DBA Forum (B) - Chris Roy
2014-10-22 09:00:40 UTC
Having problems with my CAV pump so sent it back to the people who refurbished it 2 years ago.
They cannot find anything wrong with it, so I am posting the symptoms here in the hope that someone might have a solution.
After about 1 hour of running, the engine starts to hunt. i.e. From 900rpm the engine revs increase to around 1,000 then back to 900.
This happens rhythmically with about 1 second between each cycle.
When the engine is stopped, the oil overflow drips for a short time.
I have noticed that the governor chamber has diesel in it on the venturi tube side of the leather diaphragm. Which leads me to think the problem is that the movement of the diaphragm is being muffled by the diesel in the chamber.
Also, on the day I ran my air cooled generator in the engine room for 5 hours (Heavy washing machine day) and then started the engine the problem occurred without any delay. Possibly because the engine had by then been preheated by the generator to a temperature similar to that achieved after 1 hours running. So heat seems to be a major factor.
Fuel filters have been changed.
Fuel is new, not old and therefore not degraded.
Colchester fuels have checked:
The diaphragm does not leak air.
The actual fuel pump is sound.
Bench test gives no problems.
Any ideas.
Anyone?
Regards
Chris Roy
They cannot find anything wrong with it, so I am posting the symptoms here in the hope that someone might have a solution.
After about 1 hour of running, the engine starts to hunt. i.e. From 900rpm the engine revs increase to around 1,000 then back to 900.
This happens rhythmically with about 1 second between each cycle.
When the engine is stopped, the oil overflow drips for a short time.
I have noticed that the governor chamber has diesel in it on the venturi tube side of the leather diaphragm. Which leads me to think the problem is that the movement of the diaphragm is being muffled by the diesel in the chamber.
Also, on the day I ran my air cooled generator in the engine room for 5 hours (Heavy washing machine day) and then started the engine the problem occurred without any delay. Possibly because the engine had by then been preheated by the generator to a temperature similar to that achieved after 1 hours running. So heat seems to be a major factor.
Fuel filters have been changed.
Fuel is new, not old and therefore not degraded.
Colchester fuels have checked:
The diaphragm does not leak air.
The actual fuel pump is sound.
Bench test gives no problems.
Any ideas.
Anyone?
Regards
Chris Roy