Richard Farrant Posted May 20, 2012 Share Posted May 20, 2012 Tim and Steve, This might be worth following up, a clearing sale in Australia, with two Thornycroft chassis'. No details, but might be worth contacting the auctioneers to see if they have any photos. May be something built quite later, but WW1 era trucks do show up over there. http://www.elders.com.au/livestock/upcoming-sales/plant-machinery-clearing-sales/detail?id=C1802 regards, Richard Quote Link to comment Share on other sites More sharing options...
Great War truck Posted May 22, 2012 Author Share Posted May 22, 2012 Not much done to the Thorny these last few days because of other “obligations”! However, we did pick up the water couplings that joins the facing bottoms of the water jackets on the two cylinder blocks. These consists of two castings which lock together when in position – one is bolted to one cylinder block and the other is held in place on the other block on studs. It is not possible to put them both on studs because of lack of space to manoeuvre them on when assembling the engine. When we took the engine to pieces, we had to cut the bolts holding one casting as they were rusted up so solidly, just to lift the cylinder blocks off the crank case as there was no way that the two cylinder blocks could have been lifted off the crank case together with out a severe risk of breaking something if they had remained joined together by this connection. After cutting those bolts, it was possible to lift the blocks off one at a time. These two pictures show the two couplings still very firmly stuck together after an initial sand blasting. There was no way that they could be taken apart in that condition. The two castings were eventually separated by getting them a dull red hot, allowed to cool and then held in a vice – and gently tapped with a hammer. They started to move – some WD40 was inserted in the joint – and continually “worked” until they came apart. These three pictures show them when newly separated. These final three pictures show the two castings after wire brushing. You will notice that there is a groove in the female part to take some sort of packing to seal the joint – what would that have been – graphited yarn? Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted May 22, 2012 Share Posted May 22, 2012 Could be as simple as tarry rope, for that temperature :angel: Sort of material you'd use for a crankshaft oil seal Quote Link to comment Share on other sites More sharing options...
Old Bill Posted May 22, 2012 Share Posted May 22, 2012 The seal is described as a 'rubber ring' in the parts book. Thumpercross very kindly offered to make us one on page 24 when this part of the engine first came up for discussion. Looking at the photos, it may be possible just to use a thick section O-ring but I need to have a look at the surface first. We may yet take him up on his kind offer! Steve Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted May 22, 2012 Share Posted May 22, 2012 Maybe one of those rubber rings they use on exhaust hangers, scarf cut to get the right diameter? Quote Link to comment Share on other sites More sharing options...
Redherring Posted May 25, 2012 Share Posted May 25, 2012 Tim and Steve, This might be worth following up, a clearing sale in Australia, with two Thornycroft chassis'. No details, but might be worth contacting the auctioneers to see if they have any photos. May be something built quite later, but WW1 era trucks do show up over there. http://www.elders.com.au/livestock/upcoming-sales/plant-machinery-clearing-sales/detail?id=C1802 regards, Richard Auctioneer sent me some photos... if you're interested I have his details regards Robert Quote Link to comment Share on other sites More sharing options...
