[farhadtarapore]

Had a quick question regarding coolant top-up: where exactly to fill the coolant from ? There is a cap on the radiator and there is a small plastic knob on the front side of the petrol tank which says "Coolant". Couldn't find any Youtube videos which tells how to change or top-up coolant for the 2017 Duke 390. Any insights/pics would be immensely helpful! Thanks in advance.

[unk9ja]

Originally Posted by farhadtarapore

Had a quick question regarding coolant top-up: where exactly to fill the coolant from ? There is a cap on the radiator and there is a small plastic knob on the front side of the petrol tank which says "Coolant".

Topping up is done from the plastic cap near the petrol tank. That is what I seen guys at SVC doing. When the radiator is flushed, then they fill the coolant from the cap on the radiator and on slight overflow, the cap is closed and the remaining is dumped into the plastic container on the top. The min and max marks help you to top up the coolant, but it is advisable to fill it in between these. There are cases of overflow as mentioned in the earlier posts if it is filled to max.

[ShashankM]

Originally Posted by FlyingSpur

I borrowed a friend's 390 recently, and the bike was straight up spitting coolant all over the right side of the bike (and my leg). There was a leakage in the line supplying the engine and I heard it was a recurring issue. I can see how this info isn't a huge value add to your problem, but perhaps voicing it will catch the attention of other owners that are facing recurring issues and a solution can be found - I checked out of this 390 scene a while back when I sold mine, and haven't kept up with recent developments.

Cannot deny that It might have happened with a D390, especially if the bike in question is from an earlier batch, or it could have happened because of a shoddy servicing, however, mine is from the last batch of 2016 and I must say that it is a reliable machine. Proper service support is missing which eventually might result in these type of cases. Particularly in my case, with 18400 on odo, nothing has been done by service centre except fluid changes and some part replacement. This is first time I am facing some issue.

Today I went to service centre and the technician told me that the next thing they can do is to open up head and see if the head is ok or not. Now, this means engine needs to be removed and opened up to diagnose the problem.
So I have taken a bottle of readymade coolant to keep topping up until I have another opinion from some other service centre.

[ashwinprakas]

Originally Posted by ShashankM

Today I went to service centre and the technician told me that the next thing they can do is to open up head and see if the head is ok or not. Now, this means engine needs to be removed and opened up to diagnose the problem.
So I have taken a bottle of readymade coolant to keep topping up until I have another opinion from some other service centre.

I would suggest that you first diagnose where the coolant is vanishing to, if your head gasket is at fault then you'll notice emulsification in engine oil and white smoke from exhaust which would be more prominent at high revs.

If the head-gasket is not at fault then inspect the plumbing, every single bit of it and it wont hurt to proactively change them cause better spend a few hundreds doing that rather than spend thousands recovering from a seizure.

[VijayAnand1]

Originally Posted by ashwinprakas

I would suggest that you first diagnose where the coolant is vanishing to, if your head gasket is at fault then you'll notice emulsification in engine oil and white smoke from exhaust which would be more prominent at high revs.

If the head-gasket is not at fault then inspect the plumbing, every single bit of it and it wont hurt to proactively change them cause better spend a few hundreds doing that rather than spend thousands recovering from a seizure.

If he knows from where the coolant is evaporating or vanishing from, the user wouldn't have asked the question in the first place, don't you think Just kidding.

Originally Posted by ShashankM

...Recently, I had my ride serviced, it was first paid service. After the service I discovered that coolant level has been going down, I got it topped couple of times but the level keeps going down. Water pump and water pump seal was changed as part of first trobleshooting session recently. Still the problem persists. After a ride of approx 150 km the level went down by 5 to 6 mm. I nèed to go for another round of diagnosis now. From my side,
I have gone through some of the earlier discussions on this forum and checked couple of points.

1. Engine oil colour - Got it checked by technician who mentioned the colour is ok and do not see any engine oil - coolant mix problem. He checked oil colour at the drainage plug point.

