oil pressure light concerns
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Fleet Owner
Joined: Dec 2000
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From: Central PA
oil pressure light concerns
The idiot light that indicates low oil pressure on my 54 F100 with a 239 has been coming on lately. I have been checking the oil level and it is right on. This of course concerns me, being afraid it might be an indicator of a bigger problem.
The light comes on when I am accelerating. It goes off when I level off or maintain or lower the speed. It goes off when I push the clutch pedal in to shift.
Any ideas here?
The light comes on when I am accelerating. It goes off when I level off or maintain or lower the speed. It goes off when I push the clutch pedal in to shift.
Any ideas here?
Fleet Owner
Joined: Jul 2004
Posts: 27,296
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From: NM
First thing I'd do is put a known accurate gauge on it.
But I hate to say it, I had a '53 that behaved similarly, and it was excessive main bearing wear. If you aren't hearing any rod noise, you probably have plenty of time to do diagnosis.
But I hate to say it, I had a '53 that behaved similarly, and it was excessive main bearing wear. If you aren't hearing any rod noise, you probably have plenty of time to do diagnosis.
Believe Nothing
Joined: Jun 2004
Posts: 7,516
Likes: 401
From: W. Central FL.
Not really uncommon for the light to flicker at very low idle and high temperatures. Make certain the dipstick stop has not moved and allowing the dipstick to go farther into the oil pan. Results, low oil level and intermittent low oil pressures. Not uncommon at all for the oil pressure to drop when going down a steep hill or when braking hard with these old Y block trucks. Relatively flat pan allows the oil to flow freely to the front of the engine, away from the oil pickup.
I agree with Ross completely. Put a mechanical gauge on it. Many vehicles had aftermarket gauges installed even back when. We won't kid you for going only that much toward the dark side, Abe.
I agree with Ross completely. Put a mechanical gauge on it. Many vehicles had aftermarket gauges installed even back when. We won't kid you for going only that much toward the dark side, Abe.
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Fleet Owner
Joined: Dec 2000
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From: Central PA
Ray, the light is not coming on at low idle. I, too, have noticed that my Y-block's oil light comes on sometimes when braking hard or going fast around a corner, but the light is coming on when I accelerate and goes off when I decelerate and when I clutch to shift.
So, is there is any chance that my engine might have some blockages some where that would prevent oil from getting to where it should be and therefore causing the light to come on?
Believe Nothing
Joined: Jun 2004
Posts: 7,516
Likes: 401
From: W. Central FL.
If the valves are not rattling, chances are it is getting oil throughout the engine.
The sensor is most likely located at the rear passenger side of the engine, right above the oil pump which should read pressure if you have it. Again, the first thing I would do is install a mechanical gauge. Have you traced out the wiring to the sending unit, make certain it is not frayed or being contacted by the clutch mechanism? How long since the oil and filter were changed? No rattles is a good indication.
Edit: The oil galley runs along the passenger side of the engine and has multiple clean out plugs. If memory serves me right, there are clean out plugs hidden behind the block and inside the front timing cover.
Edit again: There is always a chance the sending unit has gone bad.
The sensor is most likely located at the rear passenger side of the engine, right above the oil pump which should read pressure if you have it. Again, the first thing I would do is install a mechanical gauge. Have you traced out the wiring to the sending unit, make certain it is not frayed or being contacted by the clutch mechanism? How long since the oil and filter were changed? No rattles is a good indication.
Edit: The oil galley runs along the passenger side of the engine and has multiple clean out plugs. If memory serves me right, there are clean out plugs hidden behind the block and inside the front timing cover.
Edit again: There is always a chance the sending unit has gone bad.
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Fleet Owner
Joined: Dec 2000
Posts: 25,394
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From: Central PA
If the valves are not rattling, chances are it is getting oil throughout the engine.
The sensor is most likely located at the rear passenger side of the engine, right above the oil pump which should read pressure if you have it. Again, the first thing I would do is install a mechanical gauge. Have you traced out the wiring to the sending unit, make certain it is not frayed or being contacted by the clutch mechanism? How long since the oil and filter were changed? No rattles is a good indication.
Edit: The oil galley runs along the passenger side of the engine and has multiple clean out plugs. If memory serves me right, there are clean out plugs hidden behind the block and inside the front timing cover.
Edit again: There is always a chance the sending unit has gone bad.
The sensor is most likely located at the rear passenger side of the engine, right above the oil pump which should read pressure if you have it. Again, the first thing I would do is install a mechanical gauge. Have you traced out the wiring to the sending unit, make certain it is not frayed or being contacted by the clutch mechanism? How long since the oil and filter were changed? No rattles is a good indication.
