Shi**y brakes

[alexandervanbaelen]

Hi all,

I am having some brake issues with my 1999 HZJ75 with 240.000 km.

Since a few weeks I am having seriously bad brakes: the pedal is hard and there is no brake power. I have read about it and try to find the best solution without making unnecessary expensive replacements!

Some weeks prior to the issue I replaced my front brake discs and replaced the pads which were still fine.
After I went to the technical control, after which the issue occurd. At first I thought one of the techniciens might have messed around with something, but I highly doubt this.

I have conducted the following tests:

- When the engine is turned off I depress the brake pedal, when starting the engine, the pedal goes down (not as much as before, but it goes down)
- After having the engine on for a while, I turn it off with the pedal pressed. The pedal does not move down significantly (when pressing it I did have the impression there was a tiny bit of move in it (like 1 or 2 mm), but I think this was more because I was focussing on it)
- When pressing the brake I do not notice any difference in rpms when running idle, nor do I hear a real sounds coming from the brake pedal.
- In the past I did notice some blowing noise when changing of gear (no idea if this is related)

So I started to check the issue and started at the rear drums. Who knows that after 240.000 km they are worn and that causes me to have bad breaks. Well it turns out they are okay. To my surprise I saw that my pads are in near perfect condition after being on for 60.000 km!! My susprision is reltated to the LSPV, which hasn't been amended after the car got an OME lift kit of 7cm/3 inches. Anybody can confirm this?

So having noticed that the rear brakes are fine I will do the following checks:

- Bleed brakes and LSPV to ensure no air is in the lines (okay, this is not really related to my symptoms but doesn't hurt I think)
- Check the tubing going to the Brake boosters and verify if there is a vacuum which gets stronger when increasing the rpms while also checking on cracks
- Check the calipers, maybe one of them is seized after putting the new discs (mine where at 16mm when they should be replaced at 19mm), maybe the large difference makes them to seize?

Do you think something else should be checked? Maybe the vacuum pump itself? I am a bit worried not to find the issue and to replace parts which should't be replaced yet. I understood that the brake booster is expensive and that failure is rare. I assume the same applies to the vacuum pump?

Would love to hear your input!
Thanks!

 

[Aussie 25]

Hard brakes and no stop.
1 Look at the fount calliper, remove the pads and see if you can push the pistons in easy,i put a clamp on the line and as you push one in the others come out then push the others. if they are sized rebuild them.
2 If they are good remove the power booster and turn it upside down and see if fluid comes out.
3 Cheap and nasty pads will also do this.

 

[jblueridge]

I had this problem and it was the brake booster... I had to get some professionals to test it and then rebuild it.

While I was trying to identify the problem I clamped off various rubber brake hoses to help me find the cause.

I believe I need to re-build my vacuum pump or add a larger vacuum "reservoir"; the brake light comes on when it is cold outside and when the engine has just been started.
I now also wonder if I need to get the clutch booster re-built.

 

[Bob Richards]

Vacum pump rebuild kit is like#90 USD and not much to it. Boosters can be purchased for as low as 300 to 400 depending on the specific year and the brake master cylinder is something like $125 at least for the one I purchased...

 

[alexandervanbaelen]

Hard brakes and no stop.
1 Look at the fount calliper, remove the pads and see if you can push the pistons in easy,i put a clamp on the line and as you push one in the others come out then push the others. if they are sized rebuild them.
2 If they are good remove the power booster and turn it upside down and see if fluid comes out.
3 Cheap and nasty pads will also do this.

Thanks Aussie 25, will have a look at this in the weekend. Somehow I am hoping that the calliper is seized - although it might be the same price to rebuild them and more work than replacing the brake booster!

I had this problem and it was the brake booster... I had to get some professionals to test it and then rebuild it.

While I was trying to identify the problem I clamped off various rubber brake hoses to help me find the cause.

I believe I need to re-build my vacuum pump or add a larger vacuum "reservoir"; the brake light comes on when it is cold outside and when the engine has just been started.
I now also wonder if I need to get the clutch booster re-built.

Hi Jblueridge! Good to hear you were able to fix it! You think that the faulty vacuum pum is related to the issue or it is just a coincidece? I was thinking that if the vacuum pump would be faulty you should notice something in your clutch as well, no?

Vacum pump rebuild kit is like#90 USD and not much to it. Boosters can be purchased for as low as 300 to 400 depending on the specific year and the brake master cylinder is something like $125 at least for the one I purchased...

Hi Bob, you suggest to replace the VP and the MC together with the brake booster in case its faulty?

 

[Bob Richards]

My understanding is that the master cylinder fails first (as far as brake parts under the hood) and the cost to rebuild the vacuum pump is low and it gives you a good chance to clean all the connections and go through the vacuum hoses really well. I think I am going to have to replace the booster however myself... when you lift the truck and put larger tires on it and the fact that they are roughly 30 years old justifies to me of a complete replacement of your brake system in the order you can afford it. I actually am using 80 series brake parts everywhere I can as they have better braking.

I was also thinking about getting a bigger vacuum reserve canister as mine is the size of a large tuna fish can right now

 

[jblueridge]

My vehicle is RHD: the brake and clutch masters are easier to rebuild than replace.
I think you are right saying its a good idea to replace all the hoses too.

 

[alexandervanbaelen]

Hi all,

Small update:

So last weekend I tackled the issue and started to verify everything:

- Vacuum was good
- Booster seemed to function normally

So I started to check the callipers. When undoing on of the lugs a thread ofthe bolt got stripped, making it unable to remove it! Given the many variables in the brake system I decided to bring the car to my preferred mechanic to check it out and to remove the stripped bolt.

The repairs still need to be done so I still cannot confirm that the issue had been found, but based on their analysis they say the braking issue is due to a faulty lpsv and that it has to be replaced. Apparently there was no brake power to the back. This I had noticed myself as the pads were intackt.

In addition, the mechanic only does land cruisers and mentioned he had never ever had a faulty brake booster. Not saying that it doesnt happen, but whenever there are brake issues, the brake booster is most likely one of the last things to fail...

Hope that this resolves the issue on my side.

Thanks all for the input!

 

[Aussie 25]

Gee that's no good of the bolt stripping. Not a big problem just fit a recoil. I fixed a another one today with a seized calliper. It had a fairly hard pedal & wouldn't stop. 1 piston sized in each calliper.