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Discussion Starter · #1 ·
My mate bought one of the first 390's off the factory here and since some kids dropped his parked bike and damaged his radiator he had a new radiator installed by the SVC.

Since then, he has a mysterious issue of coolant disappearing but absolutely no leaks on the bike. The first time it happened after the radiator replacement, he took it in to the SVC for a dekko and they drained and rechecked his coolant system and proclaimed no leaks. Well, it just happened again last week and we took his bike in. Today they informed us that it was likely his head gasket as they refilled his coolant and confirmed the leaks after just a few Kms of riding.

Interestingly, another bike in there was being worked on for the same issue and the mech had just unmounted the engine. We can see the head gasket clearly in the 3rd pic, apparently the coolant is going inside the engine. I asked how the engine gave zero indication that it was burning coolant instead of fuel but got no real response. Just wanted to share and get opinions from the people on here about the issue.

Bonus pics of the Bajaj ECU diagnostic unit testing a D200, they use the same one for a 390 :)









 

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Maybe water pump seals

If not the head gasket, it is possibly the water pump seals. If the water pump seals are leaking a little it may not be obvious, as the oil will not show as emulsified (white / milky) unless heavy leakage. The engine will cook off the traces of water if the leak is small. If you remove the the clutch cover you may see a build up of frothy emulsified oil / water vapor mix. Water leaking from a head gasket usually goes directly into the combustion chamber. If after the head gasket has been changed you are still loosing coolant, check / change the water pump seals.

Good luck
 

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Discussion Starter · #3 ·
If not the head gasket, it is possibly the water pump seals. If the water pump seals are leaking a little it may not be obvious, as the oil will not show as emulsified (white / milky) unless heavy leakage. The engine will cook off the traces of water if the leak is small. If you remove the the clutch cover you may see a build up of frothy emulsified oil / water vapor mix. Water leaking from a head gasket usually goes directly into the combustion chamber. If after the head gasket has been changed you are still loosing coolant, check / change the water pump seals.

Good luck
Thanks, I'll confirm the SVC checks the clutch housing and change the water pump seals.
 

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Thanks, I'll confirm the SVC checks the clutch housing and change the water pump seals.
I had the same problem. I have already changed water pump seals. Here is the link to my post on TBHP about my the same problem.
The KTM Duke 390 Ownership Experience Thread - Page 148 - Team-BHP

Have done only 300 kms on the bike in the last couple of months but im still skeptical that it has been fixed as the coolant level has dropped again.

BTW i too am from Pune and get my bike serviced at Karve Road Service Center by Sachin.
 

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Discussion Starter · #5 ·
I had the same problem. I have already changed water pump seals. Here is the link to my post on TBHP about my the same problem.
The KTM Duke 390 Ownership Experience Thread - Page 148 - Team-BHP

Have done only 300 kms on the bike in the last couple of months but im still skeptical that it has been fixed as the coolant level has dropped again.

BTW i too am from Pune and get my bike serviced at Karve Road Service Center by Sachin.
Was your head gasket changed or just the water pump seals?
Mine's at SNK Wakdewadi, the mech's Prasad.
 

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Was your head gasket changed or just the water pump seals?
Mine's at SNK Wakdewadi, the mech's Prasad.
Just water pump seals. They said if coolant enters the combustion chamber then exhaust will emit white smoke. Since that wasnt the case they didnt change the head gasket.

In my case it was a slow leak, the coolant level would reach MIN after 600kms. Haven't ridden the bike a lot after changing water pump seals to check if it has been fixed.
 

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Discussion Starter · #7 ·
Just water pump seals. They said if coolant enters the combustion chamber then exhaust will emit white smoke. Since that wasnt the case they didnt change the head gasket.

In my case it was a slow leak, the coolant level would reach MIN after 600kms. Haven't ridden the bike a lot after changing water pump seals to check if it has been fixed.
So the SVC guy showed us a pic he took of the head with coolant all over it and deemed it a faulty head gasket which got replaced. They added coolant and it did not drop for a day at the SVC and they rode it around.
Fast forward a few days after taking the bike home, the coolant level has dropped considerably (we marked it on the reservoir).

So the only other place to look are the water pump seals? The owner isn't amused, keep in mind this is a bike from the first batch and was absolutely fine till they replaced the damaged factory fitted radiator.
 

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Did the engine get run dry or overheated at any point? If it was cooked theres a good chance the head can have a warp in it, no amount of gaskets can fix that.
 

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Discussion Starter · #9 ·
Did the engine get run dry or overheated at any point? If it was cooked theres a good chance the head can have a warp in it, no amount of gaskets can fix that.
No, nothing of the sort. Guess we can check for the head having a warp this time.
 

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Im having exactly the same issue, coolant gets used up super fast. I had waterpump issues and got a new pump fitted, less than a month later (maybe 300km) and its the same issue....
 
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