TR6 Metering unit fuel leak

[Mike C]

Make sure you buy  a quality diaphragm suitable for unleaded. I bought & shipped out   a diaphragm  at great expense from one of the major British TR6 component suppliers about 7 years ago and it failed after an hour or so.

Spent the morning fitting it to the MU then reinstalled and re timed it. Started the engine and everything worked properly. Returned from lunch and restarted the engine and the fuel leak had returned. Very disappointing.

I then disassembled the MU and found the unleaded petrol  had caused the diaphragm to swell until it was a loose fit on the shaft.

I then had a Viton diaphragm fitted by a shop that could source them back in those days and all has been well ever since.

 

[ken foster]

On 8/20/2023 at 6:25 PM, John L said:

Im sure this will be a good part but worth checking with Chris, it is E10 compatible. https://www.chriswitor.com/proddetail.php?prod=519870V

John

I ordered said seal 519870V from Cris Witor costing £40.74 inc vat and postage.

The item received is 519870N... that says to me it is Nitrile not Viton. The invoice says 519870V Viton rubber.

Nitrile is cheaper and inferior to Viton.

Thoughts on this  please any one.

I have emailed Chris asking for an explanation. I didn't see a Nitrile option on his website.

Regards Ken.

[Mike C]

You need assurance it's a Viton diaphragm before you start installing it.

[Waldi]

Hi Ken,

I’m not sure if it is a sandwich construction (with more than one material), otherwise I would put it in a jar with ethanol containing petrol (E10)  and see how it comes out after say 2 days.

Off course await suppliers response first.

Waldi

[ken foster]

Hi, thought I would update incase anybody is interested.

Chris Witer replied to email with.... these seals come from KMI, and his reply from KMI was; The N stands for "new" they are Viton seals.

I had emailed KMI and their reply was... The N stands for new....we only use Viton.

I haven't asked... new as opposed to used or... new as in new stock?  

Still confused as to why there is no V suffix on the label.

I could soak the diaphragm in E10 but I'm not about go to the petrol station to get some.

Chris Witor and KMI have excellent reputations so I'll probably just fit it.

Ken

 

[Peter Cobbold]

2 hours ago, ken foster said:

Hi, thought I would update incase anybody is interested.

Chris Witer replied to email with.... these seals come from KMI, and his reply from KMI was; The N stands for "new" they are Viton seals.

I had emailed KMI and their reply was... The N stands for new....we only use Viton.

I haven't asked... new as opposed to used or... new as in new stock?  

Still confused as to why there is no V suffix on the label.

I could soak the diaphragm in E10 but I'm not about go to the petrol station to get some.

Chris Witor and KMI have excellent reputations so I'll probably just fit it.

Ken

 

Its not the ethanol that kills that seal it is the aldehydes from its oxidation that does the damage, slowly. So soaking in E10 tells us nothing useful. Peter

[roy53]

2 hours ago, ken foster said:

Hi, thought I would update incase anybody is interested.

Chris Witer replied to email with.... these seals come from KMI, and his reply from KMI was; The N stands for "new" they are Viton seals.

I had emailed KMI and their reply was... The N stands for new....we only use Viton.

I haven't asked... new as opposed to used or... new as in new stock?  

Still confused as to why there is no V suffix on the label.

I could soak the diaphragm in E10 but I'm not about go to the petrol station to get some.

Chris Witor and KMI have excellent reputations so I'll probably just fit it.

Ken

 

with those replies from reputable companies you should be fine

Roy

[ken foster]

Hi, I have spent 3 hours in the heat fitting the new diaphragm, it started easily and seemed to be running smoother than before.

The old diaphragm was perished and split.

Job done you think yes?  Ah Ah not a chance, petrol pouring out from the body joint area as before. (or near to)

I took the return pipe off from the metering unit and it was dry, so no fuel coming out of there,therefor the return pipe can't be  blocked.

I was very careful to make sure the diaphragm was sitting in is groove.(not easy, it's a bit like seeing if the fridge light goes out when you close the door). I was surprised I had to push out the centre of the seal. Imagine the price if it included the metal centre.

Have I made an error assembling it? I surely can't have deteriorated as I was assured it is made from Viton.

If anybody has experienced this and can tell me what the problem is please tell me.

I am not supposed to drive this car, as I was checking my work and looking for any thing left in the engine bay I noticed a core plug leaking from a pin hole, all the core plugs were new when I rebuilt the engine some 33 years ago... hope the others are ok. The ones hard to access.

I digress. back to metering unit.

Any help gratefully received.

Ken.