graniteman Posted July 3, 2013 Report Share Posted July 3, 2013 Hi everyone Tr has been running really well until sunday when i could smell petrol in the car. I looked for a leak and can see a drip from the metering unit near the two bottom screws that secures the black plastic Lucas cover. Can anyone tell me if this is a common thing being new to all this. Is there a Gasket here that may have failed ? any advice would be a real help. Thanks Shaun Quote Link to post Share on other sites
john.r.davies Posted July 4, 2013 Report Share Posted July 4, 2013 Shaun, Is this the recatangular plastic cover? There should be no fuel behind that. There is a diaphragm between the airfilled cam chamber that it covers, and the barrel shaped part to the left. The diaphragm can rupture. It is supposed to confine the vacuum that controls the MU, as well as keeping fuel out, so I fear your MU is probably not working very well anyway. If you have recently aquired the car, and do not know for sure that the MU has been renovated, it probably has the OE seals which are vulnerable to modern lead-free petrol. Consider a reconditioned unit. The usual suppliers are Malcolm at Prestige (http://www.prestigeinjection.net/) or K.Raven Smith, who happens to have one on eBay right now: http://www.ebay.co.uk/itm/TR5-6-LUCAS-TRIUMPH-METERING-UNIT-AND-2-5-PI-/141009483837#ht_131wt_1170 John Quote Link to post Share on other sites
k_raven_smith Posted July 4, 2013 Report Share Posted July 4, 2013 Give me a call after 3pm.cheers neil Quote Link to post Share on other sites
Jonathan_bell Posted July 5, 2013 Report Share Posted July 5, 2013 Hi there, I have just had the same problem with mine Neil. Quote Link to post Share on other sites
k_raven_smith Posted July 5, 2013 Report Share Posted July 5, 2013 Hi you can call me on 07977001571.cheers neil Quote Link to post Share on other sites
Jonathan_bell Posted July 11, 2013 Report Share Posted July 11, 2013 Great service, problem with my metering unit solved in less than 4 working days, including return post. Thanks Neil!!! Quote Link to post Share on other sites
john.r.davies Posted July 11, 2013 Report Share Posted July 11, 2013 KRS, Please - what was the problem? Without knowing, this thread loses all purpose. And I don't know if I was right or not.! John Quote Link to post Share on other sites
Bob59 Posted September 4, 2021 Report Share Posted September 4, 2021 Evening All, was there an answer to this as I too have got petrol leaking from behind the Lucas cover. I had not used the car for a while due to work commitments, too it out and filled it up and now have the leak. I have clamped the fuel intake and capped off the return pipe to stop the tank emptying onto the garage floor but now need to work out the next step. Thanks in advance Bob Quote Link to post Share on other sites
c.hydes Posted September 4, 2021 Report Share Posted September 4, 2021 + 1, likewise. I also had the same problem last month, big leak from RHS below the LUCAS black plastic cover plate, had to be transported home by AA. I removed the MU and had it refurbished by Neil Ferguson (K.R.S), brilliant service at a very reasonable cost. Refitted with no problems, but then found inlet main hose was also faulty and leaked fuel. This was replaced with new from TR Trader and now all seem good. I would say however, that these two components have lasted for 20 years without issues, so cant really complain !! Colin. Quote Link to post Share on other sites
Mike C Posted September 4, 2021 Report Share Posted September 4, 2021 I'd suggest that the elastomers in your fuelling diaphragm and hoses are being attacked by the fuel. Have your local fuel suppliers changed the composition of the petrol lately? I had similar problems about 5 years ago and had to switch to Viton elastomers/Gates Barricade hoses Quote Link to post Share on other sites
