cylinder liner material & fitting

Hi all.

I have got to the stage of pressure testing a Plastows Burrell traction only to find that the casting is porous between the steam passage to the regulator chamber, and the now finish bored cylinder. The original casting was bought many years age and bored correctly to size. Finish is nice and smooth with no obvious flaws in the machining, the leak appeared at about 20PSI hence I am assuming a blowhole/ slag inclusion failure.

My thinking is to use some 2" leaded phosphor bronze bar I have on stock to make a liner with say 3mm walls, and insert this into the existing bore. I really don't want to remove the cylinder from the boiler if at all possible and as the bore is true don't see any point in overboring the existing casting.

My queery is how to ensure the new liner stays tight in the bore and creates a steam tight fit. It must also stay in the same relative postion to allow the steam ports to flow . I don't know if loctite will stand the sustained temperatures which would be on both sides, shrink fitting is feasible but in service would the increased expansion of the bronze inside the cast iron cylinder block cause problems?

Steamseal might work with a peg(s) & the end covers to maintain location but it is quite dense and would need a fair gap between the original bore and liner to work I imagine.

Over to you please, given the vast knowledge base out there, and that you all have been so helpful on past occasions.

Many thanks

BK.

I used to work at a company making large stationary engine. The C.I. cyclinder liners were tested under pressure and if found to leak, a handful of alum was added to promote rusting of the porous area. This cured any leaks within minutes. The liners were then washed out and, I assume, sprayed with dewatering fluid. Further rusting was prevented by water treatment that was used wether there had been leaks or not.

Brian

Many thanks Brian . That sounds interesting and a potential solution, It would mean me removing the cylinder from the boiler which I am loathe to do for various reasons.

Hello BK, I'm assuming that the pressure test that revealled the porosity was carried out with the cylinder attached to the boiler. If that is the case then just redo the test but with alum in the test water.

Brian

Again requiring dismantling, but maybe a possibility if you need to, could it be 'ceramic sealed'?

Back over 30 years ago I had an engine with a cracked cylinder head (an exhaust valve fell into the cylinder which hammered the head, bore and piston until the engine seized) which was metal stitched and 'ceramic sealed'. I just accepted the process and cost, as a new cylinder head was out of the question (1940s production) and importing a second hand cylinder head from the US was not an easy option back then, if even available. No problems with it since. I had no idea what the process involved and was just very pleased to have it repaired.

****Please ignore my earlier reference to Alum****

The correct material is sal-amoniac. Funny how these things pop into ones head unexpectedly. In my defence I should point out this this all happened 50 years ago!

Brian

Hi Brian, If I filled the boiler with Sal amoniac, would the crystals not also form anywhere else where there is interaction with the air,e.g pipe connections, gauge glass plug cocks etc?

Any boiler inspectors like to comment on filling a boiler with the solution, I does seem a good potential resoloution to the issue.

Many thanks

BK.

Loctite 638 is used to secure cylinder liners and is temperature rated to 180 deg C.

My preference though is for a shrink fit.

Paul

I can't really comment on the effects of sal-amoniac on boilers, it would be better confined to the cylinder casting alone.

Brian

As usual I can't find the right book when it's needed so you'll have to trust my memory!

A damp mixture of iron filings and sal-ammoniac paste was used in the old days to plug voids in cast iron. In the presence of water the sal-ammoniac reacts with the filings and the casting to produce a solid mass of corrosion, a kind of super-rust. It's said to work very well. I guess flooding a porous casting with a saturated sal-ammoniac solution would have the same effect; a reaction that fills the gaps with 'rust', an effective way of fixing a small leak.

But it works because sal-ammoniac is corrosive. I'm not sure I'd trust it NOT to attack brass, copper, silver solder, steel, oil or anything else that happens to be inside the boiler, steam passages, valves and cylinder of a complete engine. For example, I can imagine it gumming up the safety valve or regulator. As there are so many unknowns, I wouldn't risk it. Treat the faulty casting alone.

Sal Ammoniac is Ammonium Chloride. Not dangerous and easily available.

Dave

I think I would go for the liner method but make it from cast iron, make to a good push fit any sort of sealer would most likely scrape off as the liner is pushed in so I wouldn't bother with this.

The liner will be finished flush with the cylinder end faces and the cover spigots refitted to the new liner bore, the cylinder cover gaskets and a bit of sealer will seal the joint between the new liner and original bore, once tightened down nothing is going to move and the steam leak will be sealed off, and with a cast iron liner the mating faces between the liner and original bore will self seal with a bit of corrosion from the steam leak. Mike.

Edited By MichaelR on 18/10/2017 10:06:32