Radiator cap pressure ?
08-02-2009, 10:09 AM
#1
Race Car
Thread Starter
Radiator cap pressure ?
85-euro: Anyone know the correct pressure cap for this model?
Mine is a Stant 230 16 Lbs I just added some water wetter and it is running a little hotter, not what I envisioned. The cap is a little old and want to replace it.
Mine is a Stant 230 16 Lbs I just added some water wetter and it is running a little hotter, not what I envisioned. The cap is a little old and want to replace it.
08-02-2009, 11:50 AM
#2
0.9 - 1.15 bar I believe where 1 bar = 14.5 lbs approx. If you drained the coolant in this process have you got all the air out? Have you run the engine with the heater on yet?
08-02-2009, 12:20 PM
#4
Race Car
Thread Starter
Car temp is fine just above the first white line. If I'm in traffic goes up close to second line yesterday. The only change was removing the cap and adding water wetter. So I assumed the cap may not be sealing tightly auto zone has a 13.5 for less than 5 bucks the one on it was 16 Lb. It's pretty hot and this maybe normal but it was lower 1/3 below second line before I opened it with the same traffic conditions. The front condenser fan is working but have a air pump bypass and the lawn mower belt is not that tight. It could be due to some slipping wish there was a better solution to the main fan belt.
08-02-2009, 02:46 PM
#5
Rennlist Member
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The main effect of the cap pressure is to change the temperature at which boiling occurs. It does not normally affect running temps at all.
08-02-2009, 02:54 PM
#6
Rennlist Member
exactly. when the pressure gets too high, as with the water boiling, the reservior will push fluid out the overflow hose. to relieve the presure. This reduces the water level which can add to the overheating, and continue pushing water out the vent hose.
This is why, you can run without a cap if the engine temp is below boiling. (cracked water bottle, or bad cap) As wally says, the cap just allows the water to be at a higher temp than boiling, but not boil and create more than 1 bar pressure at the overflow.
This is why, you can run without a cap if the engine temp is below boiling. (cracked water bottle, or bad cap) As wally says, the cap just allows the water to be at a higher temp than boiling, but not boil and create more than 1 bar pressure at the overflow.
08-02-2009, 03:18 PM
#7
Tampa 928s, don't be tempted to fit a higher pressure radiator cap, for the reasons Wally and Mark have pointed out. If, with the standard cap on, your car is overheating then that is something that needs to be investigated and properly corrected. But is your car really overheating? How about buying a cheap-ish infra-red temp. gauge and doing some comparative readings between your car and others (check radiator top, radiator bottom, thermostat bridge, cam covers, etc).
Also I reckon don't be tempted to fit a non standard 'cooler' thermostat. If it really is overheating then that won't help either. By definition, either thermostat will be in its 'maximum cooling' position if / when the engine gets too hot.
Also I reckon don't be tempted to fit a non standard 'cooler' thermostat. If it really is overheating then that won't help either. By definition, either thermostat will be in its 'maximum cooling' position if / when the engine gets too hot.
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08-02-2009, 06:41 PM
#8
Race Car
Thread Starter
I took a 100 mile drive today and everything seems fine. It may have been cap was not on secure lowing the boiling point. I have a new 13.5 Lb cap coming the 16 Lb was on it when I bought it.
