Lesson learnt from OVER tightening things

Unread post by **citroenxm** » 06 Oct 2011, 21:38

Hi All.. Directed towards XUD TD drivers.. but could be for anyone.

I had a customer car with a fuel drainage problem.. However, it was NOT an obvious problem.

The car would drain fuel from the pump back after a few hours! would always go with a re-prime.

check all the obvious, leak offs, return pipes, feed pipes, the "Loop" pipe on the rear.. etc etc nothing. So I assumed the fuel filter area. Moved the fuel feed pipe directly to the pump inlet.. The problem continued!

It had to be the Pump.... So I set about removing the pump and for some reason decided to remove the Banjo knuckle, rather then the pipe off the back.. The 17mm banjo felt a little slack... I tried to re tighten it when It felt as though it was gonna give.. so I un done it and removed it to find it was starting to split across the drilled out hole.. Luckly I had anther one.. however this had done the same and started splitting!!!

In the end, I removed a Return Banjo bolt, and a bit of drilling out and cleaning up fitted it on the Inlet... I left the car all primed up ready for next days result..

Result?? OH YES!! Problem solved!! The car started first time twice with no priming needed!!

So previously I must have tightend the Banjo up just that little tooo much without realising it...

Looking at the Bolt, It looks like the hollow out is TOO big and weakens the bolt and a slight over enthuisastic tighten with a spanner splits the body.. This results in a Fuel drain INTERNALLY, as air gets in, but fuel does not come out!

Thank god, the poor owners have suffered with daily priming for around 6 months!

Paul

Unread post by **Peter.N.** » 06 Oct 2011, 21:58

A case of 'one good turn not derseving another'

Peter

Unread post by **CitroJim** » 07 Oct 2011, 05:59

Excellent stuff Paul

Tell Sarah you only want two Weetabix for breakfast in future and not three!!

And ask Santa to bring you a torque wrench...

Seriously an odd one and worth keeping in the back of one's mind for the next unexplained air leak...

UFO · Unread post by **UFO** » 08 Oct 2011, 04:39

Tighten it till it starts to strip and then back off half a turn?

Timmo · Unread post by **Timmo** » 08 Oct 2011, 09:38

Banjo bolts are one of the ones where torque settings arr very usefull! Had simolar on mountain bike brakes!

Refers? Somewhat back to a saying avery close family friend told me many moons ago, was something that his dad had told him,
'Spanners were made that length for a reason! '

Unread post by **CitroJim** » 08 Oct 2011, 09:48

Timmo wrote:
'Spanners were made that length for a reason! '

Indeed, although a very long 10mm and 13mm spanner would be very handy in some circumstances...

Also with Banjo Bolts, always anneal the copper washers, even new ones, before use. They'll be softer and thus need less tighten of the Banjo to seal them..

Banjos should only ever be nipped up just to the point they don't weep...

addo · Unread post by **addo** » 08 Oct 2011, 10:16

CitroJim wrote:Banjos should only ever be nipped up just to the point they don't weep...

You mean your banjo doesn't gently weep?

Unread post by **myglaren** » 08 Oct 2011, 13:40

addo wrote:
CitroJim wrote:Banjos should only ever be nipped up just to the point they don't weep...
You mean your banjo doesn't gently weep?