Slant Six Oil light coming on — need a new pump?

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Charlie71 said:
About those sending units... if you or anyone else wants to replace them instead of getting a mechanical gauge, keep this in mind... the replacements they sell down at the local parts stores are not so great. About 3 years ago, I had to replace the one in my 77 F150. It was leaking. Pulled it out, and it was the original FoMoCo oil sender. Been in the 4 decades. Went to Oreilly's, got a replacement, put it in, and all was good in the universe again. Until.... a year later I am driving home from Houston and the oil light starts to flicker while going down the highway. Seeing an oil light at 70 mph will certainly make your sphincter tighten up! I didn't have anywhere safe to stop and continued about another mile looking for a good place to pull over and then it came on solid and wouldn't go off. Now I am starting to sweat as I finally get off on an exit. The engine never made any funny noises or ran poorly. Checked the oil and the level was right where it should be. Being it was another 60 miles before I would get home, I called a tow and had it brought home. A 350 dollar tow was certainly cheaper than a few grand for an engine.

The next morning as I'm out there poking around, I consider the oil sender and then decide out of all the possibilities, this one would be the least expensive... and off to the store I go. Come home, put a new sender in it, started the truck, and the light went out as soon as the engine came on! I was really relieved... until...

A year or so later, I thought I saw the oil light come one for just a moment. It was a bright day, so maybe it was just my imagination. Later that night, it came on for a moment and went off. Now it's dark and I know this wasn't my imagination! Checked the oil and it was fine. The next day, the light took an unusually long time to extinguish after starting the engine. I thought, "Really? Another sending unit? Can't be!" Well, it could, and it was! THANK YOU CHINA!! I got the Ford number for a Ford sender and went to my local dealership. The guy said they didn't make it anymore, but there was one sitting on a shelf in the next county and he would have it the next day.... and he did. It was 70 dollars. I put it in and haven't had any issues since then.

I've found more often than not, I am deeply disappointed with parts I buy from the parts houses. Orielly's, Advance, Auto Zone... it doesn't matter which company. So now, for my truck and my old Charger, I try to find original FoMoCo or Mopar parts on ebay or other places on the internet. Depending on the part you're looking for, it might be wise to seek out an original factory piece.

A mechanical gauge is always best. In my Duster, I found a brass tee that I was about to mount both the original idiot light sender AND a fitting for a mechanical gauge.

As far as getting the old one out, using the penetrating oil it likely your best bet... and get that special socket someone showed earlier. I have one... made life really easy for me on the truck... especially considering how many times I had to do that job!
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Recycled yak turds!
 
What type and weight of oil did you use. 10W30 is what I use and recomend
 
volaredon said:
Id rather have the original sending unit AND an aftermarket sunpro/Stewart warner type gauge. A simple tee will allow you to have both. And yes new aftermarket parts are absolutely crap
As far as penetrating oil on the sending unit to get it out ive never had one break off. Ever. And I've changed many. That specialty socket does make the difference though.
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That's what I did with mine. I hawked an NOS Chrysler sending unit on ebay and then put a tee off the pump and put a manual gauge under the hood. I still use the light in the dash too.
 
Ok, so I have updates.

First of all, my local Advanced Auto had an oil sensor socket with both 1" and 1 1/8" patterns inside one socket. Of course, the socket bottomed out before the 1" pattern actually come in contact with the flats on the sensor. My choices were to order a 1"-only socket online, or work with what I had in hand, so I got out the angle grinder and cut the 1 1/8" pattern tip off the socket. Kind of annoying..

Anyway, I got a tee on there, and plumbed in my new mechanical gauge as well as my old oil idiot light sensor. Then drained the oil, got rid of the drain back spring, and even pulled my relief valve and spring. The relief valve was very clean and smooth. But I buffed it up anyway, and shot some carb cleaner up in the orifice to boot. Bolted it back up, and mixed up a concoction of 3 qt motor oil, 1 qt Marvel Mystery Oil, and 16 oz of Berryman's Fuel Cleaner. Put a new filter on and poured in the concoction.

