P/S pump blowing cap off

[JHardwick]

A few months back I had a P/S leak that looked like the steering shaft seal. Upon further investigation is more closely resembled a pump shaft seal. I took it to the deal only to be told it was the "O" ring between the reservoir and pump housing.



A couple days later the cap went "awol" and was replaced as a mistake at the same dealer.



The other day coming through Memphis, I noticed some oily spots on the side of my truck and sure enough, the cap was missing. I stopped in Sikeston, Mo and purchased a new cap ... ... ... ... ..... it lasted as far as St Louis.



I drove from St Louis to southern Ohio (Ahia)without a cap and lost very little fluid, but why is the system building that kind of pressure without spewing fluid?

 

[Blu-meanie]

When I had a puddle under my '01, it was caused by the brake accumulator discharging into the power steering pump. The brake booster assembly was replaced and all was good in Dodge Land again.

Maybe you have a partial failure of that and it's discharging nitrogen into the power steering pump. If it is, it will quit when there is no more pressure left in the accumulator and your brake emergency boost pressure will fail.

The next guess is the pump is putting out too much pressure or the fluid is too full.

Good luck

 

[rbattelle]

This has happened to others. Even my P/S cap holds pressure in the reservoir, but I have yet to lose one. Here's a thread about the problem:



Link



Link... post 2 has more links.



Link



Jeff, as an interim solution, what about drilling a tiny hole (or 2) in the cap, then overlaying a small piece of cloth to keep dirt out? When I say "tiny" I mean TINY... like 3/64". This would allow the pressure to vent without blowing the cap off. A temporary solution, at least.



-Ryan

 

[JThiessen]

Yes, there is some relationship between steering box failure and over pressurization of the power steering pump. I had to have both replaced, and both had TSB's. DC covered half the cost (but that was at 37K on the ticker)

 

[JHardwick]

I had to have both replaced, and both had TSB's.

Are you sure? I asked the service manager before ordering this last cap and he found nothing.



Well, my 4th cap came in yesterday. Looking into your solution Ryan, I found that the cap seals about 1/2" down inside to reservoir fill tube with an "O" ring on the cap and does not seal at the cap. What I did was cut a small notch in the "O" ring.



I also noticed what appeared to be a broken reservoir. I figured the cap should lock into place at 90*. Two slots 0* and 180*. Mine has slots at 0*, 90*, 180* and 270* and no stop. You can twist the cap until it comes loose again ... ... ... ... ... . if any of this makes sense? The only thing I could do was turn the cap 45* between the open slots.



I'm sure I'll be buying a cap and reservoir next time :{

 

[Rockcrawler]

After the 4th cap, no help from Dodge and reading a few threads I realized there is no vent to the system- it needs one, fluid gets hot, expands, makes a gas, no place to relieve itself. I drilled and tapped my cap to 1/8 pipe, put a 3/16 poly line to a brass fitting, ran the line up in the xcompartment, but a couple loops in it (dirt trap) and zip tied it out of the way. Worst case- I have a tether if I was wrong- caps been there ever since.

 

[Turbo1Ton]

I noticed a few evenings ago that my PS reservoir was wet along with the frame rail and tie rod underneath it. Never noticed this before. I wiped everything down and took the cap off of the reservoir and man was that thing full! I haven't done it yet but this weekend I am going to return the oil level to normal. I have only had the truck for a few months and that was the first time I have had the PS cap off. Not sure if it was overfull like that when I got it or not. Guess I should have checked all of that stuff out when I first brought it home.



Anyway, mine hasn't blown the cap yet but it is leaking. This thread immediately came to my mind when I saw that it was leaking. Gonna keep an eye on it and see what happens.



Jeff

 

[EB]

I've gone over 130K miles since replacing my hydroboost unit on my truck with no problems or leaks from my power steering pump. I believe there is an obstruction someplace and it causes a "kickback" into the pump and blows the pump cap off. I went through two pumps, then changed the rack and pinon out at Dodge's advice with no change. I then changed the hydroboost unit out on advice from some that had the same problem on Ford 450 and 550's. They have the same type of brake setup with the hydroboost. I was told that there was an obstruction in the hydroboost unit. All I can say is it worked, I haven't had any problems since, over 130K miles.

 

[JThiessen]

I'm fairly certain there were two TSB's that covered mine - maybe the one for the PS pump was under the hydro-boost unit. However, i could be worng!

 

[SKing]

My P. S cap did the same thing and I lost 3. What I found was if you put the cap on and pull up on it, it will come off. The lip that holds the cap on is sometimes broke off the resovore. What I did to fix it was to turn the P. S cap 3/4 turn and it has held ever since.

 

[Sgt Craig]

While I havent had the cap blowing off there is alot of pressure in the system and I found a puddle the other day under the truck. Did some searching and found fluid leaking out of the booster. Went to the dealer to order the booster and aparently there is a revised part list to replace it. The old part# is 5093406aa and Im getting the last one in the chicago area. The revised part list is



5179891aa for the booster

5093407ab for the master cylinder

5093410aa for th nuts

5143262aa for the bracket



My Truck is a 03 SRW 2wd. i dont know if they part numbers will be the same for the 4wd or not.

 

[Superdawg]

EB,
You caught my attention when you talked about an obstruction in the hydroboost. I have replaced the steering gear and pump (factory parts) recently and I still think the steering feels too stiff. Did the steering feel stiff before you replaced the hydroboost? Did it require less effort to turn the wheel after you replaced the hydroboost?
thanks,
Tom

 

[EB]

That happened a long time ago. I really don't recall the steering being stiff or anything else, the cap would just blow off. That was an immediate problem on the truck from day one and was fixed under warranty the first several times. The hydro-boost I had to pay for myself. It did solve the problem. I'm over 420,000 miles on the truck and have never had it happen again.