1990 240 DL "Brake Failure" Light and Excessive Pedal Tr

PaulSimonon · Post by **PaulSimonon** » 13 Mar 2010, 14:25

I'm experiencing a mostly constant, but intermittent "Brake Failure" light. The brakes stop the car fine, but the pedal does not feel firm and will drop if pushed hard enough. During ordinary driving, the pedal will not drop, but feels spongy.

This car is new to me, and I did not do the brake work so I don't know if they were properly bled, but it certainly feels like they were not. Could air in the system cause this light to come on? What are the other causes of this light and/or symptoms?

Post by **billofdurham** » 13 Mar 2010, 15:32

The excessive pedal travel would indicate air in the system as the pedal goes further when you push it hard. Try power bleeding, which is the quickest and most efficient way to go. I bought my power bleeder more than 25 years ago and have never regretted it.

Usually the light comes on when hydraulic pressure has been lost in one side of the brake system or the fluid level in the master cylinder is dangerously low, usually due to a leak somewhere in the brake system.

Whichever it is you need to sort it out ASAP as it could be dangerous.

Bill.

PaulSimonon · Post by **PaulSimonon** » 13 Mar 2010, 17:00

Is there anything that is more prone to failure that I should be looking for? Any easy checks that I can do before I get it up on the lift?

The fluid is millimeters below the max mark on the reservoir, so I don't think the level is a problem.

PaulSimonon · Post by **PaulSimonon** » 14 Mar 2010, 19:50

After driving it a lot recently, I can tell that the car pulls to the right during braking. Also, if the pedal is moved slowly down there is a complete loss of brakes.

Post by **billofdurham** » 15 Mar 2010, 13:23

You either have a lot of air in the system, a leak or a bad seal in the master cylinder.

Bill.

PaulSimonon · Post by **PaulSimonon** » 18 Mar 2010, 14:37

I replaced the master cylinder because the pedal would just drop if held but would be firm if pumped firmly. The light has gone off, and after bleeding braking power has been restored.

Replacing the master cylinder is very, very easy. Remove the fluid from the reservoir (I used a Mityvac hand vacuum bleeder, turkey basters also work.), then unbolt the brake lines with a line wrench. I covered the ends with plastic wrap to prevent air exposure, since it was a rather humid day. There are two bolts holding the cylinder to the booster, and after unbolting them the whole assembly pulls off easily. The new MC I purchased did not come with a new reservoir, so I put the stock one on the new MC. It is a press fit, and comes off with a bit of effort. I cleaned out the reservoir, cap, and screen with hot water and dishsoap, and made absolutely sure it was bone dry before replacing it. Water in brake fluid is never a good thing, because it will boil and create steam. Steam is compressible, like air, and will affect the braking power of the car. To replace it, I just greased the seals with fresh brake fluid, and pressed it back in. I then bench bled the MC, still using the mityvac since it's a bit quicker. Installation is the reverse of the above.

After installing, I bled the whole brake system, and voila! No more "Brake Failure" light, no more pulling, and no more pedal dropping.

Thank you for the help Bill!

This car is starting to come together pretty nicely, now I just have to take care of that pesky check engine light, replace some seals and the cam, overhaul the suspension, and she ought to be a joy to drive.

Post by **billofdurham** » 18 Mar 2010, 16:30

You are welcome. Thank you for the update.

Water in brake fluid is never a good thing, because it will boil and create steam.

Very true. A colleague was on his way to a serious accident. Approached a T junction at a high rate of knots. Hit the brake pedal, which had taken some hammer along the way, and it hit the floor. Because of our training he managed to negotiate the junction by using cadence braking and the emergency brake. He arrived at the accident where the car stood for about 1 hour. The brakes were back to normal. Our fleet manager had the system drained and sent the fluid off for forensic checks. It came back at 2% water. The service records showed the fluid hadn't been changed although the car was nearly 2 years old and had covered just under 80,000 miles.

The moral of the story is change the brake fluid at the scheduled intervals as it is hygroscopic.

Bill.

RicksBrick · Post by **RicksBrick** » 12 Apr 2010, 18:40

The brake failure light came on in my 89 240DL recently. It turned out to be the brake junction box. I had it replaced, the light went out and have had no problems since.

Post by **billofdurham** » 13 Apr 2010, 11:42

RicksBrick, welcome to Matthew's Volvo Site.

That is a another of the common problems and is often overlooked.

Bill.

RicksBrick · Post by **RicksBrick** » 20 Apr 2010, 17:32

Thanks for the welcome, Bill.