To my surprise it fired right up and the mechanical gauge read 50 psi at high idle (choke on)! I even bled the gauge's oil line to make sure. Also, the light did not come on at all..

Once it warmed up and i kicked the choke off, it was down around 20psi at a low idle. Yippee! I ran it for 15 minutes, drained it, tossed the filter, and replaced with 3.5 qt motor oil, 1 qt Marvel Mystery Oil. The concoction I drained was dark brown, but not overly black. I ran this second concoction through, with about the same PSI numbers. Tomorrow I hope to drain and replace with a conventional 30 weight oil.

So, problem solved! I'm very happy I didn't have to do too much. I guess my problem was either due to the busted up drain back pieces, or perhaps a bad connection at the oil sensor? Hard to tell. Either way, I'm happy..... Thanks guys!
 
Did you cut the blade off the old sending unit? If not, that's what was holding your socket off.
 
ScampNYC said:
I hope to drain and replace with a conventional 30 weight oil.
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I would use 5W-30... Faster oil flow to the engine, Easier on the oil pump gear (which is one of the few weak points of this engine), And easier to source..I Don't believe there is any down side to running 5W-30...
 
Can I use synthetic, or no? I happen to have a bunch of 5w-30 full synthetic. Pennzoil Platinum synthetic, to be specific.
 
ScampNYC said:
Can I use synthetic, or no? I happen to have a bunch of 5w-30 full synthetic. Pennzoil Platinum synthetic, to be specific.
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That'll work very well. Just keep your eye on the dipstick at first. That oil has a high natural solvency, so it will keep cleaning. If it quickly turns black, change it and the filter. Keep that up until it slows turning dark.
 
How about stretching the oil pump by pass spring
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Better: how about diagnosing and repairing whatever is actually causing the oil light to come on? It's not coming on because the pressure relief valve spring hasn't been stretched.
 
ScampNYC said:
Can I use synthetic, or no? I happen to have a bunch of 5w-30 full synthetic. Pennzoil Platinum synthetic, to be specific.
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That oil will be just fine, unless your engine is well and truly whipped (overdue for an overhaul), to the degree you have to prop it up with extra-heavy oil while you make arrangements to rebuild or replace it. Doesn't sound like you're at that point, so go ahead; this is a much smarter choice than straight 30-weight.
 
ScampNYC said:
Once it warmed up and i kicked the choke off, it was down around 20psi at a low idle. Yippee! I ran it for 15 minutes, drained it, tossed the filter, and replaced with 3.5 qt motor oil, 1 qt Marvel Mystery Oil. The concoction I drained was dark brown, but not overly black. I ran this second concoction through, with about the same PSI numbers.
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Terrific. Problem solved and further problems staved off.

ScampNYC said:
perhaps a bad connection at the oil sensor?
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The pressure sender completes the wire's path to ground in order to turn on the light on the dashboard. Frayed or pinched insulation anywhere along that wire's length will make the light come on.
 
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This info is for anyone planning to buy a oil pressure switch socket.
Some tool companies make two lengths : a short socket and a deep one.
The deep one will not work on Abodies.
Lisle brand sockets make both lengths.
Tool number 13200 is the short socket and number 13250 is the long one.
Other brands may or may not have both sizes.
Just something to be aware of.
 
Hey guys. I have an unfortunate update. The oil light came back on yesterday!

After about 20 minutes of driving, close to home, the oil light came back on while idling in gear at a stop light. I noted sub-5psi pressure on the gauge.

I got it home and immediately drained and replaced the oil and filter while it was still hot. Then I started it, and it was back to 50psi at high idle. Idled it for about 15 minutes and put it in gear with the wheels chocked and it was at about 25psi at the lower idle speed.

