2007 KJ Brake Power Booster Vacuum issues

The vacuum system is slow to recover, at startup and after several repeated brake applications, resulting in loss of power assistance for brakes and the dash venting system not responding to switch positions.

The wheel and master cylinders all function normally while the booster has vacuum, so the hydraulics should not be the problem.

With the main hose from my Vacuum pump connected directly to a gauge, it shows it pulls the vacuum straight down below 25 in Hg, so the pump is OK.

With the main vacuum hose reconnected to the Power Booster Check Valve and the Gauge connected to the smaller port of the Check Valve it shows a slowed rate of drop in vacuum. If you wait several minutes, with engine idle lifted to about 1500 - 2000rpm, the vacuum will drop slowly, and then if the engine is switched off, the vacuum remains, so the booster has no internal leaks.

I now suspect that the Check Valve has internal issues, that are restricting the ability of the pump to restore the vacuum in the power brake booster and the other vacuum operated systems for the dash vents and turbo boost.

Do these "Power Booster Check Valves" have a history of failing?
As the original part listing in Australia, 05072500AA, was deleted in 2019, does anyone know of an aftermarket valve that can replace the original?

 

Not an easy part to find. Don't know if they have a history of failing, but they did sell them as replacement parts till Mopar discontinued them. Appears to also fit Dodge Ram 1500's in those years. Does it look like this? https://www.qocean.top/index.php?main_page=product_info&products_id=81943

 

Yes, thanks, and this is the first time I have seen them listed as new parts.
All the other listings with actual stock have been for 2nd hand units.
As far I as know, they were fitted to the 2007 KJ Liberty/Cherokee, 1500, 2500 and 3500 RAM utes.

Shipping costs certainly inflate the price.

I've done more testing, and besides the possibility of restriction in this valve, the slow increase in vacuum may also be due to the Turbo Boost "Modulator" (52109543AA MODULATOR, Vacuum Electric) not closing off fully.