Last time I changed my oil I let it drip out for a couple hours before refilling it. When I started up the oil pressure indicator would not come up to normal for about one or two minutes. And then it just came up a little bit at first before coming back to normal. I figured it was the electrical connector as I had had trouble with that before and the engine never made any abnormal noise (best I could hear over the loud muffler).

Yesterday I bought some old Popular Mechanics magazines and here is what I found in the Oct 85 issue. It said that if the oil pressure light stays on for more than a few seconds after a change, shut the engine down, pull the filter and put 5 drops of SAE 30 oil in the inlet side of the oil filter mount to prime the oil pump (my references say this is the hole to the side of the threaded mounting tube). And to repeat this procedure until the light does not stay on. They suggested that the oil change may have drained the oil in the pump causing a loss of prime. I bet that is what happened to me. Spooky!

What to do? I figure it may be best to squirt motor oil into the return hole every time you do an oil change to ensure prime. Can't hurt, right? Why PM recommend 5 drops (actually I think they got the tip from Allied Signal) of SAE 30 oil I don't know. Dosen't seem like enough. None of my automotive repair/maintenance books address this. However, they do address priming the pump for installation and most say to use motor oil (Haynes weirdly says use petroleum jelly---whhhhhaaat ). Lastly, what keeps the pump from loosing prime if if is just sitting in the driveway for weeks? Ideally a car should have an electric oil pump primer that you can use to juice up the bearings before crankover (race cars probably do have this).

INLINE SIX POWER! '95 F150 XL
300 Cubic Inches of Low RPM Truck Torque! And twin-I-beams too!
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Did you pre-fill the new oil filter with new oil before you put in on the engine?

 

No. I almost never have and have not had this kind of problem. Usually the oil pressure comes up in a few seconds. However, I am planning to fill the filter (partly at least) for future changes. Still, that would not help on oil pump prime but I suppose could have an effect on oil pressure readings if the gauge pickup is after the filter.

 

I don't think that priming is really necessary nowadays - modern oils have all the goodies inside of them that leave a film all over everything - I would hope that 5 seconds without oil wouldn't totally destroy the pump.

I do, however, prime the filter. Call me a sissy, but I'm paranoid.

I get oil pressure right away.

Just my $.02

XXL

 

>I don't think that priming is really necessary nowadays -
>modern oils have all the goodies inside of them that leave a
>film all over everything - I would hope that 5 seconds
>without oil wouldn't totally destroy the pump.
>
>I do, however, prime the filter. Call me a sissy, but I'm
>paranoid.

It is easy enough to do, so might as well. But I am suggesting it may also be worthwhile to squirt oil down the hole in the block that leads to the oil pump in case the oil pump lost prime as then it will churn air and may take a while to pull oil up. Remember, most oil pumps are located several inches above the oil level in the pan. It's the oil pickup that is submerged. So if prime is lost in the pump (not the filter which is after the pump) it could churn air for who-knows-how-long until enough vacuum is developed to pull the relatively heavy oil up the pickup tube. Now maybe I am a worry wort as this is the first time I had this happen in 26 years (that I am aware of) and maybe it was just an electrical gauge malfunction.

 

Paul, I know it's frustrating to try to draw conclusions based on observation of the 'idiot gauge' Ford has bestowed upon us.

The way I understand it, by the time you see the needle move off the peg, it has already built sufficient oil pressure. Having the 'L-Normal-H' display range on the gauge is supposed to make us feel warm and fuzzy, but instead it just causes us to worry obsessivly!

The tip out of PM mag is kind odd though. Since as you say it doesn't really prime the pump because it's on the discharge side of the pump. I would guess what it is really doing, is preventing air from back flowing into the pump, allowing it to build enough vacuum to prime itself.

In any case, filling the filter with oil and allowing it to soak through the filter media fills the cavities on both the inlet and outlet sides of the filter. Prefilling the filter allows you to observe almost instant build up of oil pressure. Even with the 'idiot gauges' on our Fords! ;-)

 

>The tip out of PM mag is kind odd though. Since as you say
>it doesn't really prime the pump because it's on the
>discharge side of the pump. I would guess what it is really
>doing, is preventing air from back flowing into the pump,
>allowing it to build enough vacuum to prime itself.

I think they mean for you to displace the air that is within the pump (which is why I wonder why only 5 drops) so it can pull suction quicker.

