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5 psi, too low?

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Old Sep 3, 2008 | 10:14 PM
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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?
 
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Old Sep 3, 2008 | 10:29 PM
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No smoke, suppose to have 73k, but im thinking it might be 173k. I think im gonna run some higher weight oil soon, I have 10-30 in it now.
 
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Old Sep 3, 2008 | 10:30 PM
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Either a weak oil pump, or your main bearings are wearing out.
 
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Old Sep 3, 2008 | 10:43 PM
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Can I change the main bearings without pulling the motor? I know I did a rebuild on an escort without pulling the motor, but I did rod bearings and no main bearings.
 
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Old Sep 4, 2008 | 05:34 AM
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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.
 
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Old Sep 4, 2008 | 11:01 AM
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If your oil pressure is 5psi, it doesn't matter what oil you put in the motor. Stick a fork in it, because it's done.
 
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Old Sep 6, 2008 | 08:33 PM
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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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Old Sep 7, 2008 | 11:03 AM
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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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Old Sep 7, 2008 | 03:13 PM
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Originally Posted by UTfball68
As far as tired engines go...my Bronco starts with 40, then drops to the 20-25 range. I was always told 25 is about as low as you want to go. For a good engine, my red truck starts at 60 then drops to 45.
You were told wrong. 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.
 
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Old Sep 7, 2008 | 06:43 PM
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Originally Posted by UTfball68
I didn't say it wouldn't run, or be capable, I was just saying 20-25 psi is the lowest on a healthy engine.
I didn't say that you *did* say that; and you're still wrong. I'm not going to pull an engine out and rebuild it when it was pushing 19 psi, and neither is anyone else who knows what they're doing.

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.
I guess I should have said that 7 psi is the minimum oil pressure necessary to properly lubricate an engine. Anything below that is close to or at the point of needing a rebuild.
 
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Old Sep 8, 2008 | 12:21 PM
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your not running a fram filter right? any oil leaks present like a rear main?
 
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Old Sep 8, 2008 | 11:21 PM
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Kemicalburns, are frams no good? which filters are good and why? ..Sorry if you answered these more than a few times already...
 
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Old Sep 8, 2008 | 11:27 PM
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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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Old Sep 9, 2008 | 02:14 PM
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and are known to cause low pressure issues on our motors. Motorcraft,purolator and good filters.
 
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Old Sep 14, 2008 | 01:54 PM
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Originally Posted by Kemicalburns
your not running a fram filter right? any oil leaks present like a rear main?
No Fram filter, I am running a off-brand made by wix though. And I do think it has a rear main leak.
 
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