Oil pump

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Liuhisn

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Oct 5, 2018
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Hello all. It has been awhile since my last post. To bring everyone up to speed. I have a 1995 Dolphin RV with a F53 superduty engine. A family friend was able to get it running, plugged fuel lines. While it was running after about 5 min, the oil pressure dropped. The engine was turned off and was not started. I was not there when this happened but was told of the event. According to the family friend that got it going, a “pin broke” on the shaft under the distributor cap. This shaft goes down to the oil pan. This seemed odd so I inquired with another mechanic and was told that the oil pump was not primed. Failure to do so will cause the problem just described. Apparently an easy fix. Has anyone else heard of this? Thanks
 

Ex-Calif

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Yes it can happen. The proper method to bring an old engine back is to motor the engine with the plugs out until you get oil pressure. Depending on how dormant the engine has been it can be wise to remove the oil pressure sender and pump oil into the pressure system.

If it's just the distributor drive broken it can be a relatively easy fix but if the pump is seized the oil pan needs to come off. It's pretty important to find the failed pin as it can do damage in there. That's the trickiest part.
 

Liuhisn

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Oct 5, 2018
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29
As far as I know, this pin broke and the oil pressure just dropped. It seems odd that the oil pump drive shaft would come in two parts requiring a pin to connect them. As far as I know the oil pump did not seize. Hopefully this pin is easy to find and repair.
 

CharlesinGA

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50 miles south of Atlanta, GA
That would be a 460 motor, and yes, the oil pump shaft is separate from the distributor, two parts, in virtually every V8.

From what I can read in the Ford460 forum (yes the 7.5L is a 460) the oil pump shaft is a 5/16 hex shaft from top to bottom. Its possible the shaft sheared or the distributor drive gear shaft roll pin sheared. The distributor gear is actually pressed on and then drilled and the roll pin put thru, so I really don't suspect that roll pin, in fact since the engine kept running, it cannot be the roll pin at all or the engine would be out of time and quit/backfired, etc.

Some Ford products used nylon coated teeth on the camshaft timing gear, I have no idea if this one does or not. If it does, the nylon becomes old and brittle and breaks off and on occasion the chain will jump time, but many times not, if just one piece. The piece that broke then finds its way thru the grommet in the middle of the oil pump inlet screen, jams the pump, and shears the shaft. I HAVE seen a 289 do this. Old Pontiac 389's also used these plastic gears, and many others have too. Its to keep the chain quiet.

You really need to drop the oil pan and see what is in the pan, and if the pump shaft is sheared.

The retainer in the illustration is a C clip in a groove on the shaft. It prevents the shaft from coming out when you pull the distributor.

Distshaft.jpg

Charles
 

Liuhisn

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Oct 5, 2018
Posts
29
Thankyou for the response! Seem like a pain in the neck fix! Best case scenario, oil pump priming? Worse case, what you described? The motor was shutdown as soon as the pressure dropped. No mention of any bad sounds or grinding.
 

56safari

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Jul 4, 2013
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85
Location
Beavercreek, OH
Not second guessing the diagnosis, but since you weren't there, I would suggest you pull the distributor and prime the oil pump with a priming tool ( its a shaft that reaches the oil pump and can be run with a drill). That will tell you if the oil pump is OK. While the distributor is out, you can check the distributor shaft pin as well. If the pump primes and the distributor checks out, the no oil pressure is a gauge, sending unit or wiring issue. And, since the distributor has to come out to replace the oil pump, you will not be wasting much time.
 

Liuhisn

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Oct 5, 2018
Posts
29
Not second guessing the diagnosis, but since you weren't there, I would suggest you pull the distributor and prime the oil pump with a priming tool ( its a shaft that reaches the oil pump and can be run with a drill). That will tell you if the oil pump is OK. While the distributor is out, you can check the distributor shaft pin as well. If the pump primes and the distributor checks out, the no oil pressure is a gauge, sending unit or wiring issue. And, since the distributor has to come out to replace the oil pump, you will not be wasting much time.
Hello 56safari
Here is an update on the oil pump issue with the RV. Yesterday, I had another mechanic come with me to the rv to give me his diagnosis. He primed the oil pump and turned it with his drill, charged the battery and realigned distributer cap and the RV started right up! The oil pressure gauge was pegged passed the L. So at this point, it could be the pump, oil pressure sensor or a faulty gauge. we replaced thee sensor with a brand new one and still got no oil pressure reading on the gauge. Oil was poured into the engine through the valve cover opening and we waited for a few minutes. The engine was started and an inspection camera was into the engine through the hose coming out of the valve cover and we both saw oil flowing. the question now is Is the oil pressure gauge faulty or the pump? I am going to replace the gauge first. It was not moving at all. Any advice would be appreciated. Thankyou.
 

