Probably solved Brakes going hard/ weak braking. Alamosa, CO. (1 Viewer)

[landcruisertx]

Just got to Alamosa, CO while heading to Moab, UT. Went over a mountain highway pass that was about 8000ft and got down into town now my brakes are very weak. About to start doing some field test to see if it’s the booster or something else. Also preparing to do a brake bleed. Any advice would help. I am doing my own research on mud too but figured getting everyone’s brains in this would help. Thank you all!

 

[landcruisertx]

So with research looks like this could be "normal" due to altitude... that being said, will purchase brake fluid and a bleeder to have in case of an emergency.

 

[ajax1]

Your brAkes don’t get weaker because of altitude. Did you ride them a bunch and burn them out? Depending on what trails you are doing in moab and the fact that you are driving around here having good brakes is pretty important. How about some more clues to your issue.

 

[landcruisertx]

Didn't use them a single time going down, it was Highway 160 where the altitude climbed like crazy, and then after going down it acted up. Will probably end up doing a full brake bleed. I honestly don't have any other clues.

 

[coax]

Yea post up some details on what you mean by weak. Not normal for braking performance to be affected by altitude. Did they get squishy?

 

[landcruisertx]

Squishy and there isn’t much breaking happening the first push, then they go hard then next time I try to get them to engage and still not much breaking happening

 

[Shipwreck]

Hard brake pedal pressure is usually indicative of a failing booster or a vacuum leak. Check for leaks first, then focus on the booster. A failing booster is often progressive. Sometimes it works, sometimes not, until it finally fails completely.

Brake Booster Failure.......................Confirmation, Please?

 

[FirstToy]

One thing I've been told, and always do is bleed with the motor running.
I'm not even sure if that's needed, but always did it this way on the 80.

Just got to Alamosa, CO while heading to Moab, UT. Went over a mountain highway pass that was about 8000ft and got down into town now my brakes are very weak. About to start doing some field test to see if it’s the booster or something else. Also preparing to do a brake bleed. Any advice would help. I am doing my own research on mud too but figured getting everyone’s brains in this would help. Thank you all!

 

[Bambusiero]

There is a grommet seal where the manifold vacuum hose goes into the break booster - that has to be a vacuum seal - if it's old and hard or cracked - could cause a small vacuum leak - bleeding away your booster force (I had this once). spooge a bit of silicone grease around there to seal it up & check?

 

[landcruisertx]

There is a grommet seal where the manifold vacuum hose goes into the break booster - that has to be a vacuum seal - if it's old and hard or cracked - could cause a small vacuum leak - bleeding away your booster force (I had this once). spooge a bit of silicone grease around there to seal it up & check?

I purchased the Wit’s End kit for the vacuum line which also came with the Gromit and metal bit. Am now in Moab and the brakes feel better. Thinking that also since I got my vacuum line replaced the booster which may have been slowly dying could have been agitated. Did several booster tests and it passes most but I can hear a hissing noise when I push the brake pedal.

 

[jfz80]

That hissing noise is your vacuum leak. Find that source and you’ve found your problem. I would not gamble on this being ok and hit trails in Moab before fixing.

 

[landcruisertx]

I believe the leak I hear is conning from the booster, any other likely spots?

 

[jfz80]

Not likely unless it’s the main vacuum line running from motor. The leak could be booster internal, booster to firewall, hose or connector, check valve.

This is the one I replaced mine with.

New Toyota Land Cruiser LX450 OEM Seiken Brake Booster with Gaskets 44610-60792

New 80 series, FZJ80, FJ80, 1991, 1992, 1993, 1994, 1995, 1996, 1997, brake, brake booster, OEM, Seiken, japan, 44610-60792

www.cruiseryard.com

 

[60wag]

That's how my 60 booster failed. It would hiss when the pedal was pushed. You got one push of the pedal with boost, then the pedal was rock hard. I'll pulled the booster and took it to a shop for a rebuild. The shop confirmed the leak but a rebuild kit was not available so I replaced the whole booster.

