Mayonnaise in Oil breathers.

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alan s
RIP 2010
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Joined: 26 Jan 2001, 16:53
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Mayonnaise in Oil breathers.

Post by alan s »

I reckon you guys over there should refer to the period of time between about September & April as "Salad Days;" everything seems to be swimming in Mayonnaise
It doesn't have to be a blown head gasket, in fact in most cases it's not!
It is usually moisture contamination of oil vapour in the breathing system caused by condensation. The condensation comes about by cold air making contact with warm oil vapour, kind of like the fog you get if you breathe on a cold window. This then emulsifies with oil and the lot turns into this white milky mess that stinks like a sewer at times, clogs breathers & can create blockages. It's also worth remembering that it is water so not the best lubricant in the World & can cause major problems if too much gets into the oil supply or sump.
To successfully remove: Clean out as much of the breathing system as is practical. This may have to include the tappet cover in some instances (another place where it can accumulate) after which it is adviseable to do an oil & filter change, so it is adviseable costwise to do this at normal service time unless it's particularly bad.
The mineral oils seem more prone to moisture attraction than synthetics & semi synths, hence the use of those types is more recommended.
Cause and cure:It's long been accepted that short runs in cold weather are the cause of this problem. This is aided & abetted by the longer service intervals, mineral oils and motors running cooler than normal.
In practical terms though, it has to be remembered that the cars didn't do this when new and the fault whilst being reasonably common is not applicable to all cars hence, we need to look for the reason why or the fault that has caused it. Common makeshift cures include only doing long trips & reducing the number of short ones, increasing the number of oil & filter changes, altering the circuit of the breathing system as well as insulating parts of the breathing system all of which work to a degree but are really hiding symptoms rather than attcking the cause.
Experience has shown that thermostats in a lot of these cars are either faulty or inoperable and as a result the ability to claim that the car runs "cool as cucumber in Summer" is in fact a sign that the thermostat is either faulty or totally inoperative. The job of a thermostat is to hold the coolant within the motor until the recommended temperature is reached, whereupon it releases it into the radiator at which point it begins to circulate warm water throughout. This in reality takes minutes to achieve and doesn't require a 50 mile round trip, so in most cases a cheap little thermostat if replaced every two years will prevent future build ups; just remember to go through the process of properly removing the stuff in the first place, change oil & filter & see what happens. People who have always followed a routine change of thermostats tell me it's a problem they never have experienced.
Hope that explains it in (and not too much) detail.
Alan S