Oil leak, I think from a stone hitting the sump

[andy_harries]

Hi all

Thought I would post a few pics to get some thoughts on where to start looking for the source of a very small leak.

Just looking over my car ready for Blyton sprint next week I found a small patch of what I think is engine oil on the floor underneath it.  The car hasn't moved for around 4 weeks (thanks to a stupid foot injury causing me to drop out of the Curborough sprint) and has been sat under a cotton cover in the garage.

It looked at first like a leak in the seal between the engine block and bell housing, but when I ran my finger along the sump I found a very thin layer of oil down one side, leading to what looks like a knick taken out of the sump by a stone.

Closer....

The question is, does that look like it could be the culprit for what is quite a small leak, and if so do you think its repairable or is it new sump time (@£500 or so!).

OR, am I looking in the wrong place for the leak?

Car is a 2016 ex Academy, Sigma engine.

[Beagler]

Drain the oil drill and tap the hole and put a bolt in it with sealer.

[ScottR400D]

Before you do anything, you need to be certain of what the issue is. Is it a wet sump or dry?

In any case there's unlikely to be enough wall thickness to tap a hole in it, and there are likely to be better ways of fixing that, if that's the problem. 

[revilla]

A bolt head sticking out (or in!) on the lowest point of a thin-walled alloy sump doesn't sound like a good plan. As above, make sure you know for sure it's the issue. If it is, then I'd get a local welder to seal it flush. I once got a whole new replacement threaded boss welded into a Caterham sump for £30 so a quick spot of weld to repair a small patch shouldn't be expensive.

[K7 VCT]

You sure it's not oil from above somewhere else ?

Clean it all off with solvent degreaser, run upto temperature and look again ?

A friend had an oil pipe to the catch tank rub against the engine and he had a drip at the rear of the engine, turned out to be the hose above.

[andy_harries]

It's a wet sump.

Cant see any oil further up anywhere, but have wiped it all down and will try and track the path of the oil later tonight, if any has come out

[ScottR400D]

The wet sump would have, what, 4-5 litres of oil? Wouldn't most of it come out if that was a through hole? 

[Tom_Arundel]

That looks like a casting defect (sand inclusion), could be filled with aluminium putty.

[ScottR400D]

I agree with Tom, it doesn't look like a stone hit. 

[ScottR400D]

I agree with Tom, it doesn't look like a stone hit. 

[Beagler]

As its on the corner the metal will be thicker so drill and tap is practical. Use a mushroom head stainless screw and wont be so obtrusive. As the oil leak is small so the screw will be. Wouldn't want to weld in situ as heat could distort.

[SM25T]

Very easy to remove sump to attend to it. I really wouldn't drill and tap it !

[ScottR400D]

Absolutely,; if the job's worth doing........ 

[revilla]

Just seems to me like the difference between bodging it or repairing it properly. I definitely wouldn't drill and tap it with the sump still in place, that's just asking for swarf in the oil. And if you're taking it off anyway ... give it a good inspection for any cracks that may not be visible from the outside get a proper repair. It won't be an expensive job.

[OldAndrewE]

Is it confirmed that this is where the oil is coming from?

[Beagler]

Grease on the drill bit will retain any swarf.

[OldAndrewE]

"Grease on the drill bit will retain any swarf" - so you hope but I wouldn't chance it.  

[revilla]

Especially when drilling into oil!

[Beagler]

Wouldnt drill a sump full of oil obvious thing to do is drain first

[revilla]

And have you ever seen one drain completely dry?

[ScottR400D]

Beagler, I'm sorry, but that's bodge engineering of the highest order. I'm amazed that anyone claiming to be a trained engineer would even suggest it. I bet you wouldn't warrant such a 'fix'.

Firstly, the sump is highly likely to be too thin to stand being threaded. Have you actually looked at one?

Second, there's a significant risk of ending up with swarf either from drilling or tapping. 

Third, you'd be introducing an unnecessary stress raiser in a casting, the effect of which would be quite unpredictable.

Fourth, you're recommending a stainless fitting in an aluminium casting that can regularly get wet, just asking for corrosion. 

Finally, it's just not worth it. A proper repair would not entail that much work and at least you'd have peace of mind knowing the repair had been done properly. 
 

[Beagler]

Scott, We are all entitled to our opinion no matter how rudely expressed. The OP is free to decide the remedy to his problem and I'm content for him to decide.

[ScottR400D]

Hopefully the OP will sort the wheat from the chaff. 
 

 

[Beagler]

Either way I'm sure we'll all sleep soundly. 

[7 wonders of the world]

Remove sump, clean thoroughly, if the origin of the leak is not fully obvious locate with crack detection fluid, drill the ends of the crack, prepare and weld, refinish and refit.