fesm_ndt Posted May 25, 2012 Share Posted May 25, 2012 ............... then sealing the gaps between the new plates and the old original aluminium tanks with Devcon, an aluminium putty. And then finally painting the whole of the inside with a couple of coats of an expoxy resin. We thought that there was no way of water penetrating through that lot again! And although we were confident that the job was done and completed successfully, we found that he was right! Numerous fresh leaks - mainly pinholes appeared ......... This is quite interesting as I do a discussion on something like this in my training courses. Corrosion, as everyone knows is caused by the reaction between the anode and cathode I your case the aluminium header tank is the anode, as the anode corrodes and the rest of the radiator is the cathode that doesnt corrode ok I know, boring the interesting part is when you coat the inside of the header tank with devcon or epoxy you have created a bigger problem as coating is never perfect and always have holidays or pinholes. So the result is a very big cathode and a microscopic anode. The size difference creates more accelerated corrosion and you end up with pinholes very quickly. To reduce the corrosion you would coat the cathode so the pinholes in the coating leave a small cathode and a large anode = slow corrosion. Anyway coating the inside creates a bigger problem Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted May 25, 2012 Share Posted May 25, 2012 Thanks, Mike! HMVF is marvellous - we have so many members with so much extensive knowledge about so many different things and I am convinced that there is not a question that cannot be comprehensivally answered by some one! So now we know technically "why" - but the bottom line realistically remains that the answer is still to make new tanks and start again. I guess that if new ones last another 100 years, then we will not worry too much about it! Tony Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted May 25, 2012 Share Posted May 25, 2012 Auctioneer sent me some photos... if you're interested I have his details regards Robert Thanks, Robert - not "J's" I think - something newer and smaller. No doubt when Tim and Alan (Runflat) come along, they will identify them exactly! Tony Quote Link to comment Share on other sites More sharing options...
Runflat Posted May 25, 2012 Share Posted May 25, 2012 Cheers, Tony. No pressure then. I can't name the type precisely but it looks like an early 1930s model. There'll be someone in Thornycroft Register who can provide chapter and verse: http://www.thornycroft.org.uk/index.htm Quote Link to comment Share on other sites More sharing options...
nz2 Posted May 25, 2012 Share Posted May 25, 2012 My initial thoughts as to the Australian Thornycrofts. Bt or Bx models of later 1920's. Later models had a different radiator shell. Doug Quote Link to comment Share on other sites More sharing options...
Old Bill Posted May 25, 2012 Share Posted May 25, 2012 The size difference creates more accelerated corrosion and you end up with pinholes very quickly. To reduce the corrosion you would coat the cathode so the pinholes in the coating leave a small cathode and a large anode = slow corrosion. Hi Mike. I used to design tooling for electrochemical (anodic) machining and should certainly have spotted that one! Thanks for reminding me. It is obvious now! More pattern making beckons I think. Steve :-) Quote Link to comment Share on other sites More sharing options...
Asciidv Posted May 27, 2012 Share Posted May 27, 2012 Returning to the radiator, hasn't a little bit of science been skipped as to what makes an anode or a cathode and electrochemical potential? Even, if Tony had an 'earthed' block of zinc in the header tank as a sacrificial anode I bet the water would have weeped out just the same. However, this is all to our benefit, as we can now watch Steve make the patterns for the new tanks :nut:! The header tank is no mean task as more than one core will be required. Barry. Quote Link to comment Share on other sites More sharing options...
Chris Suslowicz Posted May 27, 2012 Share Posted May 27, 2012 Returning to the radiator, hasn't a little bit of science been skipped as to what makes an anode or a cathode and electrochemical potential? Even, if Tony had an 'earthed' block of zinc in the header tank as a sacrificial anode I bet the water would have weeped out just the same. Barry. It would, because the zinc would have no effect on the aluminium corrosion - it's lower down the electrochemical series than aluminium. To protect aluminium you would need to use magnesium as the sacrificial anode. (And that's the last one in the series that can be used, everything above it will spontaneously react with water and either fizz or actually burst into flames. Electrochemical series is here: http://www.chemguide.co.uk/physical/redoxeqia/ecs.html This also explains why die-cast "pot metal" is so horrible once it starts to corrode, it's "Mazak" - an alloy of magnesium aluminium and zinc, so you've got the top three right there. Add the fact that car door handles were cast in this, then copper plated as a base for the final chrome, and once you've got a pinhole through the plating, it eats itself from the inside. :argh: Chris, Quote Link to comment Share on other sites More sharing options...
