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1948 Chrysler leaking fuel pump


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My fuel pump just started leaking out of one or both of the nostril shaped holes on the side of the fuel pump as shown in the image in the mirror.  I'm wondering is this a fixable problem or will the pump need replacing?  I read in a 2015 posting here that a fellow ordered one but he got a glass bowl style from Andy Bernbaum.  As  you can see in the image mine is not that style. So I don't understand about the heat shield he made reference to?  Is he referring to the fact that the upper body is steel, that being the heat shield?  Or is there an actual shield. I don't see a shield on mine, but perhaps because of the manifold I'm just not looking hard enough.

More importantly I'm having the car serviced for another issue tomorrow.  Is there a way of stopping that stream of gas from coming out temporarily for a 5 minute drive?  It's pumping it out as steady as lets say the stream of gas going into the carb when you push on the throttle linkage.

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5 minutes ago, TerryB said:

You might have a Carter fuel pump.  Carter M639SB is what my book shows for a 1948-54 Chrysler six.  Your photo shows what appears to be a Carter fuel pump.

Thanks Terry. Good to know about the make and model.  In the 2015 posting here, the fellow said the part # was 683 056.  The local parts stores don't have it so I'm going to pull it off where the car sits and perhaps I can get a rebuilt kit for it.  My mechanic said those holes were designed to pop and spit fuel when the fuel pump is faulty.  He suspects that the diaphragm has deteriorated from ethanol gas over the years.

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28 minutes ago, timecapsule said:

  He suspects that the diaphragm has deteriorated from ethanol gas over the years.

 

It doesn't take years for that type of damage from corn gas. Get a kit that will work with modern gas or use non-ethanol.. That rubber fuel line is next to go! Mine did going down the freeway.

Edited by JFranklin (see edit history)
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Re the heat shield, generally it's an add on piece of folded sheet metal to cover the pump and shield it from the heat radiated by the exhaust manifold. It's held in place by utilising nearby bolts or studs.

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Looks like it's a Carter MO-532.  In the one image you can see a long stud replacing one of the screws that hold the two bodies together.  I'm assuming the heat shield was attached to that at one time.   In the image that shows the diaphragm you can see that the mounting holes are offset so to say.  I'll see if I can just get a rebuilt kit first.  There is a number on the metal part of the diaphragm M203-16s   Perhaps that's a clue regarding a rebuilt kit.  None of the local parts stores have anything so it looks like I'll have to try Andy Bernbaum.  Their P/N seems to be P-104.  But no pictures.  Moparpro have what looks like the same as mine with detailed pictures. But it's ebay only so I can't call them.  Moparpro is $20 cheaper.  Moparpro says it's ethanol safe and made by Vintage American Parts.  Has anyone had any experience with MoparPro?

 

Good point about the fuel getting into the oil.  I'll do another oil change to be safe.  Good point about that short rubber hose as well.  I'll replace it too.

 

So it looks like I'll probably end up with the glass top replacement fuel pump  Is it just a matter of fabricating a heat shield plate and positioning it between the manifold and fuel pump?  

 

Thanks for the help guys.

  

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Then and Now automotive has been supplying rebuilding kits for a long time and are often mentioned here.  I purchased other parts from them, not fuel related and they were good to work with.  They are also a sponsor of this website.

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The long bolt is to hold the heat shield. It is a flat piece of sheet metal bent into a J shape that goes between the exhaust manifold and fuel pump. At the top, there is a tab that goes under the end manifold bolt. It is not a very complicated piece and you could make one at home, if you want to buy one I think Bernbaum or Vintage Power Wagons sells them.

 

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6 minutes ago, Rusty_OToole said:

The long bolt is to hold the heat shield. It is a flat piece of sheet metal bent into a J shape that goes between the exhaust manifold and fuel pump. At the top, there is a tab that goes under the end manifold bolt. It is not a very complicated piece and you could make one at home, if you want to buy one I think Bernbaum or Vintage Power Wagons sells them.

 

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As I was saying it looks like I'd probably end up with the glass replacement fuel pump if I can't find a rebuild kit for mine.  In that case it looks like it's a simple matter of replacing one of the screws with the long post from my carb, and attaching a home made shield similar to the one in this picture.  Thanks

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1 minute ago, timecapsule said:

As I was saying it looks like I'd probably end up with the glass replacement fuel pump if I can't find a rebuild kit for mine.  In that case it looks like it's a simple matter of replacing one of the screws with the long post from my carb, and attaching a home made shield similar to the one in this picture.  Thanks

Btw.  At the risk of wondering off topic for only a moment, what is that protrusion just behind that shield.  I've been looking at that on my engine wondering what it's purpose is?

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Anyways, back on topic.  I'm using Chevron 94 since I've owned the car but is there anything else that should be replaced or attended to as a result of ethanol fuel such as that short flexible fuel line just before the fuel pump that I will be replacing?

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9 hours ago, TerryB said:

Looks like the new AirTex replacement pump sold for this Chrysler has a glass filter bowl on it.  Found that on both Rock Auto and the AirTex website.

