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Cubflyer



Member Since: 25 Sep 2021
Location: Suffolk
Posts: 278

United Kingdom 1994 Defender 90 300 Tdi SW Arles Blue
Defender TDi 300 Thermostat / Radiator Plug
Hi folk - thought I'd share this with you as I've been "Around the block" with this subject. It all started when I had difficulties removing the thermostat plug as written in this thread:

https://www.defender2.net/forum/topic81561.html

I should add at this point I am NOT being DISRESPECTFUL or here to CRITICIZE ANY seller but I am wanting to make you aware of the issues with various plugs.

Now there are no less than FOUR plugs I've tried and here's the results. I will start at the cheapest and end with the most expensive.

OK, at just around £1.50 you can get a Bearmach or Allmakes plastic plug (The one I first had issues with) Part number ERR4686. It also comes with a 28mm x 2.5mm "O" ring that is located in a locating recess under the plug.


Click image to enlarge


Click image to enlarge

This plug is cheap and cheerful but can seize in the aluminum thermostat fitting.
It "Should" require a 20mm socket/spanner to remove it but the three I've had are all OVERSIZE (20.3-20.6mm) so a socket/spanner is difficult to fit!
It has an internal hex slot for an Allen key ... but guess what it's too big for a 10mm and two small for an 11mm!

Next in the line the metal version of the above, Part number ERR4686B (for Brass) and costs around £5.00


Click image to enlarge


Click image to enlarge


Quality control for the socket/spanner is relevant again. Again designed for a 21mm tool but it's oversize at 21.3-21.4mm and being brass you just cannot get a socket or spanner on it! It does however have a deep slot in the top so a wide bladed screwdriver will allow you to get the plug out.

Continuing to increase in price at £6.50 / £8.00 is an "Anodized" aluminum plug available in red or blue ... AGAIN poor sizing and has a 10.4mm SQUARE recess in it's top for which VERY few of us have a fitting for!

Click image to enlarge


... and LASTLY there is the Foundry4x4 Plug (A present from my wife):
They call it: Land Rover 300Tdi X Eng Radiator & Thermostat Bleed Screws (X Cap) and comes as a pack of two for £21.00 + postage.

It looks good, feels good and is anodized in blue. It has a 27mm head designed for the wheel nut wrench but it also has a very deep and wide slot so just about anything from a screwdriver shaft, lever, bar or a knife or fork handle will get it out.

Click image to enlarge


BUT and here's a BIG but! All the above cheaper plugs have a locating groove machined into the underside to keep the "O" ring in place as it's tightened ... This plug does NOT and out of a number of trials the "O" ring wants to work it's way out of the plug surface as it's tightened. Only once in 6/7 attempts did I get the "O" ring to stay in a "Considered" safe place.

This plug really carries a design flaw in my opinion and should be treated with GREAT care when fitting! It really needs an "O" ring retaining groove in my opinion. See images below:


Click image to enlarge


Click image to enlarge


Click image to enlarge


Finally, I've had all these plugs in the last 6 weeks and returned the most expensive two back to their suppliers. I've now reverted to using the basic brass version now ERR4686B.

Hope this helps someone from "my" findings and experience.

John 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994)
Post #936972 9th Jan 2022 7:54pm
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Mo Murphy



Member Since: 01 Jun 2008
Location: Letchworth Garden City, Herts
Posts: 2062

United Kingdom 1984 Defender 90 200 Tdi HT Pennine Grey
You don't use an o ring with the x-eng plug, it doesn't need it. you've sent back the 2 easiest to use plugs 😳
HTH
Mo The Land Rover 90 - Many are called, few are chosen.
Post #936974 9th Jan 2022 8:01pm
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landy andy



Member Since: 15 Feb 2009
Location: Ware, Herts
Posts: 5408

2006 Defender 110 Td5 USW Zermatt Silver
Wow. A real spread in price and quality. Can’t believe the last one. It would be better with a dowty washers, or even a rubber washer but the O ring is ridiculous. I seem to recall I fixed one with a end cap off a house radiator and even used one that had the bleed screw fitting so it could be bled.
Post #936975 9th Jan 2022 8:04pm
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Cubflyer



Member Since: 25 Sep 2021
Location: Suffolk
Posts: 278

United Kingdom 1994 Defender 90 300 Tdi SW Arles Blue
So why do they supply an "O" ring with each plug ??

