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MG Midget and Sprite Technical - Manifold Gasket

Hi all sorry not rid of me yet.

just topping up the engine with oil for potential viewing and found it leaking out onto the inlet manifold.

just wondering if it was likely to be just a problem with the gasket?

also found these

and wondered if anyone has had dealings with swifttune or the product etc?
D Sartain

The intake/exhaust manifold gasket seals against air, not coolant or oil. If you have oil inside the intake manifold, the gasket is not the problem.

Les Bengtson

From your description, it sounds like the leak is from the cork rocker box cover gasket. Either the cork is damaged, or possibly just not seated correctly.

The gasket you link to is a manifold gasket, and not likely to be anything to do with the problem.
Guy W

Rocker cover gasket:
Guy W

thanks all and sorry for my mechanical noviceness. think it was a blind panic and the coincidence it leaked onto the inlet manifold. Since then found the rocker cover gasket damaged and has been replaced.

Once again thanks all.
D Sartain

As Guy notes, leaking rocker arm cover gaskets are fairly common and, since the oil leaks downwards and rearwards when driving, the source of the leak is not immediately obvious.

However, as I noted in my original post, the intake/exhaust manifold gasket does not seal for oil--it seals for air leaks. So do all of the other gaskets between the cylinder head and the air filters. For a rocker arm cover gasket leak to show up inside the intake manifold would require the oil to flow out of the rocker arm cover, down to the intake manifold, across the intake manifold, around the carbs, around the air filter housing, through the air filter, then into the intake manifold. Never seen such a thing happen in almost 50 years of driving these cars.

The most common source of oil inside the intake manifold is from the PCV system (depending on what model you have, and the year, these systems have varied significantly). The systems having a "mushroom" PCV valve on top of the intake manifold will begin to import a significant amount of oil when the rubber diaphragm fails. The system using a Y connector to go to both carbs will suck up a little oil, as fumes, on a regular basis. Systems using a connection from the PCV take off point on the engine and going to an air filter housing will also suck up some small amount of fumes which may be seen as oily residue in the intake manifold.

Thus, you have not found the source of the problem, nor do you know how much of a problem you actually have. Knowing the car and its production year (sometimes significantly different than its "first registered" year) would be of use in attempting to identify the actual cause of oil in the intake manifold. Also, the amount of oil present would be worth knowing. (Again, some PCV systems, factory and aftermarket, will allow a very small amount of residue to collect in the intake manifold.)

Les Bengtson

All true Les, but he never suggested that oil was appearing inside the inlet manifold. He says " leaking out ONTO the manifold"

Oil is just leaking past the cork gasket and running down the side of the head and appearing on the top of the manifold. Its no big deal - very common! :-)
Guy W

For a minute I thought Nigel had changed his name and moved to Arizona. LOL. Just kidding.
Bernie Higginson

This thread was discussed between 09/07/2015 and 13/07/2015

MG Midget and Sprite Technical index

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