Thanks for the video and explanation of what can fail. Recently picked up a lexus gx 470 and the motor is running constantly and when is off for a few seconds I can hear a hiss around the accumulator. Haven't seem any brake fluid leak. I'm going to replace the small o-ring on the accumulator threads and clean the plunger.
A hiss is probably internal high pressure bypass. Try testing your relays first to see if they are stuck in the ON position, overworking the pump. The accumulator is filled pump up with brake fluid. If the factory nitrogen fill has leaked out you will have no power assisted brakes and likely will have a bunch of error lights on the dash.
Hey Marius, I've got a 2005 NP 3.8 litre petrol Pajero with the same Brake booster HBB. My issue is that I have aloud alarm, traction control & ABS lights on and the pedal is rock hard. When I turn the ignition on, I can hear the pump motor going, and then stops. I have zero knowledge on this type of brake booster, but it seems to me that the pump is switching off because there is adequate pressure in the accumulator. To the best of your knowledge, is that how the pump works? I would occasionally hear chirps sounds from the HBB. But that didn't happen very often. What re your thoughts please?
Brilliant explanation, thanks for sharing. I have a 2003 Pajero which is making an awful squeel when pressing the brakes. Sounds similar to the sound you described. Is replacing the reservoir fairly straight forward, as the sticker mentions to use caution high pressure nitrogen?
Recently changed accumulator and system was working fine, until I heard that annoying sound from under the dash, again, however when I hear the sound, the brakes gets hard after a while, then I tap the accumulator and then I hear the motor comes in and starts pumping. I've tapped the reservoir and nothing, only when I tap the accumulator the motor comes In and I have brake again... What could be the cause?
Hello, Marius. Thanks for the detailed video! I had a brake failure a couple of weeks ago which turned out to be the pump motor, so I changed it out and the error lights switched off. Now whenever I press the brake pedal I hear a loud hissing sound and the pump motor turns on to re-accumulate pressure. Do you know what might be the issue?
If the dashboard have 2 lights abs and hand brake lights it makes a sound like pip sound but the sound is contineus not breaks like pip. What could b the problem
@@MariusFourie i have the same problem for a Pajero 2004 , but i found that everyime i press the pedal some air bubbles came out to the resevoir, and the pressure drops
Thank's for the Video,i got this system, mines a 2004 NP glx Australian 3.8L pajero, would be nice to know what a good one sounds and works like, eg does it make any charge up sounds.? just bought car few months ago and wondering if normal to hear a like a pump charge up cycle for eg 10seconds on key on then again for 3seconds again then stops. Brakes seem fine no lights on dash etc just i got no clue to what's normal on these 3.8L but looks just like your pump system..
1.Turn the ignition switch to the LOCK (OFF) position. Depressurise the power supply system of the hydraulic brake booster (HBB) by depressing the brake pedal at least forty times until the pedal effort becomes high. 2.Check that the reservoir fluid level is at the MAX position. 3.Chock the wheels and release the parking brakes. 4.Turn the ignition switch ON, and measure how much time is elapsed after the pump motor starts until it stops. Standard value: 20 - 80 seconds 5.After the pump motor stopped, start the engine. The brake warning lamp should not be turned on. 6.Stop the engine, and then turn on the ignition switch again. 7.When the brake pedal is depressed four or five times, the pump motor should start and then stop. 8.Depress the brake pedal four or five times again, and then measure how much time is elapsed after the pump motor starts until it stops. 9.Depress the brake pedal fully consecutive 15 - 20 times for ten seconds. The brake warning lamp should illuminate and the buzzer should sound. Standard value: 2 - 11 seconds. caution : Turn the ignition switch ON, and wait for at least 120 seconds before carrying out the checks.
Hello sir. My 06 had the motor fail 4 mths prior. Replaced and was working fine. Had the accumulator chirp noise for a while. Noticed the accumulator started chirping when driving or coasting as well rather than only braking/releasing the brake. Bought a used accumulator and swapped. Now, the motor runs every 5-10 seconds and there is a slight hissing from the unit whenever the motor stops. No leeakage externally. Any ideas? No codes or warning lights. I stopped driving it. My country has no mitsu dealers so will have to import if i need the entire hbb unit. Thanks Edit: the pump does indeed stop. Sometimes, when you turn the key in the morning, pump runs for 30 seconds and stops. No hissing either. Then, if i press the pedal a few times, it starts acting up....running every 5-10 seconds and there is a slight hissing.
Press and hold the brake while idling. If the pedal stay gradually drops, then you have a master cylinder problem (or leak at the brake piston on one of the corners). If it stays stiff but HBB pump cycles, then you have an internal leak in the HBB which will need replacement as a whole. Remove accumulator (ignition off, pump brake 40 times - unscrew accumulator), then try to press the inside through the whole with a screwdriver. If it yields the accumulator is bad. If it's rock hard it's likely the accumulator is fine. If you know someone else with a pajero, swap out accumulators with him and see if the issue follows the accumulator.
