Gregball Posted August 14, 2017 Share Posted August 14, 2017 Hello group. I need some help on my'95 mack r model. E-7 300horse. It was running hot so I replaced the t-stat and did a flush. Test run with t-stat out and still runs hot but only at hwy speed. Putting around the city it runs normal temp. Is it possible that the waterpump isn't doing its job? What would be most suspect? Any help would be appreciated. Thanks. Quote Link to comment Share on other sites More sharing options...
dogg rescue Posted August 14, 2017 Share Posted August 14, 2017 Is your radiator, and air cooler plugged with bugs? It doesn't take much crap stuck in them to make them run hot. My CH had paint flaking off the charge air cooler in every opening that would seriously restrict airflow. Quote Link to comment Share on other sites More sharing options...
fjh Posted August 14, 2017 Share Posted August 14, 2017 Fan working? Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted August 15, 2017 Share Posted August 15, 2017 And also what is hot? Quote glenn akers Link to comment Share on other sites More sharing options...
h67st Posted August 15, 2017 Share Posted August 15, 2017 Is your radiator, and air cooler plugged with bugs? It doesn't take much crap stuck in them to make them run hot. My CH had paint flaking off the charge air cooler in every opening that would seriously restrict airflow. Thumbs up on that one, dogg rescue. When I worked in truck shops we found a lot of radiators plugged on the air side. If that's not it, how does the inside of the radiator look? Was the old coolant nasty? If that's okay, the water pump could be the culprit. Quote Link to comment Share on other sites More sharing options...
j hancock Posted August 15, 2017 Share Posted August 15, 2017 You can also check the spring in the lower hose. Highway speed rpm may be causing the lower hose to collapse and cause a restriction. Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
Lucky dogg Posted August 19, 2017 Share Posted August 19, 2017 Hey there, so I have a 1998 r model and it ran hot at highway speed and pulling an empty Trailer. Loaded forget it. I took the radiator in after I flushed it and it didn't solve the problem and the radiator Shop said it self destructed from the inside although the outside was perfect. Put a new radiator on and it never ran better. I had also replaced the t stat and I figured not the water pump bc it was a remack only a year old. Maybe check that radiator out. Good luck man Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted August 19, 2017 Share Posted August 19, 2017 i hope you reinstalled the stat because it will run hot it no Tstat in it. Quote glenn akers Link to comment Share on other sites More sharing options...
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