Andy Roe

OK, being a C4 makes sense now.

Do a search on the 964 forum for PDAS and Brake Pressure warning lights and you should get plenty of info about this.

medent

I used a turkey baster and removed a little of the brake fluid. It is a scarlet color. Is this DOT 5? I was told that if I mixed DOT 5 with DOT 4 or 3 it would thicken up (like snot) and not work.
Any advice?
I would just like to top it up for the next month or so and then do any major work over the winter while the car is sleeping in the garage.

Makmov

That is dextron from the PS res.

medent

Thanks. And from another post I now know that the brake fluid is in the trunk up front. So I checked that and the reservoir is filled up to the top line (chevron actually). The liquid is straw yellow in color.
So that brings me back to my original concern about the warning lights. If the reservoir is filled to the top level, what then could have caused those lights to go on?

Makmov

I would start with loose connections. Check and clean them all. The system is very sensitve to voltage.
Even a lazy alt can throw up the lights.


Others, the next like suspect could be the pump. They do go bad and maybe it's not building enough pressure.

You could have someone check the fluid level in the bomb.

Ken D

See Andy's post at the top of the page, and search for "PDAS" warning lights.

You may have a faulty acceleration sensor, a faulty wheel speed sensor, failed differential lock, or an electrical 'gremlin'.

There are fault codes stored in the ECU that should pinpoint the cause of the warning lamps. You will need to locate a shop that has a Bosch 'Hammer' tool (9288), or someone with a Scantool/Durametric software, they will be able to pull the codes so you can determine the problem.

Quadcammer

I'm also a bit curious as to why your oil pressure is only 1 bar at idle. seems quite low to me.

Makmov

I don't think that is an issue.

I think the spec is 1.2 bar per 1000rpm.

If 850 is idle 1 bar seems appropriate.

Laker

Up the the top line with the Engine running for at least 45 seconds?
The system draws fluid from the reservoir as it pressurizes. The C4 fluid level should be checked with the car running.

Quadcammer

seems low compared to all the air cooled cars I'e been around, which usually have 1.5+ at idle.

Makmov

I checked. There is no spec for oil pressure at idle from Porsche.

It is aprox 1 bar for every 1000 RPM.

I have read everything from 1 to 2.5 bar at idle. It could be at idle you don't get a reliable reading.

Mine, Hot, on the guage is just over 1 bar at 850 and 4 bar a 3500 and 5 at 6.

tokoro

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carlskisWP

FWIW - my oil pressure reads the same as Makmov's. And as Laker said check brake fluid level after the system is pressurized not after the car has sat for a while.

stinkydog

I don't have a C4 (and can't add any specific advice that's pertinent to your issue), but I can say...

Buy Adrian's book!




It's more useful than the owner's manual, and for at least 75-90% of the work I've done, has been a better reference than the workshop manual.