Here's the story of Bad Mr. Oil Pump.

I had been driving yesterday and noticed that my oil pressure was a lil lower than usual, but it wasnt dramatically lower, mabye 5PSI lower than usual. I shrugged it off and thought that maybe it's because the engine is still cold or something. Drove around from store to store to get parts and tools needed to replace my brake pads.

So I go home, do my brake job and decide I need to drive it around! Right as soon as I put it in gear I could tell it didnt have as much power as it should. I thought perhaps it was just brake drag, since these are brand new pads I could just have to break in the new pads for the rotor to find the new "sweet spot" so I wouldnt have brake drag.

So I drive it around, and stop in a 7/11 and get a slurpee, come back out, start up my car and all the dummy lights except the Check Oil light turns off, I go "hmm, that's weird" and look at my oil pressure, it's at like 3PSI! Now at this point I was idling extremely rough and the PSI was at the "safe" level since it was at like 350RPMs, so I figured, I've got people in the back of the car, I dont wanna have to call AAA and have them tow me. So I give it a rev, and the oil pressure goes up some, but it stays very close to the 10PSI / 1000RPM mark.

So I drove it home (very slowly, didnt get over 2,000 RPMs) and shut it down.

Now what I experienced while driving it was that it had a resistance to revving up any, or movement all together, it just all around felt sluggish. I fear turning the car on again until this gets cleared up. I kicked myself all the way home as I drove it knowing the oil pressure was sub-par.

My normal oil pressure stays around 30 at idle, and up to 60 as it gets up to high rev's (as it should I assume?)

Anyways, that's what happened and why I suspect the oil pump. I told Stekman this info last night when it happened and he agreed that it was more than likely a clogged oil pump.

Stekman also stated that in order to R/R the oil pump you must, MUST, move the engine in order to get to it.


What is the exact procedure to R/R a oil pump? I really fear moving the engine off in my driveway, but i have no other place to go with it.

 

I've done this a couple times. You have to remove the bolts at teh motor mounts and jack the engine up while leaving the car body in place. Remove the starter. Jack the motor just high enough to get the oil pan out from under the engine and over the K-member. After that you have access to all of the bottom end including the oil pump.

 

so is the pump inside the engine, or mounted outside? I'm confused as to why I need to take off the oil pan lol.

 

It connects to the engine inside the oil pan. It has a pickup thats submerged in the oil. A lot of people insist that priming a SBC engine is a waste if time, because the oiling system is designed good enough that it doesnt matter.

 

will this oil pump work? It costs less than the oil pump repair kit for some reason.

 

Melling M-55 oil pump ($13, Autozone)
Melling 55-S pump pickup ($5, Autozone)
Mr. Gasket #26 pressure spring
Lightweight oil pump driveshaft (I like ARP's)

Depending on what driveshaft you get, it's like a $30 combo.

Like stated, the pump is under the oil pan (or above, depending on which way you are looking at it). It is bolted directly to the rearmost main cap of the engine. The driveshaft then extends upwards and locks to the bottom of the distributor gear (which is how it is turned)

 

m55 is the only pump to use along with a one piece oil pan gasket form fel pro. weld a brace on the pick up and bolt it to the pump body.

 

ok, I ordered the parts, they should be in by Thursday.

Was a little more expensive than I thought it would be though.

my reciept from Schucks.

Mr Gasket #26 Pressure Spring - $6.99

Melling M-55 Oil Pump - $13.99

Melling 55-S Oil Pump Pickup - $13.99

Melling IS 55-E Driveshaft - $12.99

- Grand Total = 47.96

I was going to buy one of those once-piece oil pan gaskets as well, but it was like 30 dollars, and it was a set with some O rings, so I passed on that.

Hopefully this will go smoothely.

BTW, Is there anything I can do if I absolutely cannot use a engine hoist in this project? Anywhere that I could jack to get the engine up high enough to get the oil pan out?

