5 psi, too low?
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Joined: Sep 2008
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5 psi, too low?
I have an 89 bronco with a 4.9, was having problems with the gauge going down to nothing. I hooked up a mechanical gauge and warmed up and at idle it reads about ~5psi. I am running 10w-30, and suggestions on boosting it up other the running stupidly high weight oil?
Posting Guru
Joined: Apr 2005
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From: Longview, TX
Yes, do not go to 20w XX anythiing. 10W-40 is the highest I would consider. I would suggest only a Motorcraft filter also. Do you hear any noises at first start of the day? My 5.8 182K miles reads 19psi in summertime at idle after hot highway run. I like 10w-30 Mobil Clean High Milage. It gradually cleans so the screen and oil galleries do not get plugged with stuff breaking loose all at once. Even so, the first change will remind you of a Diesel oil change. You might get lucky and improve the pressure. I suscribe to the theory of flow being preferred over pressure. Low pressure and adequate flow is better than high pressure and limited flow.
Freshman User
Joined: Aug 2008
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From: honolulu
just curious...what is your pressure when you first start up cold? I have a tired engine that starts out fine, then drops when it heats up.
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Joined: Sep 2004
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From: Columbia MO
I had similar issues with both my 300's. I replaced the oil pump with a high flow pump and yes you can drop the oil pan and get to the rod bearings and main bearing . A word of CAUTION... when I did this to my wifes fire bird the parts store sold me all the standard bearings. I got them home lined up all the boxes they were all the same. Except the manufacturer slipped the wrong bearing in the box. Long story short check the bearings for the over size markings before starting the job. changing the pump and the lower bearings will give you back really good oil pressure.
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Post Fiend
Joined: Mar 2002
Posts: 19,402
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From: Bonita Springs FL
At hot idle, my truck pushes out about 17 psi. You only need about 7 psi to properly lubricate the engine. 25 is healthy, you have a lot of miles left on that motor.
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
And if "about 7 psi" is all you need to properly lube an engine, then why did you say he needed to stick a fork in the OP's engine. 5 is "about 7 psi". I know this sounded kinda jerkish, but I am seriously just wondering.
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
frams are the worst oil filter you can buy (notice I didn't even capatalize the name). There is no reverse flow check valve so if the filter is mounted horizontally, the oil drains right back into the pan. They also have the smallest filter surface area of any filter on the market.
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New User
Joined: Sep 2008
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No Fram filter, I am running a off-brand made by wix though. And I do think it has a rear main leak.