===========

Need some expert suggestion on what should I do next as Service centre guys are in trial and error mode.

From your above post,

1. Engine oil colour - Got it checked by technician who mentioned the colour is ok and do not see any engine oil - coolant mix problem. He checked oil colour at the drainage plug point.

Though the mechanic checked the oil, the issue can be more sinister than it actually seems.

2. Frothing - I dont see any milky / white frothing from the oil observing glass. However, I do see dark brown froth inmediately after ride but it disappears when the bike is stand still for 15 seconds with engine running. Technician told me that, it could be because of water/water vapour but not coolant. I have attached a picture of the froth.

The mild frothing that you see is of no worry. Most Dukes do the same, but once the engine is warmed up, it should disappear. That layer of froth over the oil that you see is because of the engine oil being whipped by the clutch which momentarily causes to froth and should disappear once the engine is warmed up. If the froth layer stays irrespective of the engine's temperature condition, say after a long ride, we have a leaky coolant system.

3. Coolant leakage - I tried to check if there are any signs of visible coolant leakage but could not find any.

Sometimes mild coolant leakage can vaporize due to the engine heat when riding, or coolant leaks happen when the system is pressurized, which happens once the engine is on the move and a mild leak can go unnoticed. Just Murphy's Law.

4. Burnt coolant - There is no sweet smell of burnt coolant.

Burnt coolant smell would be similar to caramelized sugar, it can be confusing at time, and foul smelling at the same time. It's not always the right way to determine a coolant leak.

5. Exhaust check - Checked exhaust for any oil traces but it is clean and dry. Just 'traces' of black soot.

Again, unless it's a leak that is significant, coolant will almost instantly vaporize when it touches the exhaust system, due to the heat and all you'll be able to see touch and see is mild to medium carbon soot.

6. Radiator grill - I have attached a pic of radiator grill. Technician did not mention any problem with the grill so far but I do see linings bent. Can this be the cause of coolant disappearing?

Though your radiator fins are bent, the effective surface area is still in good shape, so there is absolutely nothing to worry. Your cooling efficiency won't take a hit or is it a cause of your coolant leak, unless there is a leak in the radiator itself or the tubes or the coolant reservoir

There are 2 more points that I want to mention related to the last paid service -

1. Some oil seepage was there from the top of the engine. Some bolt was tightened to fix this. The oil seepage thing was fixed but I felt some sort of 'tighness' in the engine after this.

2. When the bike was started for the first time after the wash, there was 'white smoke' from exhaust. It disappeared when the service supervisor revved the engine. I have checked for white smoke again during the cold start but I do not see any smoke, white or blue.

Need some expert suggestion on what should I do next as Service centre guys are in trial and error mode.

Most Dukes do weep some amount of oil from the valve cover. Usually, the SVC just tightens the valve cover and/or replace the gasket and it arrests the leak, it's become a trait of the motorcycle itself, these days. It has nothing to do with the engine performance.

The white smoke that you see can be of two types, either it's a water vapor which appears like steam and vanishes like steam. The other is a thick smelly smoke which comes at times during early morning starts or after wash due to rix mixture provided by the EFI itself which again is normal and this smoke vanishes once the engine is heated up.

If the white smoke appears after the engine has warmed up or after a ride, or when you rev the engine after a ride, we have a faulty piston ring set and or valve stem oil seal. But that's for another day.

Hope it helps!

Cheers!
VJ

[ashwinprakas]

Originally Posted by VijayAnand1

If he knows from where the coolant is evaporating or vanishing from, the user wouldn't have asked the question in the first place, don't you think Just kidding.

Ah! Missed the post where he said he'd already checked the obvious culprits. So I guess now safe to recommend changing the coolant cap.

