FUEL PUMP LEAK

[LAS VEGAS DAVE]

My fuel pump was rebuilt less than two years ago. Its now leaking on the outside at the diaphragm, I tightened the screws and it helped but it still leaks some. Why does this happen? Is it the ethanal? I hate leaks so it looks like it will have to be done again.

[JFranklin]

Was it rebuilt with ethanol resistant parts? If not make sure this time.

[LAS VEGAS DAVE]

37 minutes ago, JFranklin said:

Was it rebuilt with ethanol resistant parts? If not make sure this time.

 

I don't know the answer to that for sure but the next time I will. I thought the ethanal would make it rip but not leak on the outside.

 

[Bloo]

I saw a 37 Buick pump that had failed. It had a very old diaphragm, probably from the 1950s. The diaphragm was just a whole bunch of layers of very thin cloth that had apparently been soaked in some sealer, probably shellac. The cloth had been washed clean of the sealer, and the gas was just running through the cloth. There was still a shellac-like substance in the part of the cloth around the edge where it is clamped by the screws. It wasn't leaking there, but I imagine it was only a matter of time before the sealer washed out of that part, too.

 

Today I believe new diaphragms are reinforced rubber. That is what my new "'ethanol resistant" diaphragm for the 36 Pontiac was. It came from Then n Now.

 

It is tough to imagine (assuming your diaphragm is rubber) how it could leak if the screws are tight. You will probably just have to take it apart and look. The rubber diaphragms are fairly thick, and the surface would have to be pretty uneven for it not to seal.

 

Quote

I don't know the answer to that for sure but the next time I will. I thought the ethanal would make it rip but not leak on the outside.

 

I would expect the same thing if the diaphragm failed from Ethanol, or for any other reason. It is exactly as it looks from the outside. The screws are just clamping the outer edge of the diaphragm as if it were a gasket.

 

Edited December 26, 2017 by Bloo (see edit history)

[Morgan Wright]

I always use ethanol free gas. www.pure-gas.org and look it up.

 

Ethanol makes the rubber swell and it doesn't fit anymore and you get a leak. If you start using ethanol free it might shrink the rubber back down and stop the leak.

[FLYER15015]

Dave,

I rebuilt my pump about 4 years ago using a kit from "Bob's".

So far no leaks, and we only have "corngas" here in Colorado.

 

Mike in Colorado

[LAS VEGAS DAVE]

I pulled off the pump and it seems both the diaphragm and the oil seal BOTH leak. Trying parts that ethanal supposedly won't hurt this time. The last time the pump was rebuilt a new spring was put in it. After that I had to run a fuel pressure regulator. This time a weaker spring will go in it. Maybe I can get rid of the regulator, it works great but they didn't need them in 38 so I would prefer not to have it on the car now. 

[Rod Frazier]

Mine's been leaking for 2 years and you have inspired me to fix it.  Ordered the kit from Bob's today, along with a master cylinder repair kit, which I discovered I needed just a few days ago.  Another leak that's bothering me appears to be coming from the transmission somewhere.  That leak I may tolerate for a while since it looks like major hassle to replace the gaskets.  Glad you mentioned the spring.  Hope I can remember to use the old one, which does not overpressurize the system.

[Bloo]

Pay close attention to your check valves. See if they hold vacuum. If they are assemblies with an elastomer inside you MAY want to replace them.. maybe... If they are a phenolic disc and a spring, NEVER screw with one that is sealing properly.

 

The kit will include new parts. Don't get hung up on using it all. Make sure those valves seal while the pump is apart.

 

If the spring has an open end, note which way it is installed when you take the pump apart.

 

If you are going to check fuel pressure, that should be done on the car because how high the cam lifts the diaphragm affects the pressure. Good luck!

 

Edited December 29, 2017 by Bloo (see edit history)

[Kenneth Carr]

My pump worked fine but leaked a bit at the diaphragm. I tightened all screws. One was loose and not even

engaging the threads. I got it to tighten. It still leaked after a 10 mile run. I sent it for a rebuild to

Classic Car Trader in NJ. He did a nice rebuild and found that he had to put a helicoil in the hole where the

loose screw was. I suspect my 'repair' never held. So, a bad thread possibly?

By the way, the rebuild looks good and is OK 6 months later. Cost was very little more than a kit.

He did take over a month because I sent the unit just as he was going on vacation. Check ahead on

return time. Carl (owner) uses only modern materials that resist damage from modern fuel. He also

pays for return shipping.

[Elpad]

13 hours ago, Roadmaster71 said:

My pump worked fine but leaked a bit at the diaphragm. I tightened all screws. One was loose and not even

engaging the threads. I got it to tighten. It still leaked after a 10 mile run. I sent it for a rebuild to

Classic Car Trader in NJ. He did a nice rebuild and found that he had to put a helicoil in the hole where the

loose screw was. I suspect my 'repair' never held. So, a bad thread possibly?

By the way, the rebuild looks good and is OK 6 months later. Cost was very little more than a kit.

He did take over a month because I sent the unit just as he was going on vacation. Check ahead on

return time. Carl (owner) uses only modern materials that resist damage from modern fuel. He also

pays for return shipping.

Carl Constantino of Classic Car Trader has done two fuel pumps for my 50 & 54 plus has rebuild a carb and a water pump. Very Happy and very reasonable... highly recommended.

[LAS VEGAS DAVE]

Today I put the rebuilt pump back in the car. We took it out for a test drive of about twenty miles tonight and there are no more leaks. It was hard to get all the hard lines back in their fittings but I finally got them. I had to put the front of the car on jack stands and take off the sheet metal piece that bolts to the frame with the louvres in it and get under the car to get to the fuel line and one of the fuel pump bolts. My car has the optional double diaphragm pump and many vacuum lines besides the fuel lines. Some I got from the top and some from the bottom. It was more work than I expected but its done an d there is no leaks so it was a good day. It was cold out tonight and  we stopped to fill our tank. Here is a picture of my wife in her pajamas as we didn't leave till after midnight, she likes the cold.

 

 

 

 

 

 

 

 

 

[Jim Nelson]

Rod Fraizer,   If you have a leak at your transmission, it comes from two area’s.   The torque ball can be a significant leaker.  My ‘37’ was bad.  My task was to replace thr third member to get a descent road car.  While the torque tube and rear were out, I rebuilt (?) the seals on the torque ball.  Next, I pulled the transmission.  I took the input bearing off the front of the transmission.  This bearing from the Buick factory is designed to leak oil but it has a casting in front of the bearing to channel the oil back into the case of the tranny.  Some of you know me as the bearing nut as I try to upgrade points like this to keep oil where it belongs.  You need to replace that bearing, which is called a ‘shielded bearing with a snap ring’ with a modern configeration called ‘sealed bearing with the snap ring.  You take the modern bearing and remove the seal from the surface the faces the transmission.  The sealed side faces the throw out bearing.  You then replace the  front casting that holds the bearing in place.  BTW,  do not buy chineese bearings for this.  Their quality is not there. (I had a bearing shop for 18 yers).  Spend the bucks for quality.  I do not have any oil leaks from that area anymore.   A few dribbles in the engine area.  I believe its called a. ‘6207-2Rs-NR’.  Same bearing in either my ‘37’ or ‘38’ tranny.   Same solution for any front bearing replacement.