Slant 6 oil pressure woes…

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SpriceyStuff

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Hey guys. Twice now, my oil pressure light has come on on my way home from work, and i find that my oil is all thin and smells of gas. I can’t figure out why. I replaced my fuel pump last week and changed the oil and now it’s doing it again. Any ideas why? It’s a mechanical fuel pump. I don’t know how they make the new ones. Is it maybe too much pressure? Overloading the needle and seat? I don’t know what’s happening but it’s getting expensive and annoying.
 
If you were getting raw fuel into the oil pan, you could see the high level on the dipstick. Is that the case? On older cars like these, it's pretty normal to get gas smell about the oil, because they aren't fuel injected and running lean on the jagged edge. If it's higher than full on the dipstick, I'd be worried. It "could possibly" also be doing it if the carburetor was running rich. It would have to be so rich though, it would be blowing black smoke and burning your eyes.
 
If you were getting raw fuel into the oil pan, you could see the high level on the dipstick. Is that the case? On older cars like these, it's pretty normal to get gas smell about the oil, because they aren't fuel injected and running lean on the jagged edge. If it's higher than full on the dipstick, I'd be worried. It "could possibly" also be doing it if the carburetor was running rich. It would have to be so rich though, it would be blowing black smoke and burning your eyes.
Thanks for the replay. I’ve been on the phone with my dad about it and he agrees with you. I know the back side (plate) of the oil pump leaks a bit. One thing I mentioned to my dad is that once upon a time (a couple years ago) I ran this engine without a valve cover and it was flinging oil all over hell and now it doesn’t really do that even after a fresh change. I get a steady flow of oil at the rockers but it takes a while to get there. So my dad is telling me that I’m probably having a problem with my pump, and possibly a circulation issue that’s causing the oil to get hot. He’s coming over tomorrow to help me look at it and try to do some diagnostics. I know the oil pump came off an older motor than what’s in my car so I don’t know for sure that it’s quality. I have a new oil pump that I was saving for the eventual rebuild but I may go ahead and put it in now. I’ll update you tomorrow after we look at it.
 
If you were getting raw fuel into the oil pan, you could see the high level on the dipstick. Is that the case? On older cars like these, it's pretty normal to get gas smell about the oil, because they aren't fuel injected and running lean on the jagged edge. If it's higher than full on the dipstick, I'd be worried. It "could possibly" also be doing it if the carburetor was running rich. It would have to be so rich though, it would be blowing black smoke and burning your eyes.
To answer your question, I can’t really tell. Every time I stick the dipstick in and pull it out, I get an oily residue on the stick, but nothing that drips off the end. When I wipe the residue off on my fingers, it appears clear but has some traces of black in it. It feels oily. But that’s about all I can tell you.
 
To answer your question, I can’t really tell. Every time I stick the dipstick in and pull it out, I get an oily residue on the stick, but nothing that drips off the end. When I wipe the residue off on my fingers, it appears clear but has some traces of black in it. It feels oily. But that’s about all I can tell you.
So you cannot read the level?
 
So you cannot read the level?
Correct. Another point worth mentioning is that I haven’t driven it since I replaced the oil and fuel pump until today. I only moved it from one parking spot to another. So since the leak is on the oil pump, it is very possible that I’m just puking oil down the road, but since I haven’t been driving it, it wouldn’t have been leaking (and it didn’t) until I drove it today. The more I talk aand think about it, the realer the possibility is becoming that the “oily residue” is just was left of the oil I had that was flung all over the walls by the crank.
 
This is just food for thought. Also I need you to clarify you have replaced the fuel pump and also the oil pump that now leaks. ? I have owned many Slants over the years and have experienced your same problems.
Not knowing the condition of your engine I have to assume it has never been rebuilt.
Lets start with the oil and dipstick. Sounds like your oil pump pickup is on it's way to clogging with sludge.
I have seen some Slants so thick with sludge that the oil light would flicker or come on while driving/idling.
Maybe your traces of black is a tale tale sign.Also rubber valve seals that crumble with age can clog the pickup causing low oil pressure.I have had some that are like a baby's rattle after pulling the pan and pickup and finding debris.
Rusty has said about the smell of fuel in the oil as a well known fuel pump leaking internal into the engine and filling the oil with gas. Be careful, pull the stick out away from the car and light the tip of it with a lighter. If it flame up its gas in the oil. Quality of parts now a days suck so even new,it may be bad.
I think you are destined to pull the pan and see what is inside.
Had a 67 Dart given to me as a kid and went thru low oil pressure. I too started with the oil pump,nope same thing, then pulled the pan to find a clogged pickup. Just my thoughts.
 
I guess I'm just not understanding how on Earth you cannot read the level on the dipstick.
 
I guess I'm just not understanding how on Earth you cannot read the level on the dipstick.
Well now that the morning has come, I’ve checked it again, and the oil level sits just below the full line. Before I drove it yesterday it was just above the full line. So the oil level hasn’t changed a lot, so I’m thinking the oil leak isn’t all that severe. Im headed to the store right now but when I get back I’ll be checking the flammability of it as suggested above. At this point I have no clue what’s going on. Unless the oil is leaking and it’s just being replaced by gas that quickly. It is pretty clear on the dipstick. Like I said I’ll be checking the flammability later. Will update you soon.
 
