Firstly: all the best for the new year to you all.


Question: Since the temperature has dropped I've noticed that my brake pedal is very hard in the morning (after a night in the garage). Just like when you've pumped the pedal a couple of times with the engine off.
When I start the car the pedal drops a bit instantly and all's back to normal, until the car has had to sit for a night again.
Is this normal?

If not, am I right to think the vacuum check valve in the booster is the likely culprit?

How would one go about at changing this valve, or is this a job for experienced technicians?


Thanks in advance,

Dietbrand Vandenberghe
--
'92 Volvo 240GL 6cyl. Diesel

Changing the check valve is a very easy task for a do-it-yourselfer.

First, it's very accessible -- look at the booster, and you'll see a plastic fitting coming out the right (passanger) side of the "drum" to a large sized hose. That plastic fitting IS the checkvalve.

All you have to do is pry it out and replace it (also using a fresh rubber seal -- very important). But before you do all this, also check that hose -- you may have trouble getting it on the new check valve without splitting -- so maybe investing in some length of new hose (and clamp) would also be a wise precaution.

And as the other guy suggested, if it's really cold where you are, drive around first for a while in order to warm up the engine compartment -- this will make the old seal a little more compliant.

Good luck.

Losing vacuum over time means some seal is leaking - either the check valve's seal, the seating of the check valve in the rubber grommet, or the seal on the vacuum booster itself. If you never have a situation where you hit the brake while driving, and the pedal is hard then, I'd say your problem is more likely the check valve - at any rate, it's the simplest to deal with first.

When I had a problem with the check valve for the heater duct vacuum motors, I had success in just cleaning it by running hot water through it. You may want to try that before buying a replacement unit.

Be careful when removing it to clean however; in cold weather, the rubber plug it seats in is not very pliable; I've broken one while trying to remove it. Try heating it with a hair dryer first.


--
David Armstrong - '86 240(350k km?), '93 940T(270k km), '89 240(parts source for others) near Toronto