[Paul Mellerowicz]

Have a 1998 E-320 with 145,000 miles I'm putting on new brake bads. I'll clean up the calipers and use again. I'll push out the pistons (not all the way out, of course) and blow out under the boots with compressed air (about at 50 PSI). But what should I lubricate the pistons before I push them back in (using a c clamp)???

Do I just squirt brake fluid in side the rubber boots? Or will the brake fluid degrade the rubber boots. I will push the pistons in and out a few times before I reinstall. Any thoughts on the fluid to lubricate the pistons?

 

[Franasia]

Paul, it appears that brake fluid is all you need for lubrication.

Check this tutorial.

I hope it helps.

Cheers.

 

[Kajtek1]

Blowing compressed air on the cylinder boots brings risk of pushing dust under them, so I would not do that.
If you see mud or dust on the boots, I would clean it gentle with soft brush and that is it.
Opening the boots if you don't have a problem is a good way to start one.

 

[Paul Mellerowicz]

Thanks for the reply..... Most helpful.

 

[Check Codes]

Blowing compressed air on the cylinder boots brings risk of pushing dust under them, so I would not do that.
If you see mud or dust on the boots, I would clean it gentle with soft brush and that is it.
Opening the boots if you don't have a problem is a good way to start one.

Plus 2,267.

If the boots are fine, leave them alone.

A cheap nylon-bristled paintbrush (1/2" or 1" at most) is great for cleaning them up. If you need a little more stiffness, trim the bristles shorter.

Good luck.

 

[Kajtek1]

I never hear about anybody promoting rubber conditioners, but I am using Formula303 for extending the life and beauty of my tires and I would advise to spray some of that stuff on the boots as well.

 

[G-AMG]

I wouldn't Monkey, at all, with any of it...

If the Piston Rubber "Boots" are INTACT, Just Press back the Cylinders, and Call it a Day...

 

[Paul Mellerowicz]

Big development. I tried the PB Blaster with a Mapp Gas (plumbing) torch again on the bleeder screw. Heat and re-applied the PB Blaster a few times. Then used a small vice grip on what's left of the bleeder screw. It let loose, fluid came out. So I bought a new bleeder screw and bled the drivers side front caliper for the first time since I owned the car (2008). Bled it till new fluid appeared. Now the caliper piston goes out and fully retracts back. Like it should. So that takes care of that.

 

[G-AMG]

Paul, glad you have an Inexpensive Fix to your problem.

In general, you want to bleed At Least 80 cc of new fluid, per caliper.

 

[vr2whf]

I am considering to use the can compressed air to blow out the piston for the caliper rebuild. Anyone tried the can air like this before?

I checked the air pressure with the gague. It reads 40 psi. Should be enough to blow out the piston?

 

[Benzyle]

Rubber grease is also fine to use on both seals and the piston sides,but obviously don't put any inside the caliper chamber.The inner seal will prevent rubber grease entering the brake fluid area.
Piston should come out with around 15 psi,you can even use a sport/bicycle pump with appropriate fittings/nozzle to force the piston out.

 

[Kajtek1]

Aren't those airs in the can a propane based gases?
If you are DIY, you should have at least small compressor. Prices start at $40 at HF