[Gordon]

Originally Posted by ShashankM

........Recently, I had my ride serviced, it was first paid service. After the service I discovered that coolant level has been going down, I got it topped couple of times but the level keeps going down. Water pump and water pump seal was changed as part of first trobleshooting session recently. Still the problem persists. After a ride of approx 150 km the level went down by 5 to 6 mm. I nèed to go for another round of diagnosis now. From my side,
I have gone through some of the earlier discussions on this forum and checked couple of points.

1. Engine oil colour - Got it checked by technician who mentioned the colour is ok and do not see any engine oil - coolant mix problem. He checked oil colour at the drainage plug point.

=============

Need some expert suggestion on what should I do next as Service centre guys are in trial and error mode.

To summarize,
1. The coolant level in the top tank is decreasing. After every ride I'm assuming?
2. You tried topping it up, but still see decrease after every ride?
3. When cold, did you check the coolant level in the radiator itself?

During service, after the top coolant tank has been topped up, the radiator must also be filled completely. Did you check this?

[ShashankM]

Originally Posted by VijayAnand1

If he knows from where the coolant is evaporating or vanishing from, the user wouldn't have asked
...
Sometimes mild coolant leakage can vaporize due to the engine heat when riding, or coolant leaks happen when the system is pressurized, which happens once the engine is on the move and a mild leak can go
...
Again, unless it's a leak that is significant, coolant will almost instantly vaporize when it touches the exhaust system, due to the heat and all you'll be able to see touch and see is mild to medium carbon soot.
...
Though your radiator fins are bent, the effective surface area is still in good shape, so there is absolutely nothing to worry. Your cooling efficiency won't take a hit or is it a cause of your coolant leak, unless there is a leak in the radiator itself or the tubes or the coolant.

The white smoke that you see can be of two types, either it's a water vapor which appears like steam and vanishes like steam. The other is a thick smelly smoke which comes at times during early morning starts or after wash due to rix mixture provided by the EFI itself which again is normal and this smoke vanishes once the engine is heated up.

If the white smoke appears after the engine has warmed up or after a ride, or when you rev the engine after a ride, we have a faulty piston ring set and or valve stem oil seal. But that's for another day.

Hope it helps!

Cheers!
VJ

Thanks VJ.
I see following options now -
1. Invisible coolant leak which is very hard to detect.
2. There is no white smoke from the exhaust on cold start or during running.
3. Head gasket problem.

Originally Posted by Gordon

To summarize,
1. The coolant level in the top tank is decreasing. After every ride I'm assuming?
2. You tried topping it up, but still see decrease after every ride?
3. When cold, did you check the coolant level in the radiator itself?

During service, after the top coolant tank has been topped up, the radiator must also be filled completely. Did you check this?

Thanks Gordon.
1-yes
2-yes
3-No I have not checked the coolant level in radiator, rather I compared the coolant level in the reservoir.

Radiator was emptied and filled up again and I checked when the job was completed. Actually SC guy idled bike for half an hour and topped up coolant in reservoir. So, I see little to no chance that coolant refill was not done properly. Besides, I have again added coolant to half way of min-max to see it going down again. I mentioned some of the options above that I will try now. I am also thinking of getting the engine oil and oil filter changed to prevent any problem.

[unk9ja]

Can you check the following

1. If the drain plug is tightened and not leaking. FOr this you need to check the insides of the bottom cowl. If it is wet, then there is a leak from the drain plug. This will be flung off towards the rear wheel when you ride and leaves no trace behind.

2. When the radiator was filled, was the vent screw on the opposite side of the filling loosened/ removed and air let out completely. If not, then there is a chance that coolant level would go down as the air locks gets released.

3. How hot does your bike run? If the temperature bar on the console is always on the top, then there is a chance of evaporation of the coolant. This tends to happen during summer. In that case, you will have to top up the coolant but it is not often.

[Siddy]

Coolant woes!!

Okay, here is my experience.

I purchased my D390 back in June 2016, throughout the monsoon season the coolant level was perfect, did not move a mm. Moreover, rides during monsoon were pretty sedate as compared to rides during dry seasons, this could be a reason that the coolant did not evaporate.

