Colin Lindsay Posted September 12, 2018 Report Share Posted September 12, 2018 I've traced a coolant loss on the TR7 engine to the thermostat housing; it was weeping out around the thermostat cover. On checking I've found no threads at all on one side of the housing, with the other not great either, so nothing to hold the bolts in bar a fairly tenuous grip. I've bought two new setscrews which are 5/15 UNC, one 1" and one 1.5", which if anything grip worse than the originals and one is even longer by quite an amount. The thermostat housing on the 2.0 litre engine is an integral part of the inlet manifold. SO: bar getting an entire inlet manifold in better condition, can I helicoil this? I take it the fact that it's alloy won't make any difference, or is there a particular helicoil I should use? Link to comment Share on other sites More sharing options...
Clive Posted September 12, 2018 Report Share Posted September 12, 2018 Helicoil away! Ideal in ali. I have just helicoiled my TR7 head for the exhaust manifold bolts. But being a philistine I used metric (I don't have any imperial helicoils, only metric were available locally when I needed them in an emergency. And being that they are often needed in an emergency, I have never had the foresight to order up imperial sizes. 1 Link to comment Share on other sites More sharing options...
poppyman Posted September 12, 2018 Report Share Posted September 12, 2018 https://www.ebay.co.uk/itm/THREAD-TAP-REPAIR-CUTTER-KIT-M8-x-1-25-x-8mm-Helicoil-Compatible-NO-CASE/201454190107?hash=item2ee79afe1b:g:EdcAAOSwDVtaUzmh These are brilliant for the money and work really well. Tony. 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted September 13, 2018 Author Report Share Posted September 13, 2018 Thanks Clive and Tony; I've never helicoiled in my life so it'll be a new experience. What length do the inserts come in ie do you use two for longer screws? One concern I have is getting the larger hole drilled at the right angle; I don't want to take the manifold off if I can help it so it will have to be drilled on the car. This is obviously the reason why the old screws were so hard to remove; you can see the remains of the Araldite on the threads... Link to comment Share on other sites More sharing options...
Mad4classics Posted September 13, 2018 Report Share Posted September 13, 2018 Helicoil in alloy material is stronger than the original. they come in lengths that are a multiple of the diameter eg. 0.5D, 1.0D, 2.0D etc. The key is getting the insert in straight - seen Mini gearbox drain plugs helicoil (which are 5/8 UNC) done on the wonk, and it always leaks a little like that! Having been faced with a mixture of the correct unified fasteners, unified fasteners with metric heads!! (why?); and metric fittings - I'm always keen to replace like for like and keep a selection of thread repair kits to get me out of trouble. If you're going to buy something in, UNC and UNF kits are not expensive. https://www.rallydesign.co.uk/product_info.php?products_id=22020 If you're really faced with a BIG repair the EZ LOK Inserts are available here; but they're more expensive:- Carbon Steel: https://www.amafasteners.co.uk/product/319-5 Stainless: https://www.amafasteners.co.uk/product/303-5 Link to comment Share on other sites More sharing options...
poppyman Posted September 13, 2018 Report Share Posted September 13, 2018 Hi Colin, the best thing to do is to practice on a scrap piece of metal first, just get get the hang and feel of of it. Dont be afraid of it... It is really easy. I find helpfull to use a small square if you have one, to keep it straight. Tony. Link to comment Share on other sites More sharing options...
