460 Oil Pressure Dropping
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Mountain Pass
Joined: Feb 2002
Posts: 243
Likes: 1
From: Houston USA
460 Oil Pressure Dropping
I have an 86 F350 with a 460, 130K miles and when I drive the oil pressure is fine, but when I stop and the engine idles after the engine is hot the stock oil pressure gauge starts showing almost no oil pressure. I put 20W-50 in it and it still does that after about 45 minutes of driving. Any ideas on whether this is a worn oil pump, or inserts? I don't hear any knocking, and the pressure is good at highway speeds, so I thought the inserts/bearings are ok. Any ideas? I would like to drive this for a little longer before a rebuild.
Thanks
Mark
Thanks
Mark
Hotshot
Joined: Dec 2003
Posts: 18,423
Likes: 9
From: iowa
Well the first thing to do is put a mechanical gauge on it, as the factory one is not very accurate at all and if the sending unit is getting weak it can show bad pressure. But low pressure at idle can be both a pump, or the main or cam bearings, usually I figure bearings.
BTW Ford specs on oil pressure are not at idle but at something like 2000 rpms which is where it's important, as long as you have some pressure.
BTW Ford specs on oil pressure are not at idle but at something like 2000 rpms which is where it's important, as long as you have some pressure.
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
On top of what monsterbaby said, for does not spec. oil pressure at idle. The give a number for 2000 rpm only, so technically no pressure on the Gauge at idle could be ok as long as you have 35 psi at 2000. Of course if the motor is rattling because of no oil pressure at idle then turn it off. Otherwise it's likely a bad gauge or sender.
Elder User
Joined: Dec 2006
Posts: 881
Likes: 1
From: Sudbury, ONT.
I have a Haynes Manual for 70's Ford cars with 460's. It says 6-8 psi at idle for 460's. I have Stewart Warner gauge, along with the original functioning idiot light in my truck. At idle, the needle on the gauge is hovering just below the 10 psi mark, and the idiot light has never come on. It's been doing it for years.
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Originally Posted by 68murc
I have a Haynes Manual for 70's Ford cars with 460's. It says 6-8 psi at idle for 460's. I have Stewart Warner gauge, along with the original functioning idiot light in my truck. At idle, the needle on the gauge is hovering just below the 10 psi mark, and the idiot light has never come on. It's been doing it for years.
Tuned
Joined: Jul 2004
Posts: 275
Likes: 0
Back when I had an 81 F250 351M the preasure would go to almost 0 when hot and at idle and it always freeked me out. Never had a problem related to that. Even the C6 would slip going into second all the years I had it and it never quit either. I did run 20-50 though and it seemed to help a little.
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