Booster going out? or maybe its the abs valve

[davlun]

While it seems to be stopping ok, I have not tried to panic stop nor do I wish too. Shop near my office says there is a problem that is outside their services (ie, it is not wheel cylinders, pads, drums, etc).

Doing my own research before posting, I think it is likely to be the brake booster with possible complications from the abs valve.

Here is a video with me pushing on the brake pedal: https://www.youtube.com/watch?v=rF5XeV36Tfg

I would like to diagnose and see get fixed, though will probably hire it done as it is 20 miles from where I live.

Booster?

David

 

[goatwrangler]

Definitely sounds a boost problem to me ! (whoosh is a dead give away )

 

[madpogue]

I wonder if it's that little check valve on the booster.

 

[davlun]

Check valve? Is that something to release the vacuum when finished?

I do get a firm pedal if I step on it fast, but it does not have much stopping power. That is why I "originally" thought it was the leaking rear wheel cylinder that caused the issue, thought it was slipping. However, the leak on the rear wheel cylinder is not that severe and there is no pooling or puddling of oil.

I found talk of there being an issue with the rabs valve on these trucks and it causing what appeared to be a master cylinder issue by dumping fluid, some people appear to have bypassed that altogether.

I seem to have both a sinking pedal and a boost issue maybe?

 

[79jasper]

Start with the booster.
Sounding like that, it's obviously bad.

Sent from my SM-G900R4 using Tapatalk

 

[Greg5OH]

1) socks and sandals-nice!
2) your engine sounds awesome

 

[94f450sd]

Yup you need a booster.easy job to do yourself to save money.its only 6 nuts,a clip and a hose.

 

[davlun]

Ha!

1) socks and sandals-nice!
2) your engine sounds awesome

It is pretty funny, but thats the way I roll, err... walk.

 

[79jasper]

Least it's not socks and flip flops. Lol
You get a booster yet?

Sent from my SM-G900R4 using Tapatalk

 

[davlun]

Nope. Talked with owner of a local diesel shop, he said to take care of the wheel cylinder first as it will need to be done and will help test rest of system by eliminating that. Also, he is so busy, won't be able to do more until next week.

He did say booster is holding vacuum, tested that. Based on his experience, it would likely to be either master cylinder or proportional valve.

He also said my tranny is leaking, oil is leaking and diesel is leaking... add in the wheel cylinder and axle and I am a rolling pin cushion of leaks. Disappointing to be sure but have a desire to get it running and keep it a long time, I do like this truck.

 

[madpogue]

The check valve is that little plastic valve, right where the vac hose goes into the booster. It's about five bucks at the FLAPS. It keeps the booster from losing vacuum if there's vacuum lost from the source. May be acting up when you let go of the pedal. JAT.

 

[davlun]

The check valve is that little plastic valve, right where the vac hose goes into the booster. It's about five bucks at the FLAPS. It keeps the booster from losing vacuum if there's vacuum lost from the source. May be acting up when you let go of the pedal. JAT.

I think I may have tested that without knowing it was a check valve. I started the car, let it idle, then turned it off. Then went to booster and pulled that at the end of the line out. I heard air sucking back into the booster so think maybe it was holding.

Either way, $5 sounds like a good reason to try it out.

 

[94f450sd]

The sinking peddle is the wheel cylinder.it might not be ******* fluid out but it is sucking in air.has no effect to cause the booster to hiss.

Master cylinder wont cause the booster to hiss either.we dont have a proportioning valve.

Replace the booster and the hiss and firm peddle will go away.replace the wheel cylinder and the sinking peddle will go away.

 

[davlun]

Maybe I am calling it something that is different on a diesel, but isnt there a valve that sits between rear and front brakes? I am at work so cant go crawl under truck, but thought that thing was what he was he was talking about.

I have done a lot of google foo and was wondering, since i need drums, brakes, wheel cylinder and at least one axle seal, the cost to convert to disk would be significantly absorbed by those part purchases. I have the bookmark on my other computer at work, but found a kit that allows you to use the calipers from a dodge 3/4 4x4 and a stock rotor that was very inexpensive and seems closer in usage for the replacement equipment than the kits that use the cadillac calipers.

Thoughts? Anyone done this?

 

[79jasper]

Most of those rear disc kits aren't worth it. Especially if you tow any.
That valve is in line with the rear line. It's the rabs valve.

Sent from my SM-G900R4 using Tapatalk