AC Fuel Pump repair

[Emma-Knight]

When looking at a good selection of fuel pump housings, I found they all suffer from fixing ear bending. This is resulting in about 0.7 to more than 1mm up and down play to their mating surface (just a flat surface for testing). Grinding them flat would weaken the mounting ears even more. I tried to “flatten“ them in a strong vice - no success.
Question is - does it matter anyway, as they are fixed on a kind of Bakelite block? The inbetween cardbord seal cannot compensate for this...
2. Are there any experiences with this repair kit? It’s old english nos.
I just want to use the membrane, which is in good shape.

Anna (tested 5 housings, also one from Ray)

[Emma-Knight]

Anybody? Just to bring back this topic... Got four housings and im stuck with this problem...

Anna

[oldelanman]

Hi Anna,
Some rebuild kits available nowadays claim that the diaphragm material is compatible with ethanol fuels, it's unlikely that the diaphragm in your old kit would be. However, I found that the valves in the new kit were a larger diameter than those removed and would not fit in the recess in the pump body. I ended up using the diaphragm from the new kit and the valves from a NOS AC rebuild kit.

Regarding the bow in your pump mounting face, personally I would just rub it flat with emery cloth on a sheet of glass and install with a smear of sealant on both sides of the gasket and don't overtighten the bolts. I don't think removing that small amount of material will significantly weaken the mounting lugs.
If that doesn't work you have 3 more to try something else

[GLB]

I ground mine flat on a stationary belt sander with a flat steel platen behind the belt. I have done two and no problems. Yet. Gary

[Emma-Knight]

Ok, with three in mind I start grinding
For the diapraghm - I could try the NOS, as I only use Ethanol free 100 Octane fuel. And order an ethanol resisting one to rebuild another pump. Just put it in the boot, so the first one won‘t fail...
Thank you for the advice,
Anna

[2cams70]

It's largely a waste of time grinding them flat unless they are really bad. They just bend again. I don't bother. The fibre spacer compresses enough to accommodate the bow and once they reach a certain limit they don't tend to bend much further.

If they are really bent I prefer trying to straighten rather than grind. If you grind the metal you are weakening the flange and making it even more likely to bend in future.

I was able to successfully straighten the bent mounting flange of a Weber 40 DFAV carburetor once by getting it really hot with a heat gun and using a block of wood and a hammer to tap it flat. It was made of zinc die cast material like the AC fuel pump.

Make sure you always use a torque wrench on those bolts though and tighten evenly - that's largely the cause of the problem!

[Emma-Knight]

So first heat, bending, Offering to block and if no success - grinding a little.
Thanks again,

Anna

[Mazzini]

What torque do you tighten them up to? I torque them up to whatever is in the manual, but on my S3 I recently found a dribble of oil, so I re-torqued the bolts and it was okay after that. I thought about using Locktite on them.

[2cams70]

What torque do you tighten them up to? I torque them up to whatever is in the manual, but on my S3 I recently found a dribble of oil, so I re-torqued the bolts and it was okay after that. I thought about using Locktite on them.

Torque spec is 12-15 ft/lb. I wouldn't bother with Loctite. Not a critical bolt and Loctite is a pain to clean when it comes to bolt removal time. Any loss in tension is due to the spacer compressing and not the bolt coming loose. Again they usually reach a limit point and don't get any worse.

[Mazzini]

Thanks for that.

[h20hamelan]

Any use checking break away strength before undoing bolts you are concerned with?
I suspect always tightening 0.5lbs or a bit more than what was previously torqued to. Or when your dealing with less than 20-30lbs bolt stretch is not as big of an issue considering the bolt is steel.
Maybe I should look up a stretch chart?

https://www.fastenal.com/en/69/bolted-joint-design

Suppose the old Ford or Volvo etc steel is of better quality?

[2cams70]

So first heat, bending, Offering to block and if no success - grinding a little.
Thanks again,

Anna

If you have a big vice a good way may be to try using blocks of cushioning wood at three points - the end of the body and each of the two flange ears and tighten in the jaws of the vice. Heat with the electric heat gun whilst doing this. At least you have three to experiment with!