Another Douglas SV 54

I picked up this Douglas SV 54 LB recently.















It looks like it has sat for a while. The valves appear to be opening (as viewed from the adjustment chamber) but there is NO compression.

The carb is free and will clean up well. The Wico magneto is covered in oil and dirt but looks to be in good condition, just got to check for a spark.

The fuel tank is shot and will need to be replaced, the exhaust is non standard and there is no starting handle. More to come when I get the engine into the workshop.

The strip-down continues:























The Aluminium castings have a poor finish and hardly any original paint has survived but it looks like the engine was painted Black while the tin-work cowling was Blue.

There is a bit of carbon build up on the cylinder head (which I have already removed) and on the valves and piston. I was unable to remove the cylinder barrel by drawing it upwards as the piston got progressively tighter towards the bottom of the barrel for some reason, when I drain the oil I will have to open the crank inspection cover, remove the con rod from the big-end and push the piston out from the top of the barrel for the de-carbonizing to continue. I can also check for big and little end wear. I am hoping to be able to re-use the copper head gasket as it looks to be in good condition but I will anneal it before re-use as I don't know where to get spares for this engine.

More to come later.

They look like casting marks, after all it wasn't built as a high performance engine with mirror polished combustion chamber

Stuart

OK, so I removed the big end bearing which allowed me to separate the cylinder barrel from the engine but I have a problem. I still cannot remove the piston. If I try to remove it from the bottom of the barrel it gets so far then sticks solid, it's the same if I try to remove it from the top, it gets stuck just past TDC.

There is a 'very small' lip at the top of the bore and I have cleaned the area well, the same at the bottom. I think that because water has been present at some time one or more rings are stuck and because the bore is slightly smaller at the top and bottom of the piston travel it can't pass the slightly smaller diameter with a stuck ring (rings).

Could I use some 'persuasion' to force the piston out from the bottom or will I damage the piston/rings/barrel doing this? I don't want to break a piston ring as I don't know if they are still available.

Can anyone suggest a way of getting the piston out of the barrel.

I think I can remember Henry and Sam having the same problem with a motorcycle engine on the TV show 'Shed & Buried', in the end they used a piece of hardwood and a mallet to force the piston out of the bottom of the barrel.

The piston will not come any further out than this from the bottom.


The piston will not come any further out than this from the top.
 

The bottom of the barrel.


The top of the barrel.

Soak the top of the piston with penetrating fluid, Diesel etc. so it runs down the sides onto the rings, get the piston near the bottom and gently rock it side to side using the conrod, this may get the rings moving in their grooves and allow them to compress just enough to get them past the lip?.

Robotstar5 wrote:Soak the top of the piston with penetrating fluid, Diesel etc. so it runs down the sides onto the rings, get the piston near the bottom and gently rock it side to side using the conrod, this may get the rings moving in their grooves and allow them to compress just enough to get them past the lip?.

That did the trick!! after about one hour of gently rocking the piston it finally gave in! as suspected the top compression ring is seized solid in its groove the middle compression ring was stuck three quarters around but I managed to free it and the bottom oil ring was not not seized. Just got to free off the top ring and I'll be in business. I'll have to purchase a valve spring compressor, the type that just clamps on the coils of the spring to compress.

Put the head back on and the plug in turn thecylinder on its head and fill the bore with diesel and ley it soak it usually does the job.
Regards,
Chiefy.

chiefy wrote:Put the head back on and the plug in turn thecylinder on its head and fill the bore with diesel and ley it soak it usually does the job.
Regards,
Chiefy.

I managed to get the piston out today but will now have to soak it in Diesel to hopefully get the top ring to free up.

Garak wrote:

I'll have to purchase a valve spring compressor, the type that just clamps on the coils of the spring to compress.

https://www.buyamower.co.uk/product/briggs-stratton-valve-spring-compressor-19063.aspx

Woodsman wrote:

Garak wrote:

I'll have to purchase a valve spring compressor, the type that just clamps on the coils of the spring to compress.

https://www.buyamower.co.uk/product/briggs-stratton-valve-spring-compressor-19063.aspx

Thanks, just what I was after, I've ordered one.

Garak wrote:

chiefy wrote:Put the head back on and the plug in turn thecylinder on its head and fill the bore with diesel and ley it soak it usually does the job.
Regards,
Chiefy.

I managed to get the piston out today but will now have to soak it in Diesel to hopefully get the top ring to free up.

The piston has been soaking in Diesel for three days but the stuck top ring refuses to budge.







Has anyone got any other tips for releasing the stuck ring?

Evenly applied heat?, if the piston and rings are different materials they should expand at different rates and hopefully break the "sticktion"

Stuart.

I have freed a few ring by boiling in water. When you remove from water spray with wd40 and gently work on the ring. Then boil again Keep doing this. Good luck Arthur

Garak wrote:

Garak wrote:

chiefy wrote:Put the head back on and the plug in turn thecylinder on its head and fill the bore with diesel and ley it soak it usually does the job.
Regards,
Chiefy.

I managed to get the piston out today but will now have to soak it in Diesel to hopefully get the top ring to free up.

The piston has been soaking in Diesel for three days but the stuck top ring refuses to budge.







Has anyone got any other tips for releasing the stuck ring?

