Minesweeper Posted May 3, 2012 Share Posted May 3, 2012 To ovoid damage to thin liners we used to, in my motor engineering days, use a liner with an undersize bore; press it in as normal and then bore to the finished size, this then removed any chance of the liner splitting whilst it was being pressed in.Some liners were pegged and you could do this by using a tight fitting (oversize thread) screwed peg or pegs through the side of the cylinder and through the liner, low down in the area where there is no water jacket. This should, of course, be done before boring the liner to size. John Very pleased to see your first posting John! Lots of members of this Forum can and would like to benefit from your knowledge and experience! Tony Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted May 3, 2012 Share Posted May 3, 2012 If you look at the January 2012 pictures in this link http://www.bluebell-railway.co.uk/bluebell/locos/atlantic/latest.html you will see stepped liners being used in a new-build steam locomotive. They have followed the method used on BR Standard locomotives, and have also fabricated (rather than cast) the cylinder block. Some would say thats cheating! A really fascinating website - thank you! Tony Quote Link to comment Share on other sites More sharing options...
Barney Posted May 3, 2012 Share Posted May 3, 2012 (edited) Many thanks for your kind words Tony. I would be very wary of fitting a stepped liner which is a loose fit above the step or a Loctited liner to these Thornycroft pots; Loctite requires a working clearance of about 2 thou. Normally on engines where a separate (bolt down) cylinder head is used both wet and loose dry liners are fitted so that the tops of the liners protrude above the block face; around 3 to 5 thou in the case of loose dry liners. The head gasket then covers the top edge of the liner so protecting it from the heat of combustion. When fitted in a pot the top of the liner is not protected and any gap, however small, between liner and block will lead to localised burning of the liner's top edge. John Edited May 3, 2012 by Barney Quote Link to comment Share on other sites More sharing options...
Old Bill Posted May 3, 2012 Share Posted May 3, 2012 That is only one advantage, if you make several steps of the same length you only have to press it in for the length of one step which eliminates the risk of getting stuk halfway if you have to press it in over the whole length. Yes I am thinking on a shim between case and block, a sort of piston ring would be a possibility but with the piston dropping below and the liner so thin that does not seem the way to go. Of course! Now I've got it! The final pressing force will still be the same though and I am frightened of crushing the water jacket. I am beginning to come to the conclusion that what I want to do is to use a liner with a clearance fit and then secure it with Loctite 620, the high temperature grade. This will avoid applying any serious pressing forces and, with a 24 hour cure, will give me the time to fit it without the risk of it sticking that I would have if I used liquid nitrogen. 620 grade is good for over 200° so although the top couple of inches would get cooked, that would still leave 8" of liner protected by the water jacket or piston where the Loctite would hang onto it. I could also drill and tap axially in the joint between the liner and block and fit some grub screws to prevent movement. Does anyone have experience of Loctite in this situation? Steve Quote Link to comment Share on other sites More sharing options...
Chrisg Posted May 3, 2012 Share Posted May 3, 2012 Speak to loctite technical They are very helpful Of course! Now I've got it! The final pressing force will still be the same though and I am frightened of crushing the water jacket. I am beginning to come to the conclusion that what I want to do is to use a liner with a clearance fit and then secure it with Loctite 620, the high temperature grade. This will avoid applying any serious pressing forces and, with a 24 hour cure, will give me the time to fit it without the risk of it sticking that I would have if I used liquid nitrogen. 620 grade is good for over 200° so although the top couple of inches would get cooked, that would still leave 8" of liner protected by the water jacket or piston where the Loctite would hang onto it. I could also drill and tap axially in the joint between the liner and block and fit some grub screws to prevent movement. Does anyone have experience of Loctite in this situation? Steve Quote Link to comment Share on other sites More sharing options...
mattinker Posted May 3, 2012 Share Posted May 3, 2012 Just out of curiosity, sometimes people who are very organised and focused succum to the simplest errors. I know the piston rings look very neat all lined up, but you wouldn't ever assemble an engine with the gaps all inline now would you.!!! I remain in awe of your acheivements. You are an inspiration to the rest of us impatient souls. I agree with you entirely, but, my instructor, whilst training as a motor fitter said "there's nothing to stop piston rings turning" he did add that he had no proof either way. Regards, Matthew Quote Link to comment Share on other sites More sharing options...
alixcompo Posted May 4, 2012 Share Posted May 4, 2012 I guess the chance of the gaps alighning by chance are very slim. suffice to say that on 2-stroke engines the rings locate on pegs Quote Link to comment Share on other sites More sharing options...
