Classic cars forum & vehicle restoration.
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RPisarski
Joined: 10 May 2011
Posts: 1
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 Posted: Tue May 10, 2011 5:12 pm Post subject: Head Gasket? |
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I have a 1948 Alvis TA14 which runs reasonably well, however the other day I noticed some "mayonnaise" under the oil cap, it also consumes water very quickly.
I ran a compression test on the cylinders and got a reasonably even result 100 to just over 110 psi across all 4 cylinders.
It could be my imagination but it does also look as though there are signs of leaking from the head gasket line around the engine. Above is clean, below oily.
Finally when I took out the spark plugs numbers 1 to 3 were dark/a bit oily perhaps but number 4 was absolutely bone dry and tan coloured – I suspect this is unrelated to the above issue.
I'm pulling the engine to replace the clutch this weekend so I had three queries:
Firstly does anyone know what would be a reasonable value for an Alvis in terms of compression; 100 psi seems low but then its an older car.
Should I be thinking about a head gasket replacement?
On spark plug number 4 any reasons why it should be so different. It's a single SU carb and there's a good spark to that cylinder. Compression was just over 100 psi
Many thanks
Richard |
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Inglewood
Joined: 28 Dec 2010
Posts: 183
Location: Stone, Staffordshire
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| Posted: Tue May 10, 2011 5:59 pm Post subject: |
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Main concern on compressions would be if one cylinder is lower than the rest.
The head gasket can leak oil into the water or vice-versa without affecting compressions but the cure is the same - replace the head gasket but inspect the head for cracks whilst it is off
The spark plug colour is likely to be due to mixture or heat. The rear cylinder will be the hottest if the cooling is compromsed |
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Ray the rocker
Joined: 01 Aug 2008
Posts: 187
Location: south wales
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| Posted: Tue May 10, 2011 10:11 pm Post subject: post subject |
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Mayo is normally attributed to bad breathing--especially if the are no signs of water pressure to push out via the head gasket..I`d check any breather piping for internal collapse or blockage.
Cheers--Ray the Rocker... |
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Jim.Walker
Joined: 27 Dec 2008
Posts: 1229
Location: Chesterfield
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| Posted: Wed May 11, 2011 9:02 am Post subject: Re: post subject |
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| Ray the rocker wrote: | Mayo is normally attributed to bad breathing--especially if the are no signs of water pressure to push out via the head gasket..I`d check any breather piping for internal collapse or blockage.
Cheers--Ray the Rocker... |
The white sludge (Mayo?) is simply water sludge, an amalgamation of water and engine oil. Unfortunately, every gallon of petrol burnt produces a gallon of water. Inevitably, some of this will get past the rings and mix with the oil. So even if there is no internal water leak the oil is exposed to water.
Cars which do infrequent and short journeys often suffer from it because the engine never gets hot enough to clear it. It looks unsightly when the engine is stripped, but does no harm.
Many years ago I had a Morris Oxford which always collected quite a quantity in the rocker box. As an experiment I lagged the rocker box with felt. Hey Presto! The water sludge disappeared!
Jim.
_________________
Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then! |
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