Edit: The oil galley runs along the passenger side of the engine and has multiple clean out plugs. If memory serves me right, there are clean out plugs hidden behind the block and inside the front timing cover.
Edit again: There is always a chance the sending unit has gone bad.
I knew my wire to the sending unit was frayed. I went out just now in a thunderstorm to check how bad it was frayed.... It is frayed bad and bare in some spots and coated with dirt and oil. It is amazing it worked this long!
I will have to check and see who sells them.... maybe NAPA. Would the whole sending unit need replaced or just the wire?
Fleet Owner
Joined: Jul 2004
Posts: 27,296
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From: NM
It's just a switch. Most turn off the light at 3 psi. I'm sure NAPA can fix you up. But I'd still hook up a gauge for peace of mind, do some testing.
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Believe Nothing
Joined: Jun 2004
Posts: 7,516
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From: W. Central FL.
I think you mean the rear drivers side unless 56's were different.
I knew my wire to the sending unit was frayed. I went out just now in a thunderstorm to check how bad it was frayed.... It is frayed bad and bare in some spots and coated with dirt and oil. It is amazing it worked this long!
I will have to check and see who sells them.... maybe NAPA. Would the whole sending unit need replaced or just the wire?
I knew my wire to the sending unit was frayed. I went out just now in a thunderstorm to check how bad it was frayed.... It is frayed bad and bare in some spots and coated with dirt and oil. It is amazing it worked this long!
I will have to check and see who sells them.... maybe NAPA. Would the whole sending unit need replaced or just the wire?
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Thread Starter
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Fleet Owner
Joined: Dec 2000
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From: Central PA
I checked my MidFifty catalog. They sell a sender for $14, but they are only 12 volt. I will call NAPA tomorrow.
I guess I will have to make my own wire unless NAPA sells it. What gauge wire should I use? Or does it really matter?
Fleet Owner
Joined: Jul 2004
Posts: 27,296
Likes: 1,059
From: NM
18 ga. would be fine, it's a little light.
You don't need a sender, tho, you need a switch. Ford - Ford Pickup Truck Oil Pressure Sending Unit - F2 With Warning Lights - Not For A Dash Gauge | 41A-9278 - Macs Auto Parts
You don't need a sender, tho, you need a switch. Ford - Ford Pickup Truck Oil Pressure Sending Unit - F2 With Warning Lights - Not For A Dash Gauge | 41A-9278 - Macs Auto Parts
Thread Starter
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Fleet Owner
Joined: Dec 2000
Posts: 25,394
Likes: 5,401
From: Central PA
18 ga. would be fine, it's a little light.
You don't need a sender, tho, you need a switch. Ford - Ford Pickup Truck Oil Pressure Sending Unit - F2 With Warning Lights - Not For A Dash Gauge | 41A-9278 - Macs Auto Parts
You don't need a sender, tho, you need a switch. Ford - Ford Pickup Truck Oil Pressure Sending Unit - F2 With Warning Lights - Not For A Dash Gauge | 41A-9278 - Macs Auto Parts
thanks
Believe Nothing
Joined: Jun 2004
Posts: 7,516
Likes: 401
From: W. Central FL.
From what you're telling us about the frayed wiring, that would be my first repair, before I changed out the switch. You have to fix the wiring anyway and it may solve your problem if the bare wire is touching ground anywhere. Since we talked about where the oil passages are on a Y block, I'll put up the driver side picture of a Y block that I just happen to have hanging on my engine stand. The pressure switch and clean out plugs can be seen.
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Fleet Owner
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From: Central PA
This block is upside down, right? So, the oil pressure switch is on the left, correct?
Is this a 54 Y-block? I see some red paint.
I went to NAPA today. They did not have the switch. But in my driving around the oil light did not come on once. I think it is because I was jiggling the wire around last night. So I will rewire it soon. When I put a new wiring harness on in 1999 there was not a new wire for the oil pressure switch so I kept the old one.... Now it is time to do it!
Thanks for your help, Ray and Ross!
Is this a 54 Y-block? I see some red paint.
I went to NAPA today. They did not have the switch. But in my driving around the oil light did not come on once. I think it is because I was jiggling the wire around last night. So I will rewire it soon. When I put a new wiring harness on in 1999 there was not a new wire for the oil pressure switch so I kept the old one.... Now it is time to do it!
Thanks for your help, Ray and Ross!
Laughing Gas
Joined: Dec 2007
Posts: 792
Likes: 3
From: Sandy Run SC
Had the same trouble on a couple engines and it was the oil pick up screen in the oil pan sludged up so bad it would starve the oil pump when you accelerated lowering the oil pressure. At low engine rpm the pump had enough oil to keep the pressure up. Lack of service and the sorry oil we used to have caused a lot of sludge in engines.
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