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Best Way to Bleed a 240?

OldCarNewTricks

Well-known member
Joined
Oct 23, 2016
Location
Oregon
Hello,

Both my friend and I's 240s require brake hose R&R. Curious to hear what bleeding tools people have the most luck with on these systems?

I own a vacuum style, and also have a bottle set up for good 'ol surge style bleeding, as well. I do not have a pressure bleeder.
 
The vacuum bleeder and giving a few good taps on the proportioning valves did it for me before I got a pressure bleeder.

Gravity bleeding also works if you have the time and don't have someone to help.
 
If you don’t want to open Pandora’s Box, change the lines one corner at a time and then bleed each corner. If you fill the reservoir and then cover the reservoir cap with duct tape to block off the breather hole the fluid won’t drain out of the metal lines while they are open.
 
If you don?t want to open Pandora?s Box, change the lines one corner at a time and then bleed each corner. If you fill the reservoir and then cover the reservoir cap with duct tape to block off the breather hole the fluid won?t drain out of the metal lines while they are open.

I wish I knew that before changing all of my lines to stainless all at once.

Now the brakes don't work and the failure lamp comes on (air in system) How best to correct it? I didn't have a pressure bleeder at the time (used vacuum bleeder) but I do now. What is the right order for a RHD car?
 
IDK what's best & it's sorta a trick question/YMMV as you discover what's needed as you go, but I've definitely had some real 240 problem children, proceed methodically with 'abundance of caution' as they say w/the average crusty 240 octopus/medusa.

Having some really good penetrating oil, a wire wheel for crustier cars, a heat source (temp controlled heat gun with an attachment to wrap around the brake hose w/female recepticle & metal hose ferrule to be discarded for the fancier among you, or little compact torch applied cautiously), & good line wrench/crows foot wrench & some spare short strut hard lines & lines to the junction on the x-member from a mid-cycle car that they come off of easily might be wise?

If you take those prep steps & the hard lines are on hand, it'll probably go smoothly, corner at a time, as 2manyturbos sez.

-Flush with clean fluid first (motive power bleeder makes this easy, just don't allow it to run dry and blow air thru the system! :omg:), verify all bleeders flow & aren't a total ball of rust or don't snap off with the existing lines.
-Pump up/extend rear caliper pistons as much as you dare (fully worn out rear pads you have laying around?).
-Stick on brake pedal with brake lamp fuse pulled (replace at the end of the procedure) / introduce as little air as absolutely possible. Usually the diameter of the lines is such that if the master's any good, nary a drop is lost per line changed.
-Corner at a time or even just 1 circuit in each corner caliper at a time, checking that you have a pedal after each hose/corner diligently/cautiously gingerly pumping up the pedal massaging it until the pads make solid contact without dragging an old MC seal/piston over an unused portion of the MC bore.
-Send no air back to rear prop valves under any circumstances if at all possible or else you're in a world of hurt / (smokey, you're) 'entering a world of pain.'
-Front corners/1 circuit ea first, checking gingerly, usually...it's tedious, baby steps, keep it wet with no air sent back or into the junction, lose as little fluid as possible!
-Rears last (if at all for hoses, I rarely bother with the rear hoses on cool weather 240s if I don't know how long I plan to keep the car & just junkyard replaced front hoses...rear hoses that close up is more of a 700 thing or MUCH more a 140 original hoses thing (they swell up & close or have liner problems moreso than 240 hoses), compress rear caliper pistons back/reinstall near new rear pads to push the air forward at each rear caliper, but because you flushed it with clean fluid you shouldn't be sending gross fluid/rust crap into the master if you dun-did-it-right / did your homework right!
-Reverse bleed the master a couple times at the very end as needed if you're fortunate enough to have an assistant.
-Gingerly massage brake pedal with minimal travel until pistons make contact again/don't drag the master piston over the whole master cylinder bore.

BTDT a ton of times with various crusty 240s to replace raspy soft hoses with good results/no surprises, but you have to be really careful.

Particularly up front, tho I'm lazy and don't always replace rear hoses as they tend to last a long long long time (comparatively) on the last of the 240s in a mild no UV rainy climate, but the fronts the jackets get all hammered out & flexed around a lot more in their sorta 'elevator cable' shape to the strut eyelets....why they didn't make those eyelets stainless or alloy & removable god only knows...I guess BNE has a kit for that/cute little clasp for coilover kool-aid drinkers...or just people that have molested cars even (I've seen hacks cut the eyelets open).

