I run out of vacuum.... (1 Viewer)

[ALX4X4]

Not sure how to test at home, but 5 minutes after switching off my engine I have no vacuum left in my brake system.
Which is a pain in a manual trans. You stop on a really steep hill, leave the car in gear, yank on the useless hand brake lever, get out, do whatever you have to do, then to restart the car you put your foot on the brake and depress the clutch. Problem is there's no vacuum assist and you have to jam your foot down so hard its more than annoying on anything steeper than a carpark. Used to get 2-3 brake applications with the engine off with servo assistance, now inside 5 minutes I have none. Brakes still work like a demon when engine is going, just not holding a vacuum 'charge'.
Any ideas or what can I do at hole to check ?
Cheers.

 

[Woofythewolf]

Sounds like a bad check valve, in US models it is PN 44730-28010. You'll also want the grommet, PN 90480-24015, and it just sticks into the brake booster itself like a PCV.
I'm guessing the Australian part numbers won't be any different, but that is just a guess.

 

[robnicko]

You may want to check the seal that sits on the output plunger between the booster and master cylinder.
after you turn the engine off have a listen or put your hand right where the MCyl is bolted to the booster and if you hear a hissing sound of air escaping or feel air then this is where the Vac is escaping from
Mine is doing it at the moment and am going to replace it this week. Mine will hiss and let the reserve vac air out after about 30sec once the engine is shut off

its this

 

[Zjohnsonua]

Check these small parts. And adjust the hand brake... it's stout enough to hold the truck and then some when properly adjusted.

 

[robnicko]

update - I replaced the seal on mine last nite.
pretty easy to do so, just unbolt the MC and move to the side, use a curved pick to remove the star washer that holds the seal in place and remove the seal.
I cleaned up the pushrod to ensure it was smooth and used a little rubber grease on it and the seal itself upon reinstallation. Push the star washer back in with a suitable sized socket and bolt the MC back in - note the MCyl applies pressure to the star washer & seal as well.
Took for a little test drive and stopped for a coffee, still had reserve vacuum after about 10 mins and no hissing after shutdown. Felt the brake pedal this morning and still had two pumps worth of vac reserve before the pedal went hard.

The old seal was hardened and perished in spots. There was a small amount of rust on it however back of the MCyl clean and dry?? I cleaned up as best I could and gave it a quick spray of black paint.
Possibly condensation, who knows but ive never had to top up brake fluid. The paper gasket was toast as well so made up a new one with some gasket paper i had on hand.
I beleive this would have been a small vac leak as well whilst the engine running...

sorry - i forgot to take pics ! but an easy job and done with the Booster in the car

 

[Woofythewolf]

Great to hear, I'm probably going to replace that as PM.
I have an auto so nowhere near as critical, but brakes are important.

 

[93yotasr5]

I’m having a similar issue but it’s happening while driving as well. It feels as though my booster is not getting vacuum as the pedal will intermittently get hard to press. Brakes will still work, but you have to muscle them to stop. It always happens when I’m backing up or going slow in a parking lot. Going to check vacuum lines today and see if anything obvious sticks out.

Sounds like a bad check valve, in US models it is PN 44730-28010. You'll also want the grommet, PN 90480-24015, and it just sticks into the brake booster itself like a PCV.
I'm guessing the Australian part numbers won't be any different, but that is just a guess.

Is there a way to test the check valve to ensure this is the culprit?

You may want to check the seal that sits on the output plunger between the booster and master cylinder.
after you turn the engine off have a listen or put your hand right where the MCyl is bolted to the booster and if you hear a hissing sound of air escaping or feel air then this is where the Vac is escaping from
Mine is doing it at the moment and am going to replace it this week. Mine will hiss and let the reserve vac air out after about 30sec once the engine is shut off

its this

View attachment 3486449

View attachment 3486452

What is the part number for this rubber piece ?

 

[Malleus]

 

[robnicko]

I’m having a similar issue but it’s happening while driving as well. It feels as though my booster is not getting vacuum as the pedal will intermittently get hard to press. Brakes will still work, but you have to muscle them to stop. It always happens when I’m backing up or going slow in a parking lot. Going to check vacuum lines today and see if anything obvious sticks out.


Is there a way to test the check valve to ensure this is the culprit?




What is the part number for this rubber piece ?

I actually used the below one which I believe is for a 60 Series but exactly the same size
My booster is a two bolt type where the MC mounts by the way. The image above shows a 4 bolt type so the pushrod seal may differ however highlighted in the part numbers is the valve seal, not the one I have pictured below
Your issue does sound like the one way valve is not operating / sealing properly

 

[ToyotaDon]

I’m having a similar issue but it’s happening while driving as well. It feels as though my booster is not getting vacuum as the pedal will intermittently get hard to press. Brakes will still work, but you have to muscle them to stop. It always happens when I’m backing up or going slow in a parking lot. Going to check vacuum lines today and see if anything obvious sticks out.


Is there a way to test the check valve to ensure this is the culprit?




What is the part number for this rubber piece ?

To test the check valve, you carefully remove it and blow through it both ways. It should not allow air to flow when blowing from the hose/engine side. I recently had to replace my booster after it started acting up, and my guess is you are going to have to replace the booster for this intermittent issue. Mine was a Seiko unit from CruiserYard (@arcteryx )

 

[93yotasr5]

To test the check valve, you carefully remove it and blow through it both ways. It should not allow air to flow when blowing from the hose/engine side. I recently had to replace my booster after it started acting up, and my guess is you are going to have to replace the booster for this intermittent issue. Mine was a Seiko unit from CruiserYard (@arcteryx )

That was my initial thoughts, but wanted to be sure there wasn’t some other special method to get it.
I’m about to go outside and test the valve and diagnose this a bit more. I hope you’re wrong about needing a new booster.

Update- check valve is working properly:/ ruined the grommet so I’ll order a new one of those……

 

[BILT4ME]

That was my initial thoughts, but wanted to be sure there wasn’t some other special method to get it.
I’m about to go outside and test the valve and diagnose this a bit more. I hope you’re wrong about needing a new booster.

Everything you're describing points to the booster.

When you're at idle, your vacuum is high and that's when you describe your pedal as hard. That's a bad booster.

Start shopping.

 

[93yotasr5]

Everything you're describing points to the booster.

When you're at idle, your vacuum is high and that's when you describe your pedal as hard. That's a bad booster.

Start shopping.

Looking at them online now. Jesus they are not cheap! Can they be rebuilt? I may look into used options.

 

[BILT4ME]

Looking at them online now. Jesus they are not cheap! Can they be rebuilt? I may look into used options.

Don't get a used one. You're just going to have the same issue again later.

Get a Seiken unit from @arcteryx he has some of the best pricing for a quality unit that's not OEM and not your FLAPS garbage.

 

[arcteryx]

Thanks fellas, here is the link, comes with a 2 year warranty.

New Toyota Land Cruiser LX450 OEM Seiken Brake Booster with Gaskets 44610-60792 - https://www.cruiseryard.com/80-series-new-oem-seiken-brake-booster-and-oem-gasket/