 

[jonheld]

That hissing noise is your vacuum leak. Find that source and you’ve found your problem. I would not gamble on this being ok and hit trails in Moab before fixing.

Sorry, but this vehicle is not safe to drive on the street with questionable brakes. Taking it on a trail is just plain foolish.

 

[greentruck]

Sounds like the vacuum leak is the biggest part of the problem. However, if the system hasn't been bled of old fluid and there's water present, the changes in altitude could make the water more of an issue since altitude will affect the boiling point of the water. The solution is to thoroughly bleed out the old fluid and replace with fresh unless the water has been present long enough to damage things internally through rust, etc, which would require new parts, too.

 

[landcruisertx]

Sounds like the vacuum leak is the biggest part of the problem. However, if the system hasn't been bled of old fluid and there's water present, the changes in altitude could make the water more of an issue since altitude will affect the boiling point of the water. The solution is to thoroughly bleed out the old fluid and replace with fresh unless the water has been present long enough to damage things internally through rust, etc, which would require new parts, too.

Thank you, have an OEM booster on order with all the gaskets,hoping this is the main issue.

 

[landcruisertx]

Sorry, but this vehicle is not safe to drive on the street with questionable brakes. Taking it on a trail is just plain foolish.

We have gone down thousands of feet in altitude and the booster is now working a lot better as it used to. Brakes feel more or less like brakes now... That being said everything that is needed to bleed the brakes is in the car. A new booster is also on its way to Mi Casa. We also have the mindset in place that if we feel that it's completely failing we'll tow or leave the truck.

 

[greentruck]

Thank you, have an OEM booster on order with all the gaskets,hoping this is the main issue.

If you hear the leak, it probably is. But I poked around a little to find some numbers on elevation change vs the boiling point of water to better define the issue for you. Only you know what the status of your brake fluid might be. It's often neglected, until problems crop up. You'll be doing some bleeding in R&Ring the booster, so might as well plan a good thorough purge to ensure this won't be a problem in the future if you suspect water in the brake lines is potentially an issue.

Found a good quick synopsis of the boiling point issue in a USDA food safety guide, where lower boiling points can mean that food needs to be cooked longer to be safe at altitude.

High Altitude Cooking and Food Safety

As atmospheric pressure decreases, water boils at lower temperatures. At
sea level, water boils at 212 °F. With each 500-feet increase in elevation, the boiling point of water is lowered by just under 1 °F. At 7,500 feet, for example, water boils at about 198 °F.

I'm quite familiar with the route you're on, as that's the way I get to the San Juans from Illinois often when I travel to Colorado. La Veta Pass, to the east of Alamosa on 160, crests at 9413', so the boiling point there is roughly 194 degrees F. Wolf Creek Pass, to the west on 160, is at 10,850', so the boiling point there would be about 192 degrees F. If you turn north at South Fork and head toward Lake City on 149, as many Texans do, you cross Slumgullion Pass at 11,361' where the boiling point would be down to around 190 F. So it was good you stopped at Alamosa and evaluated the situation.

 

[flintknapper]

We have gone down thousands of feet in altitude and the booster is now working a lot better as it used to. Brakes feel more or less like brakes now... That being said everything that is needed to bleed the brakes is in the car. A new booster is also on its way to Mi Casa. We also have the mindset in place that if we feel that it's completely failing we'll tow or leave the truck.

It is most certainly your brake booster (hissing sound is a dead give away). Good that you have one ordered.

You likely also have air and water in the brake fluid too, so a good flushing is in order. The condition of your Master Cylinder (if as old as the other components) might be worth looking into as well....since you are already will be knee deep in the brake system anyway.

As for altitude, it DOES affect the performance of Vacuum Assisted brakes since at higher altitude you not able to achieve 'as much' vacuum as at lower elevations (the immutable laws of physics being what they are) BUT a properly working 'system' should not be so affected that it becomes a safety issue.

Good luck with your repair.