Licensed to kill Posted July 15, 2021 Share Posted July 15, 2021 I painted my engine last week (E6-350) which involved removing the oil cooler/filter housing. Yesterday, I decided to fire it back up to check for leaks and such. I started it and let it run for maybe a minute, then walked around to the left side and noticed that I didn't have oil pressure. I shut the engine off and considered this for a bit, filters where installed full, why no pressure after about a minute?????. So I restarted it and watched the cause and after 10-20 seconds the pressure starts to come up. Whew. The pressure goes up to about 35lbs then backs off to 28 (which is where it runs at idle), sits for a few seconds then slowly drops all the way to zero and stays there. WTF!!!. I shut the engine off, ponder awhile, I'm at a loss so I start it back up again. Pressure comes u to 28 then goes back down to zero. Shut it off. Thinking this through I have no clue what is going on. I start it back up and let it for for perhaps 30 seconds, no pressure. OK, so this is getting annoying. I change gauges. nothing, I remove the gauge and put a hose to a pail, crank it over a bit, nothing comes out. I did have an oil leak at the base where the filter pedestal bolts to the block so, under protest, I remove the oil cooler/filter housing. I blow air through the passage from the block to the filters and they are clear. I blow air through the gauge port and it is clear. I crank the motor and oil burps out the port in the block so the pimp is working. The ONLY thing I have left is that perhaps i just didn't wait long enough for the cooler to fill BUT, why did it make pressure then fall off???. Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/ Share on other sites More sharing options...
Freightrain Posted July 15, 2021 Share Posted July 15, 2021 It should have filled the cooler by now. My first thought is pull the relief valve and make sure it is not stuck open. I assume it is still at the bottom of the pedestal like my 237. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476867 Share on other sites More sharing options...
Licensed to kill Posted July 15, 2021 Author Share Posted July 15, 2021 Relief valve????. What would that look like?. Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476868 Share on other sites More sharing options...
Licensed to kill Posted July 15, 2021 Author Share Posted July 15, 2021 I went out and looked and there is a spring loaded plunger going sideways in the base of the housing. Took the end cap off and removed the spring. Spring is clean and the plunger moves freely. Put the spring back and the cap. Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476869 Share on other sites More sharing options...
mrsmackpaul Posted July 15, 2021 Share Posted July 15, 2021 Sounds like something was in a filter some how that is almost blocking the gallery and pushes across with pressure as soon as you start it Dunno, pretty hard to guess much more with out been there, it will be most likely something silly Paul Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476882 Share on other sites More sharing options...
mrgumby Posted July 15, 2021 Share Posted July 15, 2021 Did you pull the stick and check oil level is it full. Hey ya never know Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476884 Share on other sites More sharing options...
terry Posted July 16, 2021 Share Posted July 16, 2021 Do you have the right gasket under the filter stand where it bolts to lower left side of the block? terry Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476916 Share on other sites More sharing options...
Steve L Posted July 16, 2021 Share Posted July 16, 2021 (edited) I have experienced this last week, a mate of mine removed the oil cooler on his E6 to replace leaky water gaskets, assembled everything including new filters and after starting the oil pressure took ages to make 30psi ( it usually makes 70 immediately ) so he called me, I told him not to run anymore until he fitted an aux gauge on the crank pressure, 30 psi at the crank so 30 is constant throughout the engine. So reworked everything he done and the last resort before removing the sump was to change the filters again. Removing the filters found then half empty even though he filled them before assembly, so we fitted new filters and the oil pressure was back to normal. In 50 years of servicing and repairing Mack’s I have never seen this. Not sure what make the filters were but were non genuine, they only had part numbers on them so I guess could have been fuel filters. Edited July 16, 2021 by Steve L Re phrase Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476918 Share on other sites More sharing options...
Licensed to kill Posted July 16, 2021 Author Share Posted July 16, 2021 15 hours ago, mrgumby said: Did you pull the stick and check oil level is it full. Hey ya never know Yes, and you are right, ya never know LOL. Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476924 Share on other sites More sharing options...
Licensed to kill Posted July 16, 2021 Author Share Posted July 16, 2021 3 hours ago, terry said: Do you have the right gasket under the filter stand where it bolts to lower left side of the block? terry As near as i can tell. I looked that up and see that there a few different ones but appears that I have the correct one for this engine. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476925 Share on other sites More sharing options...
Licensed to kill Posted July 16, 2021 Author Share Posted July 16, 2021 2 hours ago, Steve L said: I have experienced this last week, a mate of mine removed the oil cooler on his E6 to replace leaky water gaskets, assembled everything including new filters and after starting the oil pressure took ages to make 30psi ( it usually makes 70 immediately ) so he called me, I told him not to run anymore until he fitted an aux gauge on the crank pressure, 30 psi at the crank so 30 is constant throughout the engine. So reworked everything he done and the last resort before removing the sump was to change the filters again. Removing the filters found then half empty even though he filled them before assembly, so we fitted new filters and the oil pressure was back to normal. In 50 years of servicing and repairing Mack’s I have never seen this. Not sure what make the filters were but were non genuine, they only had part numbers on them so I guess could have been fuel filters. Interesting comment about the filters. When I took the filters off to remove that housing/cooler, I noticed that they were only about 2/3 - 3/4 full. I thought "how can that be???". After I had this issue and had to take it all apart again, again the filters were only 2/3 - 3/4 full. I don't know how that can be possible but there it is. These filters are new NAPA filters so should be made by Wix and would have about MAYBE 10 minutes total run time on them. Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476926 Share on other sites More sharing options...
Popular Post Licensed to kill Posted July 17, 2021 Author Popular Post Share Posted July 17, 2021 Found the problem. After exhausting everything I could think of I finally broke down and pulled the pan. The pick-up was broke off the oil pump. Looking at the broken opening to the pump and lining it up with the dip stick I can see that the oi level was about half way up the opening so when i started the engine, the pump could get some oil but as soon as it pumped that oil upstairs the level would drop to the point that the pump starved and the pressure would drop off. The pick-up must have broke off when the truck was rolled and the oil level was higher when i initially started it up so it didn't starve. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476974 Share on other sites More sharing options...
mrsmackpaul Posted July 17, 2021 Share Posted July 17, 2021 A good result then Paul Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476981 Share on other sites More sharing options...
Joey Mack Posted July 18, 2021 Share Posted July 18, 2021 👍 Nice!!! Stop scratchin..... jojo Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476989 Share on other sites More sharing options...
Licensed to kill Posted July 18, 2021 Author Share Posted July 18, 2021 5 hours ago, mrsmackpaul said: A good result then Paul Yup, not a big deal. I called the guy I got the engine from and he said to just go poke around the sheds and see if i can find one. I didn't find one so he said he would check with his boys on tuesday to see which engine they can open up to pull an oil pump from from. In the mean time i will order a pan gasket and blast and paint the pan. Quote Link to comment https://www.bigmacktrucks.com/topic/67359-something-of-a-head-scratcher/#findComment-476996 Share on other sites More sharing options...
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