Okay, so I’ve tried the oil burning test. Held a butane torch up to it and it just makes it run of the dipstick, but it doesn’t catch fire. So I guess the problem lies not with gas being in the oil, but rather with a sort of circulatory issue.
 
I recently had a '64,/6 here that I was able to get running while on my trailer before I separated the trans from the engine, but once I got them apart and the engine on a stand I took the pan off and it was full to a point where it was covering the pickup completely with a sludge thicker than mayo. I drained the oil from it before I pulled the pan and it was the thinness of gas but didn't smell like gas. What came out of the drain plug was definitely as black as tar.... Have no idea how long it was in there.
 
Same as you volaredon. Slant 6 cars that were never driven far daily were known for being a sludge mess.
Never got hot enough to burn off moisture I guess.
 
Okay a quick update. I drained everything out and flushed it with new oil until fresh oil was all that came out then I plugged it up and filled it. I popped the back cover off the pump to drain what was left of the old thing oil out of it too. New filter. I guess we’ll see what happens. As far as it sitting goes, I should note that I drive this car to work usually twice a week. So it never sits long. (I have to drive it or my apartment manager will tow it away for sitting too long).
 
Okay so quick update. I filled it up after the flush. I put in 6qts of 10w-30 and 1qt of Heavy duty Lucas stabilizer. Ran it and let it warm up. Sounded nice and smooth. I tried to take it around the block and no sooner than I get out onto the street, the oil light comes on again. I immediately pull back in and park it. Turn it off and pull the dipstick out. Dipstick reads full. Oil is warm, but doesn’t otherwise feel strange. It spreads out across my fingers the same way it does straight out of the bottle, and feels very very slick. I’m beginning to lean now toward having a sensor issue. I don’t know. Tomorrow I’ll look for problems with the wiring connection and go from there. But I’m done for the day.
 
Did you replace the "O" ring for the oil pump cover? Also make sure the PCV is hooked up and working properly.
No I didn’t, but I need to. Moving that cover didn’t help my leak at all. Made it worse. I’m ordering one now. The PCV is hooked up but I don’t know if it’s working or not. I assume it is, because there’s no big plumes of smoke coming out of the exhaust.
 
Okay so quick update. I filled it up after the flush. I put in 6qts of 10w-30 and 1qt of Heavy duty Lucas stabilizer. Ran it and let it warm up. Sounded nice and smooth. I tried to take it around the block and no sooner than I get out onto the street, the oil light comes on again. I immediately pull back in and park it. Turn it off and pull the dipstick out. Dipstick reads full. Oil is warm, but doesn’t otherwise feel strange. It spreads out across my fingers the same way it does straight out of the bottle, and feels very very slick. I’m beginning to lean now toward having a sensor issue. I don’t know. Tomorrow I’ll look for problems with the wiring connection and go from there. But I’m done for the day.
So you're TWO QUARTS over full and don't think that's a problem?

Besides all that, have you put a manual oil pressure gauge on it to verify that it is losing oil pressure?
 
Because even though I just put 5qts into it, it was still a good bit low, also, I have a high capacity filter on it.
What's the filter part number? I run a Motorcraft FL299, which IS a high capacity filter. It's a 2 quart filter, whereas the stock one is a one quart filter. Although I do run six quarts, I'd never put seven in it. That'd certainly risk hitting the crankshaft.
 
The PCV is hooked up but I don’t know if it’s working or not. I assume it is, because there’s no big plumes of smoke coming out of the exhaust.
Don't assume. It is a common problem for the PCV on a slant to be plugged up. Don't check just the valve, check the complete system. A lot of times the passage in the carb is plugged up. I should have asked a long time ago. Have you hooked up an oil pressure gauge to see what the pressure really is?
 
So you're TWO QUARTS over full and don't think that's a problem?

Besides all that, have you put a manual oil pressure gauge on it to verify that it is losing oil pressure?
I’m not two quarts over full. I put a quart in to bring it up level and a quart to fill the filter, because the filter was dry. So by the end of the deal, the dipstick is reading level on the full mark.
 
What's the filter part number? I run a Motorcraft FL299, which IS a high capacity filter. It's a 2 quart filter, whereas the stock one is a one quart filter. Although I do run six quarts, I'd never put seven in it. That'd certainly risk hitting the crankshaft.
Wix 51515
 
I’m not two quarts over full. I put a quart in to bring it up level and a quart to fill the filter, because the filter was dry. So by the end of the deal, the dipstick is reading level on the full mark.
Something is wrong. Should read full on the stick, with 4 qts in the oil pan and 1 qt in the filter = 5 qts total. You might have the wrong dipstick. By running 2 qts over full you could have excessive oil consumption, and aerated oil. Then you wind up showing low on the stick (but not really) and you add to bring it up to the full mark (but really over full).
 
Don't assume. It is a common problem for the PCV on a slant to be plugged up. Don't check just the valve, check the complete system. A lot of times the passage in the carb is plugged up. I should have asked a long time ago. Have you hooked up an oil pressure gauge to see what the pressure really is?
My brother has a manual gauge and I’m gonna try and pick it up from him tomorrow and check it. I’m also gonna be tracing wires to see if I’m just having a wire issue.
 
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