Hydroboost issues - what's inside?

[aecavender]

I have a 77 IH Scout that I am installing a hydroboost unit from an Oldsmobile in (one of the ones from the late 70s/early 80s with the 5.7L diesel). I am also installing the Oldsmobile master cylinder.

I had the whole setup working 2 weeks ago, I took it for a test drive and it was great! The only problem was that the power steering pump was leaking, so I pulled it out and resealed it. Put it back in, started the truck and the belt squealed for about 20 seconds, then stopped and it sounded fine. I went to drive the truck and had no power steering and only manual brakes. My diagnosis was that the pump was bad (as in, I probably did something wrong while I had it apart ), so this morning I put in a brand new pump.

No squealing this time, but no power steering or brakes, still. The pump and the high pressure line into the hydroboost got really hot (the outside of the pump was smoking), but the high pressure line out from the hydroboost was not nearly as hot. When I disconnect the high pressure line going into the booster and turn over the engine I get flow (so the pump appears to be functioning). When I hook that line back up and disconnect both the high and low pressure lines coming out of the hydroboost and turn over the engine I get no flow shooting from the hydroboost.

When I hook the power steering system up the way it was before all of this (no hydroboost) it works fine, but when I hook it up to the hydroboost there is only manual steering (and manual brakes).

It appears to me that something in the hydroboost has got to be blocking the flow, which is causing the pump to build up pressure, revert to a bypass state and get really hot. However, I don't know a whole lot about what I'm looking for inside of the hydroboost in order to fix the problem. I saw a diagram of the internal components over on the Hydratech forum, and I'm pretty sure I could dissassemble the whole thing, but I really don't know what I am looking for!

Please help!

Thanks,
Aubrey

[Bill usn-1]

Hey Aubrey,
Your welcome to look at my hydroboost pics in my photo post.
I have the booster completely disassembled.

Not an expert on them, just stripped it down for a reseal.

I have only found a couple places for kits and they are all about $50.

It's basically a reseal kit.

If you find them somewhere else, post it up.

I know Vanco carries them. He's in the vendors section.

Good Luck.

[CareyWeber]

Aubrey,

Did you bleed the power steering system?

http://www.binderplanet.com/forums/s...237#post208237
http://www.binderplanet.com/forums/s...oboost+rebuild

http://www.dieselplace.com/forum/showthread.php?t=13682

Carey

[aecavender]

Would improper bleeding really cause NO fluid to come out of the hydroboost when the engine is running? I didn't really even get a chance to bleed it, as the pump got hot so darn fast.

I suppose I could try bleeding it as listed on the Hydratech forum, as that doesn't really involve running the engine until you are part way through the procedure.

[ruderunner]

I can't remember exactly but, isn't there a screen type filter in the inlet for a Hydroboost? Paerhaps its plugged with something (silicone?)

[Vancopbs]

You fried the hydroboost. That's probably what took out your pump. If you install everything right a hydroboost will last 15 years, do it wrong you can have catastrohic failure in days to weeks.

First thing you need to do is make sure it all hooked up right. The rod, hoses, fittings etc. Then you need to get that hydroboost fixed or grab another one.

Teching it here would take us about 25 posts, just give me a call sometime when your by the vehcile.

What would work best is a photo library. Pictures of the rod connecting to the brake pedal, all the hoses, the booster master etc. Post them here or email me at Vancopbs@aol.com

[Vancopbs]

Note: I don't sell kits, I have done it, but that's over seas for the most part.

[aecavender]

Here are links to photos of my setup:

The whole thing

The hose on the top of the photo comes from the power steering pump, the high pressure hose on the bottom goes to the gear box and the low pressure hose on the bottom tees into the low pressure hose from the gear box and they both go into the pump

The pushrod

The picture is kind of messed up, but here you can see the slightest bit of an angle side-to-side on the pushrod between the pedal and the hydroboost. There is no binding or other issues when I push on the brake pedal, so my guess is that this is not a problem.

I have a reman. hydroboost on the way, and before I put this one in I just want someone to verify that I had the first one in right, and that the failure was probably not because of something I did wrong!

[Vancopbs]

The way that bolt goes up looks like it may be too long, it's hard to tell. To see if you have the plumbing right you' have to call while by the vehicle and explain the plumbing to me.

[aecavender]

Ok, I got a new (reman.) hydroboost unit, put that in and bled it according to the directions that came with it. Drove it around the block, PS and boosted brakes work fine. However, the lines are still pretty hot to the touch, as is the pump (which is brand new). Do I need a cooler? I was under the understanding that most systems could run fine without a cooler, but I don't want to damage the hydroboost or the power steering system by too much heat...

Help!