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Smoke from exhaust after oil change


Guest tsugha

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Guest tsugha

Hello there,

My bikes oil and filter recently changed in a service, they drained the bike and put new filter and 3.5 lt oil (motul 5100 10w40), a little smoke came off the exhaust when we start the bike, service said it will be gone in 100-200 kms. They didnt check the oil level with cap after change, asked them to do so, but replied they know how much it requires.

After leaving service, i started the bike again that evening, much more smoke came out, and smoke flow reduced once the engine is warm again. We checked the oil level and it was 6-7mm more than the high level mark. (bike was upright and engine was just warm and we didnt screw the stick while measuring).

1- have any one experienced how much mL excess oil it takes to make the level mark on stick that high.
2- i'm wondering if that amout of excess oil can hurt piston rings or valve guides or something to make the bike burn oil.
3- bike was drained in sidestand, is it enough to drain it properly to make it stand still while draining or moving bike left/right is required to fully drain the oil.
4- service claims that they didnt fill the bike more that it requires. they called the bike back after my complain and handed me later the day after, and when i check oil level again, it was between two lines. 

 

Bike is manual, 2016 nc750s, 35k km in odo. 

 

Video of bike, ambient temp is not cold, engine is just warmed, video is taken after they handed me the bike for the 2nd time (oil level is between 2 marks)

https://1drv.ms/v/s!AvvfQDfJeO9CgP8sPjZjOgpcLawXHA

i'm kinda in a trouble. Please share your experience.

Regards,
Tolga

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rjp996

Yep sounds like incorrect service procedure - steer clear of them in future...

drain with Bike upright else will leave more than normal in. 

Not checking the oil level after a fill is plane lazy... don’t use them again

 

way to much oil can cause issues with a wet sump engine - however from what you have said I would think the smoke will go now the correct level is in without further issues as you have not mentioned the engine running poor except the smoke. Just steer clear of them again, next time the lazy mechanic may forget to torque up you break capiler...

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Cannot help on 1 and 2 but...

3. I drain on sidestand and think that it s enough to let it stand still. There is no need to move bike from left to right

4. They wouldn't admit that they put excess oil, would they?

 

Some observations

i. 3.5l is already 100ml MORE than recommended by Honda for an oil AND filter change for a manual.

ii. Are you sure that they actually did change the oil filter? If they didn't, 3.5l is 400ml more than recommended.

 

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3 minutes ago, rjp996 said:

drain with Bike upright else will leave more than normal in. 

Beg to differ... drain on sidestand but check upright after 3min with engine running and 2min after those to let oil return back down... s said with dipstick not screwed

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SteveThackery

I wouldn't think you'd do any real damage by having too much oil in the engine, especially as it was "only" 6 - 7mm overfilled.

 

I must admit, though, it does look like an awful lot of smoke.  I think the only thing to do now is ride the bike for a while and see if it begins to reduce now that the level is correct.

 

Meanwhile, are you definitely sure it's oil smoke and not steam?

 

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Guest tsugha
1 hour ago, SteveThackery said:

I wouldn't think you'd do any real damage by having too much oil in the engine, especially as it was "only" 6 - 7mm overfilled.

 

I must admit, though, it does look like an awful lot of smoke.  I think the only thing to do now is ride the bike for a while and see if it begins to reduce now that the level is correct.

 

Meanwhile, are you definitely sure it's oil smoke and not steam?

 

 

smells like smoke, and it wouldn't make sense if it was coolant since amount of smoke flow reduces as the engine gets hotter.  and this smoke doesnt disapper in long term in a closed enclosure like garage, steam would condense and disappear.

and there is a huge air blow when i open the oil filling cap when bike runs idle. i say it is %90 piston rings but we will see once the engine is open

Edited by tsugha
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SteveThackery
11 minutes ago, tsugha said:

 

and there is a huge air blow when i open the oil filling cap when bike runs idle. i say it is %90 piston rings but we will see once the engine is open

 

Oh, sorry, I'd missed that bit.  I agree - with that much air blow it does sound like rings.

 

But I'd be amazed if over filling the oil could do that much damage.  Does anyone know of a mechanism?

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Don't judge it on what appears to be blowby coming from the dipstick hole with the stick removed. The geometry of the crank/pistons mean they will be pushing crankcase gas in/out of the hole in quite large volumes (nearly engine swept volume more or less), you won't be able to differentiate subjectively between in/out and net outflow.

