Date: Fri, 1 Aug 97
From: "Joseph Little" <js-little@msn.com>
The brakes on my 1970 1800E are alarmingly spongy. In a panic stop type of situation, it is necessary to shift down several times to supplement the brakes. I've piddled with them a bit, but can't figure anything out. I have determined they are not of the self-adjusting variety, but little else. Any ideas?
As a temporary fix, it might be helpful to pump the brake pedal once or twice when stopping, but it is imperative to repair this problem before it gets bad enough to cause an accident.
Brake sponginess is almost always caused by air in the brake lines. You must bleed the entire brake hydraulic system to remedy this. It's a simple, but somewhat tedious job requiring a couple small containers of brake fluid (Castrol LMA preferred) and an assistant. In lieu of an assistant, you can use a one-person brake bleeder. Use the Haynes manual or almost any car shop manual for the procedure. The trick to getting all the air out is to operate the brake pedal very slowly when bleeding the system. Ten pumps at each wheel should be enough. Tip: Use a 7/16" socket wrench to loosen the bleeder nipples initially. Don't overtighten when finished.
On early cars, the rear brakes should be adjusted before bleeding the system. To adjust, turn the adjuster screw in until the wheel begins to bind, then back the adjuster out until the wheel spins freely.
Next question is, how did air enter the system? Check the calipers and brake drums before bleeding to see if there is fluid leaking from them. You'll need to replace the seals in any leaking caliper or cylinder. Seal kits are still available from Volvo, but any competent brake shop can do this if it's too big a job for you. Another place to check for leaks is the master cylinder. Again, leaking means some seals need replacing.
There is another possibility that can render the brakes ineffective. If one of the rubber brake hoses going to the front wheels or the rear axle is damaged, it might be ballooning whenever you apply the brakes. The symptoms will be good brake performance at first, but the longer the brakes are applied, the pedal will gradually sink to the floor. The way to diagnose this problem is to have someone look at each hose as you apply the brakes.
The one-person brake bleeder illustrated below is one of several types available. It is the one I prefer because it is simple and inexpensive and it works. -Glenn.