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Mkiv Golf 4motion breather

Hello. The car is a 2003 2.8 v6 4motion golf and it has a leaky crank case breather tube (connects crank case to air intake, to consume fumes). The tu be is about a foot long, 25mm internal diameter and made of ribbed plastic that feels to be of a quality not dissimilar to a McDonald's drinking straw . Of course, VW wants 70 quid plus for this item.

I'm going to substitute the original breather for nitrile pipe. One issue t hat occurs to me is that the original has a section (an insert) with a whit e "nipple" that communicates with the atmosphere. It's only a small apertur e in the nipple (about 2mm), but I wonder whether I need to put this insert into my new nitrile pipe.

I'm not actually sure that the nipple should allow communication with the a tmosphere. Its appearance suggests that it might, at some point, have had a tube attached. That said, maybe it is simply an air bleed to prevent high vacuum arising within the breather tube and crankcase.

Any ideas? Is an air bleed normal within a crankcase ventilation system?

Thanks.

Terry.

Reply to
terry.shitcrumbs
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only if it leads to the air filter, all internal engine fumes are meant to go back and be burnt. Sounds like something is missing or disconnected. fit the new pipe and if all is well, running and fault light wise then ignore it.

Sometimes there are spurious connections that may be used in a different country to meet some local standard.

Reply to
MrCheerful

Perhaps it's a valve that allows for the pipe being at lower than atmospheric pressure under some circumstances, so that air can enter the system? If so, it is essential.

Chris

Reply to
Chris Whelan

In which case it would still be fed from the air filter.

Reply to
MrCheerful

You might be better off using silicone rather than nitrile, because of the engine compartment temperature. There's a wide range of tubing on eBay for petrol heads of various sorts.

You will need to pick something which won't "collapse" too much under the reduced pressure in the air filter.

Reply to
newshound

Thanks. I was thinking of resistance to the fumes (nitrile is better than silicone). Resistance to vacuum collapse is indeed important and a thin tube will be no good.

Regards.

Terry.

Reply to
terry.shitcrumbs

I know that the compatibility charts tend to give silicone a "2" for hydrocarbons, rather than "1" as given to nitrile, but I've never seen silcone obviously degraded in that chemical environment (whereas I have seen plenty of nitrile that has gone hard with heat). I've used silicone for replacement fuel pipe on chain saws, mowers, etc.

Reply to
newshound

Silicone hose for oily environment is supposed to be fluorocarbon lined.

Reply to
Peter Hill

Perhaps this is why the VAG item is £55.

I'm not really criticising, I am not in any position to give definitive advice for this application, just saying that the OP should be careful with nitrile assuming that this is a reasonably warm location.

That said, if the chosen material fails in (say) six months it is not really a disaster, the OP now has experience in selecting and fitting the replacement and can choose the next one accordingly.

The other thing I like about silicone is that it is more stretchy and flexible than nitrile, so easier to get into tight spaces, and less likely to get flattened by awkward kinks. But definitely horses for courses.

Reply to
newshound

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