Blown diaphragm on fuel pump??? 75 Dart Slant 6

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YoungDart75

YoungDart75

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Just a question guys. I was doing some cleaning up while the car warmed up today and noticed two small fuel leaks. One was easy enough to fix but the other Is leaking from the pump itself. Its dripping down onto the motor mount. Im guessing blown/torn diaphragm or the crimp on the metal diaphragm joint is starting to come loose. What do you guys think? Also any special tips for replacing the pump? didn't find any procedures in the manual.
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it will leak into the pan. change the pump, then change oil and filter
 
Changing the pump will cause the fuel to leak into the pan? This is annoying considering I just put new oil/filter and everything on it. Also I'm seeing two different pumps, one from August of 75 to present and on up to August of 75. Both look almost identical, but one of them is in stock and ready for me to pickup and the other isn't. Any major differences/easiest way to determine the month in 1975 that mine was made?

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YoungDart75 said:
Changing the pump will cause the fuel to leak into the pan?
Click to expand...

Once you get the pump off the engine you will notice that there is a lever that extends out from it through a hole in the engine block. The lever is driven up and down by a lobe on the camshaft. That is how the pump is powered. If it leaks, fuel can drain into the engine which ends up in the oil pan. Modern cars with fuel injection have electric pumps and are not mechanically driven.
 
So I can just replace this pump and be fine? No need to change the oil afterwards? Any special procedures or steps to replacing other then be careful of the lines and unbolt it?
 
2 BOLTS 2 lines. Pretty simple. If the bolts are original they will have 7/16 heads. Replace the rubber line while you are there.
 
Best to at least check the oil for contamination. Just see if you smell gas on the dipstick. I had no idea I had a bad diaphragm as it did not leak externally on my Belvedere. While replacing the axle/springs, it sat for over a week like this:
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when I was done with the axle upgrades, I started it up and it ran awful. It even had fluid spitting out of the valve cover breather. I drained about 2 1/2 gallons of fluid, mostly gas, from the crank case of that slant six.
What a mess! I have since changed oil twice. the second time was after idling for about 20 minutes with the first oil change. So far, so good. It doesn't act like it hurt anything.
 
I just changed the oil so if there is contamination it shouldn't be hard to spot/smell. The two bolts have the rubber caps over them still so I'm betting they are. 1/2" on the hard line to the carb. Haven't started the swap out yet because I forgot to grab the rubber line while I was at advance. But I'll be grabbing it tomorrow and probably swap it out this weekend when I have a little more free time. Thanks for all the help so far guys. The lack of coverage in the pub was a little shocking.
 
toss the mech pump get a electric pump. mount it by the gas tank. with. toggle switches set up with a over ride to fill the carb before starting. saves on the batt.
 
mount electric pump behind mech pump, itll push right through it when you need to fill bowls.
 
I'm trying to keep it as original as possible. Looks and all. Until I change my mind on that approach ill keep the mechanical. Thanks for all the advice.
 
Lol... Just change the oil after you change the pump!!! I mean, really?? A 20 dollar oil change is worth it, or you might be changing your entire engine...
 
318willrun said:
Lol... Just change the oil after you change the pump!!! I mean, really?? A 20 dollar oil change is worth it, or you might be changing your entire engine...
Click to expand...

even in montana, some of us have figured this out, LOL
 
Yea I got extra filters anyway since almost no one stocks them around here. Easy day to just change it afterwards.
 
A small amount of gas in the oil will be OK. But a lot will diute the oil enough to damage bearings. If you smell even a hint, it's time to change to be safe. A friend of mine was in CA riding with a gal in here Firebird years ago and the diaphragm failed and the engine started knocking. He made her stop, changed the pump and the oil too and all was OK, but the engine was on the verge of being destoyed with the gas in the oil.

Check on the dipstick and pull off the oil fill cap and check there too.

No real reason to not run a mechnical pump on a stock engine like this; very reliable in general. I even went to the effort of finding an old original Carter pump for my '62 /6 and put that on; now THAT'S original!
 
I didn't go that far but I put a new pump in it today and replaced the rubber line down there too. Ready for it to warm up more so I can really get this thing cleaned up rather than just doing the mechanical side done in the cold. Thanks again guys for all the help and advice. Gonna change the oil again anyway and hope for the best.


 
please do remember ANY liquid pump. I.E. hydraulic , gasoline, oil, will push much better than they pull. any small leek on the suction side will draw air long before that leek on the pressure side leeks.
 
Well the gasket sealer is setting still and ill be firing it up again when I get home tonight to verify everything is good to go and then change the oil again.
 
After swapping the pump I changed the oil again. Didn't have much of a hint of gasoline at all. But it did look a little disgusting after only being in the car about 2 weeks. Maybe I'm a little off due to never having older then a 1991 model year car before, and this car sat for a while and was only started every once in a while. But this seems a little dirty to me for like 5 miles of use and only idle time. I realize it may take a couple oil changes since it sat up quite a bit.

I also pulled the breather and found this kind of crusted up underneath it. Any ideas as to why this would be?

 
That looks awfully milky to me! There might be some water mixed in as well.
 
thats water ingress. Anything milky looking is water or moisture. There is a weep hole in the pump body, if you can stick a mighty vac in there and draw a vacuum that holds, its still good. Some of that milk may be just moisture from a sitting motor, make sure your PCV is functional, totally helps that condition. you can heat that oil to 248F and the moisture and solids will boil out. put a piece of glass at an angle over the boiling oil and it will catch the water vapor and drip it into a can if you want to see whats going on.
 
I'm going to be replacing the PVC today, I've got it at home already, I've driven It a few times(short distances) without any overheating issues but then again its been below freezing every day up here in Illinois so I doubt the temps would get very high anyway. Other than the head gasket where else would be causes for the water to get in on these motors? I ran a can of restore through this time, and put a new filter on.
 
Might be just moisture from sitting.
When you run the engine you actually need to get it hot to get rid of the moisture.
 
I got it good and warm today. Even took her through a car wash to get her all cleaned up. Found some random places dripping coolant underneath afterwards but didn't find anything actually leaking coolant when I got home(only about a mile away). Overflow tank was a little low but I checked the radiator when it cooled back down and it was full. Previous owner said he only putt 250-500 miles on it in the 4 years he owned it. Checked the oil on the stick afterward and it seems a lot clearer than before. I can still read the add/fill and the marks through it. Which is much cleaner then what I took out of it. I may drain some oil out again to see how it looks. Maybe i'm finally getting the moisture out from the car sitting so much. Also got my first two jaws dropped of 2015 with her today in the middle of adding some seafoam to the tank at fill up, then again while hand drying her at the car wash.
 
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