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View Full Version : Whats this little brake valve called???



CaifanSC
10-26-2008, 01:17 PM
This is on an 89 SC. I'm talking about a small brake valve in the drivers side of the engine bay...all the way at the bottom. It has an electrical connector and some brake lines going to it.

I noticed brake fluid at the bottom of this valve, as if it was a slow leak (checked the fluid and no notisable decrease, so its gotta be a real slow leak). I also noticed that the electrical connector was wrapped with electrical tape...im thinking the clip was broken at some point and they tried to tape it in place...but with the brake fluid the tape was not strong anymore so you could easily unplug the connector.

What does this little valve do? Is it urgent to replace or could I go by just keeping an eye on it? Thanks

KMT
10-26-2008, 01:44 PM
If it is the one I'm thinking, it is part of the brake system - the high pressure sender that triggers the ARC (auto ride control) to firm the shocks when a certain pressure is reached/exceeded (400 PSI AFAIK).

Yes, they leak when old and they are not cheap to replace. Once mine started leaking, it worsened a bit more each day. I found a good used one and then had the brakes bled.

If you let it go, you risk overworking the ABS hydraulic motor if you start triggering dash lights, running low on brake fluid, etc. Get to it as soon as you can find a replacement.

Mike8675309
10-26-2008, 02:49 PM
Power Steering Pressure Switch
Standard Motor Products PSS-18 around $90 at www.rockauto.com.

http://info.rockauto.com/SMP/SMPDetail3.html?PSS18.html

Duffy Floyd
10-26-2008, 09:01 PM
Part of the brake proportioning valve.

ecyrbh
10-26-2008, 09:44 PM
When you replace the switch/valve,get a replacement pigtail for a Bosch fuel injector,works perfectly..............

CaifanSC
10-26-2008, 11:32 PM
that part in the link is exactly what Im talking about...i'm pretty sure the leak is coming from that. I"m going to try and get it from another SC....$90 is a bit steep to pay.

This looks like something that should be ok with just some teflon in the threads dont you guys think?

Would this cause an ABS light to come on?

KMT
10-27-2008, 12:31 PM
This is a brake part - no need for teflon. If it leaks enough, the light can come on. No light is a good thing at this point.

Jeff Bratton
10-27-2008, 05:56 PM
I went through this a couple of months ago. I got a replacement and did not realize it was for another application, it did not let my ARC work correctly. I thought about this a couple of weeks and I just decided replaced the O-ring and placed it back on the car and it has been working great. Everything works on it... so before buying a new one try just replacing the O-ring on it, but make sure that is all that is wrong with it. In otherwords check over the sensor for cracks of such. Make sure before you replace the sensor, whether it is the old one or the NEW one, place some drops of power steering fluid in the little hole on the sensor, this will usually prevent you from having to bleed your brakes.

Just thought I would share this with you. I know how it is being on a budget.

Jeff B.

KMT
10-27-2008, 06:57 PM
>so before buying a new one try just replacing the O-ring on it, but make sure that is all that is wrong with it.

Good point. Especially since an o-ring is cheaper than a new switch.

Mine was leaking out the plastic connector shroud...

Mike8675309
10-27-2008, 06:58 PM
that part in the link is exactly what Im talking about...i'm pretty sure the leak is coming from that. I"m going to try and get it from another SC....$90 is a bit steep to pay.

This looks like something that should be ok with just some teflon in the threads dont you guys think?

Would this cause an ABS light to come on?

The threads on there are straight, not NPT, and it isn't a brake compression fitting. It uses an o-ring.

Typical failure is to push past the seal inside the pressure sensor out the back. If you get one off another SC make sure you stop by the hardware store and pick up a new o-ring for it.

CaifanSC
10-29-2008, 12:00 AM
Sounds good, thanks for the help guys...one last question....

Is this a TEves mark II-specific part? Or even SC specific? In other words, do I have to get this out of another 89-93 SC? Or is this same part used in other year sc's and other tbirds? THanks!

KMT
10-29-2008, 12:29 AM
Says 1990/97 Thunderbird & Cougar... (http://www.partsamerica.com/ProductDetail.aspx?MfrCode=NIE&MfrPartNumber=OP6764&PartType=2081&PTSet=A)that is when referenced as the 'Power Steering Pressure Switch: For Brake Valve Applications Only'...

Remember, not all SCs used the same brake systems, but AFAIK, they all had 'Automatic Ride Control'.

DrFishbone
10-29-2008, 12:34 PM
I just replaced that the night before last on my wife's SC. It was leaking from inside the plug also. Her's had been leaking for a good while, because it was low on fluid a few months ago, but I never found the leak, and now this time her brakes went out because of fluid loss - thankfully she wasn't anywhere dangerous when she found out. So anyway... I got one off of my 93 parts car and swapped it. Looks good now.

Her amber ABS light has been on for a gooood while now and I thought that maybe that sensor was the problem. It's still got some brake fluid on the connector, so it may still not have good contact. Does anyone know what unplugging the sensor will do as far as problem lights?

S_Mazza
10-29-2008, 01:17 PM
It shouldn't do anything. I think it's a very simple pressure switch - low pressure, open, high pressure, closed.

KMT
10-29-2008, 01:26 PM
>Her amber ABS light has been on for a gooood while now and I thought that maybe that sensor was the problem. It's still got some brake fluid on the connector, so it may still not have good contact. Does anyone know what unplugging the sensor will do as far as problem lights?

This sensor triggers the 'FIRM' setting for the electronic shocks. It could (only) indirectly trigger a warning light if it allowed enough brake fluid to leak, dangerously lowering the level in the reservoir.

As far as dash lights go, unplugging the sensor on an otherwise serviceable system would simply result in not seeing the 'FIRM' light as often.

DrFishbone
10-29-2008, 04:01 PM
Alright, so it's not ABS related... that's what I was wondering. Guess I still have some looking to do to find out why the stoopid ABS light is on...:o