 

If the oil level has been reset to the correct level and it runs OK then press on and use it. A little overfull is unlikely to have done any permanent damage, what it may have done is blown oil up into the airbox, which is where the normal blowby gas goes. If it has I'd expect the drain tube from the airbox to be full of oil. Take the plug out of the end (item 11) and catch how much comes out, if it's more than a few cc then I'd suggest having a look inside the airbox for excessive oil.

 

https://www.bike-parts-honda.com/honda-motorcycle/750-MOTO/NC/2015/NC750XAE/Frame/FRONT-COVER-AIR-CLEANER/71520/F_20/2/19332

FRONT-COVER-AIR-CLEANER-Honda-MOTO-750-NC-2015-NC750XAE-F_20.jpg.d5005b0fb75b66ea65ef997600081a14.jpg

 

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Guest tsugha
1 hour ago, embee said:

Don't judge it on what appears to be blowby coming from the dipstick hole with the stick removed. The geometry of the crank/pistons mean they will be pushing crankcase gas in/out of the hole in quite large volumes (nearly engine swept volume more or less), you won't be able to differentiate subjectively between in/out and net outflow.

 

If the oil level has been reset to the correct level and it runs OK then press on and use it. A little overfull is unlikely to have done any permanent damage, what it may have done is blown oil up into the airbox, which is where the normal blowby gas goes. If it has I'd expect the drain tube from the airbox to be full of oil. Take the plug out of the end (item 11) and catch how much comes out, if it's more than a few cc then I'd suggest having a look inside the airbox for excessive oil.

 

https://www.bike-parts-honda.com/honda-motorcycle/750-MOTO/NC/2015/NC750XAE/Frame/FRONT-COVER-AIR-CLEANER/71520/F_20/2/19332

FRONT-COVER-AIR-CLEANER-Honda-MOTO-750-NC-2015-NC750XAE-F_20.jpg.d5005b0fb75b66ea65ef997600081a14.jpg

 

 

actually we've opened the airbox just to check inside, there were some drops of oil here and there, but my own mechanic (not the one changed the oil) said that this amount shouldnt cause the smoke.But oil in airbox is also a sign of excess oil in bike.  can i reach the breather tube without removing any fairing? 

 

like i said, smoke amount is very high when the bike is cold, and only turns visible if i rev it high after it is hot. makes me think that piston rings causing the problem. what i can't understand if this amount of excess oil can hurt the rings. (either due to high pressure or oil got foamy& couldnt lubricate the rings. (which is the worst case here i believe))

 

can't assume it is head gaskets, foully sparks nor valve guides, cos smoke gets lesser when the engine is hot.

 

 

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EastSussexPete
8 hours ago, embee said:

Don't judge it on what appears to be blowby coming from the dipstick hole with the stick removed.

There is alot of pressure in the crankcase. I checked the oil level when on tour. 2 miles down the road the front of the bike was covered in an mist of oil. The dipstick was hoping up and down on its hole. This dipstick had forgotten to tighten it after the check.:doh: I was lucky. 

Edited by EastSussexPete
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TheEnglishman

If you're worried about knackered piston rings surely a simple compression test would confirm your supposition? 

 

Oil in the airbox shouldn't be a problem - I've had bikes running perfectly 60000 miles after over filling the oil quite a bit.

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As the pistons go up and down (only 90deg apart in the NC) they move a lot of gas, if the dipstick is out there will be a lot of reversing flow in/out. With other engine configurations with equal pistons going up/down, like a straight 4, this overall pulsing is minimal.

The actual blowby past the piston rings is quite small, for an engine like the NC I'd expect a net flow of something like 5 to 10 lt/min or thereabouts at maximum power, much less at lower speed/loads (a very rough rule of thumb is 0.5 to 1% of air flow). Technically legally there has to be a net negative pressure maintained in the crankcase, although with the pulsing it will be going above/below atmospheric.

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coopers12345
On ‎28‎/‎08‎/‎2018 at 06:45, rjp996 said:

drain with Bike upright else will leave more than normal in. 

 

 

How will draining with the bike upright result in more oil being left in it? The side stand is on the same side as the sump plug so the oil moves over to that side. Whenever possible I've always drained vehicles with them leaning over towards the sump plug to get as much oil out as I can.

However, when filling up I put in slightly less that the spec says and then check/top up until it's correct on the dipstick.

 

 

I'd have checked the oil level myself at the garage if they refused to, hell I'd have done it right in front of them, no arguments then about whether it was them or not. I've never known a mechanic not check the oil level on the dipstick after filling up, regardless of whether or not they 'know how much it requires.'

Out of interest was it an independent or a main dealer? Either way I wouldn't be using them again and if it's a dealer/chain I'd be passing a complaint up the ladder.

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