Renix oil pressure

[Tex06]

Just inherited an '89 xj (4.0, Aw4, no idea on axles yet) and it's been sitting over 8 years. Popped a new battery in it yesterday and cranked on it (no start, that's OK)

 

Good news: Turned over, no fires, all the lights and electrics seem ok

 

Bad news: oil pressure didn't register after 2-3 20 second cycles of the starter. Popped off the oil pressure sending unit (below distributor, right? ) and had my buddy crank on it. No oil coming out.

 

Question, was this a valid test for a faulty oil pump? If so, what kind of job is it to drop the pan and replace?

 

Also, when I cycle the key on I don't hear the fuel pump cycle like my '92. I'll attach a fuel pressure gauge next time but I'm pretty sure that means new Bosch pump time.

 

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[HOrnbrod]

If it's been setting for eight years the oil pump has lost it's prime and is probably dry. Cranking it over probably ain't going to prime the pump. You can pull the distributor and using a long flat blade screwdriver shaft and a power drill, rotate the pump cw which will prime the pump and should build up enough pressure to force some oil out the gauge port.

 

And don't just assume the fuel pump is toast. Test for 12V on the ballast resistor and at the pump connector first. Or hot-wire the pump to see if it runs. Easier than pulling the pump if you don't have to.

[Tex06]

So not like the old GM pumps that you could just crank over. I've got an oil prime extension from Summit racing for sbc motors, I bet it'll work on Jeeps.

 

 

 

Gotta drop the tank anyways and get that old fuel out. Throwing in a new FP should be a piece of cake and save me troubleshooting later on.

 

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[HOrnbrod]

So not like the old GM pumps that you could just crank over. I've got an oil prime extension from Summit racing for sbc motors, I bet it'll work on Jeeps.

 

Don't think a SBC priming tool going to work for you mate. 

[Tex06]

It's essentially a flathead screwdriver for a drill, roughly 12-14 inches long. Did I miss something on how to prime the 4.0?

 

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[DirtyComanche]

SBC priming tool should work.

 

Or throw some oil down the hole and slam the disty back in, as long as the gears are wet it will probably prime...

[HOrnbrod]

OOkay, then it should be fine. Wasn't positive on the GM pump shaft config.

[ParadiseMJ]

OP...did you check the oil level?

[Eagle]

If the oil pump has lost its prime, I don't see how spinning the shaft with a drill is going to help anything. All you're doing is trying to pump air with a pump made for viscous liquids. But -- whatever you don, DON'T crank the engine any more. The cylinder walls are dry, the bearings are dry, the camshaft is dry ... everything is dry, and has no lubrication. See if you can rig up some Rube Goldberg arrangement to force feed some heavy oil back through the oil pressure sender hole to get oil back into the system, then try spinning the pump with the drill.

[cruiser54]

What if it was as simple as this in the link below?

 

http://www.jeepforum.com/forum/f19/4-0-low-oil-pressure-idle-fixed-1304679/

[desbennett004]

On a similar note, I had the valve cover off my 89 MJ, while it was running I found that it was conciderably dryer at the back of the motor than at the front. It also has a tick coming from #5 or #6. Should I be concerned, or is this pretty usual? The motor was just rebuilt by the PO.

 

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[Tex06]

SBC priming tool should work.

 

Or throw some oil down the hole and slam the disty back in, as long as the gears are wet it will probably prime...

Slamming definitely necessary sometimes, lol!

 

 

OP...did you check the oil level?

Yep, first thing I did.  Topped off with junk oil (10w-30 strone brand) just to make sure it wasn't below the pickup.  I'm just used to Fords and Chevys that you can turn over with the starter to prime the pump.

 

 

If the oil pump has lost its prime, I don't see how spinning the shaft with a drill is going to help anything. All you're doing is trying to pump air with a pump made for viscous liquids. But -- whatever you don, DON'T crank the engine any more. The cylinder walls are dry, the bearings are dry, the camshaft is dry ... everything is dry, and has no lubrication. See if you can rig up some Rube Goldberg arrangement to force feed some heavy oil back through the oil pressure sender hole to get oil back into the system, then try spinning the pump with the drill.

Running with a starter isn't going to move it enough to seriously harm anything.  The motor wasn't going to catch with bad fuel (and possible bad pump).  This method is the most common way to prime SBC and small block Ford motors, just pull the coil wire.  

 

 

What if it was as simple as this in the link below?

 

http://www.jeepforum.com/forum/f19/4-0-low-oil-pressure-idle-fixed-1304679/

I fished a piece of baling wire down there and it came up dry.  I'll have to try the compressed air trick if I can get a portable air compressor next time I get to work on the thing.  My problem was NO pressure or even a dribble, usually a blockage like that (in most hydraulic systems) gives a partial block.

[Eagle]

Running with a starter isn't going to move it enough to seriously harm anything.  The motor wasn't going to catch with bad fuel (and possible bad pump).  This method is the most common way to prime SBC and small block Ford motors, just pull the coil wire.  