Liuhisn

Active member
Joined
Oct 5, 2018
Posts
29
That would be a 460 motor, and yes, the oil pump shaft is separate from the distributor, two parts, in virtually every V8.

From what I can read in the Ford460 forum (yes the 7.5L is a 460) the oil pump shaft is a 5/16 hex shaft from top to bottom. Its possible the shaft sheared or the distributor drive gear shaft roll pin sheared. The distributor gear is actually pressed on and then drilled and the roll pin put thru, so I really don't suspect that roll pin, in fact since the engine kept running, it cannot be the roll pin at all or the engine would be out of time and quit/backfired, etc.

Some Ford products used nylon coated teeth on the camshaft timing gear, I have no idea if this one does or not. If it does, the nylon becomes old and brittle and breaks off and on occasion the chain will jump time, but many times not, if just one piece. The piece that broke then finds its way thru the grommet in the middle of the oil pump inlet screen, jams the pump, and shears the shaft. I HAVE seen a 289 do this. Old Pontiac 389's also used these plastic gears, and many others have too. Its to keep the chain quiet.

You really need to drop the oil pan and see what is in the pan, and if the pump shaft is sheared.

The retainer in the illustration is a C clip in a groove on the shaft. It prevents the shaft from coming out when you pull the distributor.

Distshaft.jpg

Charles
Here is an update on the oil pump issue with the RV. Yesterday, I had another mechanic come with me to the rv to give me his diagnosis. He primed the oil pump and turned it with his drill, charged the battery and realigned distributer cap and the RV started right up! The oil pressure gauge was pegged passed the L. So at this point, it could be the pump, oil pressure sensor or a faulty gauge. we replaced thee sensor with a brand new one and still got no oil pressure reading on the gauge. Oil was poured into the engine through the valve cover opening and we waited for a few minutes. The engine was started and an inspection camera was into the engine through the hose coming out of the valve cover and we both saw oil flowing. the question now is Is the oil pressure gauge faulty or the pump? I am going to replace the gauge first. It was not moving at all. Any advice would be appreciated. thank you.
 

Liuhisn

Active member
Joined
Oct 5, 2018
Posts
29
Yes it can happen. The proper method to bring an old engine back is to motor the engine with the plugs out until you get oil pressure. Depending on how dormant the engine has been it can be wise to remove the oil pressure sender and pump oil into the pressure system.

If it's just the distributor drive broken it can be a relatively easy fix but if the pump is seized the oil pan needs to come off. It's pretty important to find the failed pin as it can do damage in there. That's the trickiest part.
Here is an update on the oil pump issue with the RV. Yesterday, I had another mechanic come with me to the rv to give me his diagnosis. He primed the oil pump and turned it with his drill, charged the battery and realigned distributer cap and the RV started right up! The oil pressure gauge was pegged passed the L. So at this point, it could be the pump, oil pressure sensor or a faulty gauge. we replaced thee sensor with a brand new one and still got no oil pressure reading on the gauge. Oil was poured into the engine through the valve cover opening and we waited for a few minutes. The engine was started and an inspection camera was into the engine through the hose coming out of the valve cover and we both saw oil flowing. the question now is Is the oil pressure gauge faulty or the pump? I am going to replace the gauge first. It was not moving at all. Any advice would be appreciated,thanks!
 

Old_Crow

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Joined
Nov 20, 2016
Posts
2,720
Location
Mt Laguna, California
First thing I would do is get a manual test gauge. You can probably borrow or rent one from Auto Zone or O'Reilly's. That eliminates the entire gauge system in the coach and gives a direct reading of the oil pressure.
If you have no pressure showing on the manual gauge, it's the pump, period. If the manual gauge shows good pressure, then you can start the electrical diagnosis to find out why the dash gauge doesn't work.
 

Ex-Calif

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May 15, 2020
Posts
1,822
What Old Crow said. Your mech sounds like a good guy - surprised he didn't mention a test rig.

"Pegged below L" - In some setups this could indicate no power in the gauge system. Next step (IMO) is rig up a test line.
 

Liuhisn

Active member
Joined
Oct 5, 2018
Posts
29
That would be a 460 motor, and yes, the oil pump shaft is separate from the distributor, two parts, in virtually every V8.

