Geking Posted April 12, 2010 Share Posted April 12, 2010 I have an LT1 in my 78Z. I am using the stock radiator, radiator cap, and overflow tank. If I fill the overflow tank up to the full line and let the motor warm up, it starts overflowing in a little fountain out of the air hole in the tank. Once the car settles into its temp at 210* F, this stops after a while. The issue is, after the car cools down, it sucks all the coolant back into the radiator, and then it sucks in air. What would be the solution, do I just get a bigger tank, or do I need a higher PSI radiator cap? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
hoov100 Posted April 12, 2010 Share Posted April 12, 2010 I have an LT1 in my 78Z. I am using the stock radiator, radiator cap, and overflow tank. If I fill the overflow tank up to the full line and let the motor warm up, it starts overflowing in a little fountain out of the air hole in the tank. Once the car settles into its temp at 210* F, this stops after a while. The issue is, after the car cools down, it sucks all the coolant back into the radiator, and then it sucks in air. What would be the solution, do I just get a bigger tank, or do I need a higher PSI radiator cap? Thanks in advance. How many pounds is your cap right now? Quote Link to comment Share on other sites More sharing options...
Geking Posted April 12, 2010 Author Share Posted April 12, 2010 (edited) How many pounds is your cap right now? Not quite sure, what ever the stock Datsun 280Z cap pressure is. According to Source the stock cap pressure is 4.7PSI Also, my Tstat is 195* Herm, that might be my problem... Attached should give some laughs. I thought I had just overfilled it at the time, nope. I know, I need to paint the underside of my hood... Edit, CIMG0078.mp4 You aren't permitted to upload this kind of file Herm, I guess I can't share... Edited April 12, 2010 by Geking Quote Link to comment Share on other sites More sharing options...
hoov100 Posted April 12, 2010 Share Posted April 12, 2010 Not quite sure, what ever the stock Datsun 280Z cap pressure is. According to Source the stock cap pressure is 4.7PSI Also, my Tstat is 195* Herm, that might be my problem... Attached should give some laughs. I thought I had just overfilled it at the time, nope. I know, I need to paint the underside of my hood... Edit, CIMG0078.mp4 You aren't permitted to upload this kind of file Herm, I guess I can't share... If it is a 4.75 pound cap, that is your problem. the minimum I have ever ran on any of my cars, is a 16 pound cap. Quote Link to comment Share on other sites More sharing options...
Geking Posted April 12, 2010 Author Share Posted April 12, 2010 If it is a 4.75 pound cap, that is your problem. the minimum I have ever ran on any of my cars, is a 16 pound cap. Thanks! I just found that I can get a 160* thermostat for my car as well as a 14.7 PSI cap. The two should definitely do the trick. Quote Link to comment Share on other sites More sharing options...
Geking Posted April 23, 2010 Author Share Posted April 23, 2010 Thanks! I just found that I can get a 160* thermostat for my car as well as a 14.7 PSI cap. The two should definitely do the trick. Issue was that I had not bled the air out of the water pump, so the hot coolant was not reaching the thermostat to open it. Quote Link to comment Share on other sites More sharing options...
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