October 2016 onwards I observed my coolant disappearing after weekend rides (typically when the bike was ridden at high speeds). City rides, taking the bike to work did not affect the level, reason could be less rpm less engine heat no evaporation. This story continues till date, I've purchased a Motul coolant bottle and top up every 600-1000 kms. I've got my head gasket changed, plumbing changed, bike checked thoroughly at least 5 times, checked the exhaust, oil color, clutch condition, leaks etc. Still the coolant level falls.

So, here's my conclusion. Duke 390 has a high compression engine, engine runs really hot, the bike has a weak radiator considering Indian weather conditions. Coolant gets evaporated when ridden fast or in heat for long hours. I've learnt to live with it, my bike has given no major issues apart from this in almost 2 years & 18,000 kms of ownership. She is still very punchy, very fast and reliable. Love her to the core!

[unk9ja]

A noob question, will a change of manufacturer do any good to this evaporation of coolant.

There are coolant available from Shell and Weurth. Anyone using it here, please share your views. Engine ice has mixed reviews and I think it is expensive proposition to try it out. So looking at around the same price as the stock Motul Inugel.

[nitninja]

Originally Posted by Siddy

Coolant woes!!

Okay, here is my experience.

I purchased my D390 back in June 2016, throughout the monsoon season the coolant level was perfect, did not move a mm. Moreover, rides during monsoon were pretty sedate as compared to rides during dry seasons, this could be a reason that the coolant did not evaporate.

October 2016 onwards I observed my coolant disappearing after weekend rides (typically when the bike was ridden at high speeds). City rides, taking the bike to work did not affect the level, reason could be less issues apart from this in almost 2 years & 18,000 kms of ownership. She is still very punchy, very fast and reliable. Love her to the core!

I had 2016 D390 and did almost 44k kms before i sold it off. Waterpump seals failed when the bike had done 8000 kms and the problem was solved at 13000 kms. Coolant level did not drop a bit till i hit 37000 kms, roughly around 24000 kms. So Coolant level dropping is not at all normal.

One of the 2017 D390 owner replaced a small seal inside the engine(no, not the water pump seal or head gasket) for the same coolant vanishing issue.His bike's coolant would go down in 600-800 kms, changing the seal solved the issue.

[Red Liner]

Originally Posted by unk9ja

A noob question, will a change of manufacturer do any good to this evaporation of coolant.

There are coolant available from Shell and Weurth. Anyone using it here, please share your views. Engine ice has mixed reviews and I think it is expensive proposition to try it out. So looking at around the same price as the stock Motul Inugel.

Castrol radicool heavy duty coolant, premix. Absolutely the way to go. Disappearing coolant is probably a deeper issue that needs investigation.

[ArizonaJim]

Have any of you with this vanishing coolant problem had your radiator cap replaced and if you did, did that reduce or eliminate the problem?

I ask because the radiator cap on water cooled systems has a pressure valve built into it. Its purpose is to keep the coolant inside the engine at a pressure that is higher than normal aptmospheric pressure. Often about 1 bar or 15 psi.

This higher pressure keeps the coolant from boiling until it reaches temperatures much higher than 100 C.

If the cap is defective and does not maintain the higher pressure, the coolant can boil, sometimes blowing some of the fluid out of the overflow bottle overflow tube or just evaporating into the air as steam.

This boiling would not show up on the temperature guage as being overly hot because temperatures of 100 C in a water cooled engine is in the upper normal range for water cooled engines.

Just as a low cost test, would one of you who is having this coolant problem replace or have your mechanic replace your bikes radiator cap with a brand new one?
I think we would all like to hear if a new cap fixes the problem and if it does, your problem will be gone.

[basuroy]

Speaking of coolant , mine went down by 50% over 6000km and was hovering around the minimum level mark before I topped it up . When I purchased the bike , it was above the maximum mark so that is quite a drop !!!