mattinker Posted May 27, 2012 Share Posted May 27, 2012 Electrochemical series is here: http://www.chemguide.co.uk/physical/redoxeqia/ecs.html This also explains why die-cast "pot metal" is so horrible once it starts to corrode, it's "Mazak" - an alloy of magnesium aluminium and zinc, so you've got the top three right there. Add the fact that car door handles were cast in this, then copper plated as a base for the final chrome, and once you've got a pinhole through the plating, it eats itself from the inside. :argh: Chris, Chris, I'd never heard of "Mazak", only "Zamak" I thought that it was "pot metal". I've made ZA12 ( a form of Zamak) using 11 parts Al, 1 part Cu and the remaining 88 parts Zn. Casts beautifully (at around 450°C) and is a pleasure to machine. I can see where the corrosion comes in! Old Carburetor metal. Regards, Matthew Quote Link to comment Share on other sites More sharing options...
Great War truck Posted June 2, 2012 Author Share Posted June 2, 2012 Steve is still assessing the cylinder bores. To check them for straightness and roundness, he made up a stop for his dial gauge which he bolted on so that the gauge fits across the bores. He also made a handle so that it can be held at any position along their length. He then inspected the bores in the better of the two blocks to see whether we can get away without lining them. He found that both are barrelled in shape with one being 0.020" bigger in the middle than the ends and the other 0.018" so, unfortunately, both will need reboring and then lining. At least this removes the need to decide whether or not to line two or four cylinders! This weekend, we are going to seal and pressure test the water jackets to see if there are any more cracks. If no more are found, we will get the blocks stitched and then start looking for someone with the capacity to bore them out by 0.030". Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted June 6, 2012 Share Posted June 6, 2012 (edited) The prime objective this weekend was to pressure test the cylinder water jackets up to 10 psi – to see if there were any further leaks or cracks that we had not seen in the first clean up – and to find out just how extensive they are. The method to be used was to pump them up with air after sealing up all of the relevant orifices – and then just “paint” the exteriors of the water jackets and the insides of the cylinders themselves with some soapy water to see if and where the soapy water bubbled, indicating a “leak”. Some of the original plates covering the various holes were themselves pitted and corroded so it was necessary to clean them up first so that we could ensure an air-tight fit. Some plain steel blanking off plates had to be made to cover the fitting place of the water pump and also the water manifold. A thick rubber gasket was used to aid sealing. The top plate was drilled and tapped for a non-return valve and for a Pressure Gauge – we were determined not to exceed 10 psi as that should be quite an adequate pressure – and we did not wish to risk stressing the blocks further Edited June 6, 2012 by Minesweeper Photo bucket issue Quote Link to comment Share on other sites More sharing options...
Asciidv Posted June 6, 2012 Share Posted June 6, 2012 ....and did it leak?..... Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted June 6, 2012 Share Posted June 6, 2012 Sorry to keep you waiting for the answer. Each time i post a response the forum crashes and i have to start again. I will break it up into smaller chunks. The air hose was applied to the top of the non-return valve and the pressure applied was very carefully watched to make sure that did did not exceed our specified pressure of 10psi. Soapy water was brushed on the first previously identified crack and as we anticipated bubbles appeared. Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted June 6, 2012 Share Posted June 6, 2012 No other bubbles or lines of bubbles appeared in this casting – either inside or out. We were relieved! Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted June 6, 2012 Share Posted June 6, 2012 The same process was then repeated on the second block, and much to our surprise, there was no sign of any “bubbles” over the second previously identified crack – or anywhere else on the casting. The plan now is to put the Blocks back in the car and visit our local guide and mentor, David H. who has years of experience and is a very fine craftsman and engineer. We want to talk to him about having the cylinders re-bored and the appearance of the cracks in the blocks. Further report to follow! Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted June 7, 2012 Share Posted June 7, 2012 Well, an unexpected development! Yesterday, we took the two cylinder blocks to show our old friend, David H, to seek his advice and opinion for the way forward. David is well past retirement age but is a superb Motor Engineer with a lifetime’s experience in dealing and repairing old engines and has been a wonderful friend to have had in the background in the years gone by when we restored the previous four lorries. Helpful advice was always there when we needed it and was always greatly appreciated. His first comment on the Thorny blocks confirmed our opinion that we should avoid welding the blocks if possible. Secondly – and this was the surprise – we should not trouble to try to stitch the cracks – just ignore them! He commented that the cracks were quite insignificant in this engine and that to stitch them would mean putting more holes in the blocks to take rivets. The cooling system is not pressurised and with such large lumps of iron, he did not anticipate that the cracks would worsen or cause us any great problems. So this is what we have decided – carry on with no remedial work done to the two cracks. With regard to the bores, then David is arranging through his own contacts for all four to be skimmed out by just the minimal amount necessary so that the “barrelling” is taken out and the bores returned to a true diameter throughout their lengths so that they can be sleeved down to 4 ¼”. Quote Link to comment Share on other sites More sharing options...
