04-26-2006, 11:56 PM
sweet! 
I hooked up a gauge to read coolant pressure today. I think it's the new hot thing, you ain't cool if you don't got one.
I will play with it some more, but I think it's pretty useful, (at least for me) maybe even more so than a temp gauge. When cruzing or idleing, at normal operating temp (175 for my car with its slightly lower than stock thermostat), it reads about 7 psi. But if I let it sit and idle, and don't turn on my radiator fan, just letting the coolant temp raise to 180 brings the pressure to 10. 185 is more like 13.
My GUESS is that if the temp were to go up to the 190's, the cap would start to vent, and the gauge would level off at 17 psi as that's what my cap is rated. I might test that theory later. But since my normal operating temp is lower than that, if my gauge was ever showing 17psi, I'd know something was not quite right. HOW not right, I may not know, but it's time to shut it down!
So for the most part, during normal operation, the pressure gauge pretty much follows the temp gauge.
But it seems a little more useful, because it's going to react imediatly to a sudden leak. And if there's a slow leak, or the cap isn't sealing quite right, when I shut down the car, the gauge is going to drop much faster than usual. Right now, even an hour and a half after shutting off my car, it's still at 3 psi. Remove the cap and it drops instantly.
Another plus to hooking one up, I don't think it would matter where you tied it in, the pressure should be the same everwhere.
The only drawback for some cars I can think of: If your operating temp and pressure are not below the pressure the cap was rated for, if they were equal, the gauge might not be very useful. If the temp was slowly climbing, the venting cap might keep the gauge showing that everything is ok. Installin a higher pressure cap or lower temp thermostat would fix that.
Also, I'm not yet sure if my operating pressure is always going to be around 7psi. Let's say it's 90 degrees outside. I start my car and the coolant is already 90 degrees at 0 psi. At 175, will my pressure gauge read lower than usual? Or if we start at 20 degrees. At 175, will I be hitting 17 psi? Thoughts? I guess we'll see.
I hooked up a gauge to read coolant pressure today. I think it's the new hot thing, you ain't cool if you don't got one.
I will play with it some more, but I think it's pretty useful, (at least for me) maybe even more so than a temp gauge. When cruzing or idleing, at normal operating temp (175 for my car with its slightly lower than stock thermostat), it reads about 7 psi. But if I let it sit and idle, and don't turn on my radiator fan, just letting the coolant temp raise to 180 brings the pressure to 10. 185 is more like 13.
My GUESS is that if the temp were to go up to the 190's, the cap would start to vent, and the gauge would level off at 17 psi as that's what my cap is rated. I might test that theory later. But since my normal operating temp is lower than that, if my gauge was ever showing 17psi, I'd know something was not quite right. HOW not right, I may not know, but it's time to shut it down!
So for the most part, during normal operation, the pressure gauge pretty much follows the temp gauge.
But it seems a little more useful, because it's going to react imediatly to a sudden leak. And if there's a slow leak, or the cap isn't sealing quite right, when I shut down the car, the gauge is going to drop much faster than usual. Right now, even an hour and a half after shutting off my car, it's still at 3 psi. Remove the cap and it drops instantly.
Another plus to hooking one up, I don't think it would matter where you tied it in, the pressure should be the same everwhere.
The only drawback for some cars I can think of: If your operating temp and pressure are not below the pressure the cap was rated for, if they were equal, the gauge might not be very useful. If the temp was slowly climbing, the venting cap might keep the gauge showing that everything is ok. Installin a higher pressure cap or lower temp thermostat would fix that.
Also, I'm not yet sure if my operating pressure is always going to be around 7psi. Let's say it's 90 degrees outside. I start my car and the coolant is already 90 degrees at 0 psi. At 175, will my pressure gauge read lower than usual? Or if we start at 20 degrees. At 175, will I be hitting 17 psi? Thoughts? I guess we'll see.
The only thing that stops a bad guy with a van is a good guy with a van