Oil Pump Replacement...

Been there, done that - You can do it in the car, but it is hard to do. The best way is to pull the engine.

Disconnect the battery at the battery ground terminal, remove the fan and fan shroud. Both motor mounts will need to have the large nuts that secure them to the frame removed. The trans mount will also have to be loosened, and it is a good idea to remove the drive shaft.

I also had to disconnect the cat pipes at the headers to get the engine high enough to remove the oil pan. Be prepared to have to drop the steering rack and disconnect the steering shaft. Jack up the engine with a wood block under the oil pan and watch for things that bind or hoses/electrical wiring that may need to be disconnected. I put a couple of wood blocks between the headers and the frame to support the engine. You will likely need to jack up the rear of the transmission as well to get the required clearance.

Scrape the pan mating surfaces clean as possible - old gasket stuck to the surfaces are a source of leaks.

Get a high volume/heavy duty pump, and a replacement HD pump shaft. FMS makes one, and ARP does too. When you install the pump, the funny looking washer thingy goes on the part of the shaft that fits into the hex socket in the distributor shaft. It keeps the shaft in place when you remove the distributor, which you will have to do to prime the pump. Forget to put it on, and the pump shaft can come loose and fall down in the bottom of the oil pan.

There is a one piece oil pan gasket which will help re-assembly if you can find it. If you can't get this gasket, use weather strip adhesive to secure the cork gasket to the pan rails and the rubber strips to the bearing caps. Read the instructions on the adhesive carefully to make sure the gaskets are permanently stuck in place and won't move when you slide the pan in place. Use lots of blue silicone sealer on top of the front and rear rubber seals where they mate with the pan.

Fill with oil, replace the filter. Reconnect the battery, switch the ignition on to enable the gages, but DON'T crank the car. Remove the distributor and use a 1/4" hex socket to turn the pump counter clock wise (same direction as distributor rotation) until you see oil pressure (an external gage is a great help long about now). And keep turning for about 30 sec after you see the pressure come up. A reversible drill is the best tool to use to turn the 1/4" socket. The pressure should come up to about 50-80psi with cold oil. Once you see good pressure, check for obvious leaks, and then and only then, lower everything back into place and bolt down the mounts and anything else you had to take loose.

Re-install the distributor and set the timing with the engine running using timing light (don't forget to disconnect the SPOUT plug and reconnect it when finished) 12-14 degrees BDC is good. Start up and check for leaks, let it warm up and look again for leaks. It took me 2 days plus, but I am old and slow, maybe your granny is faster.

Alternative process...
Drop the K member - let's think about that for a moment... I haven’t actually done this, so I will likely miss some details. But here’s the rough outline. Input from anyone who has actually changed a K member is welcome...

Disconnect the battery at the battery ground terminal, remove the fan and fan shroud.
Jack up car using floor jack under the K member
Remove the front wheels.
Remove the front brake calipers from their mounts.
Put jackstands under the A arm close to the ball joint.
Disconnect the roll bar links.
Chain the front springs so that they don't go flying out when you release pressure on them. Flying springs can kill you, so this is crucial.
Remove the top nut from each shock strut or remove the bottom shock strut mount bolts.
Put floor jack under the A arm, put pressure on the A arm so that you can remove the jackstand.
Move the jackstand to the K member to A arm pivot point. Place it so that it des not inhibit the A arm movement.
Slowly release the pressure on the jack while watching the spring. Once the tension is off the spring, remove the chain and the spring.
Repeat the process for the other side.
The flex coupling for the steering shaft needs to be disconnected before you can remove the K member. You should disassemble the coupling by undoing the 2 bolts that hold it together.
Both motor mounts will need to have the large nuts that secure them to the K member removed.
The trans mount will also have to be loosened and the bolts removed.
Use a chain host or engine lift to support the engine.
Put the floor jack back under the center of the K member and relocate the jackstands to support the car.
Remove the bolts on each side that secure the K member to the body.
Disconnect the hydraulic lines from the steering rack.
Lower the floor jack with the K member on it and remove it from under the car. You will need a helper on each spindle to keep the K member from falling off the floor jack. Your helpers may need to turn the K member so that it lays flat to have enough clearance to get it out from under the car.

Reverse the process to re-assemble. The springs will probably need a spring compressor to re-install them. Again, caution is the main thing, since a flying spring is very dangerous.

Some alternative possibilities are to leave the springs and struts alone and remove the bolts that mount the A arms to the K member. Again, I haven’t tried this, so I don’t know if it can be done successfully.