Thanks for the reply! I'm going to be working on it today and I'll have a go at these diag tips you mentioned. Unfortunately, here in Pakistan, pajeros aren't very common. I will post back here once I've got the issue fixed for anyone else who has a similar issue. Thanks a lot!
@@MariusFourie Well, I have some good news. I did the tests you suggested. Pedal stayed firm, motor kept running every 5-15 seconds. Then, I removed the Accumulator and tried pushing with a screwdriver. Piston was solid. Then, I took the poppet valve and spring out to look down the hole where the Accumulator fits. I put my screwdriver in there which happened to be a magnetic screwdriver. Fished out a few very tiny pieces of metal. I then remembered the used accumulator I tried to install wasn't screwing in right. The first thread was a bit 'flattened'. I think some shaving fell into the hole. I cleaned it out, cleaned out the hole, and reinstalled the Accumulator. Lo and behold, everything seems back to normal. I took it on a drive around the neighbourhood and in town a bit. Seems to be doing fine. Will report back if I have any further issues, but I think I've solved my problem. Thanks!
@@norontboyz5949after the 3 months, is still working with no chirp noise? Or it came back? I'm thinking about give a try on unscrew the accumulator, check it out and screw it back.
Morning found this video which is very informative. I've a MK3 2002 ex UK in South Africa 3.5. Mines makes at screach on brake application. With switch off operate pedal about 20 times. Switch on ABS light on. Switch off then on it goes out. Suspect the accumulator but as it's 20 years old fitting an old one off same model could be faulty. Will the later MK4s fit straight onto mine as yours later model I've got the black round accumulator. Later ones are available but quite expensive from 2nd places. But obviously a lot cheaper than dealers. Cheers
Thanx for the video, really helpfull. I got the same issue with my pajero 3.2/ 2010. I got that noise of pressure release valve from time time but i dont have any sound alarm or lights on my dashboard. Although i have been test the alarm: with ignition off pumped around 20 times brake pedal and alarm works. I got also autel ap200 and it dosnt show me any error stored in the system. Should i try in your check order: relay, hydroaccumulator, high press sensor…. Will appreciate any advice. Thx.
Thanks for the awesome video. A couple of weeks ago I changed all my calipers and one of the calipers I bought was defective and bled out a lot of brake fluid. I got that problem fixed and now no matter what I do my brake pedal continually goes to the floor. I did find a Mitsubishi documentation that was almost 200 pages about the brake system and how to bleed them. I followed it exactly and my break pedal still goes to the floor. Should I go ahead and look at the master cylinder at this point or should I keep chasing possible air in the system
Have you tried bleeding while the engine is running? This is crucial for the rears. And actually makes bleeding the rears very easy. Just open the bleed valve and the abs pump will push the fluid through. Do some abs braking on gravel to get air out of the esp valve block.
Thank you for the spot on explanation . After 20 years having a failure on my mk3 were surprising but i am sure i will be fixing the issue with relays or accumulator easily. Thank you very much .
Hello from the Philippines. Got a little issue here. I was coasting thru traffic and noticed that my brake pedal does not return up right away. Little bit later, it works fine again. The symptoms is intermittent. Sometimes it goes right back, sometimes not. Pls. Help.. 😢
Hello, I am using a translator, I hope you can help me, I have a Mitsubishi Montero 3.2, it has the annoying beeping sound, the brake motor is on for about 10 minutes and then it turns off, I used it like this during this time, the whole problem It came after changing the brake pads and now the pedal feels a little spongy. 3 days ago I heard the sound like a screeching sound, I think it is the accumulator but I don't know if it is the failure of the engine not turning off. I hope you can understand what I say
Hello Marius. Thanks for your video. I understood that the brake problem of my 2013 pajero full, s in the master cylinder. The over pressure sensor has failed. So, can i remove and clean it up?
Good day, very informative video; My car is a 2004, Pajero 3.0v6 with 6g72 Engine. Please advice could worn out brake pads cause the buzzing issue when brake pedal is pressed? Because mine when I press the brake pedal 3 times with the engine off and ignition on I get the small buzz sound and an abs dash light! This is the exact sound it started doing a few days back, sometimes when u apply brakes to put on reverse it will make a continuous beeping sound then goes off after barely 5 seconds!
Hello, Thanks for the video. What can be the problem when pump is turning on so frequently, like if I'm pressing brake pedal and holding it, pump turns on in every 8-10 seconds, but booster cylinder doesn't have any weird sound, just vibrating.