Barney Posted May 4, 2012 Share Posted May 4, 2012 (edited) Steve, I post the following in the hope that it may be useful to you in your choice of a liner retention method; if you already have this or updated info please accept my apologies. If my memory serves me correctly the mean burn temperature of fuel in an IC engine cylinder is around 700 degsC. Due to the constant exhausting of the hot gasses, the induction of the cold fuel mixture and the heat dissipated through the cylinder block into the coolant the cylinder wall surface temperature is held fairly constant at around 350 degsC. I surmise that a thin wall liner would be at this temperature throughout most of its thickness and probably for around half its length. I don’t remember there being any different figures for petrol or diesel engines so presume the above figures relate to both engines. However, today’s unleaded petrol is certainly more volatile than the old pool petrol that was available probably 60 or 70 years ago when these readings were taken so the figures may be slightly altered now. Also, if you speak to the Loctite people it may be worth asking if the Loctite layer, being basically a plastic compound, will impede the heat transfer between the liner and the block. John Edited May 4, 2012 by Barney Quote Link to comment Share on other sites More sharing options...
Old Bill Posted May 5, 2012 Share Posted May 5, 2012 Thanks John. I hadn't realised that the temperature was so high. It is always good to have the voice of experience. I am in Devon at the moment and have spent the day eyeing up the job. One piece of advice that I have had is not to do anything irrecoverable and I plan to follow this, at least to start with. Two bores will need lining and it is our intention to do this ourselves. Whilst the bores are pitted there is enough good surface to guide the liner so I shall gently hone them out to get them clean, straight and smooth and have a rebate machined at the bottom. I will have a pair of liners made to a sliding fit and with a flange to sit in the rebate which will prevent them from sliding up the bore. They will be secured with high temperature Loctite 620. As final insurance we will make a 1/16" thick shim to sit between the block and the crank case. This will have holes only slightly larger than the bore in order to trap the liners so that in the event that the Loctite lets go, they cannot move. We will lose about 1/4" in the bore but I think this will be insignificant bearing in mind that the lorry will never again run loaded. The order of work will be to finish removing the poorer studs (Monday's project) and then get the cracks stitched. I will take the blocks back to Leicestershire to get them appraised after which I will start honing. Photos to follow in due course! Steve (In trepidation!) Quote Link to comment Share on other sites More sharing options...
mattinker Posted May 6, 2012 Share Posted May 6, 2012 Hi, I like the advice about not doing anything irreversible, I hadn't thought of that, I suppose it's because at worst I can always find "another" new or second-hand. I'm a real fan of metal stiching, having seen it use on a Leyland 410 engine burnt between two cylinders. Their technician cut out the offending area, (we'd already removed the liners) he then cut out a piece of cast and fitted it into the hole. He the "stitched" it in place it was machined on-site, at the same time as the liners were bored to size. There's just one, thing I find, that there is so much interesting stuff I have to go back and re-read parts to refresh my memory! I understand the trepidation, but there will always be a solution! No Brighton for me this year can't make it over! Regards, Matthew Quote Link to comment Share on other sites More sharing options...
Barney Posted May 6, 2012 Share Posted May 6, 2012 Steve, Many years ago I worked on a couple of Coventry Climax 4 cylinder engines. The engines were around 1200cc and they had aluminium blocks and dry liners. The liners were a hand push fit in the aluminium bores and were retained at the top by a flange which was trapped between the block and the cylinder head and gasket, in a similar way to that which you are proposing. No other retaining method was used so I presume that the expansion of the liner was sufficient to hold it firm and enable the heat to transfer into the block. John Quote Link to comment Share on other sites More sharing options...
Sean N Posted May 6, 2012 Share Posted May 6, 2012 When you think about it, very little force should be needed to retain the liner in place. Hopefully the friction between piston / ring assembly and liner should be minimal otherwise you would have considerable wear problems and hot spotting / picking up. Wet liners are often only retained by the pressure of the head on the flange at the top and they don't move around (with some notorious exceptions!) Quote Link to comment Share on other sites More sharing options...
