Relationship between PU rack and brake system!?

[GodSendHockey]

Hi guys. Backyard mechanic who works on his own cars (Currently a VW beetle tdi and an 88 fiero). A friend of mine was complaining about a mushy brake pedal on his 2004 Grand prix (3800 NA auto). He had been topping up the brake fluid every few weeks.

Upon first inspection when he started the car and pumped the brakes I noticed a good stream of fluid coming down behind the brake booster. As it was getting late in the day we quickly ran to the junk yard nearby and grabbed a master cylinder. I assumed the seals had gone bad and was leaking fluid into the booster. I also noticed the booster itself was making a leaking noise, but we weren't able to grab one at the time.

Anyways, we swapped it out, and same problem. I decided at that point to jack up the drivers side, remove the wheel, and take a closer look. On top of the same leak and booster noise, there was a SIGNIFICANT spray of coming from the bottom union on the power steering rack (not the lines to the pump, but rather the hydraulic transfer tubes that face the drivers side wheel well.. not sure if that's the right term. the hard lines that run from one side of the rack to the other). The puzzling part to me is that it only sprayed (and HEAVILY) when the brakes were pushed. I thought PERHAPS the fluid was spraying up into the booster and maybe giving me a false diagnosis, but the brake fluid is 100% empting , and fast! I also covered the PS leak with a rag to try to isolate the leaks as it was getting everywhere. I still had the booster leak.


I took a look at the power steering fluid (once I found the bastard) and while it was "low" it was not as low as I would have expected given the number of times we tested this.


So, is this just two separate issues happening at the same? Why when the brake booster is applied does the PS rack leak (and by leak I mean spray out under pressure).

Follow up questions :

1) I plan on grabbing a booster from a different yard, that swap out seems simple enough. Once the MC is removed and the brake pedal removed the booster just twists off the firewall?

2) Ive done a ps rack on my beetle... similar type job. Remove tierods, support sub frame with jack, drop frame a little, curse and bruse your knuckles for awhile. Question is. I notice rockauto seems to sell those hard tubes. Is it possible to replace those with the rack still in the car? Should I just bite the bullet at grab a full rack replacement from the bone yard?

Sorry if this is the ultra noob question...

[Swiggles]

You should take another look around. I bet a brake line is rusted out.

[Gregorius]

Yeap. You have a Holy brake line shooting fluid onto something else. I know. I know. Still, it's a bad brake line.

My '04 GP GT was losing coolant. I looked underneath and saw green drops coming off the bottom of the radiator. I ordered a new radiator and swapped it in.....still had a leak. Still had green coolant dropping off the bottom of the radiator, Drivers side. It would not drip overnight. Only when driven. Not when cold. Not at idle. Drips would appear after being driven at least 15 minutes, then stop after it was shut off. I would have blamed a head gasket or maybe the LIM's, but for the dry exhaust and fresh coolant on the Radiator every time I looked. It was going thru maybe.. a quart every 30 miles. Maddening.

One day I drove the F'in thing over to my Father-in-laws house, and as I got out I popped the hood to check to coolant. As I bent over to pull the hood open I heard a faint sizzle sound. Before I could get the hood open, it stopped. But I did see a small wisp of steam...coming from under the crossover pipe on the exhaust? .

Turns out there is a cover on the back of the intake manifold.. a small 1x4 rectangle held in with 2 bolts, 8mm I think. I don't know why it's there. But it's there, blocking an open coolant port. And it has a gasket on it that um, well, can leak! Above the Trans Bell housing, below the throttle body, buried under the exhaust crossover. I didn't know the f'in thing was there. When the coolant pressure would build, it would shoot coolant under the heat shield on the cross over and steam off. Under load, it would stream out under more pressure, and clear the exhaust, and arc over forward....onto the radiator....... and drip off. So a 10 cent gasket had me pulling my hair out for a month. *top left in image*

There is no way that the Power steering can cause a Brake fluid leak. The systems are separate.

[GodSendHockey]

Thanks guys, That is what I was suspecting for the reason that the booster appears to be leaking fluid. That would 100% explain the loss of brake fluid. I did want to confirm though that the booster itself should not be making noise. Perhaps its actually the sound the fluid squirting out under pressure that's making the noise?

Aside from that, 100% I can visually see the PS rack gushing right from the fitting . Ill try to take some video tomorrow morning so you can see and just do a second check to make sure I am not crazy, but this was confirmed by another witness (the owner of the car). Does that even make sense at all?

[Scottydoggs]

there is no fluid in the booster, at all. you hear air pressure releasing as work the pedal, thats normal. if it was bad the brake pedal would be rock hard all the time.

the master can leak out the back side and run down the booster. what they do when they fail. and you get a soft to full mush pedal.

[GodSendHockey]

Confirmed two holes in the hard lines. One smaller one under the ABS unit squirting onto the booster ... and a second much larger one on the brake line on the firewall just before it goes into a fabric heat shield to run behind the engine. Second one is squirting onto the PS rack, causing the false diagnosis.

Just a tip (and probably obvious to most) is that this is much easier to diagnose with the engine and power off. The booster just adds to much power and the fluid creates so much a mist and mess you can't see anything.

Thanks for all the help. Given the age of the car ill probably just start with a few compression fittings and some universal line...

Cheers.