Power steering cap blows off

[Shadrach]

I searched and found some threads but not what I was looking for. Twice lately I have blown my cap off. I borrowed one form a friends 03 and bought him a new one only to blow it off again . This time I found it caught in the frame below the pump. What seems to be the problem? Shad

 

[Prairie Dog]

According to this old thread, it's because of the brake accumulater feeding pressure into it.
https://www.turbodieselregister.com/forums/3rd-generation-ram-forum-no-engine-transmission-discussions/151564-p-s-pump-blowing-cap-off.html

 

[ata]

The best way to see if the Accumulater has failed is to start the truck and let it run a little bit. Shut it off and step on the brake pedal. It should feel normal for two or three steps and then get hard. If it's hard on the first step the accumulater is gone.

 

[blacksheepdiesel]

Take the o-ring off the p. s. cap, it will vent the pressure and keep it from blowing off.

Godspeed,
Trent

 

[Hoefler]

There was a TSB out for replacing the cap for a vented one, because of it blowing off.

 

[Bob4x4]

K33 recall is for p/s cap blowing off. The part # for the cap is CBHAK330AA

The recall is for some 2010's

 

[Shadrach]

The pedal goes hard as soon as the truck is shut off. Is the accumulator the blue cylinder by the master cyl marked "compressed gas"? How do you change it? or can I? Shad

 

[Bob4x4]

The pedal goes hard as soon as the truck is shut off. Is the accumulator the blue cylinder by the master cyl marked "compressed gas"? How do you change it? or can I? Shad

Not something for the do it your selfer but there are rebuilders that do it

 

[ata]

Yes the blue can is the accumulater. You have to change out the hole Hydrobooster.

 

[Shadrach]

So if the "blue can" leaks wouldn't it only do it once? Why does it blow the cap off again and again? Isn't all the pressure gone? Or am I missing something? ( not a question I want to ask my wife ) I checked with my friends at the dealer and was told the hydroboost changes up to 4 pieces, must have been a n issue, but I checked with 2 different dealers where I know people and neither were aware of a common problem with the cap blowing off???
Shad

 

[ata]

You are right when the blue can fails it will only pressurize the system once normally. I was just telling you how to check the accumulator. As for it to keep blowing off I don't know.

 

[HHhuntitall]

... once it blows off, it shouldn't do it again. Don't twist the cap on all the way. The canisters lips are probably broken off where the cap is twisted on all the way. Try backing it off 1/4 turn, and it should stay on. Now, the air trapped in the system gets hot, pressurizes the canister, and then blows the cap with no retaining lip off... .

 

[07 ThunderRoad]

From the 2007 service manual

HYDRAULIC BOOSTER

The hydraulic booster uses hydraulic pressure from the power steering pump. Before diagnosing a booster problem, first verify the power steering pump is operating properly. Perform the following checks.



Check the power steering fluid level.

Check the brake fluid level.

Check all power steering hoses and lines for leaks and restrictions.

Check power steering pump pressure.



NOISES

The hydraulic booster unit will produce certain characteristic booster noises. The noises may occur when the brake pedal is used in a manner not associated with normal braking or driving habits.



HISSING

A hissing noise may be noticed when above normal brake pedal pressure is applied, 40 lbs. or above. The noise will be more noticeable if the vehicle is not moving. The noise will increase with the brake pedal pressure and an increase of system operating temperature.



CLUNK-CHATTER-CLICKING

A clunk-chatter-clicking may be noticed when the brake pedal is released quickly, after above normal brake pedal pressure is applied 50-100 lbs. .



BOOSTER FUNCTION TEST

With the engine off depress the brake pedal several times to discharge the accumulator. Then depress the brake pedal using 40 lbs. of force and start the engine. The brake pedal should fall and then push back against your foot. This indicates the booster is operating properly.



ACCUMULATOR LEAKDOWN



1. Start the engine, apply the brakes and turn the steering wheel from lock to lock. This will ensure the accumulator is charged. Turn off the engine and let the vehicle sit for one hour. After one hour there should be at least two power assisted brake application with the engine off. If the system does not retain a charge the booster must be replaced.

2. With the engine off depress the brake pedal several times to discharge the accumulator. Grasp the accumulator and see if it wobbles or turns. If it does the accumulator has lost a gas charge and the booster must be replaced.



SEAL LEAKAGE



If the booster leaks from any of the seals the booster assembly must be replaced .



INPUT ROD SEAL (3): Fluid leakage from rear end of the booster.

PISTON SEAL (6): Fluid leakage from vent at front of booster.

HOUSING SEAL (4): Fluid leakage between housing and housing cover.

SPOOL VALVE SEAL (7): Fluid leakage near spool plug.

RETURN PORT FITTING SEAL (8): Fluid leakage from port fitting.

 

[Shadrach]

... once it blows off, it shouldn't do it again. Don't twist the cap on all the way. The canisters lips are probably broken off where the cap is twisted on all the way. Try backing it off 1/4 turn, and it should stay on. Now, the air trapped in the system gets hot, pressurizes the canister, and then blows the cap with no retaining lip off... .

BINGO That describes it perfect Thanks

Thanks ThunderRoad Shad

 

[Shadrach]

UPDATE I put the cap on as described above and all was good for quite a while, although the truck did drip p/s fluid a bit. I had to remove the cap to add fluid. I have blown it off twice since then and lost 2 more caps. All the caps I have lost were yellow. The replacement I bought to give to my friend was black. The other morning I started up the truck to go to work and when I took off the pump groaned. Since it was dark and cold I drove to work and at lunch time when it was warmer and had daylight I added fluid as it was quite low. The cap was missing again. and of course I have a messy engine bay. YUK , not to mention the smell. I thought I had a leak but maybe it's just the cap that's the problem. David

 

[sag2]

If you take the cap apart you will see it has a small vent built into it. You might try enlarging the vent. It isn't fixing the underlying problem, but may keep the cap in place. If not can you drill a small hole in the side of the cap and tie it up with dental floss. It will not keep it from blowing off, but will keep from losing it again.

 

[seafish]

Here is a post with a nice pic on how to fix the cap so it vents correctly--

http://www.cumminsforum.com/forum/3...ed-power-steering-cap-part-4.html#post7707577

 

[Shadrach]

I got the new black cap and because it is cold out I just installed it as is. When I took it off the next day to check on things there was pressure but the good news is the cap stayed on. I still have a leak but I know I am over filled a bit. Will keep an eye on it. David