naddy Posted March 16, 2008 Share Posted March 16, 2008 There are six screws that hold the fuel pump and it's gasket to the right hand end of the fuel tank (yr 2000 superlight). I've a leak here which I believe to be the the gasket & in the process of removing the pump, five of the screws have unfastened nicely... But, one has not - it just turns around so I cannot remove the pump assembly. I believe these are rivnuts? Any suggestions about how to procede, without bu**ering up the pump or the tank?? I'm unfamiliar with dealing with malfunctioning rivnuts, if indeed thats what they are... Currently the fuel tank is out of the car. Thanks in advance. Nick Link to comment Share on other sites More sharing options...
Area Representative Paul Richards Posted March 16, 2008 Area Representative Share Posted March 16, 2008 Hi Nick Sorry I can't offer any advice, but just to let you know I'm the custodian of the LADS rivnut gun should you need it. Edited to say :- Is this not the fuel guage sender on the right of the tank? Is the fuel pump not on the rear bulkhead Paul Richards Area Representative - L.A.D.S. (Lancashire and District Sevens) LADS Website Growing old is compulsory - Growing up is optional Edited by - Paul Richards on 16 Mar 2008 19:20:44 Link to comment Share on other sites More sharing options...
F355GTS Posted March 16, 2008 Share Posted March 16, 2008 Nick they are rivnuts, is the tank out of the Car? if not this maybe your best option as I suspect it's going to need some surgery and it would be much safer out of the Car and empty before you start making sparks! Having said that I'm not sure if you remove the filler neck etc if it would provide you with access to get some grips on pliers on the rivnut inside the tank? Mark Link to comment Share on other sites More sharing options...
naddy Posted March 16, 2008 Author Share Posted March 16, 2008 Thanks Paul, I'll know who to call if I need the rivnut gun then As I understand it, sender unit appears to be on top of the tank, pump to the offside and filter on the bulkhead. Mark, Yep tank is out of car and I'm hoping surgery of some sort will help. However I'm sot sure what sort of surgery to perform and sparks are a worry as I expect there'll be some dregs of fuel & vapour still inside. I assume the tank has baffles inside - its not easy to get the last of it out!! Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted March 16, 2008 Area Representative Share Posted March 16, 2008 As I understand it, sender unit appears to be on top of the tank, pump to the offside and filter on the bulkhead. Yes, thats right. Link to comment Share on other sites More sharing options...
Bricol Posted March 16, 2008 Share Posted March 16, 2008 Can't remember the bolt style, but hacksaw on the bolt head sounds the best way to carry on - either to cut the head off, or to cross cut it in all directions to weaken it enough to get it off. Otherwise a hand drill (not battery or main) to drill the head off. If you are determined to make sparks with an electric motor powered device, a full tank is a lot better than an empty one - less vapour! Full of water would be better than petrol of course, right to the top, ensuring no trapped air. Bri Link to comment Share on other sites More sharing options...
F355GTS Posted March 16, 2008 Share Posted March 16, 2008 I'd probalby go the hacksaw route too and do it outside btw when you come to refit it's possible the problem I that the pump flange is distorted due to being overtightened in the past, i was told by somebody that once bent it's pretty much impossible to get them to seal again even with a new gasket ☹️ Mark Link to comment Share on other sites More sharing options...
naddy Posted March 16, 2008 Author Share Posted March 16, 2008 Excellent, thanks everyone. I've googled rivnut, so I understand their anatomy now! Plan is to cut the fibre washer out with a stanley knife or similar, which will give me a nice gap to attack the screw with a hacksaw in order to decapitate it. Once the pump's out I imagine the offending rivnut can be pulled off (or it will have already fallen inside the tank). I assume CC can supply the appropriate rivnut, screw & washers etc. Two more questions: 1) I've looked in the archive & loctite is recommended for applying to the rivnut before it's fitted to stop it failing and spinning around (as mine has done) and also for applying to the screw threads. Which 'flavour' of loctite to use?? as it'll need to be fuel resistant. 2) Blue Hylomar. is it a good idea to smear this on both sides of the new gasket?? Link to comment Share on other sites More sharing options...
