g-g-g0 Posted June 4, 2020 Share Posted June 4, 2020 (edited) My 57 is causing me to have undue stress!! 🤪🤪 Facts: 364 rebuilt, radiator checked and cleaned at radiator shop. Coolant appears to be circulating when cold and radiator cap removed. Thermostat has been REMOVED. Temperature runs 190 give or take a degree or two. Temps read from infrared thermometer and auxiliary temp gage. Problem: When engine comes up to temperature (190 +/-) and the radiator cap (new 13# cap) is on, the upper radiator hose has pressure on it. It is as hard as a rock. Condition exists with or without thermostat. Previously when the engine came up to temp and the thermostat opened or with no thermostat, the upper hose was pliable and could be squeezed. Performed as expected a. for a year or two after the rebuild. Thoughts as to what the issue could be? Where do I place the first stick of explosives? Edited June 4, 2020 by g-g-g0 (see edit history) 1 1 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 4, 2020 Share Posted June 4, 2020 (edited) Is the 13# cap the correct pound cap for your Buick? Anyway, the hoses should be very firm when the engine is up to temp. BTW, after I did a in frame rebuild of my 264 did the radiator hoses get firm when warm. Never did before the rebuild. I think I have a 7# cap on mine. Edited June 4, 2020 by avgwarhawk (see edit history) Link to comment Share on other sites More sharing options...
JohnD1956 Posted June 4, 2020 Share Posted June 4, 2020 3 minutes ago, g-g-g0 said: Where do I place the first stick of explosives? Under your wallet. It may be advisable to have the coolant checked for oil and I am not sure but is there something to test for combustion gases? I am thinking a bad head gasket. 1 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 4, 2020 Share Posted June 4, 2020 2 minutes ago, JohnD1956 said: Under your wallet. It may be advisable to have the coolant checked for oil and I am not sure but is there something to test for combustion gases? I am thinking a bad head gasket. Easier yet, check your oil for coolant. Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 4, 2020 Share Posted June 4, 2020 (edited) As a side note, before your rebuild, the old radiator cap was probably not holding pressure. Hoses were soft as a result. You now have a new cap with pressure holding ability and it is doing just that. I don't see any issue with what you are experiencing with the rebuild and new cap. Edited June 4, 2020 by avgwarhawk (see edit history) 2 Link to comment Share on other sites More sharing options...
lancemb Posted June 4, 2020 Share Posted June 4, 2020 I concur with above. If it is not overheating, it sounds like it is as it should be, pressurized when hot. In fact, lack of pressure can cause it to overheat. 1 Link to comment Share on other sites More sharing options...
old-tank Posted June 4, 2020 Share Posted June 4, 2020 What kind of driving produces those temperatures? Is there a temperature drop between the upper and lower tanks? How many miles on the rebuild? New engines produce lots of heat due to friction of components not fully broken-in. My convertible ran hot like that for 1500 miles and all I did was hone the cylinders and install new piston rings. I was about to pull the heads, but decided first to beat on it....mostly full throttle accelerations for 50 miles and 1/2 tank of gas. 1 1 Link to comment Share on other sites More sharing options...
g-g-g0 Posted June 5, 2020 Author Share Posted June 5, 2020 Appreciate the responses. As for the cap, according to the info I was able to find, 13# is the correct cap. Car probably has less than 500 miles on it. According to the gauge it does not run “hot”. Without the thermostat it gets to 190 +/-. Not sure what it read before I removed the thermostat. The core support and surrounding metal get really HOT! Before this present situation, once the thermostat opened I could always squeeze the upper hose and you could hear the fluid sloshing in the radiator. I am very reluctant to drive it as it appears that the pressure on the upper hose is excessive and I don’t want to blow the hose and/or get stranded. Oil and radiator fluids appear normal. No water or oil in the wrong places. Maybe I am over reacting but the current condition is very different that before. I am sure there is more than 13 pounds of pressure in the system. The hose is as hard as a rock. Link to comment Share on other sites More sharing options...
old-tank Posted June 5, 2020 Share Posted June 5, 2020 If you cannot test the cap, replace it. My 55's with factory a/c use a 13# cap; l had a defective one that ruptured a radiator. Or test with a7# cap or other known good cap. 2 Link to comment Share on other sites More sharing options...
MrEarl Posted June 5, 2020 Share Posted June 5, 2020 Trapped air/air pocket maybe. I always "burp" the system whenever I totally drain the radiator or refill the system. Here's a good how to https://www.instructables.com/id/How-to-Burp-your-cars-cooling-system/ 2 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 5, 2020 Share Posted June 5, 2020 Try another cap as Willie suggested. Link to comment Share on other sites More sharing options...
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