mixture of oil or carbon build up with what appears to be radiator fluid

upon changing the valve cover gasket on my 04 aveo we noticed a "mystery hose" that has this oily, chunky sludge mixed with what looks like foamy radiator fluid coming out of it and into the valve cover!!! This concerns me, we have checked the oil and it doesnt appear there are any other fluids or substances in there other than oil. This "mystery hose" is located on the valve cover to this L-shaped port and is right next to the ignition coil, it appears to lead somewhere under the intake system. I even went to the dealership and they couldnt tell me what the hose was or where it connected to.

Basically, I would really like to know what the hell this hose is for & why it would be filled with that chunky sludge.

Is the chunky sludge like an off white/ grayish putty? Although its not directly related to your prob, from my experiences with dex cool any contaminants turn that orange crap into a toothpaste like putty. I hate it. Lets hope more of us chime in, as my year n mileage increase these things become more n more common.

"sounds like" the pcv system.

the sludge is basically formed from (lets not get too technical here there are a lot of reasons) but the engine spinning and the pistons going up and down and blow by of the rings... this plus the heat of the engine "vaporizes" some of the oil..

now in the old days this sludge would just build up in the engine, and hopefully be drained with the oil. And then the pressure was realized and the blocks were vented into the atmosphere. NOW emissions kicks in and what to run those vapors back through the intake so you burn them before the are released. The reason it goes into your valve cover is because in your car the design allows the engine to act (is some way) as its own catch can. So the "solids" can go back into the engine versus coating your intake, etc.

The sludge build up is from the cool down process after the engine runs, and those passages do not get hot enough for the sludge to revaporize but it does get warm enough for it to bake and become a more solid coating.

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Originally Posted by petrified.rabbit

"sounds like" the pcv system.

the sludge is basically formed from (lets not get too technical here there are a lot of reasons) but the engine spinning and the pistons going up and down and blow by of the rings... this plus the heat of the engine "vaporizes" some of the oil..

now in the old days this sludge would just build up in the engine, and hopefully be drained with the oil. And then the pressure was realized and the blocks were vented into the atmosphere. NOW emissions kicks in and what to run those vapors back through the intake so you burn them before the are released. The reason it goes into your valve cover is because in your car the design allows the engine to act (is some way) as its own catch can. So the "solids" can go back into the engine versus coating your intake, etc.

The sludge build up is from the cool down process after the engine runs, and those passages do not get hot enough for the sludge to revaporize but it does get warm enough for it to bake and become a more solid coating.

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Good advice (as usual from Rabbit). :thumbleft:

The only thing left to say is that you should clean the gunk out and put it back together. ;)

Great info- I read it twice. For those in the know is this just a matter of changing a hose or valve or do u dig deeper?

Well i rec

Well i just changed the pvc valve along with radiator, radiator hose, pkugs & wires, ignition coil pack & valve cover gasket. Now my car is heavily leaking whart looks and feels like oily water. I do know my exhaust manifold has a crack, coukd this be the culprit of leaking water? I was told the hose coming off that Lshaped valve was part of the exhaust system for recirculation, is this accurate? It seems like every time i fix a problem a new one arises. These are my first real problems with my aveo and im at 175k

Thanks for the responses

Have you replaced the POS plastic thermostat housing? If not, that's a usual suspect for coolant leaks. Go under the T-stat housing with gloved fingers to feel for leakage coming from under there. But you also did a lot of hose work as well, and it could be coming from lots of places, so you need to locate the exact source(s). Start from the drip underneath and work back up. Clean it all up first to make it easier to see the flow.

On the sludge, IMO this can be caused by either going too long on oil changes. and/or taking frequent short trips where the engine doesn't have a chance to warm up and burn off the crud. But your mileage would tend to rule out the later. Have you missed some oil changes at any point? I didn't see any sludge in mine when I replace the VC gasket, and the PCV valve had no deposits either and worked like it was still new. I do regular oil changes and take no short trips.