engine and drivetrain Constant Buzzing of 5series Fuel Pump? Opinions Please.

[PaulTWinterton]

Looks easy enough to make one up.

 

Real easy!

 

But do I need to?  I've never heard of this before.  I have never seen one on a tii.  AND I've never had a problem with the fuel pump OR CAVITATION.

 

This issue I had on the first day of testing the 535i pump has not re-occurred, but I'm going to check fittings and filters anyway.

[OriginalOwner]

hmmm, I don't ever remember seeing a heat shield on my '74tii .......

 

SO, I just looked at the carbureted 1975 Green Loaner:  yep, heat shield in place !!

 

Cheers,

 

Carl

Edited May 4, 2015 by OriginalOwner

['76mintgrün'02]

No shield in my '76 either, but the gas tank has been replaced.

It would be interesting to feel the side of the tank after a long run, on an almost empty tank and see how warm it is.

[TobyB]

Probably not, Paul- I'll be at SOVREN the week earlier with the E30, and I'll bet I'm too broke to make it down...

 

Portland, tho, is what made me think of the heat shield- someone shot an IR thermometer at the fuel cell

on a hot race weekend, and read 145.  Then looked up the vaporization pressure/temperature curve on

pump gas, and declared that it should be boiling.  We popped the cap off the cell, lit a match to see what it 

looked like in there- and sure as shit, it WAS bubbling away!  Freaked us all out.  I went back to the 2002 with

the IR gun, got 120f- and then looked at the heat shield under there with a new appreciation.

 

If you look at the parts list for the E30, there is a tropical kit available that adds a small condenser to the 

A/C to cool the fuel in hot weather.  Not makin' that one up- Pro3 had to ban it, specifically...

 

t

Edited May 5, 2015 by TobyB

[PaulTWinterton]

TobyB...you "lit a match" and it was the bubbling that freaked you out?  Analogy, right?  Sorry you can't make it too Portland, unless you do. 

 

So WHY doesn't the tii have a heat shield?  I swear I've been under at least 6 tiis in the last 30 years and I've never seen a heat shield, or "protection plate as written in the stock 02 diagram"

 

I just talked to my BMW parts guy/02 buddy, and he agrees that he's never seen one on a tii.  But he thinks it might be a regional thing, like a hotter climate requirement for carbureted cars more prone to vapor locks. 

 

We need more owners of original cars to speak up.  Thanks Carl for starting the ball rolling.  We'll get to the bottom of this.

[JohnH]

My experience with E28 pumps is that they are near silent or a very slight hum. When they fail, they shriek and wail, and will do this for years sometimes. Any other noise you hear is a mounting problem. A inlet/outlet pipe is vibrating against something or the rubber mounts are shot or out of wack. Are your mounts tight. Its a bit fiddly under there. 

[PaulTWinterton]

My experience with E28 pumps is that they are near silent or a very slight hum. When they fail, they shriek and wail, and will do this for years sometimes. Any other noise you hear is a mounting problem. A inlet/outlet pipe is vibrating against something or the rubber mounts are shot or out of wack. Are your mounts tight. Its a bit fiddly under there.

 

That was my first thought so I lifted the car and inspected everything.  I used a mirror to get a close up view behind the CV.  All tight and no interference anywhere. 

 

The worst part is that the noise hasn't happened since. I've inspected my fittings and filters and all seems well.  As you say "near silent or a very slight hum".  That's the way it is now.   Still checking.

[JohnH]

Sounds like its snuggled itself back to where it likes to be. Fingers crossed.