My Junior Rotax Engine Leaked Coolant and Overheated and Seized

My Junior Rotax was slowly leaking coolant from the radiator and then overheated and seized.The orange ring on the cylinder head was melted so i replaced that.I believed i had solved and then found out the engine was leaking and i had lost compression.Although i think it is this and have had other mechanics check it,i want to know if it could be anything else.

Have a reliable kart mechanic look at the engine. If the piston was seized in the cylinder, there is possibly/probably damage to the cylinder, piston, ring, bearings at both ends of the rod and the water pump.

is it seized if the piston still moves.

It can be yes. Sometimes it will sieze when warm then release, but damage would still be present.

Does your engine have to be sealed or are you just using it for laps?

I seized the same Leopard three times in one day once. Kept shutting off on me on the straight and then I’d coast back, fire it up again and go. Third time it didn’t let me coast anymore…

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take it to an engine builder. Simple as that. Needs a thorough overhaul.

Do you have any rough estimates of the cost?

The engine builder should be able to take a look and see what actually needs to be done and then can give you a price.

i have found a freshly rebuilt short engine with a L9 Barrel (dont know whether its good) for cheap (£200) and running and am not sure whether to repair my current one( quick even on full pre evo ancillaries) or just get a new used engine.

If the 200 GBP short block is truly fresh (which is hard to believe as it’s so cheap) buy that rather than rebuilding the damaged motor. A rebuild on a seized motor will likely be more than 1,000 GBP.

Sorry to keep pestering everyone

I have found a sealed Junior Rotax with a ML Barrel (I believe 2011) for £375 is this worth it.It has ran for 12 hours.

You never know with used engines…how do you know it’s actually 12hours?

I think i will get a donor engine and keep testing to make sure it is running and putting out power.

Harry since you’re from the UK, find the numbers for JAG …they are the UK importer for rotax and with the engine number of any rotax sold in the UK they can verify any claims on work done to it (once it was done by a rotax certified sealing agent)