Engine Oil Leak

[Boomlander]

Seem to be losing oil from the rear of the engine, looks to be just below cylinder head level although as with most leaks the source is not immediately obvious.
Are there any suspect areas that spring to mind?
Also waiting for a replacement petrol pump as that started leaking in sympathy with the damn engine!

[bmcecosse]

There is no oil leak potential 'just below the cylinder head' at the back of the engine - so it's likely to be running down from the rocker cover gasket. And you should be able to seal up the petrol pump - where is the leak? Very unusual for them to suddenly start leaking!

[Boomlander]

The fuel pump is damp with petrol at the bottom of the joint in the housing where the diaphragm is located, it is not flooding out but obviously any petrol leak under the bonnet could be catastrophic if left unchecked.
As you rightly say it is unusual for the pump to leak but I don't know how old the unit is - it could be original (1953) and the diaphragm may be perished. It seems to be working normally though.

[Boomlander]

Managed to get a photo of the oil leak area - is it possible that the leak is coming from the rocker cover and not the cylinder head? Sorry for ignorance but I'm a little concerned. [frame][/frame]

[JOWETTJAVELIN]

You need to determine whether it's water from the heater tap or oil. Rub your finger in it and smell it, should be obvious then whether it is oil or water. Also oil would leave a black mark. Note however both will feel slippery when rubbed between forefinger and thumb due to the antifreeze.

Check your heater tap for leaks.
Check tappet chest cover.
Check rocker gasket.
Check water level in rad and how often you have to top it up.

Hope this helps.

[Boomlander]

Many thanks for the advice folks,
The leak is definitely clean oil and there is no sign of it above the black plate on the side of the engine (tappet chest cover?),
Rocker cover seal is dry as well as the heater valve and block drain tap.
I assume that there is a gasket behind the black plate that is failing.
As for the fuel pump it now seems to be worsening as the pump is clicking continuously as if there is an air leak and it is still weeping fuel, I am expecting a working replacement any time now or I may bite the bullet and order a brand new one to be on the safe side.

[Boomlander]

Is it necessary to drain all the oil to replace tappet chest cover gaskets?

[brucek]

You don't need to drain the oil at all to replace the tappet chest gaskets. Oil will settle at the lowest point (the sump) and whilst there may be some residual oil in the tappet oil gallery it will only be a small amount and can easily be caught in a clean rag. Might be worth looking at how hard the cork rocker cover gasket is too - if this is hardened it may not seal well. Over time they do tend to go quite hard and lose their sealing capability.

[bmcecosse]

There is also a seal under the head of the bolt securing the tappet chest cover - so check/renew that too. You had said the leak was at the back of the engine - the leak you show is at the side - towards the rear admittedly......

[Boomlander]

Thanks for the information guys,
Gaskets on order from ESM, just hope the weather stays dry so I can work on the engine

[katy]

Have you tried tightening up the screws that hold the fuel pump together?

[Boomlander]

Have you tried tightening up the screws that hold the fuel pump together?

Yes I tried but they were already as tight as they would go, it looks like the diaphragm is perished as it has crumbled away at the joint underneath.
I have just fitted a replacement used pump and after swapping the outlet spigot, which was loose and leaking, it seems to have done the trick.
The pump sprang into life and after a few initial rapid clicks it settled down quietly and there is no sign of petrol weeping out anywhere - £25.00 well spent, good old Ebay!

[bmcecosse]

Put a new diaphragm and points in the old pump.

[Boomlander]

Put a new diaphragm and points in the old pump.

Sound advice, I am going to order a service kit from the manufacturers and have a go at reconditioning the original pump.

[Boomlander]

Am I correct in assuming that when the carburettor float chamber is full the pump output along the supply hose to the carb is interrupted until the level falls sufficiently?

[bmcecosse]

The pressure holds the points open - when the pressure drops, the points close and the diaphragm is pulled up by the coil - pushing petrol out to the carb - and so the cycle goes on.

[Boomlander]

Ah, I see - When I connected the replacement pump it didn't actually push fuel through the filter in the output hose and as the float chamber is probably full already it must have just built up the pressure in the hose until the points were held open

[Boomlander]

Ran Jethro's engine for a few minutes and fuel started pumping through to the carb - What a relief, we might be able to finally start driving the car!

[Boomlander]

Hi Folks,
Found a puddle of petrol under the replacement fuel pump today!
Assuming the worst I said a quick prayer and felt underneath the pump where the diaphragm joint is located.
To my relief it was only the fuel filter unit that was loose and weeping and was soon fixed.
Honestly, I think I am becoming Minor Paranoid with this car!

[butterboy]

Boomlander I have a small oil leak on my 1967 MM. Not easy to see where it is coming from.It's above the water pump and I think from the head gasket.
I've been told it is from the oil way that goes from the block into the head being only a quarter of an inch from the edge.I might try retorquing the head
but it's not an emergency.
Bernard