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Author Topic: Saving A Broken Saito V4PR?  (Read 862 times)

DBS88

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Saving A Broken Saito V4PR?
« on: February 26, 2024, 06:28:19 pm »

The first time I saw a Saito V4PR it was love at first sight - these masterpieces of steam engineering have not been made now for about 40 years. Recently one came up for sale, correctly advertised as spares or repairs. I watched and waited, then decided I would bid, a problem with the engine was clearly shown in the photos so I had a good idea of what I was getting into and hoped to be able to save this jewel of an engine. Long story short, the engine arrived, and here is what I found.


The fitting screw (M2 x 11) that holds the piston valve drive rods to the drive wheel had sheared off flush with the drive wheel (clear from the photos as advertised).


The reason for this was the piston valve for one side of the engine was seized solid in the cylinder head - then probably, someone, when attempting to rotate the engine  forced things and the bolt sheared.






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DBS88

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Re: Saving A Broken Saito V4PR?
« Reply #1 on: February 27, 2024, 09:49:37 am »

As a recap, the Saito V4PR engine is a V Four Single acting engine of 2.5cc, so each cylinder has a capacity of 0.6125cc, which is tiny. It has a bore of 9mm and a stroke of 10mm. It's a piston valve engine that will rev to 6000 rpm, but produces maximum power at 3200rpm and it weights 380 grams.


Knowing the Piston Valve was seized solid in the Valve Sleeve, the whole assembly was removed from the cylinder head and the complete assembly left to soak overnight in WD40. Despite this the piston valve remained stuck fast, so a thin rod was passed through the Valve Sleeve into the inside of the Piston Valve, the rod was then used as a punch to gently persuade the piston valve from the sleeve. Once out the Piston Valve was checked over, no scores or grooves were found, just some staining.   


 



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ooyah/2

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Re: Saving A Broken Saito V4PR?
« Reply #2 on: February 27, 2024, 11:43:42 am »

Well done Dave, your a brave man taking on this project
I shall  keep watching


Geo
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DBS88

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Re: Saving A Broken Saito V4PR?
« Reply #3 on: February 27, 2024, 05:02:04 pm »

The piston valve was polished to remove the staining with Brasso, then washed thoroughly, before being coated in steam oil. The Valve Sleeve and O rings were also liberally coated in steam oil. The Piston Valve was then inserted into the Piston Sleeve. The Piston Sleeve is a clever piece of design, since this is how the steam is diverted for forwards or reverse. The engine looked like it hadn't been run and the O Rings on the Piston Sleeve showed no signs of wear, so apart from making sure they were covered with a generous coating of steam oil, I left them in place. The cylinder head was then lubricated again with steam oil and the piston sleeve slid back into the cylinder head.


Reassembly was straight forward, albeit it fiddly with such tiny components. The stainless steel Reversing Lever rod was screwed into the Valve Sleeve, this retains the sleeve in the head and the two reversing rod were then linked. The piston valve drive rod assembly was then reconnected. Having done one side of the engine, I then disassembled, checked and lubricated the second side.


The last job was to re set the valve timing which is surprisingly easy and straight forward. To do so the sump is removed. Since the engine will most likely be used in a boat, I set it to run faster in forwards than in reverse by lining up the slot in the Valve Drive Wheel with the hole in the rear crank pin - this is the standard setting. By advancing the timing by 30 degrees the engine will run at the same speed in both directions and by 60 degrees it will run faster in reverse than forwards. The inside of the engine and crankshaft was then lubricated with a good quality engine oil, not much but enough. When replacing the sump care has to be taken to make sure the flats on main bearings are facing the sump else the sump won't seat properly.
Photo 1 shows the stainless steel levers in the piston sleeve.
Photo 2 shows the timing set
Photo 3 shows the flat on the main bearing that must be flush with the crank case before putting the sump back.
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KBIO

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Re: Saving A Broken Saito V4PR?
« Reply #4 on: February 27, 2024, 05:44:43 pm »

