ptwothree Posted August 12, 2013 Report Posted August 12, 2013 Will this have any adverse effects such as freeze plugs popping out if I run a 7 psi cap? I'm installing an aluminium radiator. It came with this cap. Has anyone gone down this road before? Or should I just stick with the stock cap? Quote
DJ194950 Posted August 12, 2013 Report Posted August 12, 2013 I've got a new alum. radiator in my 50 4 dr. running 7lb. cap for over a year with no problems, tried to get a 4lb. cap for it but napa didn't have a 4 lb. to fit the filler neck of the new radiator. Radiator like that will handle a 16 lb. cap but the motor? I didn't want to try it! Doug Quote
greg g Posted August 12, 2013 Report Posted August 12, 2013 Depends on the radiator design, If the expansion / overflow outlet is below the cap, or on the expansion tank, you could put a 100 lb cap on it and it wouldn't change a thing. To much pressure on a designed to be pressurized system will strain the soldered joints in the radiator before the welsh plugs, assuming they are installed correctly. Quote
Jerry Roberts Posted August 12, 2013 Report Posted August 12, 2013 (edited) Your freeze plugs won't pop out unless they are weak . I am running a radiator from a car that had a slant 6 engine . I use a 13 pound cap and leave lots of air in the top tank for expansion . It has been good for several years now . I also had the radiator modified from 3 rows to 4 rows . Edit ; I also run a 160 degree thermostat and 160 is usually what it runs at . Edited August 12, 2013 by Jerry Roberts Quote
P15-D24 Posted August 13, 2013 Report Posted August 13, 2013 Your on thin ice due to the type of welsh plug used. I wouldn't go over 4-5 lbs. I have seen them fail. Quote
ptwothree Posted August 13, 2013 Author Report Posted August 13, 2013 Your on thin ice due to the type of welsh plug used. I wouldn't go over 4-5 lbs. I have seen them fail. This is my main concern too. Although it seems at least some others on this board are running pressurized systems with success. Have convex plugs been installed from the factory on any vehicles utilizing pressures of 5psi or more? I'm not aware of any, but then, I'm not aware of a lot of stuff! Quote
OldDad67 Posted August 16, 2013 Report Posted August 16, 2013 Will this have any adverse effects such as freeze plugs popping out if I run a 7 psi cap? I'm installing an aluminium radiator. It came with this cap. Has anyone gone down this road before? Or should I just stick with the stock cap? Don't forget your heater core, I don't know if it will take much more than 4 to 7 pounds. I'm going to try a 4 pound cap on my aluminum radiator. 1 Quote
thrashingcows Posted August 16, 2013 Report Posted August 16, 2013 Hmmmm...I never thought of this. I just installed the aluminum rad I got, with the cap it came with. Never even thought about the pressure being too high. Quote
Robert Horne Posted August 17, 2013 Report Posted August 17, 2013 After reading this thread, I checked my radiator cap by placing it on a scale and pushing down to see how much pressure it took to open up, 5 lb.... I took a 15lb cap from the shop and did the same, it took about 20lb of pressure to open..... Quote
garbagestate 44 Posted August 17, 2013 Report Posted August 17, 2013 After installing an aluminum aftermarket radiator with a 7 pound cap, I bypassed the heater core altogether, uncertain as I was about whether the heater core was going to fail under pressure or not. I figure I'll address that problem later since the car is still not roadworthy yet. Quote
55 Fargo Posted August 17, 2013 Report Posted August 17, 2013 7 lb cap, no issues or concerns whatsoever Quote
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