 

I wanted to suggest that you get a mechanical oil pressure gauge and test your pressure with that before you change the pump.
Last summer, I was sure my pump must be going bad or maybe a bearing had spun. I was all set to go into the pan when i thought I'd do a check with a mechanical gauge. It ended up my sending unit was bad.
You can tap into a hole at the front of the block on the pass side right behind the water pump. There's a 1/8 pipe plug there, thread a mechanical gauge in and check your press.
Yuo might save yourself a lot of trouble.

 

How do you know for sure it is the oil pump?? There are other things that can cause a low oil pressure....Do you trust the guage you are looking at? Bad bearings have been the culprit of many engines low oil pressure....

 

I assume bad oil pump because of the sudden loss of oil pressure. I supposed it could be bad bearings, but I have no idea how to replace those either, or even what i might experience if those were going bad.

What is common symptoms of bearings going bad?

 

if you have bad bering the will uasally be a loud rapping from in the block, also the oil pressure sending unit is nototious for going bad and giving a low or no reading, it is located (at least on older cars) behind the intake manifold, to the left of the distribitor. it is shaped like a bell and it has a singile connector with 1 wire comming out of it. it's allot eaiser to change than the oil pump and it costs like $10 or $15.

 

Look at my thread. I REALLY hope that doesn't happen to you, but if oil pressure just sorta died outta the blue (not slowly going lower and lower), its entirely possible.

 

Bearings would be a loss of oil press when the engine is at operating temp. Usually it shows itself slowly, as the wear increases, the oil press loss becomes more apparent.
With a bad sending unit or gauge the problem appears suddenly.
A spun bearing would have a sudden appearance of those signs, but there would be an engine noise (rattle) that worsens quickly.
When you're troubleshooting, always begin by eliminating the possibilities that are easiest/cheapest to diagnose/repair first.
IMO an auxilary mechanical oil press ga would be the first step to locating a problem.
It might be one of or a combination of problems, but it's bad business to begin by doing the most difficult repair first only to discover that wasn't the problem at all.

 

not all spun bearings make noise especially the cam bearings I agree with street iron check the easy stuff first....my first spot would be the sending unit for your oil pressure guage....rarely do oil pumps just quit...they fail when something else goes wrong like metal from spun bearings....If you truly suspect a clogged pickup try some automatic transmission fluid in your oil let it get warm and then change the oil dont drive it with the tranny fluid in the engine....the high detergent content should clean the pickup from sludge....Good luck

 

Thanks guys, I am so cranky from this whole thing, gotta keep my head on straight. I was really hoping that it wasnt a spun bearing. The symptoms showed up slowly over the course of a couple days now that i think about it. My oil pressure had been slowly going down over a couple days, but not enough for me to think anything about it.

If I had a spun bearing, that is in the crankshaft correct? I dont feel as though I'm ready to work with that much internals

Oh well, if that's what ends up happening then I'll have TGO to help me along

 

WHY !! ??
Check your oil press with a working gauge !! B4 you start tearing your hair out !!

 

For the first thing, oil pumps generally don't go "bad" slowly. The pump itself either works or it doesn't, again, for the most part. However, you may have caught something in the gears preventing it from turning at it's fullest, which perhaps would explain the parasitic drag that you seem to feel. That drag could also eat away the distributor gear, which could explain the roughness you experienced. Again, that is simply a "perhaps."

The bearings go around the crankshaft (rod and mains), between the crank and the mains (or rods). Most of the spun bearings I have seen were the rods.

 

Use a floorjack with a 2x8 on the saddle. Stick it under the oil pan, slowly jack up the engine being careful to watch if anything is catching, then stick a 4x4 between each halve of the motor mount. Drop the jack out and you're good to go. DO NOT do this without the board on the jack, it WILL cave in the bottom of the pan, ruining the pan and blocking off the pump pickup.

 

:hail:

okay I now have enough information to do this thing!

Thank you everyone who has helped me out so far! I owe Stekman my first child by now with all the questions i've been asking him on AIM haha. And Onebinky that is verrrry ingenious, thank you!

Parts should be in on thursday, and I have thursday off so come thursday I shall respond to tell yah how things went!

 

Thank my dad, he taught me that some 6 years ago