What a satisfaction when an abandoned engine comes back to life !
Congratulations !  ok2 
(good thing that it was not cast iron!) ;-))

SteamboatPhil

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Re: Saving A Broken Saito V4PR?
« Reply #5 on: February 27, 2024, 05:57:38 pm »

Well done Dave for taking on what was a basket case  :-))
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DBS88

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Re: Saving A Broken Saito V4PR?
« Reply #6 on: February 27, 2024, 08:37:59 pm »

As some of you will already know, I already have a Saito V4PR that I previously worked on, so was happy to buy this one as spares or repairs. It's been great fun getting the spanners out and working through the issues on this recent purchase in the hope of bringing such a masterpiece back to life.
The good news is that as soon as air was applied, the engine started to turn a run. I used generous amounts of steam oil in the rebuild, so the engine is well lubricated for test running on air.
Here is a link to a video of the first test run on air [size=78%]https://youtu.be/h_WMbO9HAPk[/size]


I have since run the engine a few more times to bed everything back in and it's running even better now than it does in the video. Thank you for watching and as always this repair would not have been possible without help and support - thank you
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Mege66

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Re: Saving A Broken Saito V4PR?
« Reply #7 on: February 28, 2024, 04:14:54 am »

Hello David,
How did you clean the outside of the Saito?
It looks very bright compared to the photos at the beginning of the thread.
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DBS88

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Re: Saving A Broken Saito V4PR?
« Reply #8 on: February 28, 2024, 09:50:03 am »

Re cleaning the engine, I did not want it to become shiny and bright, just clean, and still looking like a fifty year old engine. A friend from this site, had in the past recommended BALLISTOL so I bought some. It's a strange item when you read the instructions as to what it can be used for, from skin care, leather care, wood care, to its main purpose cleaning guns! Any way I had some and used a small amount with a toothbrush and just gently rubbed the surface over and wiped off the dirty liquid with a paper towel. Just a word of caution, while it's safe to use, it does have a strange smell while using it that will not be liked by many, hence the reason for not using much of it. So no polish used, just a wash over with this cleaning oil - hopefully it looks good now, in keeping with its age?
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Circlip

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Re: Saving A Broken Saito V4PR?
« Reply #9 on: February 28, 2024, 03:08:27 pm »

Was the smell Ammonia? Old Witches brew for cleaning Brass clock plates and wheels is a combination of Ammonia, Soft soap and Distilled Water.


  Regards  Ian.
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DBS88

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Re: Saving A Broken Saito V4PR?
« Reply #10 on: February 29, 2024, 04:30:25 pm »

Ian, the smell from the Ballistol is not ammonia not sure how to describe it. Here are the details from the manufacturers. I have used it for the wooden handles on my kitchen knives, the decking on my rc yacht and for cleaning steam engines, all I can say is that it works, and when you read the info it seems like a wonder product


Ballistol Oil fluid is one of the few alkaline oils. It does not resinify even in decades, is complete biodegradable, skin-friendly and food-safe. Ballistol is a penetrating oil that creeps into the finest angles. Ballistol Oil cares all materials, lubricates, gives rust protection and is a potent agent for disinfection. As fluid Ballistol Oil is even more versatile applicable than a spray can. Whether to apply with a brush or for decant into an oiler. Ballistol Oil is for maintaining of metal, wood, leather, rubber, synthetic material, skin, animals' coat and much more. Ballistol Oil is ideally suited for handicraft, industry, agriculture, household, gardening, vehicles, fishing, hunting and shooting sports.
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KNO3

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Re: Saving A Broken Saito V4PR?
« Reply #11 on: March 12, 2024, 10:06:09 pm »

Very nice repair work, Dave!
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DHutch

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Re: Saving A Broken Saito V4PR?
« Reply #12 on: March 13, 2024, 04:44:56 pm »

What a lovely little thing!
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