Sludge in expansion vessel

[NH1]

Any pointers on this please chaps.


My friends Megan 1.4 petrol broke down today, it cut out and was difficult to start. He left it for half an hour and then managed to drive it to my house. There was no water in the expansion vessel but there was a lot of brown sludge present. It took probably a kettle plus of water to fill it up again.

I know it was still fairly hot but the second you started it the water bubbled and seemed to pressurise almost immediately. The fan didn't cut in though and the temp gauge stayed normal, he said this was the case even when it cut out, although I would have thought it must have cut out due to getting too hot.

I think the head gasket may have gone and is pressurising the coolant system up, however what I cant work out is if there is obviously oil in the water (the sludge floats on top) then why is there no water in the oil, the oil cap and inside is clean as a whistle.

The only other thing is apparently his girlfriend topped up the oil the other week, or maybe she topped up the water with oil?

[stevieturbo]

Have a competent mechanic look at it, trying to diagnose this from afar could lead to lots of wrong and pointless work.

[99hjhm]

There doesn't need to be all the symptoms of a head gasket failure. Often its just one. Oil runs at a much higher pressure than the cooling system too.

[NH1]

Thanks for the replies, I would class myself as competant, in the past I have changed an auto box on a series 3 jag, removed many engines, stripped down and rebuilt a ford 2.9 V6, done a few clutches, indeed I replaced a dual mass flywheel in a Mondeo of mine a couple of years ago etc. etc. So I think I will be able to help him if its a head gasket, I may have to get someone to do the timing on it though who has a locking kit.

99hjhm, I understand the head gasket doesn't have to blow between everything, it could just be between a cylinder and the water jacket etc, however if there is oil in the water it must have blown between them right? the coolant certainly seems to be pressurising up so it also must have blown to the cylinder, right again?
I know you said the oil is at a higher pressure than the water but would that still apply even though it is leaking via a cylinder?

[stevieturbo]

NH1 said:

Thanks for the replies, I would class myself as competant, in the past I have changed an auto box on a series 3 jag, removed many engines, stripped down and rebuilt a ford 2.9 V6, done a few clutches, indeed I replaced a dual mass flywheel in a Mondeo of mine a couple of years ago etc. etc. So I think I will be able to help him if its a head gasket, I may have to get someone to do the timing on it though who has a locking kit.

99hjhm, I understand the head gasket doesn't have to blow between everything, it could just be between a cylinder and the water jacket etc, however if there is oil in the water it must have blown between them right? the coolant certainly seems to be pressurising up so it also must have blown to the cylinder, right again?
I know you said the oil is at a higher pressure than the water but would that still apply even though it is leaking via a cylinder?

The term sludge is a little vague. Are you talking some mild mayo, lots of mayo, light brown, dark brown, ie quantity, a thick black sludge, or what ?

Is this sludge present only in the header, or in any hoses too ? How far does it go ?

Is there an oil cooler of any kind on the engine ?

And what were the circumstances of the engine stopping. This could be related to the sludge problem ( well...if it overheated to the point it virtually seized ) or it could be a totally different issue altogether.
So was the engine cooked too ?

Bare in mind if there has been no water in the engine, the temperature gauge cannot be relied upon.

The HG may have gone now, or before...but really, there could be many other problems too.

[paintman]

Disregard mayo in the oil filler cap. It isn't the surefire hgf indicator its cracked up to be. Very common in cold weather esp on cars that only do short journeys & I sometimes wonder how many people have been charged for unnecessary work as a result.
Are you losing water?
Brown sludge in the coolant header tank could be indicative - but some cars have an oil cooler in the radiator & if that fails then you could get oil in the water.
Bubbling & fizzing like a jacuzzi with the cap off & the engine running could also suggest hgf.
HGF does not necessarily result in water in the oil.
Get the coolant gases checked for the presence of exhaust gases like this:
http://www.youtube.com/watch?v=1_SIwHMLmkM&lis...
A positive result is NOT what you want!.
Check the plugs on a petrol vehicle, if one looks clean as new & the rest are normally fouled then that suggests a water leak into that cylinder - the water will effectively steam clean the cylinder.