2003 Montero - Hydraulic Brake Booster longevity & general advice

[Wherever I May Roam]

Morning, all.

I've been lurking in the background for a while, enjoying the calm and knowledgeable atmosphere, fantastic build threads, and general camaraderie. Looking forward to learning lots from everyone and getting out there!

Located in Alberta, Canada, I've been on a look out for the standard 3rd or 4th gen 4runner, which command quite the premium up here (and come with a whole lot of kms and rust, both body and frame) for quite sometime. Not fully buying into the 'Yota hype, and having always known about the Montero (my family had a 1995 Pajero back in the 90s Russia, which was driven there straight from UAE by my dad), the search began. They are quite rare up here, but luckily, after a short while, a very clean and well maintained (new brakes as of last summer, all fluids/belts caught up on, etc) 2nd owner, 2003 limited with +/- 100k miles had popped up for an asking price of 5k USD. I was pretty well set on getting in until the dreaded HBB failure came up in my research.

My question(s) to you lot are: if you have experienced the failure, what mileage had it happened at? From what I've read, it is all over the map. I'm a bit hesitant to pull the trigger on one if it will require an immediate investment of at least a grand.
I'd buy a new pump motor and accumulator (those seem to be the two common sources of failure) and take it into the shop for the peace of mind. Basic mechanics I can do, but brakes I take very seriously.

Which reputable online outlets would you recommend: are the ones below legit?

Pump: https://www.amayama.com/en/part/mitsubishi/mn102843
Accumulator: https://www.mitsubishipartswarehouse.com/oem-parts/mitsubishi-accumulator-4630a012

Having read up a bunch, this seems like a great deal for a vehicle for its price and condition: am I being too paranoid with the HBB? Is the mileage to low to dump money into repairs asap. The truck is in really good condition but this seems a common failure for a ton of vehicles around that era (4th gen 4Runners included).

I want this truck to last me a decade and I understand it is a 17 yr vehicle at this point and will require care, and that's fine, but all has a reason. I want it to last a decade. No hardcore offr-roading/modding planned, mostly long trips and remote camping.

Any and all advice is appreciated, thank you all in advance.

 

[ChrisCosta416]

I had my whole Master Cylinder fail which is uncommon as I have not seen anyone else have a failure of the whole unit yet. Most people seem to have issues with the electric motor failing.

The legendary Land Cruiser uses the exact same braking system and has the exact same failure. In fact any Toyota 4wd with Traction Control/Crawl Control seems to have the exact same braking system. All will fail eventually over time.

 

[plh]

I have 185K+ miles on my '05 (put more than 100K of those on it) and have not had the symptoms nor failure. I do have a new re-built HBB motor on my shelf thou, hopefully will never need to use it.

IIRC some of the higher end Toyota & Lexus cars have the same system too.

 

[HMSEndeavour]

There has been a recall for some 2001-2003 pajeros/monteros:

REC-003136 - Mitsubishi Motors Australia Ltd - MITSUBISHI Pajero (NM, NP) | Vehicle Recalls

Recall notice for Mitsubishi Motors Australia Ltd - MITSUBISHI Pajero (NM, NP)

www.productsafety.gov.au

Not sure if 2004+ vehicles experience the same problem. Are there any differences between 2001-2003 HBB and 2004-2006 HBB? If so, maybe the older models were refitted with the new HBB and you could tell if the one you are considering was fixed.

 

[ChrisCosta416]

In the States - The 01-02 had the brake booster with the ball shaped accumulator. From what I heard failure is more common in those early years. The HBB was also a bit different because the was pre traction control models.

03–06 had the cylinder shaped accumulator and traction control.

different part numbers

 

[Wherever I May Roam]

Hey, thanks for the replies!

It sure seems the system likes to fail without too much of a notice (unless my research has been wrong).

On the upside, it turns out the PO of the truck in question had replaced the unit only a couple of years ago, so I'll be taking it for a drive within next couple of days.

 

[Salonika]

I wonder if routine brake fluid flushes extend the operational life of that system?

 

[plh]

I wonder if routine brake fluid flushes extend the operational life of that system?

Doubtful, Its generally either the motor (worn out) or accumulator (leak) that take a crap. Neither of these comes in contact with brake fluid.

Just remember, nothing is forever. Old parts fail at some point .

 

[ChrisCosta416]

@plh nailed it. Our trucks are getting older and more and more parts will fail. In fact a fluid flush can do harm is your master cylinder seals are close to failing. Which is what happened to mine. But I have been the only one so far.

 

[SONICMASD]

Hey, thanks for the replies!

It sure seems the system likes to fail without too much of a notice (unless my research has been wrong).

On the upside, it turns out the PO of the truck in question had replaced the unit only a couple of years ago, so I'll be taking it for a drive within next couple of days.

If the accumulator goes out then there is often a warning noise that can exist for months even - it sounds like a turkey gobbling I'm told.

However, if the pump/motor goes out then that is often without warning and creates a siren, ear-piercing noise.

I have 172k on my 2005 and was recently thinking about doing preventative maintenance on this system as well. New Accumulator is about $160 and a rebuilt motor can be had for $300 on eBay. Add to that two hours of labor for a shop to install and bleed the brakes if you don't want to do it yourself. I posed the question on the Gen3 Squad FB Group and in the end decided to just run it as is until it either gives me warning signs, fails, or I get to 200k. Many people have had their units last more than 200k, sometimes even over 250k...and then again, many people have had failures between 150-200k.

 

[Gavinndsm]

If the accumulator goes out then there is often a warning noise that can exist for months even - it sounds like a turkey gobbling I'm told.

However, if the pump/motor goes out then that is often without warning and creates a siren, ear-piercing noise.

I have 172k on my 2005 and was recently thinking about doing preventative maintenance on this system as well. New Accumulator is about $160 and a rebuilt motor can be had for $300 on eBay. Add to that two hours of labor for a shop to install and bleed the brakes if you don't want to do it yourself. I posed the question on the Gen3 Squad FB Group and in the end decided to just run it as is until it either gives me warning signs, fails, or I get to 200k. Many people have had their units last more than 200k, sometimes even over 250k...and then again, many people have had failures between 150-200k.

Bit late to this but working out an issue rn, just recently did a front brake job which I had to change the calipers. When I was bleeding them there was one long beep after pumping the brakes a ton then never again. Brakes are still soft and I have to pump ~3 times if I want to stop like normal. No lights on dash, no codes, no leaks, and no sirens.

I've got no clue what to to

 

[plh]

Bit late to this but working out an issue rn, just recently did a front brake job which I had to change the calipers. When I was bleeding them there was one long beep after pumping the brakes a ton then never again. Brakes are still soft and I have to pump ~3 times if I want to stop like normal. No lights on dash, no codes, no leaks, and no sirens.

I've got no clue what to to

Need to bleed the ABS to get the air out of it. Requires a MUT tool IIRC. The FSM has the description on how to do it. mitsubishilinks.com

 

[Gavinndsm]

Need to bleed the ABS to get the air out of it. Requires a MUT tool IIRC. The FSM has the description on how to do it. mitsubishilinks.com

Appreciated, I've looked and asked everywhere and this is the first piece of actual info I've been given lol

 

[Michael Brown]

The Shade-tree mechanic method for ABS bleed is to go down a long, straight dirt road and slam the brakes.
That activates the ABS enough to cycle the valves and help purge the air. Make sure you have plenty of road and no traffic if you attempt this.