Hello all. I searched this topic and found a few results but thought I would ask anyways. I don't post often but you guys always give great advice. I have a '57 Cad 365 in my car that has an old Holley double pumper on it. The other day it flooded so I let it sit for a few days and tried again. It started right up but the engine was very noisy. Right away I shut it off and checked the oil. The level was fine but it smelled like gas. I figured since it flooded some gas got into the oil, so I changed it. Sure enough the oil I drained was super thin and full of gas. I started the car back up and it ran alright, though it still seemed like it was getting a bit too much gas though. After running it for about 15 minutes or so I noticed the engine was getting slightly noisy again. So I shut it off and checked the oil again. It was starting to get clear and smelled of gas again. Of course I haven't ran it again. Thought I would see what you guys thought. I googled it and and the biggest answer seemed to be the diaphragm in the fuel pump. Could the carb be flooding that bad and the car still run? Anyways I could really use the wisdom of the HAMB. Thanks, Mike
check and see if all cylinders are firing. I have a 58 Edsel that had a bad plug wire and one of the cylinders was not firing and I was getting a little gas in my oil.
Could be many things.... 1- Are all cylinders firing... as stated by mlagusis 2- Is the needle and seat in the carb worn, so the fuel washes the cylinders after the engine is shut down? ___ easy test, run the engine till warm, take off air cleaner, and turn the engine off, if any amount of white vapor comes from the carb, the needle and seat or either in need of adjustment or bad... or debri in the bowl from a line deteriorating?? Is the choke stuck? so many reasons, but these are the easiest to diagnose and fix....
Gas in oil after a short time running, I would suspect diaphram in fuel pump. If the fuel pump is mor than 10 years old, date of manufacture or reman. If you bought that "new" fuel pump at the flea market it can be really old. The material may not like todays gas. You could also have a carb problem, bad needle valve or power valve. When you run it and shut it off is there gas dripping in the carb?
If you are getting that much gas in the oil that quickly, the first thing to check is the fuel pump. This is nothing to mess with. You can wipe out your bearings very quickly. One way to check the fuel pump without any gages is to pull the pump and blow some air (by mouth) through one of the fittings. If the diaphram is ruptured, you will know right away. If you have a pressure gage, install it at the carb fitting start the car (fresh oil) and see if it holds pressure. If it leaks down quickly, replace the diaphram or get a new pump.
As far as the carb goes my knowledge of them is not very good, so I'll have to get a friend over to check that. As far as the fuel pump goes, I know it's been on the car for at least thirty years. So it very well may be wore out. I appreciate all the feedback so far! Thanks, Mike
Not familiar with that particular motor, but common in small block chevy's that if the diaphram in the fuel pump dries up, rips, oil and gas can mix...happened in my brothers 67 Camaro, wiped the mains out!
See clarifications below. And don't take this as an insult, but I find it ironic that your ID is Spitbucket, and you advocate blowing on a fuel pump with your mouth. A mechanical fuel pump has two check valves, both of which allow flow in one direction, and that is from the tank towards the carb. Either valve will prevent fuel (or air) from going the other direction. You can blow air through any mechanical fuel pump, good diaphragm or not, if you blow into the inlet. The check valves will allow flow in that direction. PLUG the outlet from the fuel pump, and then blow into the inlet. That will tell you if the diaphragm is bad. Blowing into the outlet will be a lost cause, because the valve will prevent pressure from getting to the diaphragm.
I agree with fuel pomp I had a old 360 Ford that happend to. on a road trip it started running hot check it over & 1 + qts over on oil . 50 miles from home & middle of night, Needless to say it was Hammering hard by the time i got home
If the fuel pump isnt the cure (most likely fix), and the obvious carb leaks arent the issue...Some of the old Holley doubles had a cracking issue in the housing. I chased that for days before somebody correctly suggested I look there....fyi.
I plugged the outlet and blew into the inlet. Of course nothing came thru since the outlet is plugged. How do I tell if it's bad?
Ebbsspeed. No insult to me. Irony can be found anywhere. Re: my attempt at helping. I was obviously wrong and say so here. At least 51merc now has accurate information and hopefully will sove his problem before he ruins his engine. Peace.
Mike, I would suspect that the pump diaphragm would be the problem but let me relate a story to you. This from an interview with TV Tommy that I read some place. He said that on his nail head powered T the injection was so fat that every time he ran it he would have to change the oil because it was gas fouled. So although not likely that your carb is fouling your oil that quickly it is possible for an engine to run that fat.
BTTT for the evening crowd. I plugged the outlet end of the fuel pump and blew thru it. No air passes thru of course due to the outlet being plugged I would think. I guess what I'm asking is how do I know if the diaphragm is bad? Thanks, Mike
Quit pissing around with that old fuel pump and get another one! Rock Auto may have them, a decent parts store should be able to get you one in a few days. Some of the older pumps are rebuildable, if you're handy a kit may be the way to go. If you don't know the history on the carb, get a rebuild kit for it while you're shopping. Bob
If the diaphragm is bad, you'd hear air leaking through the diaphragm, and coming out where the pump lever is. Since the pump is 30+ years old, you should replace it, since it's very likely that the diaphragm isn't compatible with todays mixture of combustible stuff they call gasoline.
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