is it possible to need to reprime oil pump after an oil change?

I am picking up a mech gauge to replace my electrical renegade gauge which I believe has issues to determine more, but I do have a few questions. Gauge is suspect because sender terminal GROUNDED only gives about a 40-50psi reading. Sender itselff is 80omhs at rest...
I thought I had ground issues and ran a dedicate ground to gauge casing, that made illumination light work again but still no readings.

However it worked a bit 4 months ago when I drove the Jeep home.

Engine oil was required to be changed cold after the oil dipsitck tube broke, and I extracted it, installed new tube, and wanted any junk out. Old oil filter was left ON engine until fresh oil was put in. Over the last 4 months I did alot of drivetrain and suspension work that each end was lifted up and down, although it all lifted level was the most common position (not sure if this matters with oil pump retaining oil)

BESIDES HEADERS, PLUGS....no other engine work was done, nothing internal. Oil pump untouched.

This is a 40K mile 304 AMC.

I filled crankcase with 4qts, stick read full. Put as much oil as I could in a new filter, and spun it on (purolator brand), I got the filter maybe a third full.

Cranked....all fuel lines were replaced so it turned and turned a bit more then fired up. Noted gauge was zero and immediately stopped engine to check gauge....

*
I noted the oil level in the crankcase DID change, engine wanting almost a quart in case after cranking, short initial fireup, indicating oil DID get moved around/delivered to filter.

The above confuses me a bit, does this INDICATE I have prime, or is the above condition possible and still have no indicated oil pressure?

Thanks

 

Put the mechanical guage on it and verify. But from what you are describing it sounds like oil is circulating in the engine.

 

thanks. sorry for my probably usual rambling. after 4 months of drivetrain work and just basically a header install, I freaked a bit.

I will install a 2" gauge mechanical in the stock location tonight..

When I do that can I be ultra paranoid and pour oil into the 1/4 NPT? fitting location FOR the sender, will this 'additionally' prime the oil pump? Or will that anger the following mechanical gauge install?

I will probably do the drill to pump technique as well. I should have done it anyway to be ultra paranoid, but I thought I was so careful to save oil for the pump by not doing the oil filter until I was ready to put a partially filled new filter on with a full sump and attempting fire.........

getting so close to making this Jeep drive around as design intended instead of garage art!

 

Zero oil pressure is accompanied by loud lifter clatter. No clatter indicates that you have oil pressure.

No need to be ultra-paranoid. Under normal conditions, the oil pump only needs to be primed if you take the oil pump cover off. The tiny amount of air that you introduce due to changing the sender won't matter.

The gauge won't care if there's air in the line or not. Air transmits pressure just as well as oil.

 

well it was a quick test fire on open shorty headers to be assured it could run if shop custom bending exhaust tried to start it, which I assume they will. I didn't have the intent to run more than a few seconds, either way, but seeing zero on that makes me want to check it very thoroughly before towing to bending shop.

It's possible I am just not waiting long enough for the gauge to show anything.

Loud as hell but under the ruckus there was no other unhappy sounds. Oil level in pan did change, indicating oil going somewhere as usual in changing an engine oil, so I guess this is safe to show as indicated prime...


I was curious if you can add oil TO the pump through the sender hole, or is it a wasted effort to bother?

I probably have a gauge issue, although it did have 12v in and a dedicated gauge body ground, even out of the car and tested with a grounded sender wire it only went up like halfway when it should have quickly pegged to 80, probably can't even measure/read 5/10/15 psi.

 

you will know it when theres no pressure, been there

The oil pump it a positive displacement gear type pump, which do self prime.

I struggled for months to get a the electric oil pressure gauge to work. Until i just broke down and bought an auto meter unit with an new sender and gauge. (classic series matches the factory gauges)

 

does the typical autometer '2 1/16' gauge fit in the place of the present Stewart Warner oil pressure/amps gauges on my Renegade? Or do the holes need enlarging. hope not.

 

There's more than one size. IIRC it's the smaller of the standard sizes that fits. If you get the right gauge, it will fit perfectly.

From a quick look at teh Stewart-Warner site, 2 1/16" looks right. They also have some 2 1/32" gauges, but I expect they fit too.

 

I understand common replacements of this era are 2 1/16 and 2 5/16 ? Perhaps my original will read and I should consider one more try...

 

I had the Stewart Warner 82322 or equivalent in my '73 long ago. Fit perfectly. 2 1/16".
http://store.summitracing.com/partdetail.asp?autofilter=1&part=SWW-82322&N=700+115&autoview=sku

 

thanks for all the info. as much as I'd like to retain the original gauges, I'm probably better served with a mech oil pressure gauge and ditching ammeter for voltmeter in the future.

 

Just did the voltmeter swap, works great, no issues. Much better indicator for me of whats going on under the hood.

 

yeah I should probably ditch the ammeter also, did you simply conjoin the wires, or rewire the Jeep to rid the dash of the circuit?

 

Yes you would and you can tap the power for the volt meter off the oil pressure gauge.

 

I didn't wait long enough, after testing yet again with a brand new autometer on deck...The gauge responded normally. .... I will test resistance of sender engine running next to check coorespondance with guage reading.

It fired up with cold oil and showed approx 20psi took maybe 2 more seconds after my pervious panic point, which I'm starting to now in reflection think was only 3-5 seconds running time.

The autometer is a nice gauge but the bezel made it almost impossible to read in that location and mounting plane. The stewart warners are probably a better bet as Tim posted or maybe the Autometer's that are thin chrome outlined.

Thanks for all the info everyone.

I'm sending the Jeep for headpipe pipe bending next week and an alignment, then I get to tune and, I just might possibly have a Jeep that runs....

 

I just swapped in a new 12si alternator as part of my electric fan project. While I was at it I replaced my ammeter with a new crown replacement voltmeter. I say this because I no longer needed the heavy power wires that run through the dash since I wired the alternator directly to the battery post on the starter solenoid. I don't have my wiring diagram handy, but I think if you still have the stock setup, you would just direct connect the previous ammeter connections as they carry the Jeep power through them, which is necessary to read how many amps the Jeep is drawing.

I capped the old hot wire (again, new direct alt connection) and tapped into an accessory hot and ran a new ground wire, I wanted a hot that would give me something closer to the "sensing" voltage the alternator receives. So I believe both of you are on the right track. You want an accessory wire so it: 1) Doesn't drain the battery 2) Gives you a realistic voltage that is further away from the battery.

I reused the dash light wires to wire up the new integrated gauge light. Works Great! If you pay attention to it you can really see how the alt is performing, when the big draws occur and if the alt can respond. (which the 12si does great)

 

Yep, I've got an autometer mechanical, and it takes what seems like a surprizingly long time beofore the oil pressure registers on the gauge after initial start.

 

It was the same way with factory electric, but not with the new auto meter gauge, its intantainous. I think the factory gauge has a long response time.

 

My Stewart-Warner gauge was instantaneous. The needle moves up and down with engine speed, just like a tachometer. At startup, it would come off the peg as soon as the engine started, no more than a second lag.