Brake fluid change: pressure vs vacuum?

[1969Mk3Spitfire]

I’m planning to change the brake fluid (in my other car). I’ve had a Gunson’s Eezibleed for a number of years but recently been reading about vacuum bleeding tools.

Anyone have experience of these and care to comment, make a model/type recommendation?

[johny]

Cant recommend anything but what worries me with vacuum is the possibility of pulling air in around the threads of the bleed nipple. I did one recently using a large syringe to pull fluid through and if I applied too much suction bubbles appeared from said thread....

[dannyb]

15 minutes ago, johny said:

Cant recommend anything but what worries me with vacuum is the possibility of pulling air in around the threads of the bleed nipple. I did one recently using a large syringe to pull fluid through and if I applied too much suction bubbles appeared from said thread....

Yes that's the problem with vacuum,  but I did find by putting grease over the thread helped stop this.

Danny

[PeteH]

I have one, runs off the Air compressor. So far I have bled out 3 or 4 Vehicles, including a Mercedes Sprinter. Complete changes each time and no issues with drawing air, but tight to get onto the "nipple".

Pete

[Pete Lewis]

for years on production we used a vacuumed bleed with a light pressured reservoir feed  , this was later chnaged to a zero vacuum evacuate the fill  

this is not practiacl as a diy but its sure way of filling without any bubbles 

with a variety of electric and pressured pumped diy equipment a good size 9 on the pedal  down quick return slow  nip a nipple on return if you get paranoid 

have the tube and catch jar up high so the tube stays filled works in a few seconds of pumping the pedal and theres little to clean up after

this is not the best for any anti lock syastems with accumators in line 

these really need a decent system to keep it on song 

Pete

[Josef]

If you can get the ezibleed cap to seal on the master cylinder then they’re great. But I’ve found getting that seal can sometimes be a bit of a pain… As the others have said vacuum bleeding can give the appearance of there still being air in the system due to air being pulled in through the bleed nipple threads which makes knowing you’ve actually bled the brakes properly difficult. 

[1969Mk3Spitfire]

Many thanks to you all. I can picture air ingress from around the nipple thread so I think I’ll stick with positive pressure………….unless, of course, you, Pete and your size 9 are anywhere near Manchester in the next few days……..

[Pete Lewis]

where 's That ???????????  do you give green shield stamps ???

talk to any of the old brake manufactures and pump like mad is their take on all the silly stuff thats available as a must have 

too many after market bleed kits are made to tempt the wallet 

sealing caps is the hardest part of pressured bleeding  they all leak and pickle your paint 

there are so many varieties of equipment out there but for the every two years we need on a sunny day  the size 9 works as well as any 

Pete

 

 

 

[1969Mk3Spitfire]

The only fly in the ointment, Pete, is that pumping like mad is generally a 2-man job.

 

[Pete Lewis]

years ago i made a one way valve in the bleed tube  plug its end and stanley knife a   18mm long slit in the tube 

its worked well for 20 years ,     wash the bleed tube with water after use or it goes hard 

Pete

[NonMember]

4 minutes ago, 1969Mk3Spitfire said:

The only fly in the ointment, Pete, is that pumping like mad is generally a 2-man job.

Not if you arrange the hose into an elevated jar, as Pete recommends.

[Colin Lindsay]

I've used most versions over the years; the Gunson Eezibleed exploded and blew fluid all over my bulkhead, the vacuum-operated ones didn't, and those cheap Chinese hand-pump suction thingies with the gauge on top are worse than useless. 

I'll agree with those in the know, pedal pumping works best, and as a one-man job you can experiment so that you can get to the bleed nipple and retighten before the air goes anywhere near the system again.

 

[Pete Lewis]

Colin never rush this  you end up kicking the catch jar over spilling the old stuff and when on the floor you either lay on the spanner or the tube has to come off and dribble all over some paint that is nowhere near where youre working   

but every two years after a lifetime you get used to it 

change the fluid even when littel used every two years as its soaks up water better than a sponge    the moisture enters the breather port in the cap due to atmospheric changes 

so its age that does it not usage 

Pete

[1969Mk3Spitfire]

To add to inconvenience, the rear has a biasing/compensating valve and by lifting the wheels to improve access to the nipple, the fluid flow reduces to almost nothing and it hence becomes a nightmare to bleed. Crawling under the rear isn’t my idea of having fun but it has not been changed since prior to it going into hibernation in 1994 (if ever).

 

[1969Mk3Spitfire]

1 hour ago, Colin Lindsay said:

I've used most versions over the years; the Gunson Eezibleed exploded and blew fluid all over my bulkhead, the vacuum-operated ones didn't, and those cheap Chinese hand-pump suction thingies with the gauge on top are worse than useless. 

Do you recall the approx pressure you’d applied when it exploded?

The leaflet suggests that 20psi is max but that sounds quite high.

[Colin Lindsay]

1 hour ago, 1969Mk3Spitfire said:

Do you recall the approx pressure you’d applied when it exploded?