Clive Posted September 13, 2018 Report Share Posted September 13, 2018 My tip of the day is to drill the hole dead carefully, not hard, just take care and don't drill down too fast, the ali can grab the drill and snap it. Then a bit of WD40 on the tap, and turn it half a turn or so in until it bites, and back off, keep doing that to clear the swarf. Then ideally a blow gun to clear it out once done. However, I then run the tap up and down the thread a couple more tomes. I didn't used to, and found the inserts were too tight. Then wind the helicoil in,and break the tang off. I used 1D length on the manifold (ie 10mm bolt, the coil was 10mm long) and they hold very well. Many are 1.5d which may suit it better? and I guess shorter/longer are available. But don't worry, just one, get is a little below the surface and and it will be fine. And the nlet is a PAIN. Chap helping me at the weekend popped teh gasket on back to front, assembled up, then noticed leak from a drilling that is blanked by the gasket. And then there is the bolt at the front, difficult to get to so used a 1/4" wobble bar, luckily it came out OK. And the bypass tube.... Anyway, if you can avoid taking it off you will have a much happier day. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted September 13, 2018 Author Report Share Posted September 13, 2018 Thanks for all your help and advice, as usual I'm planning ahead and the reality, when I try it will probably be simple enough. This is my version of measure twice, cut once! Biggest concern is keeping the drill straight for the initial drill-out. I've ordered a Helicoil-style kit - I need the tools that come with it, anyway - and once I have the full kit any other inserts I need will be cheaper. I just don't want to banjax the entire fitting then have to replace a full manifold for the sake of two bolts. I suspect the end of the original bolt is broken off in the hole, but can't see it when I shine a light down; however the new bolt is longer than the original. I think I'll take Clive's advice and use a shorter length; in the stainless inserts it should grip better than the alloy. 1 Link to comment Share on other sites More sharing options...
Clive Posted September 13, 2018 Report Share Posted September 13, 2018 Don't worry about it. If you can drill a hole you can drill a hole. It will sort of self centre a bit anyway, if I can manage it, you will. Are you sure the bolt is broken? apoke with a bit of stiffwire should give you an idea if anything is left in there. The tap is a bit tapered, so needs to go much further in than he insert. If there is a bit of bolt stopping things, that may be an issue. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted September 13, 2018 Author Report Share Posted September 13, 2018 Not sure, but the end of it is a bit misshapen and it's shorter than the recommended 1.5" replacement - see the second bolt from left in my photo. I can't get a light, and my line of sight, down the hole at the same time. It's worth another exploration... Link to comment Share on other sites More sharing options...
Clive Posted September 13, 2018 Report Share Posted September 13, 2018 Just measure how deep it goes. Hopefully enough to get the tap to get a proper thread and a helicoil in there. And you only need the bolt/setscrew to go to the end of the helicoil.Any longer is a waste! Link to comment Share on other sites More sharing options...
Anglefire Posted September 13, 2018 Report Share Posted September 13, 2018 I always thought that was more than a handful? 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted September 19, 2018 Author Report Share Posted September 19, 2018 IIRC it was a mouthful, how times change. How did we get on to discussing chocolate anyway? I've had to take the entire manifold assembly out of the car to put it on a pillar drill, just to get things perfectly straight, but everyone I've spoken to including those sterling gentlemen at Robsport have confirmed that helicoils are stronger than the original threads and will last a lifetime once inserted. In any case half of the engine is now removed, so if I get as far as replacing the thermostat housing I'll be on the home stretch. 1 Link to comment Share on other sites More sharing options...
GT6M Posted September 23, 2018 Report Share Posted September 23, 2018 can always go bigger, even go metric coarse. OR, get some aally typerodsthat melt wid a blow lamp, they melt befoer the parent metal, hard an as strong as the original stuff it really is as simple as this couple of clips shows thees ar,t rods, ive done loadsa stuff wid em, they v v good. https://www.ebay.co.uk/sch/i.html?_odkw=alloy+brazing+rods&_osacat=0&_from=R40&_trksid=m570.l1313&_nkw=+low+temp+alloy++welding+rods&_sacat=0 Or, Ye need some of thee,s bolts, very handy things they are,!!! 2 Link to comment Share on other sites More sharing options...
Ian Faulds Posted September 23, 2018 Report Share Posted September 23, 2018 gt6m the rods look great iam gonna get some, but can you post the link for the bolts I cant find them??? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted September 23, 2018 Author Report Share Posted September 23, 2018 1 hour ago, GT6M said: can always go bigger, even go metric coarse. Yes, went to the father-in-law at his engineering company to see if he'll drill the holes for the helicoils, (I needed a jig or clamp as I can't get it held securely enough at the correct angle for the drill) and he simply asked why I hadn't used bigger screws... I suppose the real reason is that I've never had to use helicoils so want to try them. I love some of those bolts.... Link to comment Share on other sites More sharing options...
dave.vitesse Posted September 23, 2018 Report Share Posted September 23, 2018 To overcome the problem In the past I have seen a slightly larger metric size taped out and then a stud screwed and locktite in place. I guess it all come down to how much metal is left. Dave Link to comment Share on other sites More sharing options...
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