My Brakes Just Went Out

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

TigertreeJosh

TigertreeJosh

Joined
Sep 8, 2016
Threads
7
Messages
70
Location
Columbus, OH
I have a pretty stock 78 FJ40. Luckily was on one of my last two lights on my way to work when it happened with no one in front of me and my work lot was surprisingly empty. Basically all the resistance in the pedal just went away, I would roll maybe 4-5 feet further than usual and then stop. The shop I go to can't get me in until the week of the 14th. Any chance there are some easy things a dunce like me could check out? Sound like anything super obvious?
Oh and I will add it only happens when the truck is on. If I went and pumped the brakes in the lot it would feel normal. And the light that is usually on when the parking brake is on came on at some point but didn't stay on.
 
it may just be a hose. I like to look for the weakest link by pushing on the pedal while parked then checking for fluid on the ground. You may need to top off the fluid in the reservoir as well, thats why the light came on. I found two bad hoses on my 80 by doing this.
 
73FJ40 said:
Fluid level?
Click to expand...
Yeah I will go check that in a second. Haven't noticed any puddles on the ground but I guess it's easy enough to check that and take a flashlight out and look for a hose that might have popped off. Is the master cylinder the one other option?
 
Okay brake fluid levels are fine. Only thing out of place is this hose that isn't connected to anything and I couldn't find an obvious place. Any ideas?

IMG_6905.webp
 
There was a place it fit on something coming off the carb so I assumed it went there though it seemed too long for that to make sense. In any event it sounds better now. Brakes are still too soft for comfort but I feel like I can stop effectively though the pedal play makes me nervous. If I give it a second pump it works totally fine. Like if I let it go to the floor and start to stop and then hit it a second time it's like normal so some sort of vacuum leak or something I guess. I feel comfortable getting home to my driveway at least where I can dig in further.
 
TigertreeJosh said:
Okay brake fluid levels are fine. Only thing out of place is this hose that isn't connected to anything and I couldn't find an obvious place. Any ideas?

View attachment 1508199
Click to expand...

Port X on that VCV should go to vent on intake. S goes to vac source (BVSV), Y to lower part of carb and Z to charcoal cannister. Assuming you have one.

Check master cylinder fluid level, aka, open it. Then inspect brake lines from master to each wheel and look for wetness.

Also make sure vacuum line from motor to brake booster is intact, looks fine from the pics so far and the check valve on booster looks rather new.
 
Check for fluid into the booster. Loosen the nuts on the master and pull it away from the booster enough to check for fluid.
 
If you don't have any leaks and you don't because your fluid isn't low, you probably need a master cylinder for your brakes.
 
I did about 100 circles in the parking lot and had confidence I could get home so I took side roads and made it home alright.
I had a mechanic buddy come over last night and we were able to spend more time looking over everything and he, with a more knowledgeable foot than I, did a lot of stepping on the pedal in the driveway and some drive and stops. He feels pretty confident it's the master cylinder.
So I am going to dig into the forum today at rebuilds and options for what fits. Anyone know how long the rebuild takes? Honestly leaning towards jus buying a new one.
 
New Aisin masters aren't that expensive. If fluid got low, it was going somewhere. Also, if it got low, you probably got air in some of the lines. You would need to bleed the system to really be able check the master. Also, a hose won't really pop off completely, more likely it will have a pin hole. If you really push on the pedal, you'll expose the weak spots.

Still, there's a decent chance it's the master. Cruiser outfitters can help you find the right one.
 
If you haven't, check the front disc thickness and the rear brake adjustments. If you buy a new mc, get oem replacement and note the adjuster rod length coming from back of old mc going into booster.
 
Those are both reproductions.

Spend the money on an OEM Toyota MC. Don't skimp on critical safety systems.

Call Cruiser Outfitters.

Cruiser Outfitters
 
I had this happen to me. What happened is the wheel cylinder in my rear drum brake was leaking and I had to pump it at least twice before getting pressure. Was hard to tell of the leak because it was in the drum but my fluid would fall very very slowly over driving. I ended up taking off the drum and noticed signs of fluid, on top of that all my shoe material just fell off and was slowly melting my drum lol.(She was a barn find) Luckily I had a temp sensor that was the same screw size as the brake tee in the rear and just plugged the side that the drum was leaking until I got to a place where I could fix it. Then I proceeded to rebuild the drums. Not very difficult in concept but can be a pain.

You could also do a process of elimination, just plug the rear brake, test, then the front, test, and if it still happens then it's probably something in the engine bay. I pulled a 4runner booster awhile ago from the junkyard and am planning to put that on sometime soon.
 
pjohnson said:
Those are both reproductions.

Spend the money on an OEM Toyota MC. Don't skimp on critical safety systems.

Call Cruiser Outfitters.

Cruiser Outfitters
Click to expand...
I see an awful lot of guys on here singing the praises of non OEM versions. Maybe I can spring for it but I am hot on the heels over over 4k on a manifold and exhaust so if something else will work and save me $200 I need it to. What about splitting the difference and getting the Aisin from them?
 
TigertreeJosh said:
I see an awful lot of guys on here singing the praises of non OEM versions. Maybe I can spring for it but I am hot on the heels over over 4k on a manifold and exhaust so if something else will work and save me $200 I need it to. What about splitting the difference and getting the Aisin from them?
Click to expand...

If you're looking to not spend a lot of money make SURE that the problem is the master cylinder. You'll save yourself a headache of putting on a new part and your problem not going away.
 
Imo, Theres nothing wrong w/Aisin. B4 you pull the trigger you should do as huk mentioned, and pull the rear drums and look for fluid. I'd also carefully look under the wheel cyldr boots for fluid too. Especially if the symptom just started.
 
TigertreeJosh said:
I see an awful lot of guys on here singing the praises of non OEM versions. Maybe I can spring for it but I am hot on the heels over over 4k on a manifold and exhaust so if something else will work and save me $200 I need it to. What about splitting the difference and getting the Aisin from them?
Click to expand...

Aisin is a Toyota OEM manufacturer. It's in the notes o the website :)

As others have mentioned, make sure you need it.
 
You must log in or register to reply here.

Similar threads

6f40j9
I need to fix my brakes
2 3
Replies
43
Views
3K
charliemeyer007
charliemeyer007
Russelld53
Brakes
Replies
2
Views
299
Russelld53
Russelld53
andrewbridges1
Brakes
Replies
7
Views
816
cruiseroutfit
cruiseroutfit
Russelld53
Brakes 1968 FJ40
Replies
2
Views
366
rlong
R

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)

Share this page

Back
Top Bottom