Author Topic: Excessive Residue/Carbon  (Read 2610 times)  Share 

0 Members and 1 Guest are viewing this topic.

Offline Brett

  • Global Moderator
  • Full Niva Petrol Head
  • ********
  • Join Date: Jul 2014
  • Posts: 121
  • Karma: 0
  • City: Durban
  • Country: South Africa
  • Province / State: KwaZulu-Natal
Excessive Residue/Carbon
« on: August 08, 2016, 08:17:39 am »
Good Morning LOCSA

I have recently moved and my vehicle now parks in a carport.  I have noticed a lot of black moist residue coming out of the exhaust and splatting onto the concrete floor.  What is the cause of this?  Is it something to with the Carb? I know its due for a service as I have only used carb cleaner and havn't overhauled the carb.

Please enlighten a lightie:)

Thanks

Offline Spikes

  • Veteran Niva Petrol Head
  • *****
  • Join Date: Jan 2014
  • Posts: 1,248
  • Karma: 5
  • NoNiva4me
  • City: White River
  • Country: South Africa
  • Province / State: Mpumalanga
Re: Excessive Residue/Carbon
« Reply #1 on: August 08, 2016, 08:26:32 am »
Its normal for a carburetor engine to spew black water out on start-up. It's due to the over rich fuel mixture with the choke out. Once at operating temp it may still spew out water or water vapour(mist) especially into the cold outside temps.

If it still spews out black water at operating temperature(choke closed), the idle solenoid may be allowing to rich a mixture.

Offline Brett

  • Global Moderator
  • Full Niva Petrol Head
  • ********
  • Join Date: Jul 2014
  • Posts: 121
  • Karma: 0
  • City: Durban
  • Country: South Africa
  • Province / State: KwaZulu-Natal
Re: Excessive Residue/Carbon
« Reply #2 on: August 08, 2016, 08:58:48 am »
Thanks for the reply.  I don't have a choke currently but I guess my dumbell on the peddle is making up for that.  Feeling a bit more at ease now, thanks again.

Offline Spikes

  • Veteran Niva Petrol Head
  • *****
  • Join Date: Jan 2014
  • Posts: 1,248
  • Karma: 5
  • NoNiva4me
  • City: White River
  • Country: South Africa
  • Province / State: Mpumalanga
Re: Excessive Residue/Carbon
« Reply #3 on: August 08, 2016, 09:08:17 am »
The catalytic converter (thats the very front silencer box) needs to warm up considerably to star capturing the Co particles. So if its not coughing black when warm and after a drive, don't worry about the start up. Its because you are using the weight to increase idle that you notice it. Normally a driver would get into the car, start and pull of.

Offline Danie

  • Veteran Niva Petrol Head
  • *****
  • Join Date: Feb 2014
  • Posts: 784
  • Karma: 5
  • City: Durban
  • Country: South Africa
  • Province / State: KZN
Re: Excessive Residue/Carbon
« Reply #4 on: August 09, 2016, 09:36:40 am »
Water dripping from an exhaust is quite normal during cold startups, specially during cold winter mornings like the current weather conditions. Black smoke with black splatter with petrol odour during startup is usually an indication that the fuel mixture is not 100% correct, or the air filter could be partly blocked. Once the engine warmed up properly, the black splatter should disappear completely.

White smoke /mist with white water drops is very normal during cold startups, and is just the result of condensation when the engine and exhaust are still cold. Once the engine and exhaust warmed up completely, the water drops will disappear completely. If the water drops do not disappear, the head gasket might be blown, or the cylinder head could be cracked.

Some times black smoke with black water drops could be a bit misleading, and might "hide" a water leak inside the engine.  I.e. - when the fuel mixture is not correct while there is a coolant leak at the cylinder head gasket  the smoke / water drops will still be black.

So you have enemies ?    Good.   That means you stood up for something, some time in your life  -  Winston Churchill.

You will never reach your destination if you stop to throw stones at every dog that barks  - Winston Churchill.

Offline Danie

  • Veteran Niva Petrol Head
  • *****
  • Join Date: Feb 2014
  • Posts: 784
  • Karma: 5
  • City: Durban
  • Country: South Africa
  • Province / State: KZN
Re: Excessive Residue/Carbon
« Reply #5 on: August 09, 2016, 04:33:32 pm »
Thanks for the reply.  I don't have a choke ............

Just another thought  - while you don't have a choke, I think it might make sense to remove the air filter cover at the top,  then just have a good look at the position of the "butterfly" valve which controls air flow through the carb. You might find that the butterfly is actually restricting normal air flow through the carb ....therefore the fuel mixture might be too rich.

So you have enemies ?    Good.   That means you stood up for something, some time in your life  -  Winston Churchill.

You will never reach your destination if you stop to throw stones at every dog that barks  - Winston Churchill.