From what I can read in the Ford460 forum (yes the 7.5L is a 460) the oil pump shaft is a 5/16 hex shaft from top to bottom. Its possible the shaft sheared or the distributor drive gear shaft roll pin sheared. The distributor gear is actually pressed on and then drilled and the roll pin put thru, so I really don't suspect that roll pin, in fact since the engine kept running, it cannot be the roll pin at all or the engine would be out of time and quit/backfired, etc.

Some Ford products used nylon coated teeth on the camshaft timing gear, I have no idea if this one does or not. If it does, the nylon becomes old and brittle and breaks off and on occasion the chain will jump time, but many times not, if just one piece. The piece that broke then finds its way thru the grommet in the middle of the oil pump inlet screen, jams the pump, and shears the shaft. I HAVE seen a 289 do this. Old Pontiac 389's also used these plastic gears, and many others have too. Its to keep the chain quiet.

You really need to drop the oil pan and see what is in the pan, and if the pump shaft is sheared.

The retainer in the illustration is a C clip in a groove on the shaft. It prevents the shaft from coming out when you pull the distributor.

Distshaft.jpg

Charles
Hello Here is an update for the oil pump issue. I replaced the oil pressure gauge with a mechanical gauge and still did not get any pressure! I did notice a more pronounced rhythmic ticking sound coming from the engine. I immediately shut the engine off and thought about the situation. I realized that the last time I was there, the mechanic poured some oil into the valve cover through the pvc opening and had turned the oil pump drive shaft with an electric drill. This time I was by myself and did not do this. The clicking sound may be a stuck lifter. In theory, some SeaFoam in the crankcase and then turning the oil pump drive shaft with a drill help loosen any gunk buildup? Any thoughts?
 

Old_Crow

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Nov 20, 2016
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Location
Mt Laguna, California
Turn the oil pump drive shaft with the drill and the manual gauge installed. If you still don't have pressure, it's time to drop the oil pan.
BTW, not sure on the Fords, as I was a Chevy guy, but on a Chevy the oil pump turns counter clockwise, so you have to reverse the drill when turning the shaft. Take the distributor cap off and observe which way the rotor turns when you tap the starter.
 

Ex-Calif

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May 15, 2020
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Old Crow has got it, I think. The only other thing I can think of is a stuck open oil pressure valve. I am not very familiar with Fords but most engines have a ball bearing valve and a really tough spring. Hard for them to get stuck open but I have definitely seen at least one with a broken spring.

It should be accessible from outside the block.
 

CharlesinGA

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Oct 6, 2017
Posts
510
Location
50 miles south of Atlanta, GA
I posted yesterday but it disappeared. Anyhow, the distributor and oil pump does turn COUNTER-CLOCKWISE (LH) so the drill needs to be in reverse. A battery powered drill probably will not turn a pump that is pumping oil.

https://www.460ford.com/threads/priming-the-oil-pump-which-direction.107219/

https://www.460ford.com/threads/how-long-before-you-see-oil-pressure-when-priming-the-engine.123796/

You also can remove the filter and use an oil squirt can to pump oil into the hole that is off center in the block, this is the passage down to the pump, when it won't take any more oil, pour some in the filter and screw it back on, then start turning the pump.

Of course you need a pan with the oil level up to normal/full.

Charles
 

Liuhisn

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Joined
Oct 5, 2018
Posts
29
Thanks! I will try this! I have been doing a little research on this issue and have come to another possibility, a stuck oil pressure relief valve. Possibility number two is sludge getting pushed into the engine and thus plugging the openings leading to the engine and lifters. The plan of action that I have come up with will tackle both issues at once! Drain the oil from the pan and then pour in some engine flush. Run the drive shaft for the oil pump with the drill in both directions for 2min each. Fill with oil and run again. Replace distributor and start the engine and see what happens. Drain and replace oil. It makes sense. Strait engine flush should really clean out any sludge or blockages in the system. Theoretically this makes sense. What is your take on this option?
 

nfredrick

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Mar 13, 2017
Posts
48
Try a new Motorcraft oil filter, perhaps the bypass valve is stuck on the filter
 

Old_Crow

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Nov 20, 2016
Posts
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Location
Mt Laguna, California
Have you spun the pump with the manual gauge attached? Does it indicate pressure this way? If yes to the first question and no to the second, I don't have much confidence in the flush working, but it doesn't hurt to try.
Keep in mind, the more you run the engine with no oil pressure, the more stuff inside you damage.
If you don't have a manual gauge, a quick and dirty test is to remove the pressure sensor from the block and turn the oil pump. You should be able to tell pretty quick if the pump is pumping.
 

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