521 brakes pumping up

[banzai510(hainz)]

I notice my brakes were pumping up and geting harder everytime i hit the brakes. But wasnt enought ot really overheat them. In morning the pedxal would drop more normally but later it would start getting tight. I mean like I have my parking brakes on and just put your foot on the pedal there was no movement.

Well last night driving home It really hit and had to go to my parents. as they were cooking. Well at least the back was.

 

I told my dad I think its the master cylinder as why both back drums were hot.

He want to pop a drum off I said OK to make him feel better. But seen as I hit the blled screw it released and worked ok. never took the other drum off. Just rebleed the brakes and seems normal now.

Now the pedal goes lower enough to trip the rear brake light switch(which also had a blown fuse). Got that fixed and then thought crap I have a single resivoir master didnt even ck if the Froont brakes were hot.

 

any thoughts???????

Could it be the taiwan master with a ck valve or the distribution junction has a ck valve?

 

never had this happen before. But I assume it was the master right off.

[MicroMachinery]

This happened to me once before, and I chased the problem round and round until I found out that the little screen inside the master cylinder reservoir was pushed down too tight and not letting fluid return. I would be driving, the pedal would get stiffer and stiffer, and eventually the brakes would lock up, and I wouldn't be able to drive it for some time. I'm not saying that that's for sure your problem, but try taking the little screen out and see if that does anything for you.

 

Even if that's not it, you're on the right track suspecting the MC. There's some reason that the fluid isn't returning from the rear wheel cylinders. I'm just throwing that out there as a very unusual situation that I've seen first hand.

[datzenmike]

If the peddle was rock hard then pressure must have been trapped in the whole system. Only thing common to the whole system would be the master. Get one.

 

 

[metalmonkey47]

My brakes did something similar at one point. After I flushed the brakes it seemed to get much better, but I will be replacing the master cylinder soon anyways. So far, it's the only part of the brake system that's not new on my truck.

[banzai510(hainz)]

crap I put this in the electrical section

[datzenmike]

Easy fix...

[EricJB]

I had the same thing happen on a VW bus when I was 16. Turns out it was from my own ignorance in adjusting all the play out of the pedal, and then some, The piston was unable to travel back and relieve the pressure. So I carried a wrench with me and cracked a bleeder everywhere I went. My own worst enemy.

[jesusno2]

99% sure you got a return issue or a sticking caliper/or wheel cylinder.

[banzai510(hainz)]

It did it agin on the way home from work.Started locking up again.

Felt all the brakes and all hot so it has to be the master right? I jacked up the truck on side of road and popped the bleed valve it released.

Swapped another Brake masker in(Taiwan Dorman Brand) and will bleed to taday and see what happenes.

 

This is like the 3 brake master sinece I owned this in 12years. All Taiwan ones and thats why I say get spares or japan made ones.

 

Also the throw length might need to be adjusted as I had to shorten the threaded shaft to get the pedal to go all the way out.

[wayno]

Do you have front disc brakes Hainz?

[banzai510(hainz)]

NO I have stock brakes 1 fill cylinder.

 

I bleed the rear brakes and then went to bleed the fronts and one bleed cap the tip broke off.

The driver side bleed screw is frozen solid.

 

I said Lucky I got new front wheel cylinders then went to look at them they only have the wheel cylinder them selfs and not the backing block to plug the line in and the bleed screw. So these are more or less worthless as the new ones are made in Italy and dont want to rick swapping right now. I just tighten up the brake adjustment wheels. seems OK for now.

I guess I need a whole new wheels cylinder with all the stuff.

 

also one rear cylinder the wheel was hard to turn so I had to take it apert and WD40 and use anti seize on it. works OK now

 

I guess I should get a Disc up fron if I plann on keeping this. But stock seems ok for me.

Be honest the 521 is getting old to drive But I have so many extra parts I just keep it going.

[banzai510(hainz)]

ON rockauto seems the wheels cylinder dont come with the part on back side of the brake dust plate.

Datzenmike you got part numbers?????????? the rear Y block. really maybe I just need new nipples if that 14mm hex blocks are OK

[banzai510(hainz)]

found one on Rockauto Wagner brand #WC96461

[wayno]

How did it work out other than the bleeder valve breaking off, since you changed the master only, then all the air would flow to the open bleeder, so I shouldn't effect the drum that didn't get bled.

If I were to guess, I would say the residual valve failed in the brake master cylinder, so instead of holding 10lbs. of pressure on the brakes, it was holding a lot more.

When it does this, or when you change the fronts to disc brakes, this very issue comes up if you use the stock master, unless you pull the residual valve out of the brake master cylinder, I had to remove it in my 521KC project, I turned a driveline out of it trying to keep it moving, it's a diesel, it has a lot of torque, I opened the bleeder and we towed it home.

I have extras of what you need to replace the broken part, I keep them as backup, even though I only use them on the 320s now, as all the 521s have 720 brakes front and back now.

I can't remember where you live now, portland or alburn wa.???

The foster road pick n pull has a 521 in there yard right now that will likely have what you need also.

Let me know if you need my parts. wayno

[banzai510(hainz)]

Find out the Wagner part number I already have in boxes but no Backing Y pipe part with the bleeder. But shows this in the photo on Rockauto.

 

Wayno I will let you know. Everything works right now. If I can just fbreak the blled screw on the driver side all I need is the breed screw then.

 

Maybe Ill do a brake disc swap. Never really though much about them as I alwas considered my 521 more disposable than my 510s

[banzai510(hainz)]

Just cked with Rockauto and they said the back bleed screw part and hex dont come with the new part (You got to be kidding me!!!!!!!)

I will try Carquest aand then the nissan Dealership

then Wayno

[wayno]

I have 6 or 8 of them in a ziplock baggie, that's something I keep, as it doesn't take a lot of room to store, bag them, and throw them in a box with all the other bags of shit, keep box in spare bedroom. :rolleyes:

You live in portland or the seatac area?

[banzai510(hainz)]

I live in Covington when is By the raceway. SIR or whatever they call it now. Pacific raceways.

Kent east hill. near auburn.

 

Well I went to the Younker nissan dealer ship and ordered 2 bleeder and a 1 hex and 1block. Wendy the older gal works there and she knows the 510s and stuff. Ordered the parts and will see it they come it.

I PB Blastered the bleed screws and will do it again later and see if I can bust them loose and just replace the bleed screws and antiseize the shit out of them before I put them back in.

 

Wayno I will let know know if I need them