Oilleak / porosity

I have a persistent oil leak coming from the sump on the left hand side of the engine. It’s definitely not coming from the clutch area at the front of the gearbox.
It appears to be coming from (mainly) one allen screw in the sump on the left which also has a deep sump plate sandwiched in.

I am suspicious that the sump is porous here unless there is a minute crack which opens up when the engine is run as it doesn’t leak when not run.

Has anybody had any experience of this sort of problem and found the cause?

Also, I have had a persistent leak from one of the locating screws for the left rocker box. Again, I can’t see any cracks etc. I read earlier this year on the forum of a sealer that was a brown/red colour and an epoxy resin if I recall used to seal porosity. Can anybody advise me ? ReggieV2013-09-01 21:06:52

Loctite do a sealer for porous castings
might be worth putting a drop of thread lock on the bolts incase its running down the threads

I use ptfe tape on the sump threads and always have a washer under the head it helps.

The rocker covers , I have made this mistake, have some longer bolts and some shorter pop a long one into the 'ole for a short one it “feels” tight BUT is 1/2mm proud therefore the cover is not sealed. worth a look along the edge. look at the 2 edge bolts at the back edge of the rocker cover kinda above the intake

What he said, several of my sump screws have oily shafts when removed, so I blame gaskets (also have a sump extension so two chances); but the heads have washers, if done up properly none on the outside. So far.

Thanks for the replies. So it’s not all that unusual to have some oil weepage from the sump screws?

I have ordered a load of 6mm dowty washers today to put under the allen bolt heads, and will put thread sealer or ptfe tape on the threads and see how things go from there. Hopefully it isn’t porosity…we shall see.

Thanks again.

Much more likely to be a gasket or a screw. I presume it isn’t pouring out. Deviation alert ~ only time I’ve encountered porosity was BMW (car) carburettors, about 65k miles then, right on cue, they leak like a sieve… Weber conversion was cheapest fix (easily half the cost of a new OEM carb)

I thought I’d give an update.

I put new gaskets on the sump (and sump spacer) and I also fitted my spare sump in place of the “leaking one.” Also I fitted dowty washers to all of the allen bolts and up to now NO oil leak from the sump.

I fitted a new gasket to the rocker box and a dowty washer under the offending allen bolt…and it still leaks. So tonight I borrowed my wife’s jewellers loop (eyeglass) and I can see a hair-line crack

So any ideas for a permanent fix? I can’t really think of an easy one except I have bought some J B weld, but don’t know if I will be able to do a tidy job with it?

I did buy this rocker box from Gutsibits, but unfortunately it was about 18 months ago and so I don’t think that they they would want to take it back…and can’t really blame them.

I may possibly be looking for another rocker-box (l/h/s round barrel) if anybody has one?ReggieV2013-09-25 21:32:19

The square head rocker covers can crack along the edge nearest to the spark plug. One of mine did that but I sealed it up using Quiksteel Aluminium epoxy putty

There’s not a lot of pressure in the rocker covers, I wonder if some hylomar blue would seal a crack there, rather than risk some epoxy coming adrift?

I’d rather risk the epoxy, than crappy blue hylomar coming adrift and blocking up oilways. its been the death of more than a few engines.

In this instance I’ll be putting the JB on the outside of the cover (this morning) so no danger of dislodging into the engine. It is a very small hairline crack, probably 6mm long, so hopefully will hardly show.

I was worried about the epoxy letting go too so I roughed up the interior surface with a Permagrit tungsten carbide tool and de-greased it well before I applied the putty. It’s been on for three years and 8000 miles now and I check it every time I set the tappets. It’s showing no sign of deterioration or coming loose.

It’s also what Guzzi recommend to seal porosity in their castings.

Make sure to drill a small hole at each end of the crack otherwise it will probably travel…so the cover will have to come off, epoxy if applied to a CLEAN/ROUGHED prepared surface is ‘forever’
byteofthecherry2013-09-26 09:22:57

Surely there is something which will seal a small crack using capillary action? Would need to be degreased well first of course. This would both be safe and invisible.

I had the same problem on one of the S3’s rocker covers - a hairline crack that was causing a weep, and I could see it on the inside of the cover. I used a mixed epoxy, and heated the rocker cover a bit to get it to flow nicely into the crack. That was 1995 I think, the leak never came back and I can still see the very thin layer of epoxy still in place, so I wouldn’t worry too much about it.

I used a Loctite flange sealer on one many years ago…never a problem since…

JB has worked this afternoon. It can’t be seen as it is under the “head protector.” All is dry.

The answer to my problem is to get the hairline crack alloy-welded on the inside later this year when I get the peg re-welded onto the centre stand and that will be done when the bike comes off the road.

Thanks to everybody for the thoughts/advice given.

ReggieV2013-09-26 19:26:37