After looking at all the work, I think that I would rather pull the engine or do it with the engine jacked up to clear everything.

thehueyPilot’s comments:
That's pretty close......I did not remove the fan or shroud or the trans bolts. I used a cherry picker to hold the engine in place. The k member is held on by eight bolts (four on each side) I left the spindles in place still attached to the struts but removed the rotors to get better access to the lower ball joint.

I've done this before myself as well and as jrichker said, you'd be better off pulling the engine all the way out. I did it without pulling it and it made it harder to do. Get it towed home and then do it right, this will save some sanity and most of all, that pain of being on your back after crawling over the hoist's legs.

Same thing happened to me. I just got the motor out and on a stand last night. Pulling the engine out was not as hard as I thought it was going to be. Its a good idea to have some extra hands there. With the motor out might as well take care of a few other things. I am replacing the clutch and rear main seal. Only question I have is about the high volume oil pump. I heard things like sucking the pan dry and its not really needed. Is there any truth to that? If so do I even need a HV pump?

I'd stay away from the HV pump. Standard volume is all you need.

AZNEAL311 said:

Only question I have is about the high volume oil pump. I heard things like sucking the pan dry and its not really needed. Is there any truth to that? If so do I even need a HV pump?

Click to expand...

If you believe in vampires that bite you on the neck and suck all your blood out, the myth about high volume pumps is true. If not, here's the truth from the Melling company that makes the good oil pumps.


Thanks to bubba-dough for helping to educate all of us...

http://data.melling.com/Tech pdfs/HIGHVOLUMEPUMPS.pdf
You will need the Adobe Acrobat viewer which is also a free download – http://www.adobe.com/products/acrobat/readstep2.html

From the Melling site, for those who didn't follow the link & read the tech note...



High Volume Pumps: Advantages, Myths & Fables

Most of the stock automobile engines are designed to operate from idle to 4500 RPM. The original volume and pressure oil pump will work fine in this type of application. As the demands on the engine increase so does the demands on the oiling system and pump.

The oil pump's most difficult task is to supply oil to the connecting rod bearing that is the farthest from the pump. To reach this bearing, the oil travels from three to four feet, turns numerous square corners thru small holes in the crankshaft to the rod bearing. The rod bearing doesn't help matters. It is traveling in a circle which means centrifugal force is pulling the oil out of the bearing.

A 350 Chevy has a 3.4811 stroke and a 2.111 rod journal. The outer edge of the journal travels 17.5311 every revolution. At 1000 RPM, the outer edge is traveling at 16.6 MPH and 74.7 MPH at 4500 RPM. If we take this engine to 6500 the outer edge is up to 107.9 and at 8500 it is 141.1 MPH. Now imagine driving a car around a curve at those speeds and you can feel the centrifugal force. Now imagine doing it around a circle with a 5.581, diameter.

The size of the gears or rotors determines the amount of oil a pump can move at any given RPM. Resistance to this movement creates the pressure. If a pump is not large enough to meet the demands of the engine, there will not be any pressure. Or if the demands of the engine are increased beyond the pumps capabilities there will be a loss of oil pressure. This is where high volume pumps come in; they take care of any increased demands of the engine.

Increases in the engine's oil requirements come from higher RPM, being able to rev faster, increased bearing clearances, remote oil cooler and/or filter and any combination of these. Most high volume pumps also have a increase in pressure to help get the oil out to the bearings faster.

That is what a high volume pump will do. Now let Is consider what it will not do.


It will not replace a rebuild in a worn-out engine. It may increase pressure but the engine is still worn-out.

It will not pump the oil pan dry. Both solid and hydraulic lifters have metering valves to limit flow of the oil to the top of the engine. If a pan is pumped dry, it is because the holes that drain oil back to the pan are plugged. If the high volume pump is also higher pressure, there will be a slight increase in flow to the top.

It will not wear out distributor gears. The load on the gear is directly related to the resistance to flow. Oil pressure is the measure of resistance to flow. The Ford 427 FE "side oiler" used a pump with relief valve set at 125 psi and it used a standard distributor gear. Distributor gear failures are usually caused by a worn gear on a new cam gear and/or worn bearings allowing misalignment.

It will not cause foaming of the oil. With any oil pump, the excess oil not needed by the engine is recirculated within the pump. Any additional foaming is usually created by revving the engine higher. The oil thrown from the rod bearings is going faster and causes the foaming. This is why high performance engines use a windage tray.

