89 740 16V Brake Bleeding Problem

Raleigh · Post by **Raleigh** » 01 Sep 2009, 19:47

Hi,

My friend and I just changed the whole calipers and rotors on my 1989 Volvo 740 16 Valve, and had no issues at all until the bleeding. I simply cannot get pressure back. I get it while the car is off, but as soon and I start the car, I have 5 inches of travel before the car starts to brake. It does brake and stop, but it's SO soft. We bled in the proper order (furthest first from the master cylinder to the closest). We bled the master cylinder as well. We even bled the electronic dispersion box or whatever it's called (later found out that's a moot point, and it has no effect). I've called two Volvo specialists in my area and two things pop up: either bad master cylinder, or the system REQUIRES a vacuum flush/bleed. There is only one bleed on these calipers, not two.

My question is, before I go spend a ton of money on a shop diagnosing and solving the problem - is there something I am completely overlooking? The friend I did these with has changed a LOT of brakes, but never a Volvo. He's owned them and is fairly familiar, but not with the brakes specifically. Any help would be greatly appreciated! Thanks!

Post by **JDS60R** » 01 Sep 2009, 20:46

Volvo prefers the closest to furthest method but many have had success both ways.

The differenec you are feeling is the lack of assistance from the power brake booster.

If you manually bled the brakes (one person on the pedal and one at the caliper) then you have one of three conditions.
1. leak at the caliper (not likely as I am sure you checked for leaks)
2. Air in the system . Old bleeder screws canmake this harder.
3. When you manually bleed brakes you push the master cylinder in further than usual during diving/braking). When the MC seals go into this area they find corrosion and rust. This can put small rips in the seals . The can make the MC work poorly and need further travel before pressure is made.

Here is what you do -follow these steps until fixed.
1. Check for leaks again
2.Pressure bleed the brakes ( buy a bug sprayer bottle $10 at your local garden store and a replacement brake MC cap and a tire valve from the parts store ) make your own pressure bleed for about $17bucks (many link on the internet with pictures in the BMW world of making your own pressure bleeder. You will come out with similar to a "Motive products brake bleeder" except it will be ugly and something for you and your mates to joke about.
3. Replace Master cylinder (it is ok to manual bleed a new MC) but you have your new Pressure bleeder so you won't need to

Let us know how it works out

Raleigh · Post by **Raleigh** » 02 Sep 2009, 11:23

Thanks a lot for the advice! I will follow it and let you know the results as soon as possible. What would be the best way to tell if the master cylinder is going bad as you explained? Is there any visual test or just trial and error?

Raleigh · Post by **Raleigh** » 02 Sep 2009, 11:40

One more thing quickly, autozone has a vacuum pump for brake bleeding for $30, is this the same as what you're describing? They also have a replacement master cylinder for $79, sounds like a really good price compared to IPD and FCPGroten... Any dangers there?

Raleigh · Post by **Raleigh** » 02 Sep 2009, 18:48

Just a quick additional question. My anti-lock dash light would come on frequently before the brakes change, and afterwards went off completely. Just today it came back on and stays on... is this an indication of anything not already covered?

Post by **JDS60R** » 02 Sep 2009, 19:11

I am not sure on the anti lock light other than the module issues that you can learn to fix here.

Autozone MC - no problem - they are fine

Ways to tell if MC is bad - you have the symptoms so without a pressure tester we really can't tell.

Is a vacuum bleeder the same as a pressure bleeder - no

oh and turst me - once you have a pressure bleeder you will never go back. I can't tell you how many ties I show up with mine to a problem situation and in minutes the problem is solved.

If you buy a MC make sure to pressure bleed the system or at least pre bleed the mc.
(this is where you hooklines from the MC outputs back into the MC resivour and pump until you do not get any more bubbles.) You have to do this before you put it on if you are not pressure bleeding.