[CU2] Brake Fluid Flush

[GreyCU2]

Hi Team,

Long time viewer, first time poster.

I looking at doing a brake fluid flush on my CU2 as part of the 40k service. I have searched the forums and couldn't find a solid discussion on the sequence used to flush the system. There's a number of threads on North American Acura TSX forums which state the following sequence (per their service manuals):

Right Rear, Left Front, Left Rear, Right Front.

However due to the TSX's being Left-Hand drive, their master cylinder would be on the opposite side of the car.

Based on threads I've read, the Honda sequence is not farthest to closest and it's important to do it correctly. Does anyone know if the sequence for RHD models differs from our LHD cousins?

Thanks in advance

[Martin77]

The rule of thumb is to do it furthest to shortest. This process is not highly critical as long as the old fluid in that line has been replaced (change of colour) by the new fluid.
The sequence guide was produced to minimise possible fluid contamination (old and new) in the system/line by changing the line that contained the most amount of fluid first. You might say that it is unlikely for the new fluid to be mixed with the old (when at least 1 line hasn't been flushed) as the fluid is contained in a narrow line (static). You're right in saying that but the enthusiast would say, why not do it using the better way. And they are also right.

[AndrewRox22]

The rule of thumb is to do it furthest to shortest..

+1 from the master cylinder..... top it up regularly to minimise the chance of running it dry....

are you going to use a 1 man bleeder/ hand pump or another person?

[GreyCU2]

are you going to use a 1 man bleeder/ hand pump or another person?

Yep, I used a 1 man bleeding kit with one-way valve at the end of it. It worked alright, but leaked a little on the last wheel.

Before I started yesterday, I phoned two local Honda dealers to clarify the sequence. Both said the following:

Right-Hand Front, Left-Hand Front, Right-Hand Rear, Left-Hand Rear.

So even though the conventional way is to start at the corner furthest from the master-cylinder and work your way back, Honda does it the other way around.

One of the service guys I spoke to at Honda said furthest to closest. I questioned it, having just been told the opposite from another dealer. He then asked his foreman/technician who has been servicing Honda cars for over 30 years who confirmed it was closest to furthest. He said doing it any other way can "upset" the master-cylinder.

I took a few photos and was thinking of doing a write-up in the how-to section. Would anyone be interested?

[Martin77]

Thanks for this clarification. The rule of thumb does not apply to our Euro.
I checked the manual and the sequence is from shortest to longest line from the master cylinder.
I don't know why this is?

Im sure a how to section would benefit some of us if it is not too much trouble.

[AndrewRox22]

One of the service guys I spoke to at Honda said furthest to closest. I questioned it, having just been told the opposite from another dealer. He then asked his foreman/technician who has been servicing Honda cars for over 30 years who confirmed it was closest to furthest. He said doing it any other way can "upset" the master-cylinder.

That's interesting.... I've heard of theories that using the brake pedal to pump can cause damage to the master cylinder if the seals are going but not if you bleed it furthest to closest...., the line stays full of fluid when you bleed and generally the same amount would come put of either method

[aaronng]

I do it closest to furthest from the master cylinder. The MC seal can be damaged if you push against the brakes hard when the bleed valve is not opened. If the bleed valve is opened, then the seal should not get damaged.

[Martin77]

Do you know the logic behind the closest to the furthest aaronng?

[aaronng]

Do you know the logic behind the closest to the furthest aaronng?
It's the method stated in the CL9 service manual. It's probably because of the design of the brake system that if you do it closest to furthest, you are less likely to push dirty brake fluid into lines which had been previously flushed.