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Restoration is now well under way.

One thing I have discovered which puzzles me is that the injectors appear to inject fuel twice for every revolution of the engine.

i.e. once at the top of the piston stroke and again at the bottom.

Is this the way any other 2 stroke semi diesels work?

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Restoration is now well under way.

One thing I have discovered which puzzles me is that the injectors appear to inject fuel twice for every revolution of the engine.

i.e. once at the top of the piston stroke and again at the bottom.

Is this the way any other 2 stroke semi diesels work?

Are you sure? If you inject at around BDC then half of the fuel injected will just pass straight out into the exhaust, until the piston has risen to the point where the exhaust port is closed. Any left at that stage would at least stay in the cylinder, but could ignite at any point in the stroke (depending on temperature etc), rather than the start of ignition being controlled by the injection timing.

 

If the two cylinders are 180 degrees apart then there will indeed be 2 injections per revolution, when one piston will be at the top and one at the bottom, but the injection should only be to the one at the top.

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Are you sure? If you inject at around BDC then half of the fuel injected will just pass straight out into the exhaust, until the piston has risen to the point where the exhaust port is closed. Any left at that stage would at least stay in the cylinder, but could ignite at any point in the stroke (depending on temperature etc), rather than the start of ignition being controlled by the injection timing.

 

 

 

Not so sure about that, it'll be a fairly long stroke engine with some sort of hot bulb combustion chamber at the top, with the fuel sprayed into that.

It does sound decidedly odd, though. Apart from anything else, the first spray of fuel will tend to cool the combustion chamber making it harder for the second to ignite.

 

Tim

 

Edit - reading through again, it's probably not truly a semi-diesel, rather a 2-stroke diesel with fairly low compression ratio (like the Field Marshall), so there won't be a 'hot bulb' in the head.

Edited by Timleech

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In a mad moment I recently bought this engine from Ebay

 

 

061.jpg

 

It is a "Van Rennes" two stroke semi diesel engine and gearbox. I am about to undertake a full restoration.

 

If anyone has any knowledge or info about Van Rennes, I would be very interested.

 

Rob

Nice!

Van Rennes were made by NV. Machinefabriek Drakenburgh, Utrecht. I doubt they're still going, but you might be able to trace lineage etc. and obtain further gen. They were mainly pump scavenged engines, rather than the more usual crankcase scavenged set-up and generally reckoned to be more efficient in both breathing and lubrication because of it. If it is one of these, one of the pistons will have a step in the underside to form a plunger, and this will operate the pump cylinder, which I would guess is what you see on the rear side of your engine. I would think the bore and stroke are both about 7.5", which would give you a displacement of about 5 litres a pot. It looks direct drive, so if it's about 10hp per pot=20hp at max revs of 475, you'd need something like a 26" blade. All somewhat educated guesswork, but I don't think that's far off the mark. There's one like yours in the Museum Nieuwe Niedorp, about an hour north of Amsterdam. Another museum worth a look, if it's still going, is 'T Werf Kromhout, in Amsterdam, on the Hoogte Kadijk. I speak a little Dutch, mainly to do with boats/engines, but should think "Bargemast" on here would assist you with any translation. Good luck with restoring her, it'll be worth it.

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I should have added, should this be a pump-scavenged system, that to avoid the "fire going out" on tickover, ie. unwanted cooling, the air supply to the pump can be choked, which evidently has the necessary warming effect.

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That is very nice, and asking for a big engine room. Perfect for a tug I would hazard.

 

If you need any help with Dutch translations, drop me a line.

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I don't yet know the bore...

You've bought a vintage semi-diesel marine engine...believe me you will very soon know plenty. wink.png

 

(With apologies to fellow vintage engine bores enthusiasts)

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Oops, I'm a numpty,

Checked again this morning and the reasoning I used yesterday was flawed, it only injects once per cylinder per rev.

I am aware of the engine at the Niewe Nierdorp museum, but it seems to have several differences.

I have however found one other the same as mine in a Dutch Barge moored on the Thames in London.

The boat was up for sale several years ago and the advert claimed the engine was 88 HP.

This seems plausible to me as the single cylinder Field Marshall is 40ish HP.

I have measured the capacity of the engine at a little over 13 litres.

The stepped piston system looks very clever with two banks of reed valves per cylinder.

Has anyone any suggestions how I can free one stuck piston ring on each cylinder (all the others are free)

I am nervous of rough treatment as I cannot risk breaking them!

Rob

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SNIP>

Has anyone any suggestions how I can free one stuck piston ring on each cylinder (all the others are free)

I am nervous of rough treatment as I cannot risk breaking them!

Rob

First soak the piston and ring in diesel (colour immaterial) for 24-48 hours. Whilst its soaking cut a piece of hardwood about 2 in long 1/2 in wide and slightly thinner than the ring. Using that as a drift and a small (toffee) hammer tap all round the ring and keep tapping away until it frees up. Start at the ring-gap if you can find it. You might need more than one bit of wood. Be gentle when the ring starts to move and keep the tapping as close as you can to the not moving bit. Scrub in diesel from time to time with a toothbrush.

