I have a slow oil leak coming out the join between the engine and gearbox on my 1989 740SE, just enough to make a splash on the clean driveway overnight...
The Oil is brown/red, which as far as I know means gearbox oil?
Should there be any oil between the two or should they both be sealed?

I want to fix it myself if possible, I'm guessing its definitely going to require the engine out, and maybe replace a seal or two?
Also, where do you top up the gearbox oil from?

Anyone who has had similar problems, I'd be grateful of any help
I should say that I have NEVER taken an engine out before and I've only had the car two weeks, its just started leaking yesterday. Unless specialist tools are required, I have everything apart from an engine lift. I'd rather do it myself than spend £300 or so getting it done in a garage.

 

Welcome aboard.

There should be no oil coming from that area as there are seals on the shafts to keep it in where it should be.

You may be able to get away with taking the gearbox off as this will give you access to both engine and gearboxoil seals. That was how I did mine and it is easier than taking the engine out.

 

Red/brown implies gearbox to me (do you have an automatic?) I would suspect the front seal of the transmission. Look around though maybe it is coming from a line, fitting outside the transmission that can be fixed with no removal.

 

Thanks for the replies.
I had a closer look today and it seems it could be coming from a number of places...
Firstly, I think it was just the colour of the driveway making the oil look red, as after letting it collect in a plastic tray over the past few days, its definitely black.
On closer inspection, there is oil residue around the oil filler cap, which has a little trail of oil which seems to disappear down the side of the engine somewhere. I can also see a thin film of oil right at the bottom of the engine on the lip just before the sump starts, which could quite easily dribble from there to the clutch area and drip off there as its the lowest part.
I've got a Haynes manual on order, until that arrives I'll just have to keep carrying my little oil collector pot around with me...

 

If it is coming from the filler cap try replacing the rubber ring in the cap. It could well be the same age as the car because it is an item usually overlooked.

Your Positive Crankcase Ventilation may be in need of a clean.

These are the two easy ones as a starting point.

 

If the Distributor is mounted on the rear of the engine, next to the firewall,
Don't forget to check the distributor shaft seals.
740s are notorious for oil leaks in this area, ecspecialy if the distributor/distributor parts have been replaced(Lower paid mechanics leave the dust cover off every time!)