V8dieselnut Posted December 7, 2012 Share Posted December 7, 2012 I have a 90 mack with a 350 in it. I purchased the truck after it was sitting for roughly a year. I purchased it, checked all the fluids and drove her roughly 500 miles home. No issues at all. Now yesterday I started her and took off down the road only to have my temp gauge max out I shut her down and saw all the coolant coming from the bottom of the radaitor. Im thinking the thermostat stuck???? I tryed adding coolant only to have it run out again. I can not locate exactly where it is and if soo How hard are they to replace???? If someone can send me a pic or explain where and how hard and much this will cost me Thanks Quote Link to comment Share on other sites More sharing options...
krismoriah Posted December 7, 2012 Share Posted December 7, 2012 Had the same thing happen to one of the trucks i picked up a few months ago...this truck just ended up needing 'burped' got air lock in the system because of a bad rad. cap. Just run it with the cap off and let the air 'burp' out of the top of the radiator..if the water gets warm up there then your thermostat is open. On the flip side...if this doesnt work...could be a head gasket...but go thru the simple stuff first.. burp the air...rule out thermostats...rule out oil cooler (no oil in the coolant)...then cross your fingers its not a head gasket. Quote Link to comment Share on other sites More sharing options...
V8dieselnut Posted December 7, 2012 Author Share Posted December 7, 2012 I tryed puttuing more coolant in her and it all leaks out from the bottom. Hot or cold it seems to just come out now. The truck only has 110k orig miles also.. Im really stressed about this as its now sitting in a parking lot and I need to figure it out asap befor the church makes me move her. Quote Link to comment Share on other sites More sharing options...
V8dieselnut Posted December 7, 2012 Author Share Posted December 7, 2012 Im willing to pay cash to someone in PA to help me figure this out. PM ME if anyones interested Thanks Quote Link to comment Share on other sites More sharing options...
turckster Posted December 8, 2012 Share Posted December 8, 2012 You need to find the source of the leak first and fix it. The thermostat is in the housing under the upper radiator hose, fairly easy to replace. The hardest part would be replacing the t-stat seal. If you buy the t-stat from the dealer you might be able to get them to replace it for you. The heads on these engines do not tolerate excessive heat, hopefully there is no damage. Quote Link to comment Share on other sites More sharing options...
jakebrake86 Posted December 8, 2012 Share Posted December 8, 2012 After you get the leak fixed, and if you do replace the thermostat, take note that there's a weep hole that should be facing up when you install it. It lets air 'burp' its way out of the system. I had the same problem a few months ago. I bought a thermostat from NAPA, but it didn't have the weep hole in it. Went with a Mack part and it's been working ever since. Hope this helps. Quote Jake Link to comment Share on other sites More sharing options...
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