Question for the day. What is the correct radiator cap for my 57 235 in my 51 half ton. I was doing a general inspection on the truck and pulled off the radiator cap and found it all rusted up after only a year. Purchased it from the host here and it's was made in Mexico. I put the old one back on and noticed it said 7 lbs on it while the replacement from Mexico had no markings on it. Searched the treads here and have read where anything over 4 lbs may damage the heater core causing it to leak. So should I go back to the first one that is rusted up or leave the 7 lbs one on that appears to be in better condition? I may try Napa next time for replacement. Dave I hope the host pays attention to this forum so the can get a handle on some of there quality issues.
Is it only rusty on the inside ? might be telling you there's rust deep within the water jacket , a bad thing indeed . You can use any Phosphoric Acid based cleaner to soak it and make it look new again , Sno-Bol toilet cleaner for example . Read the fine print ! . 4 # is good as it raises the boiling point of plain water by 3? F for each pound of pressure . Add in the coolant mix and you shouldn't ever have any overheating issues .
4 pounds I use the 4 pound radiator cap on my 235. I also use the 185 degree thermostat per Nate's instructions. Jim
Thanks all, I will look for a 4 lb cap. I just installed a 160 degree thermostat for the summer, note I have not any overheat issues. Nate should I be worried about rust in the water jacket? The coolant I took out looked pretty green with no real rust color to it. Dave.
Coolant Care Hi Dave ; Id there's _any_ rust in it I'd worry . For now , just run it hard and hot ~ if the translucent coolant turns murky or red / brown , be aware you'll have to address it seriously and soon . Not expensive to do right but takes some time and you must drive it daily until it's 100 % clean then you can relax and make your own 40/60 % mix of distilled water and coolant or just buy the best (Honda , Mercedes , like that) brand of pre mix , change it every 24 months regardless of mileage as RUST NEVER SLEEPS and it can and will , eat holes right through the cylinder block , ruining it .
Thanks Nate. I will watch over time. I too have had several British cars (Mg's and Triumphs) so am use to engines that weep a little as the truck does. The electrical is a little better on the truck then the British stuff. Dave
Oil Weeps & Seeps FWIW ; I hate oil leaks and I'm now using Permatex " The Right Stuff " because it's AMAZING , unlike any RTV stuff you've ever used before . Just use a super tiny thin bead of it instead of or smeared onto , gaskets , button it up and you're good to go . Simply amazing stuff and very co$t effective too *if* you're careful . I'm using a 5 + year old foo - foo can of it now .
Citric Acid Flushing Citric Acid powder , one pound per gallon of water , use distilled water and mix it out side ofd the radiator then pour it in and DRIVE it a while . I'll usually turn dead black , this is good as it means you're dissolving the rust and scale .Solder bloom goes away too . You must first flush out all the old coolant , then drain the system and fill it with the citric acid and distilled water mix .
