Radiator cap #?
Postmaster
Joined: May 2004
Posts: 2,854
Likes: 0
Yeah, after it reaches the specified rating, it vents off.
Why all different? My first response was gonna be "why anything?", but I now think youre asking a theoretical question. My response would be "I don't know".
My 78 Grand Prix calls for a 15#. Maybe they don't all differ.
I guess if you had a higher temp thermostat it would try to operate at a higher pressure. Thoughts?
Why all different? My first response was gonna be "why anything?", but I now think youre asking a theoretical question. My response would be "I don't know".
My 78 Grand Prix calls for a 15#. Maybe they don't all differ.
I guess if you had a higher temp thermostat it would try to operate at a higher pressure. Thoughts?
Junior User
Joined: May 2009
Posts: 50
Likes: 0
Radiator cap pressure rating ?
My 1996 F150 w/4.9 L has a 13 lbs. radiator cap , is that the correct one for that year ? I have been having some problem with the radiator " bubbling " ( more like boiling if the a/c has been used ) into the overflow . This truck is a new acquisition and I'm feeling my way with it . The biggest problem being more specific with the actual engine temp is the dash gauge doesn't work despite my best efforts to repair it .
Posting Guru
Joined: May 2007
Posts: 1,208
Likes: 2
From: North Reading Mass
One of my vehicles called for a 15lb cap with A/C 13lb without. Another had a higher rating with HD cooling.
If your coolant is bubbling its probably boiling. Check the strength of your coolant. It should be 50/50 to provide the increase in boiling temp as well as freeze protection.
If the coolant is OK then the bubbles could be coming from the head.
regards
rikard
If your coolant is bubbling its probably boiling. Check the strength of your coolant. It should be 50/50 to provide the increase in boiling temp as well as freeze protection.
If the coolant is OK then the bubbles could be coming from the head.
regards
rikard
Senior User
Joined: Jun 2009
Posts: 480
Likes: 0
From: Hudson,Michigan
I think the difference is because they found that coolant circulation is better under pressure and since lots of systems are different,like a/c or not,bigger radiator,change in water pumps and on,and on,they may take different pressures.Dropping pressure may be easier on tired hoses and radiators,but also may make you over heat easier.They also like no air in the system,that's why they have an over flow/recovery system container.You put so much coolant in it,with the radiator full and if it expands it puts some in and burps the air and if it needs some,it draws it out.EPA loves it,no anti-freeze on the ground.I had a '70 Merc That I had to run straight uncut anti-freeze in during the summer because it would boil with the a/c on if I didn't.The straight got me about 10 degrees that I needed and I had a mechanical water temp guage on it,where the copper line went right to the mechanical sender,with a big copper piece in it,no mickey mouse electrical guage to guess at.Well, hope I helped some one.
