Click here to return to the home page.
Image of a road.
Who's Online Now
19 registered members (BLUE+4, pandy, Chiltern MOG, skullmog, AlyMatt, Ian Wegg, bilibib, Jon G4LJW, E1A, Heinz, jrt, waikiore, Robbie, ewn, P964, ShaunD, Rog G, MJF, Dada), 111 guests, and 14 spiders.
Key: Admin, Global Mod, Mod
Top Posters(30 Days)
+8Rich 273
John V6 142
Newest Topics
M3W Treffen 2019
by Laurens. 16/07/19 08:19 PM
Apollo 11 Moon Mission
by Gambalunga. 16/07/19 06:51 PM
Who knows about outboard props?
by ewn. 16/07/19 06:21 PM
More comfortable shocks.
by Obie. 16/07/19 05:41 PM
One for the Budster ;-)
by +8Rich. 16/07/19 05:08 PM
Middleton Garage Services Recommendation
by Fuel.inj. 16/07/19 04:53 PM
3rd August
by Chris99. 16/07/19 04:27 PM
Latest Photos
Some little planes.
M3W AT PORT GAMBLE
65 Plus 4 gas cap and new luggage
wrenching fun
Swanmog at Prodrive
Newest Members
jim skilling, Luddite, AREL2000, CarMart, Doc L
6594 Registered Users
Forum Statistics
Forums33
Topics35,619
Posts574,737
Members6,594
Most Online341
Feb 11th, 2018
Today's Birthdays
BuyBritish
Previous Gallery
Next Gallery
Print Thread
Page 1 of 3 1 2 3
Fuel cap seal #581614
15/06/19 09:42 PM
15/06/19 09:42 PM
2 Images
Joined: Jul 2007
Posts: 13,437
Suffolk
John V6 Offline OP
Member of the Inner Circle
Fuel cap seal

I have been having for the last twelve months an intermittent but increasing ECU fault on lean mixture on bank 1 and or bank 2 (P1071 & P1074). This can be caused by a small air leak. Dealers told me to ignore it & to cancel the fault via the OBDII dongle I have as they could find nothing.

A chat with Simon Daunt over dinner at the Anglemog trip to Scotland helped track down a possible cause to the seal on the filler cap.

Mine was badly perished & a loose fit in the groove. I had assumed the locking cap was the pressure & venting valve so didn't think it an issue and that this seal just allowed the cover to lock down.
But it seems this seal & the spring loaded inner pad do act as the pressure & venting valve.

A replacement was sourced from Melvyn Rutter, but they commented they were over size. This new seal has stopped the error most of the time. But fails when you stop and refill the tank.

I can obviously cut the seal to make it shorter but I am unsure how tight it should be. I am concerned that it needs to be loose to let air back into the tank when / if it pulls a vacuum Is there a kind soul out there who has a newer car & can let me know their seal diameter?
20 Comments
Re: Fuel cap seal [Re: John V6] #581618
15/06/19 10:12 PM
15/06/19 10:12 PM
Joined: Dec 2008
Posts: 17,504
South Yorkshire
DaveW Offline
Roadster Guru
DaveW  Offline
Roadster Guru
Member of the Inner Circle

Joined: Dec 2008
Posts: 17,504
South Yorkshire
I'll have a look tomorrow and take some pics if necessary.


DaveW
2005 Corsa Red Roadster S1
2016 Saffron Yellow (Narrow) Plus 4
Re: Fuel cap seal [Re: John V6] #581639
16/06/19 08:03 AM
16/06/19 08:03 AM
Joined: Mar 2017
Posts: 964
Oxon
Craig Jezz Offline
Talk Morgan Regular
Craig Jezz  Offline
Talk Morgan Regular

Joined: Mar 2017
Posts: 964
Oxon
Originally Posted By John V6
I have been having for the last twelve months an intermittent but increasing ECU fault on lean mixture on bank 1 and or bank 2 (P1071 & P1074). This can be caused by a small air leak. Dealers told me to ignore it & to cancel the fault via the OBDII dongle I have as they could find nothing.

