Forum:
Hi
I have an early fourtrax 2.5 DG engine fitted in a series 3 landrover, It had a bad oil leak which I thought was from the rear ( crank ) oil seal, I changed this and bench ran the engine , and it seems the leak is actually from the rear of the sump gasket, and stragely |'m having trouble fixing this I made up a new cork gasket, and it still leaked, and then a thicker gasket with gasket sealant and jit still leaks, I'm wondering if this is a known problem with this engine and if anyway has come across a solution 
Thanks
Paul
Oily Subject
The problem is the gasket and the way it is attached, basically you have done it incorrectly.
Remove the sump and clean both the sump and the bottom of the engine block until they are spotless, using Bostick 777 glue stick the gasket to the engine itself, cover the sump flange with glue and refit this. Leave the whole assembly overnight for the glue to work properly.
Use only an original Daihatsu sump gasket, these are thick, but compliant, sealant does not stick these together and leaks form between the sump and gasket, or the engine block and gasket.
Bostick 777 is available from engineers suppliers, engine rebuilders, and engine component suppliers, do not be tempted to use something else as this is a dedicated engine gasket glue designed for the operating conditions of an engine.
Hi Thanks for your reply,
Hi
Thanks for your reply, sounds like you have experience of this problem.
I have meanwhile tried with a silocone instant gasket, but I haven't tested it yet as,I'm only getting to work on this occassionally, I'm hoping this will work what do you think? If not I'll follow your directions.
Previously I made a cork gasket, the leaking one fitted was a 1 or 1.5 mm cork gasket , I made a 2 mm gasket and when this failed I made a 4 mm gasket with sealant which also failed.
Do you know how thick the original gasket was? the problem with thick cork is that it seems to distort and perhaps breakdown if overtightened.
Regards
Paul
Gaskets
Paul,
Original gaskets were 1.5-1.7mm thick, using silicone does not stick the gasket to the metal, the gasket needs to be stuck. No real problems with Fourtraks, but many more years than i will admit too of engineering experience.
Most people do not realise that metal is porous, particularly cast metals, they are like an Aero bar to look at under a microscope. Voids in the metal absorb oil, this is why its important to clean thoroughly with a good degreaser such as petrol, this trapped oil is why silicone does not stick. Bostick 777 is a true adhesive, unlike silicone it is designed to stick, stay flexible enough to move under constant heating and cooling cycles, and be totally impervious to oil unlike silicone.
Leaving overnight allows the adhesive to cure and obtain its true coefficient of adhesion, filling with oil the next day will swell the cork gasket to make a tighter seal.