Help! Puddle under the Truck

[MikeyB]

Went out to my truck to find a large puddle underneath it. Smelled it and thought oil but checked the dipstick and all fine. After further investigation noticed fluid all around power steering pump filler and cap. Opened cap to check fluid level and had a large pressure buildup that was relieved upon opening. Started truck to see if cap was leaking fluid and it was not. Didn't have any steering or brakes at all! Started truck a few more times and finally got power steering and brakes. I am not familiar at all with the hyrdroboost system on a diesel. I remember reading something about the hydroboost brakes and power steering systems being intertwined somehow. To me, it seems as if a pressure valve or pressure relief valve was stuck. Any help greatly appreciated!

2001 2500 HD 57,000 mi.

Mike

[DmaxMaverick]

Interesting. Where'd all that extra fluid come from? Has it been serviced lately? If so, it may have been overfilled, which will cause the symptoms you describe. If overfilled, it will operate OK for a while, but once the fluid starts to heat and expand, it starts a chain of events. Sitting idle for a few days adds another question. Not sure how that plays in. The gravity pressure at the pump shouldn't be enough to overcome the cap vent. The vent may be blocked, which could cause an overpressure, and subsequent blowoff.

Otherwise, I'd suspect a problem with the PS pump. A failed HB unit can cause loss/limited brakes and steering, but can't force fluid out of the pump. Although it could cause extreme fluid heat, but there should be some serious pump noise.

At this point, I suggest only watching the fluid level. If it happens again, replace the cap. If it continues after that, it's probably something internal to the pump.

[edit]
Just had another thought.....
Has anyone been in the truck while it's sat (like a kid)? If the steering is cycled repeatedly with the engine off, it can cause the system to bleed down to the pump, and overflow. The result can also cause loss of steering/brake boost if enough air is allowed into the upper system. I haven't seen/heard of this in the late models, but older systems (pre-hydroboost) would do this. Last week, my wife's car shredded the belt. I had to go get her, then I drove the car (2000 Impala) about 3 miles to home w/o power steering (mountain road, lots of turns). After replacing the belt, the PS pump growled for a while, and it took a few steering wheel cycles for the steering to return to normal. Check your driveway for wheel scuffs. Also, it doesn't take much of a fluid leak to look like a lot.

I don't know why they call this "power assist". The short drive I did in a "small" car was an descent workout. I doubt a "slight" person could do it (I'm fairly stout). Certainly no chance for evasive maneuvers.

[MikeyB]

Thanks alot for the info. I'll admit, it has some very strange symptoms. With the truck parked, I was totally unable to move the steering wheel.

Mike


OTE=DmaxMaverick;252397]Interesting. Where'd all that extra fluid come from? Has it been serviced lately? If so, it may have been overfilled, which will cause the symptoms you describe. If overfilled, it will operate OK for a while, but once the fluid starts to heat and expand, it starts a chain of events. Sitting idle for a few days adds another question. Not sure how that plays in. The gravity pressure at the pump shouldn't be enough to overcome the cap vent. The vent may be blocked, which could cause an overpressure, and subsequent blowoff.

Otherwise, I'd suspect a problem with the PS pump. A failed HB unit can cause loss/limited brakes and steering, but can't force fluid out of the pump. Although it could cause extreme fluid heat, but there should be some serious pump noise.

At this point, I suggest only watching the fluid level. If it happens again, replace the cap. If it continues after that, it's probably something internal to the pump.

[edit]
Just had another thought.....
Has anyone been in the truck while it's sat (like a kid)? If the steering is cycled repeatedly with the engine off, it can cause the system to bleed down to the pump, and overflow. The result can also cause loss of steering/brake boost if enough air is allowed into the upper system. I haven't seen/heard of this in the late models, but older systems (pre-hydroboost) would do this. Last week, my wife's car shredded the belt. I had to go get her, then I drove the car (2000 Impala) about 3 miles to home w/o power steering (mountain road, lots of turns). After replacing the belt, the PS pump growled for a while, and it took a few steering wheel cycles for the steering to return to normal. Check your driveway for wheel scuffs. Also, it doesn't take much of a fluid leak to look like a lot.

I don't know why they call this "power assist". The short drive I did in a "small" car was an descent workout. I doubt a "slight" person could do it (I'm fairly stout). Certainly no chance for evasive maneuvers.[/QUOTE]