The leaflet suggests that 20psi is max but that sounds quite high.

I think they recommended about 5psi? I used an old inner tyre, barely inflated, but as soon as I opened the valve it went bang and the top flew off the master cylinder. 

Re Pete's idea of a catch jar - I used a very long tube from the clutch slave, pointed vertically up and cable tied to the top of the screen surround... you watch the fluid as it rises, watch the bubbles, and hope they stop before the fluid gets to the top and overflows... same thing with rear brakes, about ten feet of plastic tubing tied to a brush shaft and pointed upright...

[Josef]

1 hour ago, 1969Mk3Spitfire said:

Do you recall the approx pressure you’d applied when it exploded?

The leaflet suggests that 20psi is max but that sounds quite high.

I usually use the front tyre on the small chassis cars, at normal pressure. Have so far not cause anything to explode, fingers crossed!

[Pete Lewis]

if you have aloas sensing valve you need to either  jack up and add load or find a way to jam it open to aid bleeding  or as you say its very restricted 

both in flow and access  ha !

]Pete

 

[Unkel Kunkel]

Coincidentally, I’ve just done a brake fluid change late this afternoon on my Freelander 2.

I often use the basic “two man system”..( “two person”,I should hastily correct my self).

(I did try a vacuum system many years ago. Disappointed.Can’t recommend). 

Today though,I  used a Gunson Eezibleed- I do this when my very experienced  pedal pusher/ assistant is unavailable doing far more important things.

I find a slightly modified Eezibleed very easy to use.

- I use a compressor rather than a spare tyre,  with a regulator to adjust it down to  around 25-28 psi - about 2 bar, with scrap pressure gauge from an old inflator , some 8mm micro bore  fittings and an 8mm B&Q LPG  type gas valve.

To avoid those really messy sprays of brake fluid, It is essential to turn up the pressure.. slowly  - whilst  all the while carefully checking for leaks  at the master cylinder’s  eezibleed temporary  “top”.

Also,  after each  “bleed” - it is important to first turn the lever  valve “off “ then slowly release  the pressure above the brake fluid in the master cylinder by very slowly releaing the top of the Eezibleed container.

 

 

 

 

 

 

 

[Mjit]

19 hours ago, Colin Lindsay said:

I've used most versions over the years; the Gunson Eezibleed exploded and blew fluid all over my bulkhead, the vacuum-operated ones didn't, and those cheap Chinese hand-pump suction thingies with the gauge on top are worse than useless. 

I'll agree with those in the know, pedal pumping works best, and as a one-man job you can experiment so that you can get to the bleed nipple and retighten before the air goes anywhere near the system again.

 

I feeling we might have identical "Shit brake bleeding devices" shelves in our garages, Colin!

I've tried many things over the years and there's only 1 solo tool I found that actually works, works every time, and works well, and that's the £4 Vizibleed (or £9 version with integrated bottle if you don't have any jam jars).

[1969Mk3Spitfire]

I appreciate the input, many thanks. Albeit I’m playing with my new, non Triumph toy, the sharing of a wealth of knowledge and experience from within this Forum is second to none. Huge thanks.

I’m still contemplating Eezibleed but reading the comments I’ve this morning tried to rig it to a model/airbrush compressor. It all seems to work and give good control of pressure and decay.

My next question, can I “fool” the brake bias control valve by removing the wheel, lowering the wheel arch to the normal ride night and jack-up the drum to normal wheel radius?

Finally, any preference of manufacture of DOT4, or even would you use 5.1 on a 35 year old car?

[Pete Lewis]

can you not get at the LSV piston and lever it open ???

there is no advantage in use of 5.1  AFAIK

here an overview

Brake Fluid Basics: DOT 3, 4, 5, and 5.1 Explained | MC GARAGE - Bing video

Pete

[Unkel Kunkel]

3 hours ago, Pete Lewis said:

can you not get at the LSV piston and lever it open ???

there is no advantage in use of 5.1  AFAIK

here an overview

Brake Fluid Basics: DOT 3, 4, 5, and 5.1 Explained | MC GARAGE - Bing video

Pete

That video is excellent…

That’s funny -after all we all know he was pretending to drink brake fluid ! 

- like everyone knows as little as 100ml has proved fatal…

[DVD3500]

There are one way valve bleeding pipes for motorcycles. I used one back in the day and it worked well by myself.

[1969Mk3Spitfire]

Done the job this morning, quite straightforward using the Eezibleed connected to an airbrush compressor. Put a pair of scissor jacks under the rear drums and dropped a pair of trolley jacks to give pre-measured ride height. This to “fool” the LSV/biasing valve. Access to the nipples was the good.

Looking at the colour and cloudiness of the fluid, I suspect it had not been changed since it rolled down the product line 35 years ago.

Thanks to you all for your help, encouragement and occasional sarcasm. I didn’t need Pete’s size 9s so didn’t have to sacrifice my Greenshield stamp collection. Result!