Cel Posted May 6, 2012 Share Posted May 6, 2012 If a hand push fit of a cast liner in a alu block does the job with the expansion of aluminium being more than double of cast iron, then a cast liner in a cast block should be no problem at all. A tight press fit would only be necessary if there were no possibility to put in a shim. Not sure if I would use loctite, if the liner has to come out for any reason that would be nearly impossible without damaging it. I am also not sure about the heat transfer rate of the loctite but if the liner expands more than the surrounding block it could cause serious damage (this is only a speculation, if have no experience in this matter). Marcel Quote Link to comment Share on other sites More sharing options...
Asciidv Posted May 7, 2012 Share Posted May 7, 2012 There is a very easy and reliable method of removing pressed in liners and quite possibly 'glued' in liners too. You simply run beads of weld (perhaps 4 or 5 of them) down the length of the liner using a stick welder. When the weld cools it contracts the liner too and then it is loose! I needed to re-liner a Perkins V8 in-situ in a fire engine chassis and was taught this trick by the local Brigade workshops. Barry. Quote Link to comment Share on other sites More sharing options...
mattinker Posted May 7, 2012 Share Posted May 7, 2012 (edited) If a hand push fit of a cast liner in a alu block does the job with the expansion of aluminium being more than double of cast iron, then a cast liner in a cast block should be no problem at all. A tight press fit would only be necessary if there were no possibility to put in a shim. Not sure if I would use loctite, if the liner has to come out for any reason that would be nearly impossible without damaging it. I am also not sure about the heat transfer rate of the loctite but if the liner expands more than the surrounding block it could cause serious damage (this is only a speculation, if have no experience in this matter). Marcel This post is virtually the same as Barry's, I tried to delete it but failed! Dry liners are usually pressed into cast iron blocks, they are then bored in place to bring them up to the same diameter as the the other bores and to compensate for the reduction in diameter due to the interference fit. The shade tree mechanic method for removing dry liners (they can never be reused under any circumstances replacement is the only reason for pulling them) is to run a couple of beads of weld down them! Regards, Matthew Edited May 7, 2012 by mattinker I read Barry's post too late! Quote Link to comment Share on other sites More sharing options...
Great War truck Posted May 7, 2012 Author Share Posted May 7, 2012 Steve joined Tony in Devon for the weekend – the main objective of Steve’s visit was to join Tony so that they could drive up to Brighton together on the Sunday to see the Historic Commercial Vehicles Society’s London to Brighton Entrants arrive at the Finish. This was the same Run that we did a year ago with the Dennis. Tony had still been removing the many wasted and corroded studs from the Cylinder Blocks that will have to be replaced, these last few days – and as we wanted to get them all out before Steve took the Blocks back to Leicester with him – Steve joined in! This series of four pictures show the last one to come out – a 1/2” BSW stud for the Exhaust Manifold. The threads had really rusted hard to the Block and these last ones seem to have proved doubly difficult to remove. They were drilled out as much as possible but the final “shell” of the stud was still very firmly attached to the female thread in the Block and had to finally be removed with the help of a carborundum on the Dremel and a hammer and chisel. As the thread in the block gradually emerged, the final bits had to be teased out with taps. The few studs now left in the two Blocks are all deemed to be sound and will live to fight another day. And with all the various parts of the project going on at present – there is another to add to the list – and that is to make even more new studs! We are now coming around to what we think is our way forward with the cylinder blocks and dealing with the two cracks. Our present thoughts are to get the cracks in the two blocks metal-stitched together – after first testing them for further cracks and ensuring that we are just dealing with only the two. After that has been completed successfully, Steve will hone out the two troublesome cylinders so that they are able to take liners which will be fixed in with a high temperature Loctite. The cylinders are at present 4 1/2” bore – the walls of the liners will be 1/8” so that will effectively reduce the bore to 4 1/4”. We think that really this will not effect the performance and power greatly – especially bearing in mind that it is unlikely that the lorry will ever be fully laden again. The liners will be of a top-hat shape so that the bottoms of the two cylinder bores will have to be bored out by perhaps another 3/16” on the diameter and perhaps by an 1/8” on depth – to match the top-hat flanges – thus trapping the liners from moving up in the bores. The liners will also be trapped against the crank case so that they cannot move downward. So, Steve has returned to Leicester today and plans now to make an appointment to call on the Metal Stitching Specialists to get their thoughts on our proposals. This visit is not likely to take place until the week commencing 14th May. Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted May 8, 2012 Share Posted May 8, 2012 Good progress. Special request here, if it can be done without any on costs, of course. Please get the metal stitching people to photograph the visible cracks, and then the same things when developed with dye penetrant. I'm sure there will be a noticeable difference that is worth the work to illustrate. I had a GMC 270 with a visible 6" crack in the water jacket, but when penetrant tested it ran right back down the block to the bell housing. Stitching saved it and that engine is still running well, last I heard, but I often wishes I'd photographed before / during / after to show the differences. I'm sure those castings will save but will probably take a little more work than is immediately visible, and such images will show you why the bill was justified. Apparently you can do this process yourself but I think money spent on a specialist would be worthwhile on this sort of stuff. Quote Link to comment Share on other sites More sharing options...
