Printable View
I'm building a custom coolant tank and am wondering how it maintains 15psi when there is an open overflow line off of it. I don't see any pressure relief valves or anything, and just want the thing to function correctly with all the time im putting into it. Thanks
Pressure control is built into the cap. The newer tanks vent off excess pressure to a point below the tank itself, there is a passage molded into the tank to carry the fluid out.
They are pressurized to around 15lbs...which isn't enough to push the fluid out the vent hole, UNLESS there is way too much fluid in there. I believe there is like a 4" distance between the 'max' line and the overflow. I've seen fluid 2" above the flow line before when truck was real hot, but it settles back down cold. (mine is slightly overflowed)
I figured the cap did, but I don't see how it maintains pressure after the truck is shutdown, at least for a little while afterward. I guess the heat is enough to
maintain 15lbs in it.
If you are talking about a coolant recovery tank, there is no pressure in it. The pressure is in the radiator. As the motor warms up and the radiator pressure rises above the set pressure the radiator cap is designed to maintain (15 psi in your case)...the cap will vent air and coolant to the coolant recovery tank as it maintains the set pressure. The coolant recovery tank is vented, so there is no pressure inside it. When the motor is shut off and it starts to cool down, the radiator will start to have a vacuum in it. The cap and recovery tank are designed to allow the vacuum to pull coolant only from the coolant recovery tank back into the radiator. This keeps air out of the system and is the reason there is a coolant recovery tank.Quote:
Originally Posted by flynaked
In the past (before coolant recovery tanks came on cars) as the motor cooled down the radiator would draw air into the system. When the motor was started and it warmed back up it would blow the air back out through the radiator cap. When the motor overheated it would blow excess coolant out on the ground. You ended up with air in the system all the time. With a coolant recovery tank this won't happen because all the excess goes in the recovery tank, and then gets drawn back in the motor as it cools down (never any air in the system).
Ok thanks a lot for the explanation , makes sense now, hope it turns out good.