I have a power steering system question. I have a small leak in my 05 TrailBlazer 4.2 power steering system. I need to get it on a lift to get a better look, but it seems to be coming from where the lines go into the rack. I am aware that there is an o ring or 2 where it goes in. However that is not my question. What I am wondering is if there should be pressure on the system itself or not? That is, should I have an audible release of air pressure when I open the full cap on the fluid reservoir right after shutting the vehicle off after being up to operating temp? I assume there is a pressure regulator of some sort in the pump to control the output on the high pressure side but I wasn’t sure if the reservoir seals the system or if it should be somehow vented. Thanks for the help.
Power Steering System Question
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Maverick6587
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I don't remember ever having a lot of pressure on the cap when removing it while the engine was at operating temp. Maybe a little pressure but, nothing that would stop me from removing the cap right after turning the vehicle off and being at full temp.
The two top leak areas for the 4.2 are at the power steering cooler (it gets rusted pretty bad) and where the lines connect to the driver's side upper fender well (next to the top of the strut mount) where it also gets very rusted. If you live in the rust belt, I would check both of those areas after you find your leak.
The two top leak areas for the 4.2 are at the power steering cooler (it gets rusted pretty bad) and where the lines connect to the driver's side upper fender well (next to the top of the strut mount) where it also gets very rusted. If you live in the rust belt, I would check both of those areas after you find your leak.
That sounds right to me, the low pressure line comes back into the reservoir if i remember right, so it might have a little pressure. But the fluid can be hot and swirling around, and if you have any air cavitation it will jump around and maybe out. Seems like even after I shut off the engine after it has warmed up there is slight pressure release when you open the cap, but not very much.
I've changed my steering rack a few times now, and never needed a lift to do it, but of course if you have one handy it makes it easier. Whenever I've had a leak it was pretty easy to figure out where just by inspecting. Anywhere metal clips are holding lines is a prime area. I would be surprised if it was where the tubes enter the rack, but then again why should I be surprised something needs to be repaired on this thing in a new location?
I've changed my steering rack a few times now, and never needed a lift to do it, but of course if you have one handy it makes it easier. Whenever I've had a leak it was pretty easy to figure out where just by inspecting. Anywhere metal clips are holding lines is a prime area. I would be surprised if it was where the tubes enter the rack, but then again why should I be surprised something needs to be repaired on this thing in a new location?
Mooseman
Moderator
That little bit of pressure in the reservoir when you open the cap is probably just air expanding as it gets hot. The cap is spring loaded, similar to a rad cap, to let off excessive pressure. Yours sounds about right to me, except for the leak of course.
Thanks for the replies. There is just a quick hiss when opening the cap when hot. I just wanted to be sure that there should in fact be slight pressure built up and I didn’t have a high pressure issue causing the leak. As far as the leak goes, I need to look further but it appears to be coming from the area where the lines go into the rack. The rack was replaced around 10k miles ago, maybe less. The lines were all replaced as a set about 5 or 6 years ago. That job wasn’t much fun so I hope it’s not the issue. By the way my line leaks were above the drivers side wheel in the typical location. Thanks again for the help.
Maverick6587
Member
There are o rings. That’s what I’m thinking too Maverick. I need to get under there one day when I have some time to look. I have another vehicle for work so this one is a night and weekend truck.
There are seals that sit in the rack that the lines plug into. (some aftermarket lines had bigger diameters however and don't use the seals, not sure if that is still the case) One small bolt holds those lines on, in lbs if I remember correctly so should come out pretty easy. When you get into this make sure you don't get into a situation where you have double seals. That's all I'm going to say about that incident.
Mooseman
Moderator
Been a long time since I've visited this but there was a change in seal types at some point. Looking through RA, pressure lines are listed as either OEM or alternate type seal. With the alternate, they say to remove the cup seal.