fesm_ndt Posted May 8, 2012 Share Posted May 8, 2012 Good progress. Special request here, if it can be done without any on costs, of course. Please get the metal stitching people to photograph the visible cracks, and then the same things when developed with dye penetrant. I'm sure there will be a noticeable difference that is worth the work to illustrate. I had a GMC 270 with a visible 6" crack in the water jacket, but when penetrant tested it ran right back down the block to the bell housing. Stitching saved it and that engine is still running well, last I heard, but I often wishes I'd photographed before / during / after to show the differences. I'm sure those castings will save but will probably take a little more work than is immediately visible, and such images will show you why the bill was justified. Apparently you can do this process yourself but I think money spent on a specialist would be worthwhile on this sort of stuff. My guess being steel the specialist company repairing it will do MT or MPI testing on it as much quicker as gives instant results. You are correct in that normally what you can see visually is only a small part of the picture. PT dye you put on, wait 15 to 30 mins for it to soak in, clean it, dry it and then apply a developer. Very useful to have a 3 can kit in the workshop. If your eyes are good you can soak the part in WD40, clean it and lightly dust it with powder as the oil will stain the dust and was how the principle was found in the first place The only problem with castings, especially old ones was that the material is not homogenous so you can pick up indications in the surface that are from manufacture. Another reason why MT testing is good as when you find something you tend to give it a quick grind to see if its got any depth instead of a scab. MT just needs a magnet and more ink, preferably fluorescent. Both these NDT techniques are fairly easy and cheap. http://hmvf.co.uk/forumvb/showthread.php?16151-Ndt But all in all I hope its all a small thing and easily repaired so you can continue with your great thread. Quote Link to comment Share on other sites More sharing options...
Cel Posted May 8, 2012 Share Posted May 8, 2012 Any idea what 'FN' stands for? Marcel Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted May 8, 2012 Share Posted May 8, 2012 Any idea what 'FN' stands for? Marcel In what context? I think of the Army Rifle - the SLR. When it was first introduced, I think it was it was known as the Belgian FN Rifle - Fabrique Nationale........ Tony Quote Link to comment Share on other sites More sharing options...
Great War truck Posted May 8, 2012 Author Share Posted May 8, 2012 The FN cast into the block! Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted May 9, 2012 Share Posted May 9, 2012 The FN cast into the block! Well, that was unobservant of me! No idea - perhaps the initials of the Foundry that cast it? Tony Quote Link to comment Share on other sites More sharing options...
broken arrow Posted May 9, 2012 Share Posted May 9, 2012 In what context? I think of the Army Rifle - the SLR. When it was first introduced, I think it was it was known as the Belgian FN Rifle - Fabrique Nationale........ Tony fabrique national is correct, althow the Belgium FN was different to the SLR in that it was not an exact copy if i remember from down at the range, god that seems soooooooo long ago, so forgive me if i am wrong old age, old fart. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted May 10, 2012 Author Share Posted May 10, 2012 Nothing very exciting has happened these last couple of days – but all of the 5/8” top studs to take the cylinder blocks have been shortened and tightened down to their final positions. Similarly, all the missing 3/8” studs on the sides of the Crank Case have been replaced and the Crank Case is now ready for the re-assembly of the engine to commence. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted May 10, 2012 Share Posted May 10, 2012 Are you quite happy that running two 4 1/2" dia cylinders and two 4 1/4" dia won't give rise to any imbalance or rough running? Is it not going to have quite an effect on compression ratio and thus combustion characteristics? Quote Link to comment Share on other sites More sharing options...
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