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Just bought an 88 bronco with a 351 in it. When it's cold it runs great except for a slight tick at around 2500 rpms.. As it warms up the oil pressure drops below the normal range at an idle and the red engine light comes on. As you accelerate the oil pressure comes up on the low end of the normal range but the tick starts around 1600 rpms and is a little louder. I've been told it could anything from an intake gasket to bearings to oil pump. I don't have a lot of time for trial and error so any help would be greatly appreciated.
 

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It could be all kinds of stuff. Got any idea how many actual miles are on the motor? That would help a lot. The motor could be just warn out and the bearing arent in tolerance anymore. This would cause the pressure to drop b/c it doesnt have enough resistance to pressure the rest of it up. I am sure the ticking is the lifters and rockers starved for oil. This will evetually burn something up. So you need to get it diagnosed ASAP.

I know this sounds stupid , but , make sure it has plenty of oil in it.
 

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I'm almost positive you're right about the noise. Double checked the oil and it's good. Don't worry that didn't sound stupid a lot of times the obvious things are most easily overlooked. The engine has 135000 on it. I wanna get it fixed before winter sets in I don't have much time before that happens. Besides that I've wanted a bronco since I can remember and am anxious to actually get to drive it. . . lol
 

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yo, Get it checked w/mech gauge asap;

Installation, Sunpro Mechanical, w/T for stock gauge in an 86
Source: by Sixlitre (Malcolm H, Eddie Bauer) at http://fullsizebronco.com/forum/showthread.php?t=31669&highlight=mech+gauge

Installation, Volt, Oil Pressure & Water Temp., Equus in an 86
Source: by Xris at http://fullsizebronco.com/forum/showthread.php?t=27589

Also, a possibility and fyi/posterity;
Fake Oil Pressure Gauge TSB 88-05-14 for 87-88 Bronco & F Series
Source: by Ford via miesk5 at FSB
Publication Date: MARCH 2, 1988
1987-88 F-SERIES, BRONCO ISSUE: An oil pressure gauge that indicates an erratic or low reading when the engine oil pressure is within specification may be caused by the oil pressure sender. The oil pressure sender may not work properly with the magnetic oil pressure gauge.
ACTION: To correct this, install a new design oil pressure sender and new design resistor wire assembly using the following service procedure. Refer to the oil pressure sender and resistor wire application chart for the correct service parts.

OIL PRESSURE SENDER & RESISTOR WIRE APPLICATION CHART
Engine Application Description Service Part No.
5.0L, 5.8L, 7.3L and 7.5L Oil Pressure Sender E6SZ-9278-A
4.9L Oil Pressure Sender E8TZ-9278-A
All Resistor Wire Assembly E6SZ-9F291-A
1. Remove the existing oil pressure sender.
2. Install the new design oil pressure sender. Torque oil pressure sender to 10-18 lbs-ft (13-34 N-m).
3. Connect the female terminal end of the 20 ohm resister wire assembly to the oil pressure sender.
4. Connect the male terminal end of the 20 ohm resistor wire assembly to the vehicle wire harness.
PART NUMBER - PART NAME
E6SZ-9278-A - Oil Pressure Sender
E8TZ-9278-A - Oil Pressure Sender
E6SZ-9F291-A - Resistor Wire Assembly

These oil senders go bad quite often.

After doing some research it seemed like it could be the oil pressure switch, also known as a sensor or sending unit.

Remove the wire from the sender (its a switch - really), ground it w/jumper
turn the key to on.
If da gauge moves to the left, the problem is the switch

btw guage needle should be at mid-way point; if not, the wiring or guage are bad.
--
Sender Failure; "Corrosion or faulty electrical connections; If the oil pressure gauge is pegged low after the engine is running, or is pegged high after the engine is running, or if there is intermittent illumination of an oil pressure indicator light, the sender could be faulty. Related Components to Check; All appropriate electrical connections to and from the sender The oil pressure gauge or indicator light; Appropriate fuses (see Shop or Owner’s Manual for fuse layout)..." miesk5 Note; enter applicable info for year, etc.
Source: by MOTORCRAFT®

Oil Pressure Mod to Actual PSI "...short R in PCB..." info & NAPA Sender, etc.
Source: by Steve83 (Steve, That dirty old truck) at http://www.supermotors.net/registry/media/281470
 

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thats alot of good info. i had the same type of problem a while ago. after i tried to fix/replace all of the little things like the sending unit and leaks in the intake the problem ended up being the main bearings. i really didn't want to rebuild that old of an engine so i got a long block crate engine, droppoed it in and that fixed all of my problems. since i plan on keeping my bronco until the day i die, i think that it was the best thing that i could of done.
 

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from what I have read it is probably time to start saving up for a new engine. But still verify the oil pressure with a real gauge.
 

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Driving Stuff Henry Built
-90 xlt, 351w, e4od, man 1356, 3.55, sag, warn hubs, 35s. -73, 400, np435, d20j twin, 35s
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What weight oil are you running? It's not really a fix, but sometimes running thicker oil can buy you some time in an engine that has worn clearances.
 
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