Mk2 Chopper Posted September 5, 2021 Report Share Posted September 5, 2021 11 hours ago, Bob59 said: Evening All, was there an answer to this as I too have got petrol leaking from behind the Lucas cover. I had not used the car for a while due to work commitments, too it out and filled it up and now have the leak. I have clamped the fuel intake and capped off the return pipe to stop the tank emptying onto the garage floor but now need to work out the next step. Thanks in advance Bob The diaphragm between the metering unit (the rounded part with the injector pipes and the control unit (the square part with the black lucas cover) is allowing fuel to leak past it. Needs changing, can be done DIY but if unsure send the unit off for refurbishment. It can also happen if the return line is blocked and displaces the same diaphragm, use an air line to blow through to check. Gareth Quote Link to post Share on other sites
ken foster Posted August 19, 2023 Report Share Posted August 19, 2023 On 9/5/2021 at 5:59 AM, Mk2 Chopper said: The diaphragm between the metering unit (the rounded part with the injector pipes and the control unit (the square part with the black lucas cover) is allowing fuel to leak past it. Needs changing, can be done DIY but if unsure send the unit off for refurbishment. It can also happen if the return line is blocked and displaces the same diaphragm, use an air line to blow through to check. Gareth I assume you mean line from the PRV to the top of the tank? Mine has a cooling coil in it. My diaphragm was changed a few years back, before ethanol certainly, I'll fit a a new one to be sure if the return line is the cause of the same problem the OP's had. Ken Quote Link to post Share on other sites
Peter Cobbold Posted August 19, 2023 Report Share Posted August 19, 2023 During long periods of standing the fuel trapped in the MU oxidises to make aldehydes that cross-link polymers in the diaphragm, which splits . Good idea to replace original rubber with ethanol-resistant nitrile. Quote Link to post Share on other sites
ken foster Posted August 19, 2023 Report Share Posted August 19, 2023 41 minutes ago, Peter Cobbold said: During long periods of standing the fuel trapped in the MU oxidises to make aldehydes that cross-link polymers in the diaphragm, which splits . Good idea to replace original rubber with ethanol-resistant nitrile. Thank you Peter, I will replace it. My pump is also being effected by oxidised modern fuel. I was hoping somebody would confirm the referenced return line is the one from PRV to the tank. It's 33 years since I rebuilt my fuel system/metering unit, getting it calibrated by Ken Mills. I became an expert then but, since all that knowledge has been moved to make room in my brain (which is slowly decreasing in capacity) for other knowledge. Quote Link to post Share on other sites
Peter Cobbold Posted August 19, 2023 Report Share Posted August 19, 2023 2 hours ago, ken foster said: Thank you Peter, I will replace it. My pump is also being effected by oxidised modern fuel. I was hoping somebody would confirm the referenced return line is the one from PRV to the tank. It's 33 years since I rebuilt my fuel system/metering unit, getting it calibrated by Ken Mills. I became an expert then but, since all that knowledge has been moved to make room in my brain (which is slowly decreasing in capacity) for other knowledge. Hi Ken, if the return from the MU is impaired then the pressure build up behind the diaphrgam would indeed hasten its failure. But splitting of the diaphram horizontally is I gathered at an IWE talk rather common. Brain fade is a pet topic of mine............see the D3 thread from a few years back! Peter Quote Link to post Share on other sites
ken foster Posted August 19, 2023 Report Share Posted August 19, 2023 3 hours ago, ken foster said: I assume you mean line from the PRV to the top of the tank? Mine has a cooling coil in it. My diaphragm was changed a few years back, before ethanol certainly, I'll fit a a new one to be sure if the return line is the cause of the same problem the OP's had. Ken I'm embarrassed to say having looked twice at the metering unit.... I couldn't see the return line, hence my question about the return line in the boot.Oh I am such a Billy Sarsted (no relation to Peter Sarsted) It's staring me in the face, well it is with my glasses on. "ad a brain "ol man as my Cornish wife would say. I will give it a blow through before I fit a new diaphragm, maybe I can calibrate the choke so it works a bit better same time. ken. Quote Link to post Share on other sites
