Fuel gauge sender gasket leak

Technical advice Q&A
User avatar

Topic author
Turnip
Posts: 63
Joined: Sat Oct 25, 2014 9:57 am
Location: Wiltshire
Great Britain

#1 Fuel gauge sender gasket leak

Post by Turnip » Wed Jan 02, 2019 8:24 pm

There’s a bit of a leakage around the gasket of my fuel tank’s gauge sender (C20429), so I have a little job on.
Looking at the parts manual, it lists 12 copper washers for the 6 screws that hold the gauge plate on. Can anyone advise on how those washers are used? It can’t be 2 under the head of each screw can it?

Also, SNGB lists 2 gaskets for the gauge sender, a cork one (as per original) and a rubber one. Is there any difference between the two? SNGB’s website doesn't help in this at all - as usual.

One thing I do know, it’s going to be a smelly job.

Simon
1965 Series 1 4.2 FHC

Link:
BBcode:
HTML:
Hide post links
Show post links


johnetype
Posts: 189
Joined: Sun Feb 26, 2012 11:54 pm
Location: Worcestershire
Great Britain

#2 Re: Fuel gauge sender gasket leak

Post by johnetype » Fri Jan 04, 2019 9:14 am

Turnip wrote:
Wed Jan 02, 2019 8:24 pm
It can’t be 2 under the head of each screw can it?
Well, yes it can. The threads in the fuel tank are blind (well at least they are on my tank) so the bolts holding the gauge plate down can only go in so far. Depending on the thickness of the gasket you use, the thickness of the copper washers themselves and the length of the bolts you may need to use two washers to ensure the bolts haven't bottomed out before the plate has closed down tightly enough to compress the gasket.

I believe that cork may have some susceptibility to ethanol in modern fuels hence the rubber alternative.
John

1969 Series 2 FHC

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

Topic author
Turnip
Posts: 63
Joined: Sat Oct 25, 2014 9:57 am
Location: Wiltshire
Great Britain

#3 Re: Fuel gauge sender gasket leak

Post by Turnip » Fri Jan 04, 2019 8:23 pm

Thanks John.
I'd come to the conclusion that 2 washers under the head was the answer. They are quite thin, so maybe stacked two together they're a bit stronger as well.

Simon
1965 Series 1 4.2 FHC

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

mark10337
Posts: 706
Joined: Wed Jul 22, 2015 11:11 am
Location: Switzerland
Switzerland

#4 Re: Fuel gauge sender gasket leak

Post by mark10337 » Sun Jan 06, 2019 11:12 am

Cork is not affected by ethanol. I had a rubber/neoprene one fitted and it disintegrated within 6 months spewing fuel out all over the boot and dripping out by the hot exhausts. This was despite assurances that it was "ethanol rated" Take the cork one and a bit of blue hylomar!

As copper is a soft metal, it will form to help seal the screws. As John mentioned, 2 maybe necessary to create the seal. I only have one on mine and it is no longer leaking.

Be careful. DO NOT overtighten these screws to the fuel tank. The threads are easily stripped and not easily re-tapped.
-Mark

1969 Series 2 OTS, Regency Red
'Life's to short to drive a boring car'

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

Series1 Stu
Posts: 761
Joined: Thu Feb 02, 2017 12:26 pm
Location: Shropshire
Great Britain

#5 Re: Fuel gauge sender gasket leak

Post by Series1 Stu » Sun Jan 06, 2019 11:59 am

2 copper washers seems like a pointless extravagance to me. A copper and a steel or brass plain washer should be fine.

Thinking about it, if the threads in the tank really are blind then a sealing washer shouldn't be required at all.

In a properly designed screw joint the threads should never strip before the screw breaks. Fundamental design rule.

There's something in my mind telling me that the screws are brass but then, my mind plays tricks on me at times.

Regards
Stuart

If you can't make it work, make it complicated!

'62 FHC - Work In (slow) Progress
'69 Daimler 420 Sovereign
'94 X300 XJR basket case

Link:
BBcode:
HTML:
Hide post links
Show post links


cactusman
Posts: 1695
Joined: Wed Nov 14, 2012 11:09 pm
Location: Hertfordshire
Great Britain

#6 Re: Fuel gauge sender gasket leak

Post by cactusman » Sun Jan 06, 2019 6:46 pm

Mine has a cork gasket....fine. 2BA brass screw have the correct thread and are readily available.
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

Barry
Posts: 322
Joined: Thu Jul 05, 2012 1:11 pm
Location: United Kingdom
Great Britain

#7 Re: Fuel gauge sender gasket leak

Post by Barry » Sun Jan 06, 2019 11:12 pm

If it’s any help, I experienced a leak, to what I thought was the gasket. A new gasket later, and a look at the screws and copper washers revealed the leak was coming from a stripped thread around one of the screws, which just could not be tightened. Petrol leaked through the thread. Retapping the thread resolved the issue. I am not saying that is your problem, but just to highlight a potential problem if the gasket has been renewed and petrol still leaks.

