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Fuel Sender Unit Bolts leaking
Posted: Tue Jul 06, 2021 12:50 pm
by Rev Tex
Hi,
I'm new to the forum and I've tried to search for any information about this problem, but had no lock today. This is my second EK (sold the first one back in 2003 - and kicking myself ever since).

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Since buying the car it has had noticeable petrol vapour in the cabin. Only recently the fuel sender uint stopped working so I took it out and realised there was fuel sitting around the bolts on top of the plate (none around the outside of the gasket). Having looked at the unit I opted for a new one from Rare Spares which came with a rubber (I assume Neoprene) gasket and some aluminium/rubber crush washers.
I don't recall my old EK having crush washers, but I thought they might fix the problem. I actually installed the new unit using a new cork gasket I bought nearly 20 years ago and used the crush washers. Anyway - it was still leaking around the bolts (nothing around the edge of the gasket. I tried nipping them up progressively, and then ordered a new fitting kit.
This time I installed the rubber gasket with new cruces washers, but I've got the same problem.
I haven't been able to find any clear information about Holdens and this issue. i can see from MG and Chev sites that some people suggest fibre or copper washers.
Can anyone help brother out with some advice? I apologise if this is dealt with elsewhere and i haven't been able to find it.

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Cheers,
Iain
Re: Fuel Sender Unit Bolts leaking
Posted: Tue Jul 06, 2021 1:54 pm
by Blacky
Welcome to the forum Tex , nice looking rig there mate
I would try a smear of Stag jointing paste on the threads of the screws
Re: Fuel Sender Unit Bolts leaking
Posted: Tue Jul 06, 2021 2:07 pm
by Brett027
Yeah Blacky, Stag is great stuff and as you say, petrol proof. Nice car Tex.
Re: Fuel Sender Unit Bolts leaking
Posted: Tue Jul 06, 2021 2:17 pm
by Rev Tex
Thanks guys - Really appreciate the quick response.
I was reluctant to apply something to the threads in case it ends up in the tank if ever need to remove the sender unit again. But it was something I'd thought about.
In that case - would I be better to not bother with the the crush washers? They certainly didn't seem to be an original component for the car, and it's twice now they haven't really help.
Re: Fuel Sender Unit Bolts leaking
Posted: Tue Jul 06, 2021 6:17 pm
by sgo
l just went through this in an fx.
New rares sender and rubber gasket installed.
Started with fumes, then major leak with full tank.
Removed rubber gasket and found it perished and car isn't even registered yet.
Replaced with "paper" gasket and "goo" and all seems OK now.
Oh, and I had to clean the goo off of some bolt threads to keep a good earth connection.
Re: Fuel Sender Unit Bolts leaking
Posted: Tue Jul 06, 2021 7:00 pm
by Blacky
i RAN A SEPARATE EARTH WIRE FROM THE SENDER TO GROUND , bloody capslock

, hose clamped it to the delivery tube where it comes out of the tank .
Re: Fuel Sender Unit Bolts leaking
Posted: Tue Jul 06, 2021 7:14 pm
by Errol62
Just used permatex gasket goo, no gasket, no leaks.
FB ute fixer upper, EK van on rotisserie
Re: Fuel Sender Unit Bolts leaking
Posted: Tue Jul 06, 2021 7:18 pm
by Errol62
The sender flange recess acts like a sump and collects any water that gets on top of the tank, corroding the screw heads. So I poured 1/4” of Fisholene in there.
FB ute fixer upper, EK van on rotisserie
Re: Fuel Sender Unit Bolts leaking
Posted: Fri Jul 30, 2021 3:11 pm
by Rev Tex
Thanks for the advice everyone.After trying both a new set of crush washers with the rubber gasket, and fibre washers, it's clear neither of those have worked. So I've got some Stag Jointing Paste for the threads (and I was going to sneak some between the bolt heads the flange), but I thought I should also use something on the gasket. I was looking at Permatex 85420 which is meant to be a fuel resistant gasket dressing. Does that sound like the right product for the job?
Re: Fuel Sender Unit Bolts leaking
Posted: Fri Jul 30, 2021 9:09 pm
by Blacky
Go with the Stag for both mate - I have found "fuel resistant" means "works for a short time "
Re: Fuel Sender Unit Bolts leaking
Posted: Sat Jul 31, 2021 7:54 am
by EK283
Nice car,
I have used Permatex Aviation # 80019 with all gaskets and threads and I have not had any leaks.
It hardens but remains soft if that makes sense, good for radiator hoses as well.
Regards Greg
Re: Fuel Sender Unit Bolts leaking
Posted: Sat Jul 31, 2021 11:43 am
by Harv
EK283 wrote: Sat Jul 31, 2021 7:54 amI have used Permatex Aviation # 80019 with all gaskets and threads and I have not had any leaks.
It hardens but remains soft if that makes sense, good for radiator hoses as well.
Another vote for Aviation Form-a-Gasket. Easy to get from SuperCheap, works well, and cleans off OK next time round (unlike the silastic based sealers).
The smell of that stuff reminds me of the old man. Aviation Form-a-Gasket, kero, prepsol and pink protect-a-lene hand cleaner.
Cheers,
Harv
Re: Fuel Sender Unit Bolts leaking
Posted: Thu Aug 05, 2021 7:20 pm
by Rev Tex
Thanks for the great advice guys. I re-installed for the fourth time now using Stag jointing paste on the threads and under the heads of the bolts, and I used the Permatex Aviation gasket goo on a rubber gasket. The good news is the bolts and gasket don't leak - the bad news is that the reproduction sender unit is leaking through what I think is a rivet (even though it looks spot-welded). By the time I got back from filling the tanks, the sender unit well was almost full of petrol. After mopping it up I could see it leaching through at that spot.
I only bought the new unit in March so I'll see what the retailer has to say. I thought about getting my old unit refurbished. The guy who did a cracking job on a couple of my speedometers was happy to do it, but he reckoned it was probably just as well to get a reproduction unit because it would be freshly nickel plated.
Anyway at least I know where the real problem is now....
Re: Fuel Sender Unit Bolts leaking
Posted: Thu Aug 05, 2021 9:11 pm
by Blacky
Re: Fuel Sender Unit Bolts leaking
Posted: Thu Aug 05, 2021 10:00 pm
by In the Shed
If you don't have any luck with a changeover unit I reckon you could solder over the rivet onto the top plate and that would solve the problem. Of course it should never have leaked from the start
Stephen