 

Should disaster occur new rings in just about any size can be obtained quite easily- have a look at the suppliers list on the Internal Fire website, forum pages, or talk to Cox and Turner. They are not cheap but not ridiculously priced either.

 

N

 

 

ETA If the pistons are cast iron you can soak them in caustic soda/oven cleaner to break up the oily carbon but do NOT do this if the pistons are aluminium. Note also that since it's two-stroke there may well be pegs or other means of stopping the piston rings rotating to keep the ring gaps away from the ports.

 

 

N

Edited by BEngo

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In a mad moment I recently bought this engine from Ebay....

Excellent work! I have so far refrained from taking up such acquisition opportunities but I feel it may only be a matter of time!

 

 

There's this one on Youtube: http://youtu.be/2PAFsqR1PAs

I do like that staring arrangement!

 

If it is around the 80hp range then a small river or coastal vessel may be the best option... I recall the 4L3 in Parfield is a similar power, cracking bit of boat!

 

 

 

Daniel

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Only starts cold in a heat wave and then a bit reluctantly. Otherwise it needs starting with burning starting papers.

In the video it was started only a few hours after it had previously been running and was still warm.

Rob

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Only starts cold in a heat wave and then a bit reluctantly. Otherwise it needs starting with burning starting papers.

In the video it was started only a few hours after it had previously been running and was still warm.

Rob

 

Much like a Field-Marshall then ;)

They are usually regarded as being full diesels.

Lots of full diesels require preheating of some sort (including my car!). To be a semi-diesel AIUI it requires an uncooled combustion area for 'surface ignition' to take place rather than true Compression Ignition, though there are no doubt grey areas with engines which rely on hot spots to initiate combustion.

 

Tim

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Very nice, good Job ;0)

 

Does anyone have a home for this one below? Got offered it today, slight catch it is currently in Argentina. 1922 Gardner VT twin cylinder marine semi-diesel

 

gardnervt.jpg

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Very nice, good Job ;0)

 

Does anyone have a home for this one below? Got offered it today, slight catch it is currently in Argentina. 1922 Gardner VT twin cylinder marine semi-diesel

 

gardnervt.jpg

 

I might have been sorely tempted, a couple of years ago, when looking for motive power for my little tug, which started life with a 3J5. I decided in the end to go modern, with a 4LW (from about 1938).

 

Tim

 

Edit to add - about 3.5 tons for 54 bhp.

Full diesel, direct reversing, air start

 

Kennetengine-1_zpsca86cdcd.gif

 

Edited by Timleech

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I knew that somewhere among my books is a reference to different pressures etc in semi-and full-diesel engines.

I haven't found the refernce I was thinking of, but 'Marine Diesel Oil Engines' by J W M Sothern (undated, but written when air blast injection was still in use) has a table of pressures and other charachteristics for different engine types.

For compression pressures, it gives

petrol and paraffin engines as 80 - 90 lbs (presume psi)

Hot bulb or Semi-diesel 185 lbs

Full diesel 500 lbs

Doxford opposed piston 350 lbs

That last one struck me as a bit odd, but elsewhere in the book it says (slightly paraphrased) " that the Doxford engine can work on lower pressures because the heat retained in the two piston faces materially assists in the process of combustion.....and the Doxford engine is, to a limited extent, of the semi-diesel type"

 

Tim

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Timeleech, having thought about your comments, I think you are right. I thought the need for lit paper inserted to start the engine was an indicator that the engine was semi diesel. However once running and warm, compression alone is sufficient to cause ignition. Both the cylinders and heads are water cooled.

The tips of the paper holders may get hot and assist ignition, but not to the same extent as an uncooled cylinder head.

 

Martyn, your showing that Gardner was a bit cruel ., it would make a great project but not viable to import, but it is tempting.

 

Rob

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I might have been sorely tempted, a couple of years ago, when looking for motive power for my little tug, which started life with a 3J5. I decided in the end to go modern, with a 4LW (from about 1938).

 

Tim

 

Edit to add - about 3.5 tons for 54 bhp.

Full diesel, direct reversing, air start

 

Kennetengine-1_zpsca86cdcd.gif

 

 

IMG_4106.jpg

 

Its the one at Ellesmere Port museum. Reversible two stroke.

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Argentina, worth a try to look for freight I'm sure. Sometimes one can stumble on a reasonable deal. Ship it in a crate.

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Freight is easy enough as we ship in quite a few engines from overseas. The big problems are getting it crated and in to the hands of a freight forwarder and the extortionate cost of getting it across the quay side in the UK. The last time we shipped in a marine Gardner, a 2LW from Hong Kong the UK charges were more than the cost of purchase and shipping all around the world.

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