1949 Inter left standing has seized

Back in the olden days (pre WW1) engines typically had a decompressor valve on top of the cylinder head  which incorporated an opening to allow the owner to inject paraffin into the cylinder to unstick the oil which had congealed overnight. Perhaps a bit of paraffin (kerosene for our American friends) down the plug hole for a day or two might help?

I believe Bugatti owners in cooler climes were instructed to drain the oil and warm it in a pan over the kitchen stove before trying to start the engine.

Old Castrol R could set solid by oxidising over a period of time.  Modern oils have de-oxidents to prevent or at least delay that.  My Inter spent several years (in a garage in a house) with 'R' in the tank, and with no problems.  Biggest drawbacks with castor oil are...cost (£55 to £75 for 5 litres...not good if the engine leaks...), also getting hold of oil to top up the tank if you are far from home  and of course cleaning it out before changing to mineral oil.

Ps..if it gets baked onto your shiny silencer, caustic soda will remove it...with care!!

A friend of mine freed a stationary engine by smashing up a spark plug until he had just the hollow steel main body, and then drilling and tapping that to take a grease nipple. Then he pumped the cylinder up with grease and left it 24 hours, then pumped it again, within about 3 days it had freed off, then he dissolved the grease with petrol and drew it out with a horse syringe.

It smoked impressively for a few minutes but otherwise showed no ill-effect.

If you switch to mineral oil, you must strip the engine and clean out every trace of 'R'.

As you are on one TDC or the other, carefully lever the valve stems to confirm they are free (minimal movement)… Guess they are…

Plug out,  spray some Paraffin on the piston.  Get to the point you can rock the crankshaft backwards and forwards…

Warm your barrel and casings indirectly, hair drier will do.  Now drain sump, keeping heat in the cases and barrel.  Warm some castor oil and coat the piston top.   Now rock the crank in both directions.    

After twelve months it should not be that stuck! If it frees move it in both directions only a short distance and listen. Clicking or scraping? Just move it to the bottom of stroke and spray some oil in again to coat the bore before you come back up. By keeping the crank at TDC to reduce the drain down you also pressure the rings; just release the plug to take that pressure off and rotate the crank off a little.

I keep my Inter MS on a fish tank warmer pad during winter. Not had issues with seizing.

cheers

jon

I spoke to Castrol about switching from R to mineral oil, and vice Versa, they say just do a few flushes and it will be fine…. I didn’t do it but don’t have any reason not to believe them.

As for freeing the engine I expect the rings have attached to the barrel or the piston has gummed up, I’d poor petrol in and leave it for a few days and try again. Back in the day we’d tow it and drop the clutch, but then we were riding old dogs!

I don't think petrol is much good  to disolve  R.      I certainly would not want to take Castrols advice .    The R is likely to go lumpy and block oilways if mixed. with mineral   Will castrol pay for a wrecked big end ?.

I run my 2 Strokes on R, it dissolves fine! After all it dissolves just about everything else ;-)

Hi Robert,

   A possible reason is the cylinder bore and rings have rusted together due to condesation when the engine cooled down. Try all the things Jon advises, but if this doesn't work you will need to lift the head to find out the cause. If you do need to disolve vegetable oil deposits, try acetone which is easily available as false finger nail remover. Make sure its 100% acetone strength.

   Other brands of castor oil are available and are cheaper than Castrol R, but don't smell the same. You can always put a small quantity of R in the petrol for the aroma.

Just BTW, I left mine for 2 years over lock-down, and it started 2nd kick.

......that it may be sumped up and is hydraulically locked? Doesn't seem like there's enough oil in the tank to do that but it's easy to check.

... I would definitely remove the head at least. The risk of "freeing it" without attending to the underlying problem would be too great for me to accept.