Lift pump 12>8mm reducer replacement.

[LBC28730]

Hello everyone.
Recently did the single pump conversion on my 1987 325is. I noticed the reducer hose from the pump to the assembly had a small crack but thought the clamps would be able to hold it together.
Unfortunately that isn't the case.

Of course as many may know, the small hose is only available with the entire stock lift pump assembly and there is no other sources that I have discovered.

I have found a couple sources in UK for the reducers but they are either not rated for fuel or are months out from possible availability.
(Polyester) https://www.autosiliconehoses.com/si...inch-blue.html
(Silicone) https://www.merlinmotorsport.co.uk/p...cer-sr12-8clbk

I'm surprised this hasn't been asked more often but, has anyone come up with a better solution?

I'm considering the possibility of casting a new part with SS300 silicone

[varg]

Temporary repair with a couple of layers of fuel resistant heat shrink tubing? Shortened tube and a brass 12mm to 8mm union with two short fuel line sections? Shorten the tube and solder an appropriately sized X to 8mm union into it?

[LBC28730]

Temporary repair with a couple of layers of fuel resistant heat shrink tubing? Shortened tube and a brass 12mm to 8mm union with two short fuel line sections? Shorten the tube and solder an appropriately sized X to 8mm union into it?

Definitely all options I've considered. I even managed to make somewhat of a reducer nipple from some old brass HVAC fittings. I was considering brazing it on but was concerned about the heat getting all the way to the upper plug fitting. I suppose I could put a heat sink on....
I also considered getting a 12x8mm barbed hose union and cutting it down to just enough to clamp both sides on.

[moatilliatta]

I gave up years ago looking for a replacement coupler... I've been bitten in the ass and lost a race because of that faulty reducer coupler. I cant imagine all the people who got stranded on side of the road from Airtex or Spectra drop in pumps because of this.

Bullshit


Not the best photo.. but one I could find. I found a compression fitting and trimmed down the barbs and 12mm housing tube till it fit in the packaged area. Try local hydraulic stores for the fitting. I believe it was a 1/2 compression to 3/8 barb.



On day I hope to have a website full of the tidbits to make E30 life a little easier.

https://www.r3vlimited.com/board/for...11#post9976983

[LBC28730]

I gave up years ago looking for a replacement coupler... I've been bitten in the ass and lost a race because of that faulty reducer coupler. I cant imagine all the people who got stranded on side of the road from Airtex or Spectra drop in pumps because of this.

Bullshit

It occurred to me today, I'm surprised this isn't an issue with every single pump conversion, as the factory lift pump is rated at <5psi, hi volume, low pressure.

I had a super simple idea that I am about to test, but I can't imagine why it would not work.

I got a section of 12mm (.5") fuel hose and cut a small section of 8mm (.375") just tall enough for the height of the nipple of the pump.
I put cut a section of the 12mm about 2x as long and then worked the 8mm section into one end until it was flush. .
I put the 8mm id end on the pump and used a clamp type like you have shown (it seems that I don't know what they are called?). I then put the same clamp (21mm I think) on the other end as well.

I just put it back in the tank and hopefully it will solve my issues of low pressure for no apparent reason!

I'd cancel the order for adapters I ordered but I realized in retrospect they were the same size I used for the external pump deletion so I may as well have them on hand.

Oetiker Clamp......I had no idea

[LBC28730]

Great success!

Pretty straightforward but here's a photo for those that are more visual:

[TobyB]

I think I just brazed a small chunk of 8mm steel tubing to the larger feed line...

t
better living through acetylene

[varg]

I was considering brazing it on but was concerned about the heat getting all the way to the upper plug fitting.

I doubt enough heat would get up there to cause any trouble in the time it takes to braze in a preheated fitting, but you could always dip the bulkhead side in water while you braze it.

[LBC28730]

I think I just brazed a small chunk of 8mm steel tubing to the larger feed line...

t
better living through acetylene

That is definitely my next step!

I doubt enough heat would get up there to cause any trouble in the time it takes to braze in a preheated fitting, but you could always dip the bulkhead side in water while you braze it.

I think you are right. I could definitely put a heat sink on before the top, too.
Going to just do this, as my previous fix was very temporary!

[Panici]

I used Submersible-rated Gates 27097 (3/8" ID)
Bit of a bear to get on there, but it's been working fine.

[LBC28730]

I used Submersible-rated Gates 27097 (3/8" ID)
Bit of a bear to get on there, but it's been working fine.

I like this option a lot!
Didn't know what line to use but I have a foot of that on the way!

[Panici]

I like this option a lot!
Didn't know what line to use but I have a foot of that on the way!

Glad I could help!

I spent money on an aftermarket FPR before I figured out my original reducer was split under the SHEER POWER of the Aeromotive 340 Stealth.

I temporarily used a regular (not submersible rated) piece of line in there (for less then a month) and the outside was already starting to go soft when I pulled it for the Gates 27097.