nckwltn
Explorer
If you have a Gen3, I'm pretty confident that unless the motor has been replaced, this is a problem that could pop up at any moment for you. I've got 166k miles on my 03.
Summary:
Hydraulic Brake Boosters commonly fail on Gen 3s. It's likely the motor, but could be the accumulator. You can find similar HBB systems on several model's of Toyota in junk yards. Grab the motor and motor mounting bracket, and swap them onto your HBB system. MUCH cheaper, but the motor will probably fail again due to similar wear.
Detailed:
Last Saturday morning, my wife was on the way to a meeting when all of a sudden the car started making a constant beep and the ABS and traction control lights came up. Thankfully she was only a couple of minutes away so she drove home. I gave it a couple of looks and didn't know what exactly it was. So I sent her off in my car and I hit the Google.
What I discovered was that my Hydraulic Brake Booster had just failed and my wife was probably only a few miles away from brake failure! A common problem on Gen 3s and other vehicles that use this type of system.
The hydraulic brake booster is electrically operated and not vacuum operated. From what I understand there is a pressure vessel (called an accumulator) that holds pressure built up by the motor. This prevents the motor from running non-stop. So when the motor stops working, you have a little pressure built up to make a few stops, but not too many.
I called the dealer, and they wanted $1,800 for the entire assembly. I also found a part number online and the dealer wanted $600 for the motor alone. Both items can be had from online for less, but it's still REALLY pricey.
I was thinking that it was quite strange that Mitsu would use a part that ONLY existed on this generation of Montero. A few google searches later I found several other Toyota models that also use the same looking part. Toyota's are much more common at my pick-a-part spots. Also, because this is a common problem on the Montero, I've seen that the HBB is usually the first thing to get pulled from a junked car.
A few online searches and I found a possible 2002 4 Runner that had a similar looking HBB system. Bought the motor for 30 bucks, put it on my HBB system.... bolted it all back up and it's working like a champ.
Short video showing the motor and hydraulic booster system. The problem is that the commutator bars are totally worn down by the brushes. Brushes don't have tons of life left in them either. The 4Runner motor that I pulled showed significant wear as well. Will be looking to pick up another motor on one of my pick-a-parts trips to have as a backup, and to see if they are all in a similar condition. Montero and 4Runner motors both were filled with that rust colored dust.
Nice detailed post about replacing the HBB unit: https://www2.pajeroclub.com.au/forum/showthread.php?t=46516
Part number for the motor only: MN102843
List of possible alternate vehicles to get the motor and/or HBB from. The electrical/computer connectors look to be identical. Only the brake fluid level sensor connector looks to be in different locations. Do you own research on this. I can say that I pulled my motor from an 02 4Runner. Don't know if all option levels of 4 runners in that year will even be equipped with HBB systems.
How I identified other possible makes/models for similar HBB systems: https://www.google.com/search?q=lex...hWHgVQKHVsDAn4Q_AUIBygC#imgrc=WrGIbFWbC7aN8M: I went through the images and looked at the pages and what vehicles the parts claimed to be for.
You can see that with the motor armature removed how much of the brushes are left. You can also see the rust colored dust that was all over the inside of the motor. Possibly acting like an abrasive.
Better shot of the dust
You can see the missing sections of the commutator. 12 sections, 4 were completely missing, 2 were partially missing. If the motor came to rest with a brush over one of those missing bars, the motor would likely no restart. You can kind of also see that the commutator is also quite worn down by the brushes.
If you pick a motor from a different make/model of vehicle, be sure to grab the rear motor mount. You can see that the motor I picked was longer than the original. The silver mounting plate is not connected to the original housing in this photo.
This seems to be a common problem on all vehicles that use this type of braking system. We are just now getting to a point where the vehicles have enough life in them that the motors are failing. If you have a Gen3, probably worth taking a look at your motor and/or replacing it preventatively. If you were out on the trail and it failed, you're in big trouble.
I don't think it's possible to remove the motor without removing the entire HBB assembly for left hand drive cars. Can probably do it on right hand drive. That's because the motor is backing up against the left side of the engine bay. In RHD the motor will be to the open engine bay. This means you have to disconnect brake lines, pull the HBB unit and upon re-install bleed the brakes.
You're supposed to have a MUT2 scan tool to bleed the brakes, but I monitored the brake fluid level, and did a standard brake bleed, making sure to control the flow of fluid out of the brake lines so that I didn't drain the accumulator or the fluid reservoir too quickly and introduce air.
