Surge tank , system pressure vavle

[richard5933]

Is the pressure valve above the coolant level or below? From what I see in the parts book the overflow comes from up above - is that where the pressure valve is?

If it's above, how do you know it's stuck open?

[bobrl]

The system pressure valve is on top of surge tank cut in so over pressure 3.5-4.5 ft lbs opens it to allow over pressure escape.  Manual says open @3.5-4.5 ft lbs. so i am assuming it is suppose to be normally closed right?  So i took a rubber hose and slipped it over the copper drain off the valve above and can blow back thru valve. Then i took a pair of hos clamps and pinched off that hose and then took another rubber hose and wrapped elec tape couple inches back from the end of it till it made a tight seal when i push it into surg tank fill door and then blow on that hose and with clamp on drain hose it holds pressure, till i release the hose clamp and then i can blow thru valve either way. So it is stuck open , right?😁. Driving me bonkers.

[chessie4905]

Sounds like it. I can't tell from the 04 manuals how it is removed, whether it uses screws or a snap ring. If it cant be repaired, you could have an automotive radiator neck soldered to the tank and use a low pressure radiator cap.

[bobrl]

Yep. Lots of options!! Do u have a parts catalog for the pd4104?  Thanks !!!

[chessie4905]

Yep, have both. If the spring is intact, the seal may be bad. If you need any parts, contact Luke at US Coach in N.J.

[bobrl]

Yes sir. Get parts from him!!! Nice guy and very helpful!!!

[luvrbus]

Why not just pressure the system up with 4 lbs of air to check and see if the valve is bad before going chasing rainbows,there are plenty of plugs to remove to air the system up and check for leaks  .Napa or O'Rileys sell that relief valve too if you can find someone with a brain between the 2 ears at the counter the last one I bought cost me 8 bucks

[bobrl]

I am not sure how i can apply 4 pounds to the system ? As i stated in my posts the pressure relief valve is stuck open!! And i dont know if you have pulled this valve before but it is a one of a kind and its mounted on top of surge tank. Thanks