WW1 Thornycroft restoration

[Great War truck]

An initial look down the bores show that again, both cylinders are suffering from some corrosion - but not nearly as bad as in the other block. We are optimistic that these will clean up and followed by honing them.

 

 

 

 

The bad news is that following this light initial cleaning, another crack has been revealed - this time in the top of the block. Again, not the end of the world.

It is interesting that neither of the two cracks that we have found show any evidence that water has seeped through them - there is no evidence at all of scale on the outside!

So tomorrow, we return to the first Block and will get out the remainder of the damaged studs - and then give it a thorough cleaning - inside and out!

 

 

 

[Gordon_M]

Ouch,

 

I think you are going to have to dye penetrant check both of those castings in their entirety, The crack fixing will be tedious and not cheap, so you would really want to find everything before you start.

 

In particular I recall the Metallock tech that fixed my block telling me that most casting cracks run on a lot further than the visible ends, which is why they d/p'd all of them before starting work.

[Old Bill]

Yes, I think that would be very wise. It looks like bringing this engine back is going to be quite a tough one so a lot of thought and preparation will be needed before comitting. At the moment, I feel that we should take the 'least risk to the block' route. I don't like the thought of getting it all hot but I think I can see some welding coming on as the first crack is so wide. The second crack should respond to stitching and I think the bore might be the last thing to tackle in case the casting moves with the heat. Lots of food for thought here.

 

If we simply bore the cylinder out, could the piston be salvaged by metal spraying or will I have to make a new one? Is a metal sprayed surface machinable or is it hard?

 

I shall be pleased to see the end of this particular job!

 

Steve

[N.O.S.]

I don't know about spraying cast iron pistons and hot environments, but have experience of metal sprayed 100mm dia. hydraulic excavator boom pins where extreme loading is involved. The first time they were done it all peeled off after a few months - the second attempt (by a different company!) was a complete success.

 

So all down to the process operator then :cool2:

[Asciidv]

For head and block crack welding I have used Slinden Services twice;

 

http://www.castironweldingrepairs.co.uk/classic-vintage-veteran-motor-vehicle-casting-repairs.php

 

Both times the work was excellent. Their web site shows photographs of some of their more extreme welding jobs. Incidentally I hope Tony is not going to be too distracted from the Thorneycroft restoration by watching his new 32" LCD television!

[Old Bill]

For head and block crack welding I have used Slinden Services twice;

 

Thanks Barry. There is nothing like a personal recommendation. I have just had a look at their site and they are quite close to me. I think a visit to discuss the job is called for.

 

Will keep you posted!

 

Steve

[Minesweeper]

For head and block crack welding I have used Slinden Services twice;

 

http://www.castironweldingrepairs.co.uk/classic-vintage-veteran-motor-vehicle-casting-repairs.php

 

Both times the work was excellent. Their web site shows photographs of some of their more extreme welding jobs. Incidentally I hope Tony is not going to be too distracted from the Thornycroft restoration by watching his new 32" LCD television!

 

Thanks for that Barry - Steve will be here with us next weekend - prior to our trip to Brighton on Sunday to watch you come in to reclaim the Dennis Cup - and I hope we can decide then on the way forward with the cylinders!

 

You made me laugh with your comments on the 32" TV! I hoard cardboard as I find it very useful to put down to protect the ground from oil and grease. We must have bought that TV about a year ago - and generally, I only turn the thing on when I want to go to sleep!

 

Tony

[Cel]

From memory, dry liners are 1.5 to 2 mm thick, with a band around the top of the cylinder, 3 to 4 mm thick. What diameters are the bores? It wouldn't surprise me if they are a standard imperial size. I'd take the cylinder and a good piston to some one who does reboreing, they may well be able to bore out and fit a standard liner from something else. Heavy pitting at the bottom of the cylinder would behind a dry liner would not be a problem. Even if the cylinder walls are thin, which I doubt, from that era, a dry liner shouldn't be a problem.

 

Regards, Matthew

 

A friend of mine fitted a self-fabricated dry liner in an old Tangye engine. Instead of having the same wall thickness over the whole length, he gave it different diameters, the smallest on the bottom side. That way he didn't need to press it all the way in. Of course, the bore has be stepped as well but that is not too difficult.

 

Regards

Marcel

[Great War truck]

The task for yesterday was to remove the last six badly wasted or rotten studs from the first cylinder block. That was all successful - although just a little tedious!

It now has to be properly cleaned - inside and out before we take the next step with it - whatever that will be - still to be decided!

 

 

 

 

[Great War truck]

Here are some more pictures of the poorest of the two cylinder blocks. In the first picture, the deepest corrosion in the worst of the two cylinders (the right hand one) is out of sight and the three pictures together show the amount of corrosion in the least corroded of the two.

 

 

 

 

This is the most "poorly" of the cylinders - and there is certainly not enough metal there to bore it right out. We think that we are getting to the solutioin of the problem - and all three of us will be glad to see it resolved.

 

 

 

 

[Jack]

Its now a sticky!!

 

GREAT WORK GUYS!!!!

[mattinker]

 

I'm a little bit frustrated by not having any actual dimensions! I've drawn (roughly!) a diagram of how I have made bore gauges, if there is enough space to get a lever type dial gauge in the cylinder. A straight edge, with parallel sides will "follow" the inside of a cylinder. Once the straight edge is in place it can be clamped in place or simply held by second person. With an "L" shaped "saddle" to carry a dial gauge, you can determine the depth of the pitting. I still think a dry liner is a workable relatively inexpensive route!