Summary:
Hydraulic Brake Boosters commonly fail on Gen 3s. It's likely the motor, but could be the accumulator. You can find similar HBB systems on several model's of Toyota in junk yards. Grab the motor and motor mounting bracket, and swap them onto your HBB system. MUCH cheaper, but the motor will probably fail again due to similar wear.
Detailed:
Last Saturday morning, my wife was on the way to a meeting when all of a sudden the car started making a constant beep and the ABS and traction control lights came up. Thankfully she was only a couple of minutes away so she drove home. I gave it a couple of looks and didn't know what exactly it was. So I sent her off in my car and I hit the Google.
What I discovered was that my Hydraulic Brake Booster had just failed and my wife was probably only a few miles away from brake failure! A common problem on Gen 3s and other vehicles that use this type of system.
The hydraulic brake booster is electrically operated and not vacuum operated. From what I understand there is a pressure vessel (called an accumulator) that holds pressure built up by the motor. This prevents the motor from running non-stop. So when the motor stops working, you have a little pressure built up to make a few stops, but not too many.
I called the dealer, and they wanted $1,800 for the entire assembly. I also found a part number online and the dealer wanted $600 for the motor alone. Both items can be had from online for less, but it's still REALLY pricey.
I was thinking that it was quite strange that Mitsu would use a part that ONLY existed on this generation of Montero. A few google searches later I found several other Toyota models that also use the same looking part. Toyota's are much more common at my pick-a-part spots. Also, because this is a common problem on the Montero, I've seen that the HBB is usually the first thing to get pulled from a junked car.
A few online searches and I found a possible 2002 4 Runner that had a similar looking HBB system. Bought the motor for 30 bucks, put it on my HBB system.... bolted it all back up and it's working like a champ.
Short video showing the motor and hydraulic booster system. The problem is that the commutator bars are totally worn down by the brushes. Brushes don't have tons of life left in them either. The 4Runner motor that I pulled showed significant wear as well. Will be looking to pick up another motor on one of my pick-a-parts trips to have as a backup, and to see if they are all in a similar condition. Montero and 4Runner motors both were filled with that rust colored dust.
Nice detailed post about replacing the HBB unit: https://www2.pajeroclub.com.au/forum/showthread.php?t=46516
Part number for the motor only: MN102843
List of possible alternate vehicles to get the motor and/or HBB from. The electrical/computer connectors look to be identical. Only the brake fluid level sensor connector looks to be in different locations. Do you own research on this. I can say that I pulled my motor from an 02 4Runner. Don't know if all option levels of 4 runners in that year will even be equipped with HBB systems.
- 98-00 LEXUS GS300 GS400 GS430
- 01-05 lexus gs300 gs430
- 08-10 hummer h3 h3t
- 03-04 4Runner or lexus gx470
- 02-05 Lexus sc430
- 03-07 Land cruiser/lx470
- 98-07 land cruiser
- 07-09 Camry
How I identified other possible makes/models for similar HBB systems: https://www.google.com/search?q=lex...hWHgVQKHVsDAn4Q_AUIBygC#imgrc=WrGIbFWbC7aN8M: I went through the images and looked at the pages and what vehicles the parts claimed to be for.
You can see that with the motor armature removed how much of the brushes are left. You can also see the rust colored dust that was all over the inside of the motor. Possibly acting like an abrasive.
Better shot of the dust
You can see the missing sections of the commutator. 12 sections, 4 were completely missing, 2 were partially missing. If the motor came to rest with a brush over one of those missing bars, the motor would likely no restart. You can kind of also see that the commutator is also quite worn down by the brushes.
If you pick a motor from a different make/model of vehicle, be sure to grab the rear motor mount. You can see that the motor I picked was longer than the original. The silver mounting plate is not connected to the original housing in this photo.
This seems to be a common problem on all vehicles that use this type of braking system. We are just now getting to a point where the vehicles have enough life in them that the motors are failing. If you have a Gen3, probably worth taking a look at your motor and/or replacing it preventatively. If you were out on the trail and it failed, you're in big trouble.
I don't think it's possible to remove the motor without removing the entire HBB assembly for left hand drive cars. Can probably do it on right hand drive. That's because the motor is backing up against the left side of the engine bay. In RHD the motor will be to the open engine bay. This means you have to disconnect brake lines, pull the HBB unit and upon re-install bleed the brakes.
You're supposed to have a MUT2 scan tool to bleed the brakes, but I monitored the brake fluid level, and did a standard brake bleed, making sure to control the flow of fluid out of the brake lines so that I didn't drain the accumulator or the fluid reservoir too quickly and introduce air.