Mk2 Chopper Posted August 19, 2023 Report Share Posted August 19, 2023 4 hours ago, ken foster said: I assume you mean line from the PRV to the top of the tank? Mine has a cooling coil in it. My diaphragm was changed a few years back, before ethanol certainly, I'll fit a a new one to be sure if the return line is the cause of the same problem the OP's had. Ken Hi Ken, Not sure if you've found the information on the return line, but it's the small diameter pipe from the MU, either a push fit or screwed in (later MU) and it's in the area where the MU mounts to the distributor pedestal. Gareth Quote Link to post Share on other sites
ken foster Posted August 19, 2023 Report Share Posted August 19, 2023 2 hours ago, Mk2 Chopper said: Hi Ken, Not sure if you've found the information on the return line, but it's the small diameter pipe from the MU, either a push fit or screwed in (later MU) and it's in the area where the MU mounts to the distributor pedestal. Gareth I did once I'd got my head straight thanks. Thanks Peter for your input too. Ken. Quote Link to post Share on other sites
ken foster Posted August 20, 2023 Report Share Posted August 20, 2023 23 hours ago, Peter Cobbold said: During long periods of standing the fuel trapped in the MU oxidises to make aldehydes that cross-link polymers in the diaphragm, which splits . Good idea to replace original rubber with ethanol-resistant nitrile. Just looking online for a diaphragm, big difference on prices between suppliers. Trenterprises sell for 20 squid inc vat. any thoughts on them? I’m a bit out of touch with suppliers. Are there any other seals/gaskets needed for the job? cheers ken Quote Link to post Share on other sites
Peter Cobbold Posted August 20, 2023 Report Share Posted August 20, 2023 11 minutes ago, ken foster said: Just looking online for a diaphragm, big difference on prices between suppliers. Trenterprises sell for 20 squid inc vat. any thoughts on them? I’m a bit out of touch with suppliers. Are there any other seals/gaskets needed for the job? cheers ken Dunno Ken, I replaced PI with an SU 30 years ago. After 250k miles on the PI with no MU failures ( but daily driver and no ethanol likely hleped). Only fialure was the steel pipe over the drive shaft that pinholed from rust. Peter Quote Link to post Share on other sites
ken foster Posted August 20, 2023 Report Share Posted August 20, 2023 23 minutes ago, Peter Cobbold said: Dunno Ken, I replaced PI with an SU 30 years ago. After 250k miles on the PI with no MU failures ( but daily driver and no ethanol likely hleped). Only fialure was the steel pipe over the drive shaft that pinholed from rust. Peter It looks brand new. Put it back together and will try now I’ve blown through the return line. if it still leaks it might be the drive shaft seal. ken Quote Link to post Share on other sites
ken foster Posted August 20, 2023 Report Share Posted August 20, 2023 34 minutes ago, ken foster said: It looks brand new. Put it back together and will try now I’ve blown through the return line. if it still leaks it might be the drive shaft seal. ken There’s a fuel diaphragm and a vacuum diaphragm. It’s the fuel one that must be at fault. I only looked at the vacuum one. it’s slowly coming back to me now. ken. Quote Link to post Share on other sites
Peter Cobbold Posted August 20, 2023 Report Share Posted August 20, 2023 (edited) 19 minutes ago, ken foster said: There’s a fuel diaphragm and a vacuum diaphragm. It’s the fuel one that must be at fault. I only looked at the vacuum one. it’s slowly coming back to me now. ken. VitesseSteve's site has archived PI manuals: http://vitessesteve.co.uk/LucasStuff/Lucas_Petrol_Injection_Manuals and this is the diaphragm that leaks fuel: https://prnt.sc/HsUpY5oFdS0Z Edited August 20, 2023 by Peter Cobbold Quote Link to post Share on other sites
John L Posted August 20, 2023 Report Share Posted August 20, 2023 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 Quote Link to post Share on other sites
ken foster Posted August 20, 2023 Report Share Posted August 20, 2023 (edited) 39 minutes ago, 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 Thank you, look good at £36 inc vat. just looked at tr trader which I believe is prestige and Neil Revingtons about £47 and £61ish dunno about postage for any. How do they compare on quality I wonder. ken Edited August 20, 2023 by ken foster Quote Link to post Share on other sites
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