fesm_ndt Posted June 7, 2012 Share Posted June 7, 2012 The same process was then repeated on the second block, and much to our surprise, there was no sign of any “bubbles” over the second previously identified crack – or anywhere else on the casting. Perhaps a surface casting defect as the outer part in the mould cools the fastest. Castings are a bugger to inspect, as had the same problem years ago inspecting some rope sockets. His first comment on the Thorny blocks confirmed our opinion that we should avoid welding the blocks if possible. Secondly – and this was the surprise – we should not trouble to try to stitch the cracks – just ignore them! He commented that the cracks were quite insignificant in this engine and that to stitch them would mean putting more holes in the blocks to take rivets. The cooling system is not pressurised and with such large lumps of iron, he did not anticipate that the cracks would worsen or cause us any great problems. So this is what we have decided – carry on with no remedial work done to the two cracks. I am a bit cautious about welding on castings as due to their inhomgenous nature they can react badly and plus your ones are quite old. Given that he is saying no pressure what about silver solder, or would that be to much heat input? If silver solder is a no go then a dab of devcon on the outside could stop the weepage. One last comment. Regarding cracks, due to the stress concentrated at their tips, they almost always grow. In basic terms, if you have a bar with a 1 ton load on it and drill a perfectly reamed hole in it you create a stress raiser which multplies the stress by a factor of 6. If said hole is nicked or cracked the stress can be increased by over a million, hence cracks tend to grow and a method of repairing cracks is drilling a hole at the ends. Anyway, glad you have had good news as is good to be able to move on....... When would you expect it to be running as you have most the bits now? Or are you missing some bits? Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted June 7, 2012 Share Posted June 7, 2012 Well, things are moving on quickly - David has telephoned this morning to say that the cylinder Blocks have been presented to his friend for skimming out the bores - and that no problem is anticipated over that - at this stage! When they come back, we can start thinking about getting the sleeves made as they will have to be "specials". The final diameter of the bores will be 4 1/4" - reduced from 4 1/2". As far as an anticipated completion date is concerned, then realy we cannot say at this stage. Quite a lot has already been done - the gearbox was stripped down some years ago and rebuilt with all new bearings - though we might want to have a look at that again in the light of all the experience that we have obtained since that early time. We have that wonderful Diff from NZ that appears to need little work - we have no Prop Shaft so that will have to be made. We have no Radiator but there is a full set of castings for that tucked away - already mainly machined. So that will have to be made - together with a core. We have front tyres - but no "backs" so they will have to be made. New front wings and rear mudguards are already in store. The water pump has to be completed. And, of course, a correct pattern steering wheel! The chassis - recovered from under a Shepherds Hut is tucked away but we have done nothing to that since we got it. It needs to be stripped down, thoroughly cleaned and sand blasted and I anticipate machining up a new set of shackle pins - but we shall see! So unfortunately, it is too early to give an estimation of the completion date - but I do hope that it will not be 10 years away! Tony Quote Link to comment Share on other sites More sharing options...
fesm_ndt Posted June 7, 2012 Share Posted June 7, 2012 Oops. I meant the engine rebuild as was hoping you had all the bits now and looking forward to a video of it running Quote Link to comment Share on other sites More sharing options...
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