A chat with Simon Daunt over dinner at the Anglemog trip to Scotland helped track down a possible cause to the seal on the filler cap.

Mine was badly perished & a loose fit in the groove. I had assumed the locking cap was the pressure & venting valve so didn't think it an issue and that this seal just allowed the cover to lock down.
But it seems this seal & the spring loaded inner pad do act as the pressure & venting valve.

A replacement was sourced from Melvyn Rutter, but they commented they were over size. This new seal has stopped the error most of the time. But fails when you stop and refill the tank.

I can obviously cut the seal to make it shorter but I am unsure how tight it should be. I am concerned that it needs to be loose to let air back into the tank when / if it pulls a vacuum Is there a kind soul out there who has a newer car & can let me know their seal diameter?


I hope this helps John, I have a 2016 Morgan and on mine it measures 78mm to the outside of the seal.






Craig Jezz

Morgan 4/4 Sports Sand (Williams & Wolf Tuned)
Re: Fuel cap seal [Re: John V6] #581640
16/06/19 08:09 AM
16/06/19 08:09 AM
Joined: Jul 2007
Posts: 13,437
Suffolk
John V6 Offline OP
Member of the Inner Circle
John V6  Offline OP
Member of the Inner Circle

Joined: Jul 2007
Posts: 13,437
Suffolk
Thanks guys. My old seal you could move out of the groove very easily by pushing one end using two fingers to grip the bottom third, the other end would then balloon out. Are yours a tight snap fit that you must pull over the groove. My original & the replacement are a loose fit that easily goes into the groove.


JohnV6
2006 Indigo Blue Roadster S1
Re: Fuel cap seal [Re: John V6] #581641
16/06/19 08:12 AM
16/06/19 08:12 AM
Joined: Mar 2017
Posts: 964
Oxon
Craig Jezz Offline
Talk Morgan Regular
Craig Jezz  Offline
Talk Morgan Regular

Joined: Mar 2017
Posts: 964
Oxon
Originally Posted By John V6
Thanks guys. My old seal you could move out of the groove very easily by pushing one end using two fingers to grip the bottom third, the other end would then balloon out. Are yours a tight snap fit that you must pull over the groove. My original & the replacement are a loose fit that easily goes into the groove.


It looks like a tight fit John, but to be honest I haven't tried to remove it.


Craig Jezz

Morgan 4/4 Sports Sand (Williams & Wolf Tuned)
Re: Fuel cap seal [Re: John V6] #581650
16/06/19 08:59 AM
16/06/19 08:59 AM
Joined: Jul 2007
Posts: 13,437
Suffolk
John V6 Offline OP
Member of the Inner Circle
John V6  Offline OP
Member of the Inner Circle

Joined: Jul 2007
Posts: 13,437
Suffolk
Thanks. I measured the ring it is 73mm on the inside diameter. The groove is 71 mm. I have cut out 3 mm to give a tighter seal.

After I wash the car this afternoon I will take it for a spin to test the result.


JohnV6
2006 Indigo Blue Roadster S1
Re: Fuel cap seal [Re: John V6] #581688
16/06/19 02:55 PM
16/06/19 02:55 PM
Joined: Jul 2007
Posts: 13,437
Suffolk
John V6 Offline OP
Member of the Inner Circle
John V6  Offline OP
Member of the Inner Circle

Joined: Jul 2007
Posts: 13,437
Suffolk
Well after washing the car I tested the reduced diameter seal.

The fault when starting cold has gone completely.
The fault when hot & simulating a refuelling is intermittent as is it starting a hot engine after a stop of 1-2 mins.
This is a far better result than last night when it was every time.

I expect to get 2 more seals in Viton next week so will then make this current one an even smaller diameter to see if that works.


