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Trouble with my Suart engine

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david newman 911/11/2011 17:52:48
47 forum posts
I recently completed a Twin Victoria and it ran perfectly, the pistons are now getting tight in the bores and I can hear them creaking when I turn it over by hand.
It seems that the oil is emulsifying and coming out of the exhausts as a brown watery substance. I only ever run it on air so it's not caused through steam. I am using very thin machine oil which I feed in by putting a couple of drops into the inlet manifold which I was advised to do, any advice please ? David
Tel11/11/2011 18:21:40
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Rings? 'O' rings? Soft packing?
 
 
david newman 911/11/2011 18:32:05
47 forum posts
Tel it's fitted with piston rings , cast iron cylinder and piston. David
JasonB11/11/2011 18:38:29
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Do you have a moisture trap on the compressor? sounds like you have been pumping warm moist air. The moisture condenses out on the cylinder and the water droplets will be what your oil has been emulsified in and also caused rusting turning the mixture brown
 
J
Bogstandard11/11/2011 18:49:21
263 forum posts
It sounds very much like your cast iron pistons/rings/bores are starting to corrode (rust) and sticking together.
 
It might be you have water in your airline (most of us do) so make sure you water separator is working and the tank on your compressor is emptied frequently. The 'brown watery substance' is most probably exactly what you have said.
 
Rather than a thin oil, maybe a car multigrade one will work a little better, they have built in corrosion inhibitors.
 
As long as you don't have any silicone seals or sealant on the engine, then you could try a squirt of WD40 into the intake, followed by a turn over by hand after running. That might help dissipate the water and stop the parts rusting together.
 
John
 
Must have posted at the same time as Jason

Edited By Bogstandard on 11/11/2011 18:50:15

Tel11/11/2011 18:49:34
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... or failing a moisture trap, how log since you drained the receiver on the compressor?
 
I don't like the sound of that 'creaking' tho - I would be inclined to strip it, give the bores a good manual clean and oil, then replace the rings with some teflon tape, twisted into strings, and see if that makes a difference.
david newman 911/11/2011 18:50:02
47 forum posts
Jason I have been running it using a Badger airbrush compressor, don't really know how I would fit a moisture trap and don't even understand how they work. David
JasonB11/11/2011 19:09:48
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What is it one of the diaphram ones like the Micon. You can pick up a combined moisture trap and filter quite cheaply from the likes of machine mart, the water condenses on the outside of the glass and can be drianed by the brass valve at the bottom.
 
To fit it just remove the hose adaptor from the compressor and fit teh filter, put teh hose adapter onto teh filter outlet, you may need a connector or nipple but tehy sell them as well, take your compressor to the shop so you can make sure it all fits
david newman 911/11/2011 20:31:26
47 forum posts
Thanks Jason , I have tonight ordered that moisture trap from Machine Mart, I will strip the cylinders and clean them out . Really suprised at what's happend it was turning over as smooth as silk and now though still running it's struggling. thanks to everyone for the input.
David
JasonB11/11/2011 20:35:18
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Just one other thought. Did you get a bit of wire down the cast in ports to clean out any traces of the core sand that were still in there
 
J
Ramon Wilson11/11/2011 21:38:01
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David, Following your posting elsewhere on piston rings I thought you were looking to improve on CI rings hence my recommendation there for PTFE packing
 
I ran a Twin Victoria for many years both on steam and air as any who have attended the Forncett ME day will testify. That engine, made to Stuarts drawings but using basic castings - ie not from a kit - was fitted with bronze pistons which in turn were fitted with PTFE packing as described on your other thread.
 
Despite my best intentions over the years the engine was never fitted with a lubricator so I used to inject neat steam oil into where the lube injector was intended - a block set central to the steam inlet pipes. This would gradually work it's way through and deposit itself in the tobacco tin tray laid beneath the exhaust - something else that never ever got improved either. After the initial euphoria of running at events declined it only ran once a year at the Forncett do after which it would be cleaned down, injected with more steam oil and run for 10 mins on the bench and then left until the following year. I can honestly say that no rusting ever occured.
Just found this pic - the oil was injected using a syringe into the small square block
on the left of the pic. This pic is one of the few I took just before I sold the engine about three years ago. Apparently the first Forncett do was twenty years ago next year and the engine was built about a year or so before that.
 
My advice then, as before can only be to ditch the rings and replace with a bronze piston and PTFE packing - and use steam oil - you won't regret it
 
With regard to air I'd like to point out that if you have a small airbrush type of compressor that is not fitted with a small resevoir fitting a water trap direct to the compressor outlet will not cure the moisture problem completely. This is because the compressed air comes through the water trap still relatively hot and cools inside the hose where upon moisture forms after the water trap .
 
I experienced this on a small compressor bought as a spare to my normal Ripmax one which has a resevoir. These are primarily used for airbrushing though both compressors are fitted with near identical water traps and operate in the same room. The Ripmax never shows any moisture problems in painting but the Spraymaster will start to show within ten mins or so of use. The air needs to be able to cool before it gets to the water trap.
 
Hope this helps and I hope you recover your engine okay.
 
Regards - Ramon

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