 

 

Not in this corner of the world. At least, not when I was crewing on the stock car. Even a new engine that we knew had assembly lube on the cam, cam bearings, crank and rod bearings, and cylinder walls got the oil pump spun over with a drill until we had positive oil pressure. Until we saw oil pressure, the engine was only cranked over by hand.

[HOrnbrod]

What was the below all about? Just make sure there's plenty of oil in the pan so the pump pickup is well below the surface, and spin the pump up slowly at first then increase speed. Your variable speed drill will soon start slowing down when the pump starts pushing the oil through. But I'm sure you know that............ 

 

If the oil pump has lost its prime, I don't see how spinning the shaft with a drill is going to help anything. All you're doing is trying to pump air with a pump made for viscous liquids.

[Tex06]

 

Running with a starter isn't going to move it enough to seriously harm anything. The motor wasn't going to catch with bad fuel (and possible bad pump). This method is the most common way to prime SBC and small block Ford motors, just pull the coil wire.

 

 

Not in this corner of the world. At least, not when I was crewing on the stock car. Even a new engine that we knew had assembly lube on the cam, cam bearings, crank and rod bearings, and cylinder walls got the oil pump spun over with a drill until we had positive oil pressure. Until we saw oil pressure, the engine was only cranked over by hand.

Much tighter tolerances there. On a engine not meant for racing in the pre-fuel injection era things were different. My shop manual for the 235 cid 6 cylinder and 283 SBC both say to prime a new pump this way. Granted this was written close to 60 years ago. Things have changed a lot since then.

 

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[Tex06]

What was the below all about? Just make sure there's plenty of oil in the pan so the pump pickup is well below the surface, and spin the pump up slowly at first then increase speed. Your variable speed drill will soon start slowing down when the pump starts pushing the oil through. But I'm sure you know that............

 

If the oil pump has lost its prime, I don't see how spinning the shaft with a drill is going to help anything. All you're doing is trying to pump air with a pump made for viscous liquids.

I think he was thinking the sump was above the oil. In which case spinning it wouldn't help, lol.

 

I like the dump some oil method and then hit it with the drill. Feels like the best of both worlds.

 

While we're all here, anyone have a convincing reason for a high volume pump on a stock engine? I like the idea for a high performance motor but if I have to tweak the oil pan I can't see why the extra time and effort (cost is about the same for melling) would be worth it.

 

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[tugalo]

wouldn't hurt to remove the plugs and squirt some oil onto the pistons before spinning it with the drill.....

[HOrnbrod]

I put in a Hesco high-volume oil pump (reworked Melling) in the stroker when it had about 3K miles on it. The pan didn't require any tweeking with the Hesco pump. The oil pressure went up on average 20 psi from what it was before with a fairly new stock Mopar pump. When starting cold the needle was nearly pegged until it warmed up, then settled back down and ran at about 60 psi. After a few thousand miles it dropped down about 5psi-10psi overall and has stayed there ever since. And yes I have changed the sensor just to verify.

 

To answer your question though I think is no, I don't think a high-flow pump is necessary in a stock engine. Probably isn't really necessary in my stroker either, but all the gurus on the stroker forum recommended one. I'd just use a good quality stock pump for a stocker.

[Eagle]

 

Much tighter tolerances there. On a engine not meant for racing in the pre-fuel injection era things were different. My shop manual for the 235 cid 6 cylinder and 283 SBC both say to prime a new pump this way. Granted this was written close to 60 years ago. Things have changed a lot since then.

 

 

 

Things haven't changed that much. The AMC FSMs from the mid-1960s said to pack a new oil pump with Vaseline as a way of getting a prime.

[Eagle]

 

What was the below all about? Just make sure there's plenty of oil in the pan so the pump pickup is well below the surface, and spin the pump up slowly at first then increase speed. Your variable speed drill will soon start slowing down when the pump starts pushing the oil through. But I'm sure you know that............ 

 

If the oil pump has lost its prime, I don't see how spinning the shaft with a drill is going to help anything. All you're doing is trying to pump air with a pump made for viscous liquids.

 

 

How is an oil pump going to start picking up oil if there's nothing between the gears but air? What you are describing is a self-priming pump, and automotive oil pumps are not self-priming.

[Eagle]

wouldn't hurt to remove the plugs and squirt some oil onto the pistons before spinning it with the drill.....

 

We're talking about spinning the oil pump shaft with a drill, not the engine.

 

[HOrnbrod]

How is an oil pump going to start picking up oil if there's nothing between the gears but air? What you are describing is a self-priming pump, and automotive oil pumps are not self-priming.

 

Try it anyhow. There's probably enough sludge oil inside the pump still to pull a suction.

[gogmorgo]

Much tighter tolerances there. On a engine not meant for racing in the pre-fuel injection era things were different. My shop manual for the 235 cid 6 cylinder and 283 SBC both say to prime a new pump this way. Granted this was written close to 60 years ago. Things have changed a lot since then.

 

It may not be absolutely critical, but tiny details like this can be the difference between an engine running for 300,000 miles and 500,000 miles. Spinning the bearings with no oil pressure, especially if there's not much oil residue left on the bearings, is still metal on metal, and those few seconds of dry wear can be the equivalent of tens or hundreds of thousands of miles of lubricated wear. Just my 2¢.