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

politeperson
Posts: 752
Joined: Tue Jun 07, 2016 8:26 pm
Location: Boston UK
Great Britain

#8 Re: Fuel gauge sender gasket leak

Post by politeperson » Mon Jan 07, 2019 8:34 am

And dont remove the sender if your tank is full otherwise petrol will go everywhere!
James

L.J.K. Setright was right.
"You just cant beat a good E-type"

Link:
BBcode:
HTML:
Hide post links
Show post links


johnetype
Posts: 189
Joined: Sun Feb 26, 2012 11:54 pm
Location: Worcestershire
Great Britain

#9 Re: Fuel gauge sender gasket leak

Post by johnetype » Mon Jan 07, 2019 5:47 pm

cactusman wrote:
Sun Jan 06, 2019 6:46 pm
Mine has a cork gasket....fine. 2BA brass screw have the correct thread and are readily available.
I believe the correct thread is 10-32 UNF. Yes, 2BA will "fit" but the BA thread profile is different as well and if you use a brass bolt it will be even more likely to strip.

A steel 10-32 bolt with copper washers to both seal and give a measure of lock washer is the way to go.

I recall it being discussed elsewhere on here but I don't believe Jaguar used BA threads on any of their engineered parts. Yes you might find BA on Smiths Instruments and similar bought in components but during my rebuild with the exception of Whitworth in the LSD, everywhere else was UNF or UNC.
John

1969 Series 2 FHC

Link:
BBcode:
HTML:
Hide post links
Show post links


cactusman
Posts: 1695
Joined: Wed Nov 14, 2012 11:09 pm
Location: Hertfordshire
Great Britain

#10 Re: Fuel gauge sender gasket leak

Post by cactusman » Mon Jan 07, 2019 6:19 pm

Mine has 10-32 unf bolts (I used stainless steel ones) but if anyone wants brass you might find it hard to get a 10-32 Inc thread hence the suggestion of 2BA. My tank holes seem to be blind so important to get ones not too long else they bottom out before being tight.
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

Bill Michigan
Posts: 3
Joined: Thu Apr 26, 2018 9:20 pm
Location: Michigan, USA
United States of America

#11 Re: Fuel gauge sender gasket leak

Post by Bill Michigan » Tue Jan 08, 2019 2:36 pm

I want to second Mark's comment that you need to be careful and not over-tighten the bolts. Not only do you risk stripping threads, but excessive tightening can actually raise the metal at the attachment points and distort the entire flange on the fuel tank, leading to more sealing problems. I found this condition on my fuel pump assembly mounting surface and had to do quite a bit of filing to get everything level again.

I also had to deal with the problem of a stripped thread on the tank. There seem to be 3 ways to fix that:

1. Insert a Helicoil. Yes, they do make them for 10-32 threads, and an installation kit is available through Amazon for about $30. This is what I did and it worked fine, except that it's a bit of problem to retain the short helicoil insert after trimming off the excess on the ends, so I had to re-do it with some Loctite on the Helicoil.

2. An alternative is to just drill and tap the stripped hole for the next larger size bolt. My only concern there would be that going to a coarser thread means there will precious few threads in that short bolt hole.

3. Another alternative is to just plug the existing hole with epoxy and then drill and tap a new 10-32 hole near the original one.

Bill
1963 S1 3.8L OTS Cotswold Blue
2013 XF
Previous:
2002 XJR Series 100
1996 XJ6

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

JulianBarratt
Posts: 6
Joined: Fri Sep 14, 2018 12:49 pm
Location: Bridgnorth, UK
Contact:
Great Britain

#12 Re: Fuel gauge sender gasket leak

Post by JulianBarratt » Tue Jan 08, 2019 8:17 pm

Agree with the original comment that the description on the difference between the cork and rubber gasket via our website is no good/non existent! I will ensure this is updated. We are working on a large program of improving the descriptions of the parts so you should start to see some improvements in this area in 2019..
MD at SNG Barratt Group
Enthusiastic owner/driver of a couple of complete E-types as well as a warehouse or two of parts...

Link:
BBcode:
HTML:
Hide post links
Show post links

Post Reply Previous topicNext topic