 

Regards, Matthew

[AUSSIE TD-40]

the so called "EASYOUT SCREW EXTRACTORS" are not very good if they are of the tapered thread type, anything with a thin wall or soft like brass just get expanded tight. The best type that I have used are the square 4 corner ones that are tap'd in and bight in on the 4 corners, need to buy these from a professional tool suppler, yes they will cost good $s but they are being asked to do a real tuff job. There are allso a spline drive in type but I have not used them, anyone tryed them?

 

Jake.

[Old Bill]

Thanks for that Matt. I hadn't thought of the clock gauge but it is a very good solution.

 

We too are reaching the conclusion that dry liners are going to be the answer. The question now is whether we have to do them all or can just get away with the worst bore. I haven't seen the bores since Father has cleaned them up but will have a look this weekend as I am going down for the Brighton run on Sunday.

 

It is now a whole year since the Dennis took us to Brighton. Where has the time gone?!

 

Jake. You are quite right about tapered screw extractors. I am always a bit cagey about them as it is only too easy to end up with a broken stud with a hard centre! I did manage to get one of the priming cock bases out of the block with one but the other will have to be drilled.

 

Steve :-)

[fesm_ndt]

Dental putty is good for measuring pits. The same stuff they use to make the moulds for mouth guards

 

We used to use it on aircraft.

 

Fluorescent MT or MPI testing would most likely give you the best dimensions on the cracks.

[Great War truck]

Steve has made contact with a cast iron welder and cylinder repair specialist - and received a positive response from him. He has invited Steve to call on him now with the cylinder blocks after seeing photographs of them for a full assessment and will provide a quotation for the work involved. This works out quite nicely as Steve will be in Devon over the weekend and can take the blocks back to Leicester with him when he returns to his own home next Monday.

Very little cleaning work has been done on this second block so far and we really need to get the broken and corroded studs out now before it leaves Devon as presumably the Specialists will want to do a pressure test on it after welding - and broken and rusted studs are not going to be a help to them!

Some more recent photographs of this second block show that the two bores are comparatively in excellent order and should cause no problem!

 

 

 

[mattinker]

Steve,

 

Whether you can get away with one liner will depend on the state of the other cylinders! If they,re OK, there's no reason why not. I'm curious to know what the pistons are like, do you know what the original bore sizes were? I wonder whether it's already been re-bored! Maybe how many times it's been re-bored! Nothing written on the pistons I imagine!

 

 

"We too are reaching the conclusion that dry liners are going to be the answer. The question now is whether we have to do them all or can just get away with the worst bore. I haven't seen the bores since Father has cleaned them up but will have a look this weekend as I am going down for the Brighton run on Sunday.

 

It is now a whole year since the Dennis took us to Brighton. Where has the time gone?!"

 

It's been a year since our paths crossed briefly in Brighton! I'm really glad you've started the "Thorny" I hope maybe our paths will cross again and I'll actually get to see the Thornycroft! I look in most days, "can't help it, too interesting!"

 

Regards, Matt

[Old Bill]

Thanks Matt. Glad you are enjoying it. We are not taking a lorry this year so there will be more time to talk and we should be pleased to see you again.

 

Dad has measured the pistons and they are 4 1/2" diameter so the engine has not been re-bored. There is not enough meat to bore all of the pitting out so it will be a dry-liner job. Fitting the liner concerns me as, with a fixed head, there is nothing to push against to get it in. The water jacket over the top would just collapse under that sort of load which is a risk I don't want to take. We could try liquid nitrogen which would shrink it by about 0.010" but I have no personal experience of that process. With the liner so thin (under 1/8") it would warm up very fast and I would hate to get stuck half way! The hole in the top of the crank case is 4 3/4" diameter which is too big for us to put a flange on the liner and trap it between the block and the case. I would value any thoughts or suggestions please!

 

Steve

Edited May 2, 2012 by Old Bill
Speeling!

[Great War truck]

Matt was asking about the pistons - all four look just the same at this stage and here are some photos of just one of them, as taken out of the engine - apart from just a quick wipe down. They are nominally 4 1/2" in diameter. Two of the three rings on the last piston are still stuck and we have been gently playing away at them in the hope that they will come loose.

 

Tony has continued to work on broken and rotten studs today with the intention of completing that job before Steve takes the Blocks to the Specialist for assessment after the Bank Holiday.

 

 

 

 

[Cel]

Hi Steve

 

You should consider the stepped liner, it is a little more work but much less risk to get stuck halfway. Instead of a flange you could put in a thin ring between block and case. I remember you writing 'nothing like a good challenge' in the Dennis thread, no doubt you have one here!

 

Best regards

Marcel

[alixcompo]

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.

[Old Bill]

Hi Steve

 

You should consider the stepped liner, it is a little more work but much less risk to get stuck halfway. Instead of a flange you could put in a thin ring between block and case. I remember you writing 'nothing like a good challenge' in the Dennis thread, no doubt you have one here!

 

Best regards

Marcel

 

I hadn't thought of that one! So if make the liner a sliding fit with a step at the bottom, that would stop it moving upwards. Then I could put a shim between the block and the case with a hole small enough that the end of the liner sits on it to stop it sliding down? Or are you thinking of a thin piston ring/circlip in a groove in the original bore to trap it?

 

Just to make it more fun, the piston drops below the edge of the bore on each stroke so the ring would have to be pretty thin.

 

As you have reminded me, there's nothing like a good challenge!

 

Steve

[Cel]

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.

 

Marcel

[Barney]

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

[Grasshopper]

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!