'90-C4 Brake Fluid Leak...HELP!

fleetline51 · 01:07 PM

(pics)Took the cover off the C4 so I can wash it and take it out for a day on this beautiful
Sunday in New Jersey. Pulled it up my 100' driveway and just about ***** my shorts when I realized that the car was not stopping!

I went to the garage to get my flashlight when I saw brake fluid all over the area where the C4 was parked. Opened the luggage compartment, removed the spare
and everything else that was in my way so that I could see better. The leak was coming from the booster pump pressure switch at the point where the switch connector in mounted to the fitting that mates up to the pump casting.
Looks like this...

I'm hoping that the pressure switch assembly can be removed so that I can replace it with a new unit. From what I can see, there is a hex type fitting that looks like a wrench can be used to unscrew it.

Has anyone here experienced this situation...can this switch be removed and replaced? Any help would be GREATLY appreciated!

Thank You and Best Regards,

Tony

porterdog · 08-12-2013, 07:29 AM

Yes, you can get this part. Yours looks like it suffered some type of impact; the electrical attachment housing isn't true to the metallic body.

fleetline51 · 08-12-2013, 01:40 PM

Thanks for the response, porterdog! Yes, when I first found the leak I noticed that
the switch part of the electrical connector was askew. After searching some and checking a few post on Rennlist, I found that I was not the only one that experienced the same situation. Thought that maybe these particular switches had some assembly defects back when they were manufactured and finally under the
gross hydraulic pressure from the brake system( especially when the brake pedal is depressed) might have caused that "rupture" that you identified.

Who knows? Very thankful that it failed in my driveway and not on the Interstate!
Already found a supplier and ordered the part. $$$, but happy it's available!

Once again, Thanks for the comeback!

Best Regards,

Tony

fleetline51 · 08-23-2013, 12:29 PM

Finally got the new brake booster pressure switch and new relay installed. I filled the reservoir with DOT4 fluid (None of the three dealer groups that I had contacted had never heard of DOT4+!) After the first time that I added fluid,I started the car and listened for the booster pump to run. It came on as normal and ran for about 30 seconds or so . After it had stopped I pumped the brake pedal and it was soft and mushy...brake light,four wheel drive light and (!) alarm all came on. Once again added fluid and pumped brake pedal...lights and alarm came on but this time pump ran for a shorter period of time ...maybe 15-20 seconds. With reservoir now at max
with fluid, pedal feels firm and pump runs less than 10 seconds. Pulled the car up the driveway and depressed the brake pedal...car stopped immediately with a full
high pedal and no more lights or alarms.

Is this just wishful thinking that the brakes are actually back to normal operating condition or does the system need to be bled before I put it back on the road?
Of course I will have the car's brake system serviced and the brake system bled...Would just like some input to know if It would be safe to road test it so that I can get it to the shop without calling the flat bed!

Any help and response would be Greatly Appreciated!

Thank You and Best Regards!

Tony

RSTarga · 08-23-2013, 01:09 PM

Your going to have it bled by someone who has a Hammer or whatever they use now for diagnostics.
Take it easy on your drive to the shop, as long as you are getting braking I wouldn't tow it. Are you sure it threaded in correctly and sealed?
Did you flush your trunk with water?
Mine failed too but it didn't leak. Common fault.

fleetline51 · 08-23-2013, 02:03 PM

Yep...The new pressure switch is seated and sealed properly. (no leaks-good!)

Everything was removed from the front trunk and rinsed individually...battery, spare, etc. After that , Simple green w/ water wash-rinse and rinse again.

Thank You!

BTW...Does anyone here know if there is a diagnostic device that has replaced the
"Hammer"?

Thank You All Again!

Best Regards,

Tony

964TargaC2 · 08-23-2013, 04:57 PM

Check out the hand held tool, PDT 999, I have it and its great, will do everything the Bosch hammer does (and bleed the C4 too1)

No Affiliation , just a happy user

Diagnostic Tool

fleetline51 · 08-23-2013, 05:14 PM

Very interested in this device...Would you care to elaborate a bit about how it helped you and how it might help me?

Also...What would it set me back $$$?

Thanks Again and Best Regards!

Tony

fleetline51 · 08-24-2013, 04:40 AM

Warmed up the C4 and took it for a 15 minute test drive around town...stop and go-up hills and down. Practiced one or two "near-panic" stops to evaluate braking under that condition. Happy to report that the pedal feels the way it did BEFORE all
this booster pump pressure switch failure occurred. So,next week it's off to the shop for brake service.

Anyone here have a general idea what a brake bleed/service might run in my area of the country? (North East New Jersey)

Also, how often should the booster pump cycle during a typical "city" drive?

Once Again, many thanks for the responses and help!

Best Regards,

Tony

TMc993 · 08-24-2013, 05:06 AM

Tony,

You really need to bleed the brakes any time a component in the brake hydraulic system is replaced. Unless you really know what you're doing, you need to either get someone who has the knowledge to show you how to do it, or take the car to a good shop and have them do it for you. This isn't something to mess with if you're not absolutely confident of your skills/knowledge.

This should be a routine task for any good Porsche shop....Probably an hour of labor and the cost of fluids.

Good luck,
Terry

fleetline51 · 08-24-2013, 06:29 AM

Terry, I AM taking it to the shop next week.

"So,next week it's off to the shop for brake service. " (Last sentence in first paragraph of my last post.)

Thank You!

Best Regards,

Tony

TMc993 · 08-24-2013, 06:17 PM

Quote:

Originally Posted by Fleetline51

Terry, I AM taking it to the shop next week.

"So,next week it's off to the shop for brake service. " (Last sentence in first paragraph of my last post.)

Thank You!

Best Regards,

Tony

Sorry....Missed that....Having lost my brakes and totalling a '66 912 many years ago, I just get concerned when folks start talking DIY on brakes....Screw up something on the engine and the car won't go....Screw up the brakes...Another story.

I hope you get it back on the road soon.

Terry

fleetline51 · 08-25-2013, 04:19 AM

Quote:

Originally Posted by TMc993

Sorry....Missed that....Having lost my brakes and totalling a '66 912 many years ago, I just get concerned when folks start talking DIY on brakes....Screw up something on the engine and the car won't go....Screw up the brakes...Another story.

I hope you get it back on the road soon.

Terry

Hey, Terry! Yeah, it's all Good Brother!

Your reasoning is sound and well taken, for sure!

This is a Sunday car only (lol) so I don't have to worry about getting around with it, 'etc. I'll report back when it comes back from the shop. Thanks Again!

Best Regards,

Tony