I wouldn't know/don't lower or lift my mid size car; it is what it is & I live with those stupid closed eyelets on the strut housing if I have the misfortune of having to replace a strut or strut insert; I'm happy to be able to get ~1 ton pickup service out of something the size of a defective by design compact pickup that fits in a 7' high door single car old Portland skinny horesless carriage/horse carriage/model A or Model T garage/shack, even if its Swedish/has expensive parts (but conservative defacto ~1967-1993 model run like a Jeep Grand Wagoneer/J-series truck, SAAB 99/C900, Jeep XJ (84-02 (& longer outside the USA) or 73-91 suburban or ~81-97 ford F-series pickup, with most/many parts basically compatible)

Good luck to ya on the dual diagonal medusa.
The line junction/failure switch is really the bugger to replace on the 240 & avoid sending air back thru the prop valves (which are starting to fail by now/prevent fluid from passing/one rear caliper sometimes refuses to bleed & no other cause can be diagnosed/found & they're not really cheap or 'rebuildable' like the 140/disc brake 1800 pre-planned-obsolescence adjustable prop valves.

I like the design of the 140/earlier 240 line junction/failure switch in theory, but in practice, the leak-proof junction & reservoir float switch is kinda the long game option.
Interestingly, they don't go bad much in the 140 or earlier 700 non-abs cars that use same part as the 240.
The chinesium cheap failure switches/line junctions or the ones in the blue box aren't worth installing, now. :-(
But with the OE line junction, it seems to last well if all the calipers move equally freely/well/rotors don't pulse & fluid is clean. :e-shrug: Seen some on well maintained cars that are super crusty with undercoating on them.
 
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Hello,

Both my friend and I's 240s require brake hose R&R. Curious to hear what bleeding tools people have the most luck with on these systems?

I own a vacuum style, and also have a bottle set up for good 'ol surge style bleeding, as well. I do not have a pressure bleeder.

Tough act to follow, there, Kjets.

I'm curious about good 'ol surge style. What is that?

Never tried vacuum from the bleeder nipple. Don't own a MityVac, just a generic hand-squeeze vacuum pump but I imagine the big issue is pulling air through the loosened threads of the bleeder. I have to bathe them in thick grease just to avoid counting all the Bernoulli Bubbles using gravity or my already turning brittle 20-year-old Motive PowerBleeder. Do the MityVacs come with tips to seal those bleeder valves?

brake5707.jpg
 
I don't know about later model 240s; but, certainly up to 1979 they continued to use the same fixed caliper arrangement as the 140s with 3 bleed ports on each front caliper. Check out the service manual because Volvo sets out a sequence for bleeding the bleed ports which helps with the removal of air. Other than that, a pressure bleeder is the way to go. Follow the factory sequence with a pressure bleeder and things will go fairly quickly with no need to go to extraordinary measures such as raising a corner of the car to facilitate air removal.
 
Keep that little hammer handy so you can tap on the pressure valves, calipers, and metal lines to make sure you get the air to move out of the system. I too bought the Motive pressure bleeder and it's made the job much better. Keep the pressure low like between 12-15psi.
 
After fighting with my brakes the last month, between pressure, vacuum and old fashion bleeding. Simply nothing beats some poor bastard pumping the pedal for you. Could never build enough vacuum or pressure to completely clear the rear prop valves.
 
Tough act to follow, there, Kjets.

I'm curious about good 'ol surge style. What is that?

Never tried vacuum from the bleeder nipple. Don't own a MityVac, just a generic hand-squeeze vacuum pump but I imagine the big issue is pulling air through the loosened threads of the bleeder. I have to bathe them in thick grease just to avoid counting all the Bernoulli Bubbles using gravity or my already turning brittle 20-year-old Motive PowerBleeder. Do the MityVacs come with tips to seal those bleeder valves?
Is the writing too difficult to understand? Every time I try to describe to someone (some ideas for?) what to check, commonly (anecdotal & I don't have a laboratory to test/prove it) & how to keep the whole thing wet/introduce minimal air it comes out as this convoluted mess.

The factory bleed order is really just for flushing to use least amount of fluid, no one really understands it/it comes out weird on the page (pictures might be good IDK?)

Same as you, I've needed thick grease if I choose to vacuum bleed some & expect there to be any ability have the clear line give any indication of remaining bubbles/air still escaping the system.

When changing calipers, I often use a water bottle & tube and draw fresh fluid into them with the vacuum bleeder & water bottle w/a cleaned copper line dipped into the bottle hung adjacent to the caliper in the wheel well & swap them onto the car quickly after doing the brake pedal stick trick and then vacuum bleed them some on the car/draw the air bubble up as much as possible & into the caliper with the stick still on the brake pedal, particularly rear calipers & compress the pistons a bit with the bleeder open, if that makes sense?

Being tidy as possible just calipers/hoses, it's usually possible to keep most of the system air-free & wet corner at a time with just a couple tiny bubbles to chase where the line comes into the caliper.
I'm afraid I'm not that tidy & had to learn / glean what I could to get more effective at it, but the cars also got older & quality (lack of) in replacement/china-pop parts is what it is...
 