Bricol Posted March 16, 2008 Share Posted March 16, 2008 At the risk of you discovering some more loose rivnuts, how about taking the sender unit out and reaching with some molegrips and hanging on to the inside bit of the loose rivnut and re-attempting to undo the original bolt? Bri Link to comment Share on other sites More sharing options...
naddy Posted March 16, 2008 Author Share Posted March 16, 2008 bricol the other five have already unfastened nicely so thats not a worry - I'm considering replacing all of them though, assuming they can be removed easily once the pump is out. Of course if they can't be removed then theyre OK!! as for the sender, it's not leaking (which is rare, according to the archive ) and i'm loath to disturb it if I don't need to... Thanks for suggestions Anyone have opinions on loctite & blue hylomar?? nick Link to comment Share on other sites More sharing options...
Sheds Moderator Posted March 16, 2008 Share Posted March 16, 2008 You can check out the data sheet on the hylomar/loctite/other material you use to seal it. It's probably on line or certainly tech services at the manufacturer. Link to comment Share on other sites More sharing options...
Area Representative Paul Richards Posted March 16, 2008 Area Representative Share Posted March 16, 2008 I stand corrected. Not a part of the car I've had any experience of. By the way I have rivnuts as well as gun. I can replenish stocks at Stoneleigh. Paul Richards Area Representative - L.A.D.S. (Lancashire and District Sevens) LADS Website Growing old is compulsory - Growing up is optional Link to comment Share on other sites More sharing options...
naddy Posted March 18, 2008 Author Share Posted March 18, 2008 thanks Paul, I have rivnuts on the way, but I'll be in touch soon about the gun if that's okay... as soon as i can get some time in the garage!! Link to comment Share on other sites More sharing options...
alextangent Posted March 18, 2008 Share Posted March 18, 2008 Fitting rivnuts without a tool might help if you're stuck. Alex McDonald PASSED THE MOT!!! Link to comment Share on other sites More sharing options...
RussM Posted February 22, 2009 Share Posted February 22, 2009 Hi, Just got eaxctly the same problem..! Tank is out of the car and empty, one spinning rivnut on the pump, all others are out. Will attempt to grab with molegrips from the sender unit hole, otherwise its a hacksaw job. As I may as well check these are all OK whilst I'm on and the tank is out. Paul, do you still have the rivnut gun and are you going to MADS this Wednesday? If so please could I borrow it? Thanks Russ Monte Carlo Blue VVC Link to comment Share on other sites More sharing options...
Mick Day Posted February 22, 2009 Share Posted February 22, 2009 1st of all check you have blind rivnuts, see here. As mentioned blue hylomar will seal the pump/gasket/tank interface. Do not overtighten the fixings & do up gradually doing opposite fixings to spread the load. A drop of araldite under the rivnuts is a good idea to stop them rotating. I reckon when you get the bolt out the rivnut can be fixed, in situ, with some araldite. To get rid of petrol vapour fill with water, several times, drain & leave to dry in the sunshine...................... Link to comment Share on other sites More sharing options...
RussM Posted February 22, 2009 Share Posted February 22, 2009 Mick, Thanks for the tips, just checked and the five that are out are all blind. Cheers Russ Monte Carlo Blue VVC Link to comment Share on other sites More sharing options...
naddy Posted February 22, 2009 Author Share Posted February 22, 2009 Hi, just to update the thread on what I ended up doing.... Hacksawed the head off the screw - new screws and fibre washers are pence from CC so i took the opportunity to replace them all. Also got a new gasket as the original was ruined by overtightening by whoever built it in the first place Existing rivnut was perfectly servicable - no drilling needed - just an extra tweek with said rivnut gun to stop it spinning. Used small flat wooden blocks and those adjustable pliers (whose proper name escapes me) to persuade the mating surface of the tank 'flat' again. this is patient work! I also had to hammer the faceplate of the pump flat too - even it was distorted by the overtightening! Reassembled everything (as mentioned - *without overtightening*) and discovered blue hylomar is not petrol resistant as well as having to accept that my 'flattening' mustn't have been perfect Researched the alternatives: 1) A new tank because once distorted the old one would never be the same & with a new tank I would not need a gasket sealant. expensive! so i tried... 2) Discovered loctite 574 data sheethere which says it retains 75% of it's original strength when exposed to gasoline. Problem was I couldn't find it at a sensible price/quantity.... which led me to... 3) A company called Bondloc who have a remarkably similar product that uncannily carries a similar name B574 (which i discovered, following a phonecall to them, is no coincidence!!) here. so then.... 4) I got some here and it worked 😬 (along with even more patient 'flattening' of the rim of the aperture on the tank) Hope this helps Edited by - naddy on 22 Feb 2009 23:23:43 Edited by - naddy on 22 Feb 2009 23:29:59 Link to comment Share on other sites More sharing options...
dannylt Posted February 23, 2009 Share Posted February 23, 2009 Where did you see that blue hylomar is not petrol resistant? It's certainly supposed to be - http://www.hylomar.us/universal_blue.shtml Link to comment Share on other sites More sharing options...