It will not cause spark scatter. Because of the pump pressure there is a load on the distributor gear. The number of teeth on the oil pump gears determine the number of impulses per revolution of the pump. In a SB Chevy there are seven teeth on each gear giving 14 impulses per revolution. At 6000 RPM the oil pump is turning 3000 RPM or 50 revolutions per second. To have an effect on the distributor, these impulses would have to vibrate the distributor gear through an intermediate shaft that has loose connections at both ends. Spark scatter is usually caused by weak springs in the points or dust inside the distributor cap.

High volume pumps can be a big advantage if used where needed. If installed in an engine that does not need the additional volume, they will not create a problem. The additional flow will be recirculated within the pump.

I have run high volume pumps for over over 10 years and not had any problems. As the engine wears, oil pressure drops off due to increased clearances. With a high volume pump, even though the clearances still increase, the pressure stays up.

I've read in the past what Melling's theories are, however I've run high volume pumps on stock clearance motors with less than ideal results regardless of what Melling says. Melling says if the engine doesn't demand the additional oil, it just bypasses. If that was the case you wouldn't have a rise in pressure. I've had stock clearance motors with hv (and yes they were high volume not high pressure) pumps see 100 psi cold / 85 psi hot. That's excessive in my opinion. If their theory was correct that wouldn't be the case. The problem is, a pump can only bypass so much oil before it's at max flow for a given psi. That's where you get pressure spikes. All this does is: #1 Require more hp to turn and #2 Pump additional unneeded oil to the top of the engine where it can create more windage on the return path and cost even more power.

but, since he already bought the HV pump i dont see why he can't use it..lets just call it an early upgrade for the blown stroker nitrous motor you're dreaming about..

~Mark~

Been there done that as well my friend, twice actully, I change the pump with a melling and i used the stock pick up tube and once around the block NO OIL Pressure back to square 1 again, i was so close to kicking the car. Ended up being a peice of the driveshaft was in the pick up tube The ARP is a good choice, I just went with a new Ford Racing High Volume pump, none of that remanufactured BS Autozone sells!!!

EMW150 said:

I've read in the past what Melling's theories are, however I've run high volume pumps on stock clearance motors with less than ideal results regardless of what Melling says. Melling says if the engine doesn't demand the additional oil, it just bypasses. If that was the case you wouldn't have a rise in pressure. I've had stock clearance motors with hv (and yes they were high volume not high pressure) pumps see 100 psi cold / 85 psi hot. That's excessive in my opinion. If their theory was correct that wouldn't be the case. The problem is, a pump can only bypass so much oil before it's at max flow for a given psi. That's where you get pressure spikes. All this does is: #1 Require more hp to turn and #2 Pump additional unneeded oil to the top of the engine where it can create more windage on the return path and cost even more power.

Click to expand...

I have used a HV pump on two different 5.0 engines and never saw more that 80 PSI cold. No problems with over 150K miles between both engines.

Are snapped oil pump shafts in early 90's 5.0's that common? A friend called me last night and that was what I told him to check based on what he discribed with his '91. Today he confirmed that the shaft had indeed snapped.

69 Rustang said:

Are snapped oil pump shafts in early 90's 5.0's that common? A friend called me last night and that was what I told him to check based on what he discribed with his '91. Today he confirmed that the shaft had indeed snapped.

Click to expand...

I wouldn't say common but it does happen. 90 percent of the time it's debris that gets in the pump that locks it up.

the melling pumps aren't reman autozone "junk"...lol they're great pumps, and if memory serves me, melling makes nearly all pumps anyhow.


as well, return that pos arp driveshaft, and buy a ford racing oilpump driveshaft instead $20. the ARP oilpump driveshafts are not the right size, and you're supposed to cut to length MAKE SURE YOU READ THIS, because if you use that arp shaft, it will be too long, and you'll have big troubles. If you use the frpp shaft, it's the exact fit right off the bat with no cutting.

v8only said:

the melling pumps aren't reman autozone "junk"...lol they're great pumps, and if memory serves me, melling makes nearly all pumps anyhow.


as well, return that pos arp driveshaft, and buy a ford racing oilpump driveshaft instead $20. the ARP oilpump driveshafts are not the right size, and you're supposed to cut to length MAKE SURE YOU READ THIS, because if you use that arp shaft, it will be too long, and you'll have big troubles. If you use the frpp shaft, it's the exact fit right off the bat with no cutting.

Click to expand...

Funny the ARP driveshaft went right in for me, absolutley no cutting it to size. no probelms over a year now. I never said melling was junk either, just dont buy an autozone remanufactured unit, period.

if you hold it close to the stocker, it is a hair longer, and directions say cut to fit.....