So I had the truck in the shop last week for a couple of things, so I had them replace the seals in my vacuum pump which was leaking while they were at it. Picked it up, no leaks. Drove around town for a few days running errands, no leaks.

Headed to Giddings this weekend, stopped in Waco for diesel on the way down. No leaks while I was doing a walk around at the pump. When I got to Giddings, I parked on the driveway and there was fluid dripping from everything on the underside of the engine. I was thinking "great, they nicked the seal when they went back together". I got underneath and discovered it was actually power steering fluid (albeit dirty fluid). So I opened the reservoir and discovered it was filled to the top and the cap was just a little loose. I figured that the tech overfilled it and it started leaking when the cap loosened up. So I drained the reservoir down and refilled back to the cold mark the following morning.

I ran errands and a couple of 30 minute trips and no more leaks. Drove back to Dallas last night, parked in the driveway at home, fluid all over again. Opened the reservior, full to the top once again. Where is the fluid coming from??

I dropped it back off at the shop today, they're looking at it right now. They are thinking it was just an air bubble that was trapped somewhere. But I'm not seeing how that would be possible. If air was trapped, I would expect the fluid to go down when it moved, not go up. I didn't get a close look at the fluid last night as it was 11pm and the engine was hot and I was too tired to climb up there and pull some out.

Any ideas?

On edit: No problems with power steering or brakes. Both feel and operate normally.

 

Never heard of power steering fluid going up. This will be an interesting one to watch for sure.

 

It could be that the vent in the power steering pump reservoir cap is plugged. The dipstick attached to the cap has a hole down the center of it. This hole connects to a shallow grove on the underside of the cap.

If these vent pasages become plugged, the internal pressure in the reservoir as the fluid expands from heating up, will overcome the spring pressure holding the cap down and oil will puke out to relieve the pressure. I had power steering leak out a couple of times due to this. Then I found a thread here about the clogged vent.

Peel back the rubber gasket/seal beneath the cap and you will see the shallow vent groove.

Use some brake or electronics cleaner to dissolve any blockages. Should be good as new after a couple of cleanings. This solved my "mystery" oil leak.

Just be careful when using that brake cleaner. Probably should use some safety glasses.

 

I've had my ps system do strange things like that too so it wouldn't bother me too much. Their probably right about it purging air. Get it all cleaned up, don't overfill the pump and be watchful of it's level over the next period of time. I you have no leaks then all is good. You could ask them how they go about bleeding the ps system. Proper way is to jack the front end up then turn steering wheel lock to lock w/o starting the engine. Do this a few times then do the same with the engine running. This is the procedure starting with a new pump and new steering box. Good luck.

 

I talk to the mechanic more in depth tomorrow when I go pick it up. I'll have to check my fluid level every couple of days and see if I'm seeing any gradual changes. Since it only has been an issue after a long trip (3.5 hours on the road) and didn't show up during daily errand running, I may not know if it's fixed or not till the next time I head out of town.

 

You may want to do a search on here. I remember some complaints of the same problem that turned out to be a leaking accumulator in the Hydroboost brake booster that would pressurize the p/s system when the truck was sitting and force fluid out past the cap. It sounds credible to me, but I've never experienced it myself.

 

exactly as Fan explains, usually this happens in the winter, as long as the truck is running"usually" it will never overflow, shut the truck off and the accumulator will push the fluid out of the hydroboost and overfill the resv. to check:
run truck with PS cap off and not fluid level, then shut the truck off and watch fluid level if you see it rising its a hydoboost issue, also you may notice with the engine off, and if you try the brakes the pedal will be hard

 

Well, the problem has finally been found.

The power steering pump is pulling engine oil into the reservoir. The last time it was at the shop, they flushed the PS system and refilled with fresh fluid. The fluid is back to being almost black again. I took it back in this morning to be checked out and that is what they found. So it looks like it's new PS pump time. Anyone else ever had this happen? Still looking at the FSM diagrams trying to figure out exactly how this would happen.

 

It CANNOT draw engine oil, UNLESS some one siliconed the nose of the PS pump into the vacuum pump AND both the vacuum seal and the PS seal is shot and leaking!!!! the odds of all 3 things happening would be almost impossible

likely the oil is black because the pump is bad and the PS fluid is burning up, does it still overflow on shutdown??

 

My question would be if it is drawing engine oil, is the engine oil level dropping? I don't see how oil could get into that closed system. It seems more likely that it is burning up. I am interested to hear the explanation of what is happening.

 

Well, I haven't seen the oil level drop any appreciable level. That's why I'm still skeptical of the "drawing engine oil" claim. Plus as nickg said, in order to draw there would have to be a seal between the two. I thought about this one all last night.

Burning the PS fluid with a bad pump would make sense, just can't see where the extra volume comes from, unless the rest of the system is starved of fluid and it all sits in the reservoir.

 

I doubt it is drawing oil from the pan...it seems more likely that in burning the fluid, it (the fluid) is expanding, or foaming and increasing in volume which is why it is "pressurized." I hope a new pump solves your problem. I am getting to the point where I am going to have to replace mine soon.

 

I've been battling this same thing for about a year now. At first I thought it was engine oil but after some thought I came to the conclusion that the PS system is a closed system and the only way engine oil can get in is through the vacuum pump (which doesn't show any signs of leaking since seal replacement). I took mine to the shop and he told me that more than likely I have it overfilled and when the trucks sets overnight the hydoboost releases pressure forcing all that fluid into the resevoir thus spilling past the cap. He suggestion to check the fluid is to turn off the truck and then repeatedly press the brake pedal until it gets hard and then check it. This was about 6 mths ago and I noticed the other day that I had some fluid get past the cap again. I discharged the hydroboost and then drained about 1 cup of fluid out. I guess if that doesn't fix it, I'll start looking into a faulty hydoboost but will check out the cap vent first. Good info.

 

Main reason it went back to the shop was that I drove it Tuesday morning from about 30 mins. Parked in the garage and when I went outside I found that it had fluid all over the floor. We'll see if the new pump solves it, if not we'll have to move into the hydroboost system.