oil filler cap

[wildgu6]

Hi guys, Dumb Q' time,
Can anyone tell me why the trol is blowing oil residue out the oil filler cap, only just noticed it when lifted bonnet to replace radiator overflow tank, not sure how long been going on. Also quite a bit of oil residue in the intercooler as well.????

Cheers Pete

[Dhuck]

Sound like you might have a little blow-by


What is Blow-by?

Blow-by occurs when the explosion that occurs in your engine's combustion chamber causes fuel, air and moisture to be forced past the rings into the crankcase. Your engine's rings must maintain an excellent fit in order to contain the pressure.

The causes of blow-by: wear, soot and deposits

As rings and cylinder liners wear away they are less capable of maintaining this seal. Consequently as a car ages the amount of blow-by that occurs can increase.
Soot and deposits left over from incomplete combustion that collect on the rings can also inhibit their seal worsening blow-by.

The effects of blow-by: loss of horsepower and oil contamination and dilution

Blow-by inhibits performance because it results in a loss of compression. When the expanding gases slip past the rings they cannot as effectively push the piston down and make the vehicle go. As a result the car will have less horsepower. This also results in a loss of fuel economy.

When the fuel, air and moisture slip into the crankcase they contaminate and dilute the oil in the crankcase.

Among the many gasses in your compression chamber are unburned fuel, moisture, sulfur dioxide and soot. Once these gasses slip into your crankcase they can dilute into your engine causing great damage.

The detergents and Molybdenum Disulfide work together to clean the soot and deposits off of your rings allowing them to better seal the combustion chamber.

The Moly fills the crevices in the cylinder walls providing a better seal:

Less blow-by means less contamination, less fuel dilution, and more power.

[wildgu6]

well thank you for that Dhucky, Much appreciated mate,
So what preventative measures should i take to avoid a costly outcome.

[Silver]

do diesels like petrol engines have positive crank case ventilation? If they do would be worth checking the valve and the pad inside the aircleaner.

[Dhuck]

well thank you for that Dhucky, Much appreciated mate,
So what preventative measures should i take to avoid a costly outcome.

The only fix I know of is new rings. But I am not sure if there are any other fixes for a diesel.


do diesels like petrol engines have positive crank case ventilation? If they do would be worth checking the valve and the pad inside the aircleaner.

Would not have a clue. I have only ever played with petrol and methanol engines.

[the ferret]

Mate, for starters, check the seal on the cap. check operation of the PCV system, If it has only just started doing this all of a sudden, it may be something simple.
But as DHUCK said, it's usually an indication of blowby, this can be caused by gummed up rings, glazed bores, broken ring, or just plain worn out.
Glazed bores is caused by not working it hard enough.
Cheers, the ferret.

[wildgu6]

do diesels like petrol engines have positive crank case ventilation? If they do would be worth checking the valve and the pad inside the aircleaner.

???????????? not sure mate will look into it


The only fix I know of is new rings. But I am not sure if there are any other fixes for a diesel.

Bugger, knew you were going to say that, thanks guys

[patch697]

The "O" ring in the oil cap could just be screwed.

[MudRunnerTD]

Glazed bores is caused by not working it hard enough.

Or go out with a smile Wild and see if ya cant clean her out mate ;)



on a side note hope it is not something terminal mate.check your PCV and maybe think about a Provent or something... Not a Solution but might be part of your management regime.. good luck

[wildgu6]

Mate, for starters, check the seal on the cap. check operation of the PCV system, If it has only just started doing this all of a sudden, it may be something simple.

Glazed bores is caused by not working it hard enough.
Cheers, the ferret.


Thanks Rod, will have a look, as said only just noticed it happening, and last time i topped up oil it felt like cap didnt screw on as usual.
Tried it several times with same result, but always in a hurry.
Might sus it out a bit closer, hopefully thats all it is.
As for not working hard enough...Ha I dont think thats the prob' but thanks for the feedback mate.