Hey all,
My apologies if this has already been posted. I have an 83 245 DL wagon with spongy brakes. I've bled the brakes in the correct sequence based on the manual and the lines don't seem to be clogged. I used a vacuum pump at the bleeder instead of the brake pedal pump method. My issue is while bleeding the rear brakes, fluid was trickling out instead of a steady flow. After bleeding, they are still pretty spongy. Front brakes seem fine with a steady flow. Before I replace the master cylinder, is there anything else I should look into?

 

The bleeder should be opened a full 1/4 turn for good flow. Any more and air may leak pass the threads. Some claim air can be trapped in the MC and it should be "bench bleed" before installation.

Bench bleeding requires special lines between the ports and the reservoir. I've improvised by connecting a long clear piece of tubing between the left front caliper and the MC reservoir. This allows fluid to flow in a circle from the MC thru the caliper back to the reservoir. Sitting in the drivers seat you can watch for any bubbles in the line as you pump the peddle.

 

drive the car and jam the brakes on you have air stuck in and

 

Hmmm also this might be the issue.. noticed a flex type hose clamped to the hard brake line saturated fluid. Looks like fix or cover up

 

Are those your transmission cooler lines? (nobody in their right mind would use rubber hose with two clamps as brake line ! But that is a common bad fix for leaking cooler lines)

 

yea I’m a noob. They are the trans cooler lines. J quickly looked at it and didn’t think. Anyway, I’m fine more “hidden gems” and will have to replace those as well.

as for the brakes, I’m going to replace the flex hoses and hopefully that’ll fix it!

 

I've rarely replaced flex hoses, unless they were cracked horribly (99-04 S40s) or collapsed internally preventing flow of brake fluid. (usually they would cause the calipers to seize due to not releasing pressure)

For a car that old - depending on how the pedal feels - it's probably your master cylinder. (I used to keep 10 or 15 in stock at a time - they seemed to fail and cause a sinking pedal. i'm not sure if more modern brake fluid (synthetic) slowed that process down - but replaced a hundreds of them in the 80s-90s- 00s- )

The trans cooler lines can be fixed cheaply with compression fittings. I think they are 5/16.

 

Thanks. Appreciate the help. I’m suspecting it’s the master cylinder but figured I’de some of the easier solutions first. The hoses are pretty damn cracked

 

Get the braided break lines from fcp uro great place for parts. Make sure to replace the one in the rear also.

 

If they are cracked enough to cause a soft/low pedal you should be able to see them bulge under pressure. I doubt that's happening.

As far as lines being an easier solution - on many cars that old the brake fittings are seized and sometimes impossible to get apart. Many have destroyed the metal lines trying to get the flexible hoses out. Then it becomes a real PITA trying to fix the metal pre-bent lines (that you can't buy new anymore.)

All I'm suggesting is BEFORE you buy flexible lines (if you really want to do that) - try to get the old ones off. It will give you an opportunity to make sure they will actually come apart without destroying anything else. And you can search for more air in the system!
Don't waste your money on aftermarket stainless flexible lines. Your 1984 has 6 flexible lines - the 93 240 above with abs only has 3 flexible lines. Save your cash for things you actually need. (yes I know they really look cool! But keep in mind it's a 40 year old 240)

How "spongy" are the brakes. Spongy brake pedal can be caused by a rear caliper where one piston is seized. The working piston tries to bend the rotor and creates a softer pedal. Are the rear pads worn evenly? (i have replaced many seized rear calipers) Your "dribbling" fluid from the rears - could be caused by collapsed (internally) rear flex hoses. But if it dribbles from both sides - both rear flex hoses would have top be collapsed internally (and I doubt that.) The usual symptom of a collapsed hose is the fluid goes in under high pressure when brakes are applied - but the caliper seems to stay on and overheat the brake with the bad hose because the fluid won't go back to the master under low pressure.

A common symptom of a worn/bad master cylinder is after initial brake application - the pedal continues to sink with pressure (usually slowly) toward the floor.

 

Before you go to all the trouble, and expense of the parts, replacing your brake flex lines I suggest bleeding the entire brake system at least one more time very thoroughly. Have you checked the piston action on each caliber? Is any wheel and rotor heating up after driving at least 5 minutes maybe 10 minutes?

 

@hoonk Yea I'm def trying to save $$ on this car and spend it on quality parts I actually need. I was able to get 5 of the 6 hoses off easily and the last was def a pain but eventually came off. The hoses were in really rough condition so I did end up replacing them with conventional hoses. Before I jump into the master cylinder, how do I determine if the issue is the master cylinder or the junction box? I know those are two common issues with 240s. Is there a way to diagnose one over the other instead of replacing and checking? From what I've read and seen, if it's the junction box, I could get a brake light warning or leaking at the top seal of the junction box and neither of those are happening. I hope it's the master cylinder bc the OEM junction box can be expensive. I haven't check the rear calipers yet only because when bleeding, barely any fluid came out the rear bleeders.

 

@245 Timber Framer I bled them again but i can't drive the car yet. I'm waiting on power steering parts but that's a great idea on checking to see if they heat up

 

Usually when a master cylinder is bad - The first sensation is the pedal is initially hard, then will sink to the floor with pressure. That occurs because the fluid is leaking past the outside lip of the seals in the master cylinder instead of being contained. Or the pedal is firm but can be "walked" to the floor by releasing slightly and pressing again. Here again the fluid is leaking past the outside lip of the seals in the master allowing the pressure past the seals.

The junction block - is there simply to turn on the brake failure light. If there is more pressure in one side that the other - a notched piston is pushed to one side grounding out the wire and turns the warning light on. A bad junction block will not cause a sinking pedal - unless fluid is pouring out of it. The only reason to replace one (at this point in time IMHO) is it's leaking. There are orings on the sliding piston and when leaking - fluid will leak past the plastic switch. (years ago when I replaced hundreds of 240 master cylinders - the junction block was ALWAYS replaced at the same time - because if it started leaking 6 months later - the customer was pissed I did not fix it right the first time, and they would tell 20 of their friends how bad a job my shop did.) Certainly you can make the point that if the switch is stuck to one side (due to a broken spring/corroded stuff) you should replace it so you know when you have brake failure. But, You know when the brakes have failed because the PEDAL GOES TO THE FLOOR! (that's what causes the failure switch to be pushed off to one side)

If the switch is stuck you can just leave the wire unplugged (to turn the light off) or release pressure (with brakes applied) on one side or the other to try to force the piston back to the middle.
I have seen plenty of corroded brake lines on junction blocks - there again, don't try to remove them unless you have too. (at this point in the cars life)

Rear calipers - just look at the pads - are they worn evenly?

 

it ended up being the master cylinder, and a good powerbleed fix it! Thanks for all the help everyone