Vacuum Bleed Your Power Steering Pump
John: One of the most common causes of noise and whines in a power steering pump is simply just air in the system.
Chase: That's why vacuum bleeding the power steering system is super important. Speaking of vacuum bleeding, I'm going to go get the tools we need to vacuum bleed our truck. Now won't you show them what it's like when you have air in the system?
John: Yeah. You can get it out, I'm going to show them how it goes in. Now air in the system is very, very common. There's several ways that air can get into the system. First of all, you know you have a return line coming right here. If any of these clamps are loose it's going to end up pulling air into the system on the vacuum side of it. You have a pressure line right here, you don't want that loose. Once it starts to compress air what happens is it creates heat. It starts doing a lot of damage to the pump. So you want to make sure you vacuum bleed it. And what happens is this pump spins around. These veins, this is a vein-style pump. Centrifugal force is going to fling them out, I'll show you that a little bit later. But what's going on is the air is going in there, it's cavitating, it's causing all kinds of problems. They actually have TSB, technical service bulletins, on a lot of cars out there today. And a technical service bulletin is nothing more than take a look at and say, "Hey, what's going on?" And they want you to bleed the system. Honda is real famous for it.
You can see actually the reservoir right here, it's all clogged up right here. Well think about that. Once it's clogged up right there, what's going to go on is it's going to start starving for fluid. If it's starving for fluid there's nothing left but air. It's going to start trying to pump that air, causing that cavitation, causing that heat, doing pump damage. Now I can show you what's going on inside, this is really cool. I'm going to knock this one apart. And I already have the shaft clip off and stuff so you normally wouldn't do this. But I want to show you the actual veins, because this is really cool. I'm going to pull the shaft out right here. Now what's going on is it's actually driving right here. And when it drives centrifugal force is going to take these little veins here... Maybe I can take one out and show you, it's really cool. Take one of these little veins and you can see I have it in the out position right now. So it's going to go around and they're going to come around and they're going to spin there.
So it has to have fluid. If it doesn't have fluid, hydraulic power steering fluid, you're actually pumping air. We want to make sure we're compressing that and that goes around. So what we need to do is vacuum bleed the pickup truck. In order to do that there's a whole sequence to do it. The old school way back and forth doesn't work any more. We're going to vacuum bleed it. We're going to stop all the noises. We're going to stop the cavitation. And more importantly we're going to protect the pump.
Chase: John, I got the vacuum pump. Let's go ahead and bleed the system.
John: Now, what's a vacuum pump? What's this all about?
Chase: Well, it's a very simple tool, John. Just if you'll pump that there I'll show you what it does.
John: All right.
Chase: I'll put my finger over this hole right here.
John: I'm pumping it up, we've going to about 15 inches of mercury there.
Chase: What's going on?
Chase: What's happened, actually, I covered the hole with my thumb here and it's creating a vacuum. Now, let's simulate a leak. If I just open my thumb a little bit, look at it drop.
Chase: And that could be happening to your power steering system.
John: And that's introducing air into the system.
John: Very important, very important. So the vacuum pump is going to go ahead and create a vacuum, get the air up to the top, get it all out, pressurize our fluid and we're in good shape. How do you hook it up?
Chase: Oh, it's really simple. All we want to do is come down to our reservoir here and remove the cap. Get that out of the way. Now we're just going to take this here, we're going to kind of wedge it into the reservoir here, get a nice and tight seal. We don't want any leaks. And also, don't forget, look at your vacuum pump. Check these lines. If there's a hold here it's not going to hold vacuum. So we always want to check our line and our tool to make sure it's in good shape. And now all we want to do is we want to pump it up to around 20 inches of mercury. We don't want to go over 20 because it can damage the seals internally.
John: All right. So I've got about 15 is probably good. We're pulling a vacuum on that whole system.
Chase: Yeah, now we just want to let it sit there for about five minutes or so. If it moves just a little bit it's okay, but we're looking for something more. Like if it moves a lot then we know we've got a leak.
John: Yeah, so what it's doing it's actually holding this vacuum. That's a good thing. If it wasn't we'd have to chase a leak down. Now hold onto this, go ahead and unhook it. Now we said earlier a couple of the leak points. Remember that return line. That return line going back? If a clamp is loose we're going to cause that actual suction on that pump, it's going to suck air right into that. Not good. The O-rings on the actual pressure lines. Anything, any time you get any leak in that system, it's going to introduce air. Don't forget about the reservoir. Remember some of the reservoirs are actually up higher than the actual pump itself. Now it sounds kind of funny, but we're pumping up to pump down. So any of those lines of gravitation, you know, pull of that fluid and pressure going down. If I get any air in any one of those lines right there it's going to go down and it's going to start some problems. So if we do vacuum bleeding with one of these reservoirs, you want to go on the top right here and make sure that you do it from this side so you get all the air out of the system.
Now you may have an external leak. If you have an external leak you can get some dye like this, you can put it in there. You can go around with an ultraviolet light and go try to find the leak, look for it. External is a lot easier to find because it's pressurized, a lot of times you see it dripping. The internal leaks are the bears, the little ones that are coming in with the vacuum cause. Now how many times do we need to do this?
Chase: You need to do it at least twice. Now I like to, like we did, we pumped it up, we noticed we didn't have any leaks. Now is a good time to release the vacuum, go in there, top it off, the fluid. And then you want to pump it up at least one more time. Pump it up, release the vacuum. If you're holding good vacuum, top off the fluid. And then you can go ahead and crank it up.
John: Yeah, it's a good idea to take it on a test drive, run it. You want to bring the fluid up to about 170 degrees, the temperature. Get it hot and then come back and recheck it again, make sure everything is in good shape. Always top it off with fresh fluid. Now, you know what? You may have to do this five, six, seven times I've heard of. I mean it's... These things with these veins and some of the intricate systems, it's hard to get the air out. There's bulletins that you have to go do this. So I tell you what? If you suspect noise or a whining pump or you ever open up a system? Vacuum bleeding is in order