>In any case, filling the filter with oil and allowing it to
>soak through the filter media fills the cavities on both the
>inlet and outlet sides of the filter. Prefilling the filter
>allows you to observe almost instant build up of oil
>pressure. Even with the 'idiot gauges' on our Fords! ;-)

I have my next filter full to the brim so the media is fully soaked. I will pour off the excess and then quickly mount it on the truck. Some may slop down the side but it does anyway when pulling the old filter. Anyway, I hope to get 1/2 to 2/3 of the filter full mounted sideways on the engine. BTY, the filter took about 23 oz of oil after all the air came out and the media was fully penetrated with oil. I still don't guess there is any harm to backfilling the oil pump outlet hole and may try it.

Thanks all.

 

Oh, I missunderstood. I see what you mean now. The 5 drops of oil goes into the filter adaptor on the engine, not the inlet side of the filter. That makes more sense now, it is actually priming the pump.

>I think they mean for you to displace the air that is within
>the pump (which is why I wonder why only 5 drops) so it can
>pull suction quicker.

Heh heh, they probably say 5 because they know guys like us will try to pour a whole quart through! They know we'll put in at least 25 drops anyway!

Scott

 

On my 302 the oil filter is located on the side of the engine block and sits at an angle. I fill the new filter until is can't hold anymore oil. When I install the new filter, some oil spills out. Could be that some of the oil is also spilling back down the tube to the pump. I've let my crank case drain over night a few times and have never had a problem with the oil pressure gauge reading pressure with a few seconds of start up.

And I get warm, fuzzy feel everytime I see the needle move towards "H".

 

I think priming the pump is probably a good idea, but I doubt I will do it unless it takes longer the 5 seconds to register oil pressure.

I also don't let the pan drain all night, I drain and fill within 1/2 hour's time. I don't care if I get every last drop of oil out since it seems insignificant.

 

I guess that would explain the one time I saw the check oil light for 30 seconds one time after a all night oil drain and cold weather and cold oil refil. Most of the times, when I do my usual 30 minute home change, the lights on all my engines go off in just a few seconds, but that one time it stayed on for what seemed like a long time.

Intersting idea and kinda makes sense.

Jim Henderson

 

My name is Glenn . . . and I am an oil-change FREAK!

There - I FEEL better.

I have changed TANKER-LOADS (well, lots of) oil, mostly since 1978, but starting in the mid-70's (I know, I know, there are guys here who have SPILLED more oil, WIPED MORE OFF THEIR HANDS than I'll EVER change!) . . . nevertheless, based on a "tip" in "Hot Rod" mag. from around 1980, I have ALWAYS filled the filter - angled, sideways, (90 degree) right-side UP, wrong-side DOWN (180 degree - THAT, is tricky) - and I have consciously, on purpose, watched gauges (or "GAGES" as it's spelled on my dash-indicator), and "idiot" lights (remember the 80's?) before that, and I have NEVER waited more than 5 seconds - TOPS - and that was only ONCE, to the best of my recollection, for an oil-pressure "gage" or "light" (lite? -haha) to allow me to "take a breath" - BREATHE!

Virtually every oil-change I've ever done has had an approx.\avg. "window" of 2.5 seconds - ok, 2-3 seconds, before the gauge registers or light goes (fL-iCk,ErS) off.

Currently, my `99 Ranger, 3.0 oil-filter (as many, if not most of you are aware) mounts at an angle (approx.? 45 degrees), I occasionally spill a few drops, and I usually lose a "glug" or two on my wife's Honda (straight 90 degrees, back-center of motor!).
My gauge usually "salutes" BEFORE I've released the ignition switch, and she turns right-over (starts quick). The Honda's "light" disappears "1001, 1002, 1000-OFF".
Granted, very cold-weather (say, 20 degrees or COOLER) changes I've done the Ranger guage has left me "hanging" until I release the switch from "start" to "on", and I've "timed-out" the Honda, with a good watch, on a frigid day (perhaps I used a "blend" or maybe even "dino") at 4 seconds - but that's it.

I rest MY case.

Love you guys (hahahahahahaha!!!!!!!) Glenn . . .

 

Hi Glen, Welcome to Oil Changers Anonymous

 

Good stuff, folks.

I just want to add my idea that some people may try: after an oil change, or after a vehicle sits a long time, the use of an ignition 'kill' switch, or pulling the coil wire, should allow the starter to freely turn the engine and work the pump without any of the pressures that ignition puts upon the engine.

Some cranking (under 10 seconds of course) for an oil change, or two under-ten-second intervals for a stored vehicle, would seem to get the oil moved around much better than not doing anything at all.

Pre-filling is a great idea, and I've done it often, but the I-6's filter is parallel with the ground, and I don't like making messes like that.

Best,