sump & silicone

[ceejayjay]

Chaps

Last week changed the sump. Balance of advice seemed to say use silicoen sealant. All went well considering the car was on stands and I was on my back ( or so I thought ) Out for a run and on full throttle ( psi rising ) I got the unmistakeable whiff of oil on exhaust. Yep - sure enough, leaking like bloody sieve. Aaaaaargh!. So off with sump again. I suppose I'm half hoping it looks worse than it is and a wee tighten all round will do it - but I doubt. Got a cork gasket ready to fit. Question - is there a smart way to clean off the silicone or is it going to be a case of scraping back to the metal. Any clever techniques??

Ho hum!

:boohoo:

[stevee8]

You can buy special remover for silicone though you may want to check how aggresive it is if you're doing this under the car.

Unless you (very) thoroughly degreased the mating surfaces before it was applied, you should find it will peel off reasonably easily with the help of a wall paper scraper or similar.

[craggle]

I think the use of Silicone was a mod carried out by Land Rover on the last of the Range Rover classics to try to stop the leaks. The steel sumps can be overtightened with the cork gasket and distortion occurs in between the bolt holes. Place your sump on a flat surface and hammer flat if needed.
Land Rover later used a cast aluminum sump that had a machined flat joining face and sealed a lot better.

There are different types of silicone. Use a proper automotive silicone that is heat and oil resistant. Standard bathroom sealer may not be up to the job.

Throughly degrease both surfaces, apply the silicone and bolt in place but do not tighten the bolts fully. Leave the silicone to dry overnight then finish tighten the bolts the next day. This should prevent all the silicone being squeezed out. I suppose you could do the same with silicone on both sides of the cork gasket to help take up any gaps.

As for removing the silicone I think the best bet is to scrape it off carefully with a spatula.

Craig.

[maxGD059]

BTW when doing your 'ammering, use a small socket & gently tap it over the bolt holes creating a slightly raised area. The tightening effect of the bolt/washer tends to make this area proud so the cork seal is not so tight inbetween the bolt holes.

[ceejayjay]

Thanks all,

I think the sump's true enough in shape and finish. Maybe I was too hasty at tightening before the silicone had firmed up and it squeezed out. At least I know I have very healthy oil pressure given how it squirted out!

I think I may go for a belt and brace of gasket plus a bit of siliocoen too. As I'm single handed with no ramp/on my back, I'll need something to keep the gasket located whilst I shimmy it into place. What a bore!!

Many thanks:thumb:

[craggle]

Unfortunatly oil coming out of gaskets and seals is not a sign of oil pressure but a sign of an over pressurised crank case.

All engines produce pressure and this has to be allowed to escape usually via tubes between the rocker covers and the carburettor or intake manifold.

Plumbing the breather tubes into the intake can actually cause a vacuum. On my chevy engine I have one breather / air filter on one rocker cover and the other rocker cover is connected to the front of the carburettor. This, in effect, should suck air in one side and out the other.

Check your breathers are clear and large enough. Older engines pressurise more. There may be a PCV valve in the system so check it works.

Craig.

[dingocooke]

The double glazing fitting boys sell a great fluid for silicone removal, not too expensive.
When I used to work at a silicone factory, we used Meths, works very well too.

[kev]

Throw the cork gasket in the bin and buy the later thick rubber gasket. Don't put silicon on it and reuse it until the cows come home.

The crankcases shouldn't be pressurised if the engine breather in the rockers is clear.

Kev

[Dave Williams]

.....as I was tellin Jordan the other day - silicon is not always a good idea.. :drive:

[Robin427]

If all else fails, use a brass bristled wire brush on your drill... worked a treat on my alloys