Jake1982 Posted April 5, 2022 Share Posted April 5, 2022 I have a 2011 Mack that pressurizes the cooling system to the point that the coolant blows out of the overflow. This only happens when the truck works. It can idle for hours or pull an empty trailer down the highway with no issues but once there it has a load on it pukes out the antifreeze within 10 miles. I have changed the compressor. When that didn't work I had the waterpump and waterpump housing changed. I have also done a head gasket, new cups and new egr cooler. I am out of ideas....any help would be appreciated. Quote Link to comment https://www.bigmacktrucks.com/topic/69486-2011-mack-mp8-pressurized-cooling-system/ Share on other sites More sharing options...
fjh Posted April 5, 2022 Share Posted April 5, 2022 (edited) There was an issue with the coolant tank pin holes on these also try changing the lid on the tank! Edited April 5, 2022 by fjh Quote Link to comment https://www.bigmacktrucks.com/topic/69486-2011-mack-mp8-pressurized-cooling-system/#findComment-494531 Share on other sites More sharing options...
Glensts Posted April 6, 2022 Share Posted April 6, 2022 Had a 97 mack that would only push a/f on big load and it was a crack in the head and the turbo was pressurizing the system. We got the head checked for cracks and found it Quote Link to comment https://www.bigmacktrucks.com/topic/69486-2011-mack-mp8-pressurized-cooling-system/#findComment-494579 Share on other sites More sharing options...
Jake1982 Posted April 6, 2022 Author Share Posted April 6, 2022 Thanks. There is a new surge tank on there and when we did the gasket we sent head in to be cleaned and tested. I am starting to think Mack may of screwed up when they put the cups in.....looks to be a bit of carbon in the new tank... Quote Link to comment https://www.bigmacktrucks.com/topic/69486-2011-mack-mp8-pressurized-cooling-system/#findComment-494601 Share on other sites More sharing options...
fjh Posted April 6, 2022 Share Posted April 6, 2022 38 minutes ago, Jake1982 said: Thanks. There is a new surge tank on there and when we did the gasket we sent head in to be cleaned and tested. I am starting to think Mack may of screwed up when they put the cups in.....looks to be a bit of carbon in the new tank... Very possible we have had EGR coolers failed right out of the box too! Quote Link to comment https://www.bigmacktrucks.com/topic/69486-2011-mack-mp8-pressurized-cooling-system/#findComment-494605 Share on other sites More sharing options...
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