The underside of the plug is machined smooth but the thermostat casting on my 90 is certainly not machined smooth and I certainly would not put plug to metal with no gasket/ O ring or sealer. 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994)
Post #936977 9th Jan 2022 8:04pm
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Mo Murphy



Member Since: 01 Jun 2008
Location: Letchworth Garden City, Herts
Posts: 2062

United Kingdom 1984 Defender 90 200 Tdi HT Pennine Grey
I've used them without o rings since their launch many years ago, never lost a drop of water.
Did you have a chat with their distributors, Foundry 4x4 and seek their advice ?
Mo The Land Rover 90 - Many are called, few are chosen.
Post #936981 9th Jan 2022 8:14pm
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Cubflyer



Member Since: 25 Sep 2021
Location: Suffolk
Posts: 278

United Kingdom 1994 Defender 90 300 Tdi SW Arles Blue
No reply from them, they just accepted my comments and refunded. I should say that I like their product and have their X-lock but IMO these plugs are below standard.

... and their eBay advert makes no mention of fitting them and here's their image with "O" rings.


 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994)
Post #936983 9th Jan 2022 8:26pm
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Oldowner



Member Since: 26 Dec 2018
Location: South west
Posts: 598

United Kingdom 2007 Defender 90 Puma 2.4 HT Aintree Green
With regards to the spanner sizing, the original plastic plugs were meant to be undone with a 13/16 spark plug socket.
Post #936987 9th Jan 2022 8:50pm
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Mossberg



Member Since: 29 Feb 2020
Location: Lancs
Posts: 552

United Kingdom 1993 Defender 90 300 Tdi HT Aintree Green
Thanks for sharing your findings.

I used the brass plugs with O ring - both seem to be working OK.
Post #936989 9th Jan 2022 8:58pm
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Cubflyer



Member Since: 25 Sep 2021
Location: Suffolk
Posts: 278

United Kingdom 1994 Defender 90 300 Tdi SW Arles Blue
Oldowner wrote:
With regards to the spanner sizing, the original plastic plugs were meant to be undone with a 13/16 spark plug socket.


Nice one chap - definately a good inject Thumbs Up

Thanks 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994)
Post #936999 9th Jan 2022 10:09pm
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Cubflyer



Member Since: 25 Sep 2021
Location: Suffolk
Posts: 278

United Kingdom 1994 Defender 90 300 Tdi SW Arles Blue
Mossberg wrote:
Thanks for sharing your findings.

I used the brass plugs with O ring - both seem to be working OK.


Yes - that's the way I'll stay too.

Following "Oldowner's" comment above I will add a 13/16th socket to my toolbox soon, hate not having the right tool for the job.

John 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994)
Post #937003 9th Jan 2022 10:15pm
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Litch



Member Since: 10 Mar 2013
Location: Oxfordshire
Posts: 758

England 
I have been using the X-Eng plugs almost since my 300TDi was brand-new and have never used an O-ring, I do however wrap the thread with PTFE tape (a roll of which is always present in my tool-kit & glove-box). ONE LIFE, GET IT!
Post #937005 9th Jan 2022 10:23pm
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Cubflyer



Member Since: 25 Sep 2021
Location: Suffolk
Posts: 278

United Kingdom 1994 Defender 90 300 Tdi SW Arles Blue
Hi Litch - It was you and your photo's in my original thread that pointed me to the X-Eng plugs.

Definately a nice plug but sadly needs a "O" ring retaining groove to use with ring IMO. I was going to machine one in but then decided against it and just returned them with my reason.

John 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994)
Post #937009 9th Jan 2022 10:31pm
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MichaelE



Member Since: 18 Jan 2020
Location: Crawley West Sussex
Posts: 155

England 
It looks to me like all it needs is a smaller diameter O ring as the one supplied is obviously far too big. Or a flat gasket type of thing. Not that you should have to mess around like this.
Post #937041 10th Jan 2022 10:54am
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Cubflyer



Member Since: 25 Sep 2021
Location: Suffolk
Posts: 278

United Kingdom 1994 Defender 90 300 Tdi SW Arles Blue
Hi Michael tried several smaller diameter rubber "O" rings and you still get some distortion of the ring (Not even putting any real pressure on).

If I'd have kept them I'd have used a fibre washer as you rightly mention too. 2010 Defender 90 300Tdi CW (White/1994)
2021 Defender 90 300Tdi SW (Blue/1994)
Post #937060 10th Jan 2022 1:02pm
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