 

You might want to read of my experiences with AirTex.......  :angry:

 

 

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Until now I hadn't really considered the probability of buying new junk. But of course it's a sign of the times. My engine has about 65,000 miles on it so it's quite possible that the fuel pump is original. Chances are whatever I buy now won't last that long. Hopefully longer that carhartley's experience.  My diaphragm does't even look that bad.  Just several crack marks but it was pissing out with a good flow of fuel out those holes on the opposite side of the diaphragm.  I didn't notice any difference on how the car was performing.  Before I noticed the dripping under the car before I parked it I drove it for about 15 minutes. Prior to that I was on grass. ( no not stoned lol! ) so I couldn't go back and check for wet spots on the ground.  On route I was stopped at a set of lights twice and I didn't smell fuel and I had my window down, so I'm guessing that it just started to leak. moments before I saw it dripping.  At any rate I'm guessing the only thing that needs replacing is that rubber diaphragm and it looks like it is permanently attached to the copper/brass backing plate.   I haven't pulled out the diaphragm shaft assembly yet but I'm guessing that there is just a spring in there as well. 

 

I noticed that Andy Bernbaum offers to rebuild fuel pumps as well.  Has anyone ever gone that route? Are there other components in my old fuel pump that could potentially fail? 

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If your fuel pump is leaking any gas anywhere at all, it has already failed. Stop fooling around with it and send it out NOW to a quality rebuilder. You should replace the old flexible fuel line NOW as well. Stop driving the car as you have a real fire hazard! After all this time your Chrysler deserves a new pump!

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Replace this pump immediately!  If you have electric wipers (probably), you need only a single-action pump, not the dual fuel and vacuum pump.  Beware of NOS pumps on eBay and elsewhere which probably don't have ethanol-resistant diaphragm materials.  By all means replace the flexible fuel line as well, and that with ethanol-resistant material as well.  I enthusiastically recommend Then and Now's rebuilding service, which is about $95 + return shipping for a single-action pump such as yours.  You'll have it back in about 8 days--and that's for me on the West Coast all the way across country from their shop.  They do this every single day, so unless you value your time at $1/hour or want the experience of rebuilding it yourself with possible foulups, just send the darn thing to them. Attach a tag to the pump with your name and mobile phone number and make and year of car.  They'll call you back, ask for your credit card number, and have it in the mail pronto.

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The diaphragm is bad! That is how the fuel gets up where it can leak out. It needs one, period.

 

Old diaphragms may not be compatible with ethanol laced gas. You cannot expect any older fuel pump these days to just work. They are meant to rebuild when bad, so just rebuild it (or send it in). I like the kits from Then n Now.

 

I took apart a leaking pump on a 37 Buick a while back that had not run since the early 50s. The diaphragm was just a bunch of layers of cloth impregnated with something, probably shellac. You could see the remains of the impregnating substance under the part that was clamped by the flange. The rest had washed out and the gas was just running through the many layers of cloth. Ehtanol is the solvent for shellac. As others have noted, many types of older fuel system rubber also dissolve in ethanol, even if they are not rotten from age.

 

If the check valves are bakelite or something hard, don't screw with them if they seal. Check with a handheld vacuum pump. If they are made with some sort of elastomer, or if they leak, you will need to replace them. Make sure they seal.

 

Then, put a new diaphragm in, and a new stem seal if the one provided in the kit fits properly. The stem seal is somewhat non-critical as it is often not a positive seal, and mainly exists to help keep some of the gas out of the engine when the diaphragm fails. You can probably get away using the old stem seal if it isn't damaged and you need to.

 

Edited by Bloo (see edit history)
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7 hours ago, The 55er said:

If your fuel pump is leaking any gas anywhere at all, it has already failed. Stop fooling around with it and send it out NOW to a quality rebuilder. You should replace the old flexible fuel line NOW as well. Stop driving the car as you have a real fire hazard! After all this time your Chrysler deserves a new pump!

So I'm curious what might give you the impression that I'm driving the car, when the above photos clearly show the fuel pump off the car and in pieces. ????

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22 hours ago, Rusty_OToole said:

The long bolt is to hold the heat shield. It is a flat piece of sheet metal bent into a J shape that goes between the exhaust manifold and fuel pump. At the top, there is a tab that goes under the end manifold bolt. It is not a very complicated piece and you could make one at home, if you want to buy one I think Bernbaum or Vintage Power Wagons sells them.

 

image.thumb.png.af497069f77d045183cd930d72703687.png

I'm puzzled about the purpose of the heat shield.  The fuel lines going into and coming out of the fuel pump are about 7-8 inches away from the exhaust manifold.  However as the fuel line goes past the exhaust manifold on route to the carb it is within about an inch to inch and a half away from the exhaust manifold. Why wouldn't there be a heat shield there too?

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I would guess the heat holding metal mass of the fuel pump along with its internal diaphragm of rubbery material might suffer more from exposure to engine heat over time.  Probably a way to ensure the pump does not die prematurely.  

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7 minutes ago, TerryB said:

I would guess the heat holding metal mass of the fuel pump along with its internal diaphragm of rubbery material might suffer more from exposure to engine heat over time.  Probably a way to ensure the pump does not die prematurely.  

oh ok.  I remember in drag racing pit crews would make efforts to keep the fuel cool because hot fuel robs the fuel of power so to say in layman terms.  So I had the impression that's what the heat shield was doing in this instance as well.

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The danger of vapor lock is in the fuel line coming to the pump, and the pump itself. After it leaves the pump it is under pressure and won't vapor lock. With today's more volatile fuel you could add insulation to the fuel line or reroute it farther from the engine but this is probably not necessary.

 

The heat shield reflects the heat of the exhaust manifold away from the pump, and helps direct cooling air around it.

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