JohnV6
2006 Indigo Blue Roadster S1
Re: Fuel cap seal [Re: John V6] #581887
17/06/19 09:25 PM
17/06/19 09:25 PM
Joined: Oct 2007
Posts: 118
Sandhurst, Berks
T
teknome Offline
L - Learner Plates On
teknome  Offline
L - Learner Plates On
T

Joined: Oct 2007
Posts: 118
Sandhurst, Berks
John

There is something odd about your cap (the fuel cap). I now have a small collection of caps, new and old. My original 2007 cap, a new MMC cap on the car, and a CLA300 cap from Newton (the manufacturers).

All the caps have the same structure for the secondary seal

The primary seal is the locking insert, the secondary seal is by way of an o-ring around the sprung loaded disc in the cap, o/d 78mm as mentioned by Dave. There is no other seal on the cap.

Your picture shows what looks to be a rubber sheet gasket in addition to the sprung loaded disc

Once the sealing disc is removed the cap looks like



The edge of the sealing disc showing the o-ring



The disc and o-ring is fairly well spring loaded and appears to make a good seal with the filler cap body. Although on my old cap the o-ring is showing signs of age.

I have to add that on my Plus 4 the seal on the locking insert definitely seals the tank and there is an intake of air when I remove the insert, so I don't know to what level this secondary seal is important if the primary seal is good.

Just wonder at what point the flat gasket (third level of seal) was added to your cap.


---------------------------
Mike Smith


1995 +8
2007 +4
Re: Fuel cap seal [Re: John V6] #581920
18/06/19 07:22 AM
18/06/19 07:22 AM
Joined: Jul 2007
Posts: 13,437
Suffolk
John V6 Offline OP
Member of the Inner Circle
John V6  Offline OP
Member of the Inner Circle

Joined: Jul 2007
Posts: 13,437
Suffolk
Mike,
there is no third gasket it is just the photo showing the dirt on the inside of the cap.

I have the large o ring & also a smaller one that seals the shaft to the disc of the cover.

John


JohnV6
2006 Indigo Blue Roadster S1
Re: Fuel cap seal [Re: John V6] #581924
18/06/19 08:18 AM
18/06/19 08:18 AM
Joined: Oct 2007
Posts: 118
Sandhurst, Berks
T
teknome Offline
L - Learner Plates On
teknome  Offline
L - Learner Plates On
T

Joined: Oct 2007
Posts: 118
Sandhurst, Berks

Won't win concours with a dirty cap !

These fuel caps are made by Newton Automotive, tracking down the locking inserts on the Car Builder Solutions web site, they are available as non-venting, and as venting.

In the case of emission control they need to be non venting inserts so the carbon filter stores the fumes.

For older vehicles they would normally be vented inserts. In that case the large disc and o-ring would become the primary seal and release fumes once the pressure is high enough to lift the disc.

The Newton locking inserts come in two styles, the older type has a sort of rubber band style of gasket

The un-vented https://www.carbuildersolutions.com/uk/un-vented-lockable-insert-for-aston-necks-excl-2

The vented https://www.carbuildersolutions.com/uk/vented-lockable-insert-for-aston-necks-excl-2

I have purchased the non-venting and it did fit my old filler cap.

The later (current) style of locking insert has an o-ring seal, the part number on the insert here on my desk, for the non-vented is #Z45LT. I haven't yet found these on a re-sellers site, There was a thread some time ago on Talkmorgan where someone got hold of Newton and purchased an insert.

Assuming your cap is in good shape, it may be worth getting a new locking insert as this should be the primary seal for a non-vented system.

Another thing to check would be the fuel hoses to see if there are any cracks. My old hose looked OK but I did find some fractures although they were under the hose clips.


---------------------------
Mike Smith


1995 +8
2007 +4
Page 1 of 3 1 2 3

Moderated by  Aeroman, Simon 

Powered by UBB.threads™ PHP Forum Software 7.7.1