Wow, I super appreciate all the responses! Great info.

I decided to order a Motive pressure bleeder for the main bleeding, and I've noted that I may have to follow it up with a surge bleed.

A surge bleed is the term we were taught in college last semester for utilizing the master cylinder as the pressure source. IOW, the classic two man brake bleed method.

Roy, I will most certainly do one corner at a time, and I'll be sure to cover the MC vent.

KJets, I'll keep the PB Blaster and a heat source near for crusty brake lines :D

Thanks all.
 
Is the writing too difficult to understand?

Not at all; it was so comprehensive it left nothing for me to add besides a couple questions for the OP.

A surge bleed is the term we were taught in college last semester for utilizing the master cylinder as the pressure source. IOW, the classic two man brake bleed method.

Thought that might be what "surge" meant. I haven't used that method in 40 years at least on any car, mostly as I quickly saw how it could be very bad for my relationship with the assistant. However, with the selection of a 240 as our only vehicle choice, I'd only recommend that for someone having a good assistant and a new or like-new master, or to someone who needs an excuse to buy a new master.

The factory bleed order is really just for flushing to use least amount of fluid, no one really understands it/it comes out weird on the page (pictures might be good IDK?)

I'm convinced this is truth, yet most everyone will argue following a particular order is imperative for success. Yet no adequate explanation follows. Could be most of us just like to be told what to do in no uncertain terms.
 
Not at all; it was so comprehensive it left nothing for me to add besides a couple questions for the OP.



Thought that might be what "surge" meant. I haven't used that method in 40 years at least on any car, mostly as I quickly saw how it could be very bad for my relationship with the assistant. However, with the selection of a 240 as our only vehicle choice, I'd only recommend that for someone having a good assistant and a new or like-new master, or to someone who needs an excuse to buy a new master.



I'm convinced this is truth, yet most everyone will argue following a particular order is imperative for success. Yet no adequate explanation follows. Could be most of us just like to be told what to do in no uncertain terms.

Yes, we were taught to use a 2?4 or similar behind the brake pedal to simulate max travel, to avoid ruining the seals.

We were also taught that only the opened circuit will require bleeding. For example, in a car with a front/rear split with only one front hose replaced, only the front should require a bleed service.
 
Start by zip tying the MC resovoir down, put 20 PSI in the motive, begin in the back when swapping calipers and do one corner at a time.

Moving to the fronts bleed the top nipple first since air rises and then the others for 2 or 3 cycles until no more bubbles are present in the clear plastic tubing as it flows.

A run of smaller IV tubing spliced into a short piece of the tubing that fits the nipples will keep the bubbles from migrating in the tubing.

For the flex line swap crack the lower / downstream fitting and gravity bleed with the cleanflametrap brake stick / plastic under the MC fill cap removed, this will insure a minimum amount of air is injected into the caliper.

Then do the recommended bleeding procedure at least twice to be sure all the air is out.

If you're methodical and diligent you shouldn't have to do the 'Tap the proportioning valves with the handle of a big screwdriver trick', and the pedal will remain firm after each corner's bleeding operation.

Lord help you and 5-6 quarts of DOT 4 if you open the system and let it drain out willy nilly.
 
Hang it from a tree and slit it's neck. Just kidding, I have fought those rear brake air bubbles since I've been dealing with my 242, 30+ years. Parking it with the rear significantly higher over night sometimes helps. Also if you replaced the rear calipers make sure they are on the correct side with the bleeder at the top of the caliper not the bottom, you'll never get the air out that way.
 
Note to the less wise/less experienced. I'd bought the motive pressure bleeder and catch bottle, made it a lot easier to do. BUT, I did accidentally push air all through the rear left caliper since I thought instead of turkey bastering out the old fluid from the reservoir I could just push it through and out, but the reservoir was so stained that the primary drained while I could only see the secondary's mostly full level. So then I had super spongy brakes until I went through and drained again. Don't be me, either turkey baster and refill, or just accept you'll use more fluid during bleed. Just for sanity it might be good for me to get a new cleaner reservoir.

It also appeared to help flush old dirty fluid by pumping the brakes some while the pressure bleeder was pushing as well.

I still seem to get the Brake Failure light showing up after holding brakes for a while (like at a light, it resets after releasing and reapplying brakes). That seems like there's some flow through between the two zones in the master cylinder, or else from one of them to the reservoir. Does this point more to poor bleeding or a master cylinder problem?
 
Sounds like there's still residual air in the system.

Revisit the left rear and tap the proportioning valve with the handle of a big screwdriver while the fluid runs.
 
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