I.Mupferit Posted February 23, 2009 Share Posted February 23, 2009 My fuel tank certainly never leaked again after using Blue Hylomar. Brent (aka Arfur Nayo) Lotus Elise Probably the best hair dryer in the world! 😬 Link to comment Share on other sites More sharing options...
Mick Day Posted February 23, 2009 Share Posted February 23, 2009 Naddy I think your problem was more to do with the surfaces not being flat than a deficiency with the Blue Hylomar. The previous owner must ave used massive torque to bend the flange on the pump! Hylomar is not a flange sealant, all it does is improve the seating/sealing of gaskets. For metal to metal sealing Hylomar is useless....... A flange sealer (such as you used)can be used for metal to metal (it replaces gaskets) joints. Well done in solving the problem. Link to comment Share on other sites More sharing options...
RussM Posted February 23, 2009 Share Posted February 23, 2009 Thanks for all the feedback chaps, I also managed to get the screw out and retightened said offending rivnut (with homemade thingy ), also reassembled with a new gasket from James Whitting as recommended on other threads, (relieved the screw holes a bit first) but not checked if its sealed or reinstalled in car yet . I like naddy also noticed non flat surfaces to tank and pump face, have flattened pump face but... Methinks will now dismantle and attempt further flattening first . I was a bit afraid to start applying force to the tank. I think this distortion is due to the original rubber gasket type having wedge shaped cutouts in which when tighetning the screws causes the gaps in the gasket to close. *thumbup* forall the info chaps Monte Carlo Blue VVC Edited to say... thanks for the encouragement and help Tim Edited by - RussM on 23 Feb 2009 12:06:28 Link to comment Share on other sites More sharing options...
naddy Posted February 23, 2009 Author Share Posted February 23, 2009 Yep, i accept all the comments about blue hylomar - it was my understanding originally that it should be up to the job and it's likely that on my first reassembly the surfaces were still not sufficiently flat - so my earlier post would be misleading! sorry. Hylomar is not a flange sealant, all it does is improve the seating/sealing of gaskets. For metal to metal sealing Hylomar is useless....... A flange sealer (such as you used)can be used for metal to metal (it replaces gaskets) joints. ....that makes sense And yes, the original builder had fastened them *very* tight - the flange on the pump was very noticably wavy! Link to comment Share on other sites More sharing options...
dannylt Posted February 24, 2009 Share Posted February 24, 2009 Good - I'm putting mine back together with fresh gaskets and hylomar tonight! Link to comment Share on other sites More sharing options...
naddy Posted May 15, 2009 Author Share Posted May 15, 2009 Further update: My repairs lasted just over a year ☹️ and I got a slight leak again from the fuel pump gasket.... (As mentioned elsewhere and by RussM 3 posts up )I spoke to James Whiting and got one of his fuel pump gaskets They are a waaay better design. They seal around the very outer edge of the fuel pump flange (where the stock gasket only has a loose flap). You can tighten the screws more because you trap the gasket between the fuel pump flange and the narrow flange of the rivnut (James advised against relieving the screw holes first) So you don't risk deforming the tank as you 'pull' the rivnut and the ally through that big daft square hole in the stock gasket. Also I gently eased the edge of the hole in the ally tank 'outwards' ever so slighty so it would seal against the inner hole of the new gasket. The whole assembly inspires much more confidence, so If you happen upon this thread & yours is leaking, speak to James Whiting . A gasket like this should be specced from new IMO I'd also add that while browsing Blatchat on this topic I found a link to an alternative source of fuel tank with a rigid boss that has threaded holes in it to fasten the pump & gasket too... Looks lovely 🥰 ....Thought it deserved a mention.... here Link to comment Share on other sites More sharing options...
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