Pretty sure that BMW says to NOT grease the guide pins. At least, on my car. If you are able to replicate the problem in the garage, remove the bleeder screw or the brake line when the brake is stuck. That will tell you if the problem exists in the caliper or further upstream.

 

Yea they also tell you not to change your transmission fluid but I can guarantee everyone is changing there's. If you bought your car new or take it to the dealership to have a brake job done they always put a thin coat of synthetic grease on the pins. Yes the book says to clean them and reinstall but there's a reason why BMW don't listen to there own manual.

 

Not sure about that. Conventional brake fluid (DOT 3, Dot 4) is a glycol, which is, by its nature, not by design, hygroscopic, ie. absorbs water from the atmosphere. Too much water absorbed lowers the boiling point of the brake fluid, leading to gas (water vapour) in the lines, which results in very poor brake performance. The absorbed water actually distributes across the whole brake system and can cause corrosion everywhere - that is why it is recommended to replace every 2 years. The silicon based fluid is hydrophobic, therefore will not absorb water from the atmosphere and therefore it is not necessary to replace at 2 yrs interval.

 

Should he just go ahead and get a brake fluid service done then?

 

Yep, that is what I would do. If the brake fluid has not been done in over 2 years, chances are that water (moisture from the atmosphere) has entered the system and possibly corroded some parts of the system, such as the pistons on the calipers. Just a thought. I'll not get into the grease - no grease of pins controversy.

 

Let's all just agree to disagree.

My mechanic says he never greases the pins. I don't do it. Some people swear by it. Just do what you feel is best for you.

 

@donpb you're disappointing me. Lol. I grease the guide pins with silicone. I say if they do it from factory and the dealership then there's a reason why. I've learned over the years owning a BMW that some of the things they tell you in the manual is for you to come back to the dealership to get it fixed (ie lifetime transmission fluid). I thought they got away from that but I took my X6 in to do a transmission fluidchange at 30k a couple months ago and they told me that it was lifetime. I just laughed and told them to do it any way. They had it 2 days because they didn't know how to do it. Bottom line I got the service for free because they tried to over charge me by $250 for a kit that required you to drop the transmission to install it. They said the kit was purchased just to use the drain plug out of the kit. Uh not with my money you're going to waist parts. Lol

On a serious note i know people who don't grease and are fine. I work on a lot of different model cars and greasing is required on some so I do it on all. A little grease never hurts anything.

 

To reply about the brake fluid service. 2 years is not long. For it to have any effect on the system it takes years of neglect. I do my changes every 3 years and never have had a failure in my system. I do own an 07 accord that I bought in 06 that I needed to replace the rear calipers last November. I chopped it up to being a 15 year old car with I've 200k on the odometer. Who knows if I changed the fluid like I should of I probably could of squeezed a few more years out of it but I was planning to do a break system refresh anyway. Calipers and fluid is cheap when doing the work yourself.

I just believe there's something wrong with the OPs system fluid wise. A bleed would of been the first thing I would of done since all you need is fluid and time.

 

A good compromise would be to use graphite as a lubricant. It won't attract dust and dirt like mineral grease or even silicon grease, which is the main reason for the no grease proponents.

 

OP, just go get a brake fluid service already.