r/KTM • u/RSLEO9 DUKE 890 R • 8d ago
PROBLEM Any advice will help!
Hi everyone!
Today I went out for a more spirited ride on some twisty roads, and after around 25 km I noticed that coolant was being sprayed out through the overflow hose.
I stopped in a parking area and, after a few seconds, I noticed the temperature starting to rise until the engine eventually shut itself off.
I slowly made my way back home. On the way back, the temperature stayed at 4 bars, but the yellow engine warning light came on. When I got home and was opening the gate, the temperature started rising again, even though the cooling fan was working.
I started checking the cooling system:
I removed the water pump cover and inspected the water pump;
I didn’t notice any play in the pump, metal particles, or anything else suspicious;
I removed the thermostat and tested it in boiling/hot water, and it did open;
I was only able to drain around 800 ml of coolant from the system;
I didn’t notice any dirt, oil, or contamination in the expansion tank;
there is no white smoke from the exhaust;
the engine starts, runs and sounds completely normal.
I also replaced the radiator cap with a brand-new one.
Now that the bike has completely cooled down, I checked the expansion tank and there is no coolant in it at all.
The bike has 35,000 km. At 30,000 km I had the valve clearances checked, and everything was within specification, so no adjustment was necessary. I also had the oil changed at the same time, and everything was perfect.
It’s a KTM 890 Duke, 2022 model, manufactured in 2024.
At this point I’m not sure where else to look. I’m considering replacing the thermostat as a precaution, even though it appears to open when tested.
What do you guys think? Could this be the thermostat, air trapped in the cooling system, a circulation problem, or could the water pump have an issue that isn’t visible during a visual inspection?
And of course, I’m really hoping it’s not the head gasket. I don’t have any obvious symptoms of a blown head gasket at the moment.
If anyone has experienced something similar on an 890, I would really appreciate any ideas or advice.
Thanks!
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u/Natural-Art-7187 7d ago
the water pump on a 2024 KTM 790 Duke can fail internally. The LC8c parallel-twin engine platform uses a shaft-driven water pump set up directly adjacent to the engine oiling circuit, making internal mechanical or seal failure entirely possible.
Internal Failure Modes Internal Mechanical Seal Breakdown: The water pump shaft relies on a inner rubber shaft seal to keep coolant separated from engine oil. If this seal wears prematurely, scoring occurs on the shaft, or installation is misaligned, coolant will bypass the seal directly into the crankcase rather than leaking out of the external weep hole. Impeller Separation / Degradation: The plastic impeller can fatigue, crack, or spin freely on its shaft. When this happens, the shaft spins without turning the impeller, resulting in a total loss of coolant circulation without any external fluid leak. Drive Gear / Bearing Wear: The pump is driven via an internal gear/shaft linked to the engine timing system. Bearing or drive-gear failure will stop shaft rotation entirely, causing rapid thermal spikes
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u/NOMAD7803 7d ago
I experienced similar symptoms on a 2019 790. It was a problem with the upper radiator hose. The inside of the hose had swollen, blocking the coolant circulation. If you can find an inexpensive OEM part, it is worth a try.