wasn't the hose, and it wasn't the filter. So... "cover me, I'm going in."
This does not appear to be the $100 pump I see online.

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Elliot
1992 Bluebird TC2000 FE, 5.9, MT643
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Elliot
Senior Member

USA
54 Posts

Posted - 09/28/2016 :  9:03:26 PM  Show Profile  Reply with Quote
Looks like I will be fabricating a tool for the upper mounting bolt. Kind'a like a distributor wrench. It probably exists, but I sort'of enjoy fabricating stuff. Or... possibly I can do it with a 1/4" drive socket and extension -- if that doesn't break. Good thing I'm not in a hurry.

Now.... Poking around on the interweb, I found pictures of a used pump just like mine that had been sold on eBay. The seller called it an Eaton BB. Does that sound right? How much trouble am I in, finding an affordable replacement, new or rebuilt?

Elliot
1992 Bluebird TC2000 FE, 5.9, MT643
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Elliot
Senior Member

USA
54 Posts

Posted - 09/28/2016 :  9:35:42 PM  Show Profile  Reply with Quote
Yeehah! Found a source, all right. And with an amazing amount of identifying information.
http://www.srtp.us/power_steering_pumps_-_medium__heavy_duty/eaton_steering_pumps_bb_series

Elliot
1992 Bluebird TC2000 FE, 5.9, MT643
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Elliot
Senior Member

USA
54 Posts

Posted - 12/28/2016 :  5:54:17 PM  Show Profile  Reply with Quote
Update – End Of Year Report

It is the season for reflecting on the outgoing year, and pledge to do better in the next.

Me… I seem to require a brain tune-up before I tear into new challenges.

With our bus-driving season having ended a few months ago, more urgent matters took precedence, and the steering problem went to the back burner.

But the human mind is a complex apparatus, and even the back burner has some heat.

And I remembered something.

Not that I didn’t already have this memory. But some Demon of the Dark Recesses had failed to flag its importance.

On our last trip of the season, I had at one point inadvertently tilted the steering column one notch further back than usual. And the suspected power steering issue became worse. Much worse. I expected I would be taking it in for professional repair in the next sizeable town.

But 12 miles down the road I stopped for fuel, and when I left there… the steering was back to the previous severity level. Acceptable for going home. Maybe being parked for two weeks had temporarily worsened the problem.

Well… that “importance flag” finally came up. I also remembered that the problem seemed to be a tiny bit worse in one direction than in the other, and that the problem varied slightly with the rotation of the steering wheel.

Yup. A mechanical problem, rather than hydraulic. Classic U-joint symptoms.

I have not driven it with the column straight up, since there is at the moment no fluid in the system.

But today I inspected the column, and here is what I found:





For one thing, the lower bearing is almost all the way out of the tube. For the other, the tube has slipped about half inch down from its original position, bringing the shaft closer to the upper edge of the slip-U-joint housing.

Bolts-nuts-and-bearings I can handle with one eye closed. But that Demon of the Dark Recesses needs a talking-to.

Elliot
1992 Bluebird TC2000 FE, 5.9, MT643
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