Hi all,

On my brake booster, there is a 'cap' next to the fluid reservoir. This cap is plastic and it is able to be removed. Sometimes, this cap simply flies out of the brake booster and looses all vacuum pressure and the car stalls. I have to find the cap somewhere in the engine bay, put it back on into the opening, and restart the engine. Everything works fine after that. Here is a picture:


In this picture, the cap is off as you can see by the opening. If i put it back in, it snaps in and all vacuum pressure is restored. My question is, why does this happen? This is the 2nd time this month it simply flew off.

 

That "cap" is your brake booster check valve. There is supposed to be a hose that runs from the check valve to the intake manifold.

You need to fix that...

https://www.ipdusa.com/products/2112...YaAk4WEALw_wcB

 

Yes, i am aware that there is supposed to be a hose running - there is. Matter of fact, i just replaced it a couple of weeks ago as it was very old and inelastic and was likely letting off some leakage. My question, however, is not if there is supposed to be a hose or not - its the fact that once in a couple of weeks, the cap off the actual check valve flies off and causes a massive vacuum leak. As a result i have to open the hood, find that cap somewhere in the engine bay, and put it back on. Why does this happen? Its obviously not accidental, as it happens once every 2 - 3 weeks.

 

As you can see in the image provided, the cap on the actual check valve is gone.

 

you need a new check valve.

 

Might there be any reason for this? I'm just trying to figure out if a larger problem is causing this which might need my attention.

 

The original check valve is 30 yr old plastic. Maybe something smacked into it.

 

Start by replacing the check valve and test. It's entirely possible that the original plastic is fatigued, and will continue to do this until replaced. If it happens to a new check valve, then something else is going on that will need to be investigated.