I agree heat usually does the job you need to be persistent though.
Regards,
Chiefy.

Agree - Propane (or butane) Plusgas (or diesel) and Patience

I ran out of the latter and bust two - I've managed to convince myself that they were already cracked.
Got new ones from Cox and Turner.

Garak wrote: .... and there is no starting handle.

Apologies - just re-read this thread.  I have one if you would like me to send pictures / dimensions

Woodsman wrote:Agree - Propane (or butane) Plusgas (or diesel) and Patience

I ran out of the latter and bust two - I've managed to convince myself that they were already cracked.
Got new ones from Cox and Turner.

I also had the same result after trying diesel, heat and gentle prying. I found this top ring was stuck with what looks like a combination of rust, Aluminium corrosion & lime-scale. I'm going to need to replace this one ring or get a new set. My piston crown is stamped +020" (I don't know if these rings were fitted at the factory or someone has refurbished the engine in the past). I have put the remaining ring squarely in the bore just under the slight wear line at the top of the piston travel and the ring end gap is 028"

This is the corrosion that had locked the ring in place.


Corrosion on the ring itself.


This is what I'm scraping out of the groove.


A gap of 028" between the ends of the ring in the wear zone at the top of travel.


Hepolite 9748 piston

As suggested before, get in touch with Cox & Turner. Pretty sure they will be able to help.

https://www.coxandturner.co.uk/piston-rings

Woodsman wrote:As suggested before, get in touch with Cox & Turner. Pretty sure they will be able to help.

https://www.coxandturner.co.uk/piston-rings

..........a new set of rings have been ordered.

As it was a nice day here in the Midlands, and as I had already prepared the main engine casing and other cast aluminium parts I decided to do some painting. Firstly a coat of etch primer followed by two coats of red oxide in preparation for the final colour, black.

The castings are very poor on this engine, roughly finished with only the minimum of clean up at the seams. I suppose just after the war these engines were being turned out at a fair lick and as the engine is mostly covered by cowling it did not matter if the castings were tidied up as they were rarely seen by the end user.

The tin work and the heavy steel castings I will be cleaning up and painting next while I wait for the engine parts to arrive. I am still going to need a fuel tank, exhaust flange, exhaust pipe and silencer and a starting handle and lastly some kind of trolley.

The fun continues.........

De-greased and prepared for paint.

Etch primed followed by two coats of red oxide

I see you use the "garden workshop" the same as me I too took advantage of today's weather to continue painting.

One comment on using masking tape, I've found it leaves a residue, particularly if left on a while so I've started using the proper Blue (or green) low tack decorators tape, it also has a better defined edge.

Stuart.

Painting continues, the engine casing is in black and the tin-work cowling I'm going to do in the same colour blue as it is in now, using my Paragon paints colour chart the colour is one of three, BS381C Azure Blue or RAL 5000, or BS4800 20 D 45.
My replacement piston rings arrived and have been gapped to the cylinder bore.

Casing in black





Cowling to tackle next.



Gapped the rings as per suppliers recommendation.

OK, so almost finished putting the Douglas back together. I've got to fit the magneto, flywheel, starter housing, carburettor with linkages & the cowling & exhaust. When I got the engine it had zero compression but after replacing the rings and re-grinding the valves I have compression once again. I'm going to wait until I have started the engine before I finish off the final paint touches (nuts, bolts, shut lines ETC) in case things have to be opened up again.

I've got an exhaust flange on order (the one with the engine had it's threads rusted away) from a Bamford engine as the mounting holes are the same distance apart. As I don't have an original silencer I've got to decide what type to purchase. I want to go for one that is as quiet as possible so if anyone has any recommendations they would be appreciated.

The Fleabay purchased starting handle should arrive soon and will require a little modification as it's outer diameter is slightly larger than the sleeve in the starter housing.

When I came to set the tappet clearances I realised that I was a spanner short. I bid not have a 1 1/18" (28mm) open ended so I took a trip to my local ex-military supplies depot and searched in all of the bins for a suitable spanner, unfortunately they did not have the size I needed but as I was leaving I noticed a box of bits with marked down items and in the bottom was an ex military 7/8" spanner marked with the arrow and embossed with the year 1953, the year I was born, so I had to have it. It quickly opened up to 1 1/8" using the bench grinder and I was able to set the tappets and it only cost £2, result!

I like the casing in black it should go nicely with the blue cowling.












I know!! the head looks like it's been finished in grey primer but
the tin of HT paint said 'Silver'!! (it won't be seen as its hidden inside
the cowling)


Flywheel & starter housing after rust treatment


A £2, 66 year old re-sized ex-military Dropstamco spanner

I like the gold lettering, nicely done.
Are you going to de-rust the head nuts ?

I must say that engine looks well! Re the rusty nuts I clean with a wire brush on bench grinder.Then warm with a gas torch and drop onto tin of old engine oil.This gives them a nice black finish. Of course referring to the the engine nuts! Arthur

blue cat wrote:I like the gold lettering, nicely done.
Are you going to de-rust the head nuts ?

I can't take credit for the lettering it's part of the casting, I just highlighted it with some gold leaf paste.

The so-far untreated nuts ETC will be sorted when I'm sure they don't have to be removed again.