Thanks for the video, did you ever get around to pulling the electronics apart to establish if the low pressure sensor switch is serviceable/replaceable. I’m fairly sure I have the same issue but reluctant to spend the $3200 to replace the entire unit if I can replace the switch.
Great video Marius, I have the 4 lights on the dashboard and buzzer going with no brakes and pedal hard, I can’t hear the pump running so I suspect the motor failed?
Hi bro.What is the correct way of the accumulator removal?Hold and twist accum. from the top or using the spanner from bottom? Accumulator makes some metal noise when brake is released.
Hello I have issue with my HBB, pump starts every 5 sec and accumulator cant hold pressure, I hear hissing from accumulator, its like air leak, but brake fluid flow immediately to reservoir and pump starts pumping to accumulator. When I turn key off, brake fluid flow to reservoir and brake pedal is very hard. I think there is mechanical issue with some leak, maybe accumulator or main piston seal in HBB, I want to remove accumulator and check small pipe and spring. Could you know, what is wrong with my HBB ?
@@MariusFourie I bought this accumulator maybe 3 years ago from dealer, they changed it and it didnt help, and they dont know what to do with it so they wanted change whole HBB for 3000 dollars. I didnt agree with it and I tried solve it myself, I found issue, it needed air bleed from brakes. I tried air bleed now and didnt help. If my issue is accumulator again I need to buy another from dealer for 400dollars.
Hi, thank you so much for this video. I own a 3.8l petrol pajero and the problem was that it had a continuously beeping sound with the abs light, asc off, traction light and brake light showing on the dash. I have just purchased a 2nd hand unit and have replaced it in the vehicle. The beeping sound has since turned off and so has the brake light. Everything else is functional however there are times when pressing the brake pedal I can hear noise from the accumulator. I did not perform any other tasks besides replacing the unit. Hoping you can give advice on what I should do etc whether its bleed the brakes .. really desperate for some help. Thank you
I need help figuring out if my issue is the brush motor or the accumulator. I have the same NS but left hand drive so my assembly is on the opposite side of the engine compartment. When the brake boost pump kicks in I hear what I think is the brake pump motor pressurizing the accumulator (this sound ru-vid.comL6w9oR-j-vE). That lasts for about 3-5 seconds and then at the end when it stops I hear a nasty scraping sound for about 1 second. It sounds like this guys video (ru-vid.comRw-n64KUjz4) but just one time, not repeatedly. I'm nervous to drop 208USD on the accumulator if it's the brushes on the mechanical pump itself... it sounds like metal on metal scraping which makes me thing the electric motor. Ideas?
The noise on the second video is the pressure bypass valve. If the pump runs then stops, then the motor, relays and fuse is likely OK. If the motor continuously runs and you keep hearing the screech noise then the accumulator or valve body or pressure sensor has failed. Go to a breaker yard and ask if you can swap out as a test. Ignition off, pump brake 40 times, unscrew the accumulator, screw on new one. Make sure you don't lose the little shaft, spring and o ring when you unscrew. Start the car once swapped (no need to top up fluid) and see if everything checks out. Motor should stop in less than a minute to pressurise accumulator
@@MariusFourie Thanks for the quick reply. The screech noise is not continuous. It happens one time for about a second and does not repeat until the electric motor kicks in again to re-pressurize the accumulator. I'll see if I can test out another accumulator at a parts yard.
@@MariusFourie Sometimes, when I'm braking, I hear this noise like the second video for a very short time. It sounds something is not working as suppose. Should I go for a fix or something? I just bought this 2008 Pajero.
The HBB failed on my early 2008MY at 13 years/120k(kms). No warning lights or noises, but could only hold the car on the brakes for about 30 seconds, with the pedal sinking slowly, before the brakes released. There was absolutely no leakage anywhere so I concluded that fluid was creeping back past master cylinder seals - perhaps damaged/worn cylinder or seals? However, as far as I could discover, there are two pistons, one of which has a one-way bleed valve. Perhaps this failed? I wasn't able to locate spare pistons/seals in Philippines and eventually fitted a brand-new HBB. Someday I may dismantle the old HBB to investigate. I still haven't managed to bleed the system to my satisfaction, but it all works (with long pedal travel). Would a vacuum pump help or do I need to use an OBD ABS bleed function?
Pedal slowly creeping to floor is master cylinder or leak (fluid will go down in reservoir over time). Bleed as normal 500ml per corner but have the car idling when you do the rears.
@@MariusFourie absolutely no leak - the fluid level in the reservoir didn't budge even 1mm. It had to be bypass of the master cylinder seals/pistons. A year later, I installed a brand new HBB and have not had to top up at all in the 2½ years since. I still have the old HBB and may investigate when I have nothing more important to do! I will have another go at bleeding the system again, following your advice, to see whether I can get a firmer pedal.
