Do I need a new master cylinders?

I've mentioned in another thread that the brake pedal in an Accord I recently bought (1998 V6 Coupe) just sinks to the floor when any pressure is put on the pedal. I was advised to try bleeding the brakes.

I was able to bleed three wheels, but not the rear passenger side. The nut wouldn't turn, so I'm gonna get some PB Blaster to try loosening it. I only got air bubbles out of the front two, but after bleeding the three wheels I could, it made absolutely difference in the feel of the pedal.

The fluid was medium brown, not the bright yellow of the new fluid. Also, the fluid had some small dark particles, especially at the rear driver's side.

Also, at the start, when I did the initial top-off of fluid, something strange happened. The fluid was above the MIN mark, but when I added fluid, the fluid level rose while I was pouring in...but when I stopped pouring, the fluid level dropped back to the MIN mark. So I poured some more in, and again it rose while I was pouring, then dropped back down when I stopped. I did this three or four times until the fluid level stayed higher. What's going on here?

Do I need a new master cylinder? Or something else?

Sounds to me like you need to bleed that last caliper and refill the system..usually pedal sinkage is air bubbles or low fluid OR you could have a.leak somewhere(check to.see if the cylinder is wet and check the pressure lines going into it)..also the fluid level rose so fast because you were pouring it in faster than the leak or whatever..im not surprised at that..if all else fails get a new MC and replace the fluid and see what happens

The service manual, on page 19-14, says, "Coat the lip of the new rod seal with recommended seal grease in the master cylinder set."

What is the recommended seal grease?

And which part of the seal, exactly, is the lip?

JJR512 said:

The service manual, on page 19-14, says, "Coat the lip of the new rod seal with recommended seal grease in the master cylinder set."

What is the recommended seal grease?

And which part of the seal, exactly, is the lip?

Click to expand...

You can use a silicone grease and the lip is the part that the pushrod actually contacts going into the brake booster similar to this pic i found

Thanks.

Looks like the new master cylinder I ordered didn't come with a new seal. I know the recommendation is to use a new seal. If the old one looks ok, is it ok to reuse it? Just asking because I can't seem to find the seal at Autozone, Advance Auto, or Napa. I'll try an actual Honda dealership next, though.

The part number to the rod seal from Honda is 46185-S04-J01 its less than $3 if you choose to replace it, which i would recommend since its so cheap wouldnt wanna risk contaminating your brake system or possibly any other brake problem but if it doesnt look f*d or torn you can just reuse it