Ok, so I thought maybe I was good. But later in the day, it happened again. I drove the car about 20 minutes to go run an errand and right around when I was reaching my destination, the light started to flicker. By the time I parked, the light was fully on and the mechanical gauge showed little if any pressure at all! I ran my errand, and about an hour later, got back to the car, started it, and my pressure was back! Then after 20 minutes more driving, the pressure went away again and I parked at home.

Hopefully I didn't wipe my bearings during these 2 escapades. Regardless, I want to try a more thorough Flush using the "soup" Slant Six Dan describes. Dan—you say to use Kroil, ATF, MMO, and Chemtool B12. It is hard for me to find Kroil—can I use another penetrating oil?
 
Pull the pan and clean it out and be done with it. While there pull a main or 2 and a couple of rod caps to see.... Then and only then will you know. Any kind of cleaner "soup" could dissolve what's in there just enough to move it to an even more inconvenient spot within the engine and take out your engine for good.
 
ScampNYC said:
Hey guys. I have an unfortunate update. The oil light came back on yesterday!

After about 20 minutes of driving, close to home, the oil light came back on while idling in gear at a stop light. I noted sub-5psi pressure on the gauge.

I got it home and immediately drained and replaced the oil and filter while it was still hot. Then I started it, and it was back to 50psi at high idle. Idled it for about 15 minutes and put it in gear with the wheels chocked and it was at about 25psi at the lower idle speed.

Ok, so I thought maybe I was good. But later in the day, it happened again. I drove the car about 20 minutes to go run an errand and right around when I was reaching my destination, the light started to flicker. By the time I parked, the light was fully on and the mechanical gauge showed little if any pressure at all! I ran my errand, and about an hour later, got back to the car, started it, and my pressure was back! Then after 20 minutes more driving, the pressure went away again and I parked at home.

Hopefully I didn't wipe my bearings during these 2 escapades. Regardless, I want to try a more thorough Flush using the "soup" Slant Six Dan describes. Dan—you say to use Kroil, ATF, MMO, and Chemtool B12. It is hard for me to find Kroil—can I use another penetrating oil?
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I don't think you've hurt anything, but it's time to get the pan off and clean it out. Anything else and you're just spinnin your wheels. I'm sorry we're not local. You could bring it over here and we'd have it out and fixed in no time.
 
volaredon said:
Pull the pan and clean it out and be done with it. While there pull a main or 2 and a couple of rod caps to see.... Then and only then will you know. Any kind of cleaner "soup" could dissolve what's in there just enough to move it to an even more inconvenient spot within the engine and take out your engine for good.
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This ^^^^^^^
 
There could be some goop or crud in the pan that slowly makes it's to the pickup while running, then when the engine is off for a good amount of time the crud or goop floats away or sinks.
 
Ant said:
There could be some goop or crud in the pan that slowly makes it's to the pickup while running, then when the engine is off for a good amount of time the crud or goop floats away or sinks.
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We've been trying to tell the op that for what 3 pages now?
 
volaredon said:
We've been trying to tell the op that for what 3 pages now?
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More of the same opinion, the better. Lol.

I could technically help the OP in person, but I have work, don't want to go to or go anywhere near NYC and I have brain surgery coming up.
 
Alright haha I'm convinced. I'm going to go ahead and order a new oil pump. What brand do folks recommend? RockAuto has a Sealed Power 2244165C for $80 and a Melling M66C for $100. Then there are the high volume/pressure units, which I have been advised against.
 
ScampNYC said:
Alright haha I'm convinced. I'm going to go ahead and order a new oil pump. What brand do folks recommend? RockAuto has a Sealed Power 2244165C for $80 and a Melling M66C for $100. Then there are the high volume/pressure units, which I have been advised against.
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Melling, but get it from a legitimate source like Summit. That does NOT include Amazon.
 
ScampNYC said:
Alright haha I'm convinced. I'm going to go ahead and order a new oil pump.
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Who convinced you this is a good idea? It's not; new \6 oil pumps are problematic.
Who convinced you this will solve your problem? It probably won't; you need to drop the pan and clean it and the pickup assembly.
 
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