mayo in the oil filler neck...
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sawood12
New member
Totally normal on our cars. Keep an eye on the coolant level to check for HG problems, but if you are not loosing any water then Mayo in the filler cap is normal. It's to do with the long oil filler neck that feeds directly into the sump where condensation builds and drips into the oil.
Neil Haughey
New member
Agreed, I used to get this all the time when the S2 was my only car. However these days I don't tend to get this effect. I would pull the spark plugs out and have a look at the plugs. It is amazing how effective this is at showing up all kinds of problems. If you see one plug that looks wildly different to the others then I would get very worried, although it is possible that the one plug could have been loose. Actually it is a good idea to check the plugs every now and then anyway. Like Scott says first check the coolant, and its level.
As a side note I had a head gasket on a SAAB years ago that had slight blow on one cylinder. I didn't check the plugs, then it got worse, couldn't extract one of the plugs and the one on the next cylinder was destroyed (head fell off). The blown gasket caused the head to overheat cracking it and effectively making the cylinder head bin fodder.
As a side note I had a head gasket on a SAAB years ago that had slight blow on one cylinder. I didn't check the plugs, then it got worse, couldn't extract one of the plugs and the one on the next cylinder was destroyed (head fell off). The blown gasket caused the head to overheat cracking it and effectively making the cylinder head bin fodder.
George Elliott
New member
My 944T does this too.
I follow your theory Scott, but my A4 has a sump and a 4 cyl turbo engine but never does this, none of my previous mainly VAG 1.8 or 2.2 five cyl cars ever did it.
Do all 944's do it, or just most of them?? Is it after a certain mileage?
What is the cause? what is different to "any other" engine which I would regard as clapped if I saw this moisture/mayo in the filler neck.
My suspicion is that it is related to vastly poorer than average piston / bore sealing and a larger % of compression leakage than a "normal engine". (My 944T compression is 130psi per cyl +/- 1psi) Been the same for 30k miles.
I just ignore it.[8|]
But I am curious as to the reason why it is so common.
George
944T
I follow your theory Scott, but my A4 has a sump and a 4 cyl turbo engine but never does this, none of my previous mainly VAG 1.8 or 2.2 five cyl cars ever did it.
Do all 944's do it, or just most of them?? Is it after a certain mileage?
What is the cause? what is different to "any other" engine which I would regard as clapped if I saw this moisture/mayo in the filler neck.
My suspicion is that it is related to vastly poorer than average piston / bore sealing and a larger % of compression leakage than a "normal engine". (My 944T compression is 130psi per cyl +/- 1psi) Been the same for 30k miles.
I just ignore it.[8|]
But I am curious as to the reason why it is so common.
George
944T
Justin85
New member
The mayo is a result of oil and water vapours condensing on cold surfaces. Peugeot XU engines are notorious for it as the oil breather pipework and filler are isolated from engine heat and stay relatively cool. This is a filler from a very healthy 1.9 which had been used for longish runs over a winter;
http://i2.photobucket.com/albums/y25/dirtyflare/Mayonnaise.jpg
This water vapour comes from blow-by gases - the combustion mixture and its combustion products which get past the piston rings into the crank case. Water is one of the main products of burning hydrocarbon fuels, the other being carbon dioxide, so these gases contain a high proportion of water vapour. In cold weather and on short journeys, and on certain designs of breather/filler, the oil and water vapours condense where it meets cold surfaces such as the breather pipework.
HTH.
Justin.
http://i2.photobucket.com/albums/y25/dirtyflare/Mayonnaise.jpg
This water vapour comes from blow-by gases - the combustion mixture and its combustion products which get past the piston rings into the crank case. Water is one of the main products of burning hydrocarbon fuels, the other being carbon dioxide, so these gases contain a high proportion of water vapour. In cold weather and on short journeys, and on certain designs of breather/filler, the oil and water vapours condense where it meets cold surfaces such as the breather pipework.
HTH.
Justin.
Guest
New member
A likely cause (if it isn't condensation) is a leaking seal in the oil cooler. As you probably know, these cars use a water to oil heat exchanger to cool the oil. If the seal decides that it's time to leak, then you lose water into the oil (it doesn't tend to go the other way, because the waer system is running at pressure, so the water squirts through the hole in the gasket).
But as the others have said, it's most likely just condensation.
But as the others have said, it's most likely just condensation.
Diver944
Active member
If conditions and useage are right then I believe that all will do it.
The filler neck is uncommonly long on a 944 engine, is on the opposite side to the hot exhaust and is probably one of the coolest places in the engine bay so condensation will naturally form there.
My new engine with only 4000 miles on it is effectively blueprinted due to SimonPs obsessive attention to tolerances and it has a nice film of mayo on it's filler cap right now.
George Elliott
New member
As Scott said, its totally normal then. Thanks for all the comments.
I will continue to ignore it.
George
I will continue to ignore it.
George
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