1979 Ford F-250 Oil pressure

Tiny
MBAROZ
  • MEMBER
  • 1979 FORD F-250
  • V8
  • 2WD
  • AUTOMATIC
  • 79,000 MILES
After I've been driving for a bit, the oil light comes on when I'm at low idle, like at a stop light. It flickers and goes out if I rev the engine. I've checked my levels and they are fine, so I'm suspecting I'm losing oil pressure but only after the truck has been driven for at least fifteen-twenty minutes.
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Saturday, October 2nd, 2010 AT 10:31 PM

5 Replies

Tiny
FACTORYJACK
  • EXPERT
I would not assume you are losing pressure just yet. First, I would have a physical oil pressure test performed. I have yet to locate a spec for your year, but I think 6-10 psi at idle would be desired. If after oil pressure is confirmed, or to keep it basic, try replacing the oil pressure sending unit. If you are getting no abnormal engine noise, this may do the trick.
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Sunday, October 3rd, 2010 AT 12:29 AM
Tiny
MBAROZ
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Okay.I think I may just try and replace the oil pressure sending unit anyways, but wierdly in my Haynes Manual there is no mention on how to. I'm not even sure where it is!
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Sunday, October 3rd, 2010 AT 9:26 AM
Tiny
FACTORYJACK
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I am not positive, but I would suggest near the oil filter. What size V8 is it, and I may be able to track down a specific location.
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Sunday, October 3rd, 2010 AT 10:54 PM
Tiny
MBAROZ
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It's a 351. Not the Windsor.
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Monday, October 4th, 2010 AT 12:07 AM
Tiny
FACTORYJACK
  • EXPERT
I did some checking on both ALLDATA, and Mitchell, and 1986 is about the first year I get any repair information. It is saying it is on the front side of the left cylinder head. It also had 5.0, and 5.8 grouped together (351 is 5.8L), and the illustration said 5.0L. Did you check under engine mechanical in the haynes manual? If so, and you did not find it, check electrical, or in the alphabetical index. I would guess that it is near the oil filter, seems to me that they had a bolt on oil filter adapter, it should also include the sending unit. Here is all I found from a ford truck forum, I googled a search.

My oil pressure gauge started freaking out after I washed the engine -it reads normally one minute, and then it jumps all over. It seems like it is shorting out. Maybe I got it too wet or something when I washed the engine, it should be dry now though. Where is this thing located on a 5.8? Does it just thread out? Do you need to drain the oil to change it? Has anbody else's done this after getting wet? Thanks

JBronco

Oil Pressure Sending Unit - where is it? (5.8)

Hey there JBronco,

The oil pressure sending unit on my 89 should be in the same spot as yours.

If you stand at the drivers fender and look at your oil filter. Look to the left and back a bit, and on the block you should see it. It is a small unit with a single wire connected to the front of it. Pull the wire and then you can use a large socket to get it out.

Some engines have a small adapter that screws into the block that moves the unit further towards the drivers fender.

But that should get you there. Check the wire. My oil sending unit goes haywire because I have a small oil leak that drips onto it. Causing the connections from that wire to trip.

Happy holidays :-X12

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Tuesday, October 5th, 2010 AT 12:03 AM

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