aw12345 Posted March 1, 2013 Share Posted March 1, 2013 Almost all our Mack trucks with the mp7 engine seem to experience a low oil pressure problem when pulling long grades.The engine warning light will come on and the pressure gauge will read low oil pressure and not long after the engines will shut down.This only happens going up a long fairly steep grade, but numerous of our trucks do this.The upgrade tomthe engines for the oil pump idler gear or what ever upgrade required the back of these engines to come apart has done.Anybody can give me a cure for this problem. Not a good thing when a fully loaded truck goes up hill and the engine dies.Thanks in advance Quote Link to comment Share on other sites More sharing options...
staxx Posted March 1, 2013 Share Posted March 1, 2013 There is a software fix for some of the oil psi issues, need to check oil pressure sending unit for leaking oil into wire harness also . Mack has a upgraded oil psi sensor migh want to replace. Quote Link to comment Share on other sites More sharing options...
aw12345 Posted March 1, 2013 Author Share Posted March 1, 2013 Oil senders are good, All the trucks (about 20) have had all but the last update done to them.This is not just one truck, almost any one of them, will do this when they drive it up this fairly steep 15 mile long hill climb Quote Link to comment Share on other sites More sharing options...
2stacksuperdog Posted March 1, 2013 Share Posted March 1, 2013 maybe its too steep and the sensors cant pickup the oil? Quote Matt Link to comment Share on other sites More sharing options...
aw12345 Posted March 1, 2013 Author Share Posted March 1, 2013 (edited) Not that steep ,just a long constant grade on the highway. The grade is brutal on a hot summer day it's hard to keep count of all the cars and trucks that overheat on the side of the road. The main point is that just about any 2010-2011 Mack truck with a MP7 engine that goes over that grade comes up with this issue.Also what is the oil pressure spec for these engines? And would high engine load, low RPM into high a gear and the resulting heat built up and then the piston cooling jets spraying more oil have something to do with it? Edited March 1, 2013 by aw12345 Quote Link to comment Share on other sites More sharing options...
staxx Posted March 1, 2013 Share Posted March 1, 2013 What oil grade are you using , had another company same problem because they were using thinner oil to make better fuel milage with changed back to 15/40 and all was good Quote Link to comment Share on other sites More sharing options...
aw12345 Posted March 13, 2013 Author Share Posted March 13, 2013 You might be on to something, since they switched to 10w30, which is a requirment for their delivery van fleet, the problem has definitely gotten worse. Quote Link to comment Share on other sites More sharing options...
Mackpro Posted June 12, 2013 Share Posted June 12, 2013 Mack finally came out with a service bulletin on this problem. After I read it i remember someone on here was having this issueFSB 221-010, Diagnostic Trouble Codes (DTCs), Low.pdf 1 Quote Link to comment Share on other sites More sharing options...
MaceFremonti Posted September 18, 2013 Share Posted September 18, 2013 I drive for UPS. All of our new Macks that are on runs over the Blue Ridge mountains do this. Compounding the problem is that UPS uses recycled oil in all the equipment!When we write the tractors up for this issue the UPS mechanics tell us that there is no problem, they are OK to run, and that if we knew how to drive/downshift there wouldn't be an issue.... Quote Link to comment Share on other sites More sharing options...
chevy1988 Posted October 20, 2013 Share Posted October 20, 2013 Theres a oil pipe that goes to the rocker shaft from the jake solenoid that provides oil pressure to the jakes theres a little purple oring on each end of it and if it gets torn or brittle from heat you will have low oil pressure on a long pull Quote Link to comment Share on other sites More sharing options...
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