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A Hyundai Sonata techie question?
Posted: Sat Apr 10, 2010 10:16 pm
by aitch
my wife runs a 2.5 litre petrol V6 hyandai sonata and the air filter housing keeps filling up with emgine oil.
I have drained and refilled the engine oil changing the oil filter and put in a new air filter but do any of you know if there is an engine breather that needs cleaning out?
or do you think it has a broken piston ring causing back pressure causing the air filter to fill with oil??
it runs fine and will cruise at 70mph with no problems and runs as sweet as anything but does burn a little smoky when first starting up for the first mile or so then no smoke at all,
sorry to ask this but my garage dont seem to have an answer and said it's not worth the expense of checking out anything as it;s an "old" car.!!!!
it's a V reg. with 82K on the clock
thanks for any advice.
Re: A not Bongo techie question?
Posted: Sat Apr 10, 2010 10:45 pm
by Bob
That is a mystery Aitch.
Not a great help, I know, but someone may have an idea, and at least your spanner man isn't changing everything in sight and charging you for it.
Re: A not Bongo techie question?
Posted: Sat Apr 10, 2010 11:31 pm
by mikeonb4c
May sound daft but would a K&N filter help? If it clogs you just clean it with petrol and let it re-oil itself. As long as the car stays running happily.......

Re: A not Bongo techie question?
Posted: Sat Apr 10, 2010 11:38 pm
by Simon Jones
Re: A not Bongo techie question?
Posted: Sun Apr 11, 2010 12:35 am
by Northern Bongolow
just a stab really but i would look around the egr side or breathing side,or the bit where you say smoking for the 1st mile could point to valves/valve seal/seats
dont know if this will help. when you stop the engine after running it,the rocker oil runs down the valve stem into the valve area then burnt off next time it is started up.
Re: A not Bongo techie question?
Posted: Sun Apr 11, 2010 11:12 am
by rita
Hi aitch ,
Does this model have a breather tube attatched to the air filter housing.
It could be that the engine is gassing,check for another breather on the crank case.
Re: A not Bongo techie question?
Posted: Sun Apr 11, 2010 11:44 am
by francophile1947
I'm afraid that's a classic sign of combustion gasses getting past the piston rings and pressurising the sump. Oil mist is then blown out of the breather into the air filter.
If it runs OK, just disconnect the breather pipe and extend it down the side of the engine - not exactly good from a pollution point of view (and may even be illegal nowadays

), but it worked for me on an old Anglia

Re: A not Bongo techie question?
Posted: Sun Apr 11, 2010 8:37 pm
by Northern Bongolow
my mate had a tuscan that had the same issue,i talked to him about it after i read your post,
he took it to hyundai to sort it, they couldnt,he after weeks found what it was.
large 2 or 3 inch pipe runs from bulk head side of engine top(black textured finish on it) runs under air filter housing towards front nearside headlight area.Under the airbox there is a bracket/mounting for the pipe to body,pipe was fractured around this bracket had to remove coating on pipe to see it though,cleaned up repaired using haroldite no problems and a clean air filter ever since.Engine moving/rocking, pipe mounting not moving somethings gona break
hope this may help
regards ady
pm me and we can talk on phone if you wish
Re: A not Bongo techie question?
Posted: Tue Apr 13, 2010 9:19 pm
by aitch
Thanks for all the replies - still trying to get around looking for a breather pipe from the crankcase - cannot see or feel one!!!
been onto the sonata owners site but have recieved no replies (not even a welcome message) not as friendly as on here!!!!
will keep looking and topping up the oil on a regular basis and I must try and clean up the road spills outside the house before the local council sees all that oil and charge me for the mess

Re: A not Bongo techie question?
Posted: Tue Apr 13, 2010 10:20 pm
by Rhinoman
On some vehicles the breather pipe has a one-way valve (PCV = Positive Crankcase Ventilation) on it that sometimes sticks and can cause similar problems.