06mack Posted August 16, 2019 Share Posted August 16, 2019 I changed the oil in my 06 granite and I used the recommended 15w40 oil and mack filters. Before the oil change on startup the oil pressure was never above 35psi but now its almost 70 when it's cold. After it warms up it does drop to about 20-25psi but the initial pressure has me very worried about blowing a head gasket or something else. The motor is a 460 by the way and my dealer said it should only be about 30-40psi when cold. I did use a Baldwin filter for the centrifugal filter which I'm going to change out for a mack as well. What else am I missing? Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted August 16, 2019 Share Posted August 16, 2019 (edited) Oil pressure will be high when engines cold. Oil will not flow the complete volume of pump's displacement out the bearings and cooler nozzles when cold, so it hits max pressure. The oil pump is designed to "overflow" excess oil volume when engine is cold. The overflow pressure is preset in the oil pumps relief valve. If you would get higher and higher top pressures then change the oil pump under suspicion of a shuttle that isn't moving freely. Otherwise, don't worry about it. If I was up over 60 I wouldn't be worried, if I was hitting 80.... maybe time to change the pump.....cheap easy repair. For the most part good cold start oil pressure is a blessing till it splits the top crimp seam of an oil filter, I've seen that happen on a different brand-X OEM. Edited August 16, 2019 by Mack Technician Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted August 16, 2019 Share Posted August 16, 2019 In case you are having stock-engine performance issues...…….. Quote Link to comment Share on other sites More sharing options...
06mack Posted August 17, 2019 Author Share Posted August 17, 2019 Thank you for the info. I'll look into changing the pump Quote Link to comment Share on other sites More sharing options...
OldRedMack Posted August 23, 2019 Share Posted August 23, 2019 That's where mine is at on start up. 2007 AI engine. Been that way since I bought it. No problems in 5 years. Quote Link to comment Share on other sites More sharing options...
06mack Posted August 25, 2019 Author Share Posted August 25, 2019 On 8/23/2019 at 9:07 AM, OldRedMack said: That's where mine is at on start up. 2007 AI engine. Been that way since I bought it. No problems in 5 years. Where does it run when its warm though? Mine will be around 25 at idle and then around 60 or more when I'm on the throttle Quote Link to comment Share on other sites More sharing options...
OldRedMack Posted August 26, 2019 Share Posted August 26, 2019 Basically the same, but I also use Lucas oil so it's closer to 30 at idle hot. That's with napa filters. Quote Link to comment Share on other sites More sharing options...
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