Mysterious Oil Leak (the return of ...)

[revilla]

Well it never really went away ...

 

Back in September I posted this thread about a mysterious oil leak. I still haven't really got to the bottom of it. I would appreciate peoples thoughts:

 

The engine gets oily here:

 

http://www.revilla.plus.com/OilLeakLocation.jpg

 

The odd thing is, even when the car hasn't started or run for weeks, you can clean all around the area with degreaser and then next day it will be oily again. It starts off as an even oily film on the surface of the metal which builds up and if you wait long enough, there will be a drip of oil from the underside of the block lug to the garage floor.

 

There is no sign of oil leaking anywhere above the lug, no sign of oil leaking out of the gap in the bell housing, in fact no real sign of the oil coming from anywhere at all, it just sort of materialises evenly distributed over the metal, whose surface becomes wet with oil.

 

So ... to try to track it down I cleaned everything up and dusted liberally around the area with talcum powder and watched it over a few days. The powder on the side of the block above it stayed clean white with no sign of oil staining. The powder on the lug where the oil appears slowly turned evenly yellow. The only clue as to where it was coming from was that the powder that had splashed lower down the lug became more stained than the powder on the top.

 

The only explanation I can think of is that the leak is actually from the sump gasket (which does indeed look as though it may be very very slightly weeping) AND THE OIL IS CREEPING UPWARDS!

 

Has anyone any experience of leaked oil tracking UPWARDS through surface tension? Is this even remotely likely? Seems a bit far fetched to me but I can't think of any other way of explaining what's going on.

[Stationary M25 Traveller]

How about crystalline porosity in the aluminium. We used to see it quite a lot with castings.

[DJ.]

How much oil are you losing per 1000 miles?

 

If the engine is running well and it is only a small amount, I'd be tempted just to run the car and try and forget about it.

 

Duncan

[Mankee]

Hi Andrew. Good use of a plentiful supply of talcum powder! 😬

 

Real long shot, but here goes. Did you say your engine wasn't an original Caterham one? Reason I ask is that I'm wondering if someone has gone too far with the modification to block to fit the starter motor. There is an oil gallery where the engine number would have originally been stamped, and if there is a hairline crack there, that could be the source of your oil?

 

Also, and I'm squinting really hard here, but is there a crack just above your red line and below the wiring? It might just be the starter motor or something entirely different though.

 

If you need a sump gasket, let me know, as I have a spare on the shelf, along with the foam, which I may or may not fit, depending on how my oil pressure behaves once I get back on the circuits.

[Birkin S3 ZA.]

Here is a trick I use for small weeps from cracks or gaskets even pin holes in my welding 😳

You might have to drain the oil, take a can of brake cleaner and a air line with a air gun and spray with cleaner then use the air gun.

 

Do this a few times until your sure its clean and better still if the cleaner has gone through the hole to the other side.

 

Then use your finger to work some silicon into the crack or hole, then use the air gun to blow it in further.

Do this a few times and then clean off the excess and that would fix your leak,as long as there is no more than crank case pressure it will work.

 

I have done this dozens on times even on long cracks as a temporary fix and its lasted nearly two years until I stripped it and welded it.

 

Chris

[Paul Deslandes]

I can't quite see where I'm looking but is it the interface between the engine and bellhousing? Are you sure its engine oil, not gear oil or clutch fluid? The smell or feel should tell you which.

[oldbutnotslow]

It looks as if the picture shows block to bell housing on a K ( can you can see the flywheel ring gear?)

if this is where you suspect the leak to be coming from then perhaps you may have a slight weep from the rear crank oil seal

You can see the flywheel back face by looking on the opposite side of the engine in the same location

You could also try loosening the block to bell housing bolts by 2 or 3 mm to create a gap between the block and the bell housing and see if this increases the drip rate.

 

However I dont think that I would be too worried if the amount is as small as you suggest

[revilla]

@SM25T - I did wonder about that when I was looking at it earlier, specifically I wondered about a bit of porosity in the area of the seal between the block and the crank bearing ladder, but Oily said he'd never heard of leaks from this area before so it would be unusual. I'm fairly sure having spent a while looking at it since that the oil isn't actually coming down from above as any talcum powder on the side of the block just above the projecting lug stays clean and white as the lug itself becomes oily.

 

@DJ - Hardly losing anything at all. Oil level doesn't noticeably drop between oil changes. There's no real volume of oil coming out and the engine is running absolutely fine, it's just one of those niggling little things that annoys me when I know it isn't right. Unless I spot something or it deteriorates, I will probably do what you say and just live with it. I'll keep my eye on it just in case anything changes.

 

@Mankee - Hi yes I've managed to find uses for talcum powder, baby wipes and even cotton buds when working on the car. When it gets bad enough to need a nappy I'll really have to do something about it! I'll have another good look but I'm fairly sure there are no visible cracks around that area, I've had a pretty good look, unless there is something that the camera flash picks out that just isn't obvious when looking at it. I'll check again, but see my earlier comments about why I don't think the oil is running down from above. I've had the starter motor off when I changed the head gasket and I had a good look at the way the block had been ground (as I was planning to do it myself on the spare engine) and I didn't see anything amiss.

 

@Birkin S3 ZA - Thanks Chris for the tips. Your repair techniques are of course dependent on finding the source of the leak in the first place, but if I do turn up any hairline cracks or pinholes in the alloy I will remember what you have told me when it comes to patching it up.

 

Edited by - revilla on 2 Feb 2014 15:53:39

[revilla]

@Paul Deslandes - Yes it's the engine to bellhousing interface and it does appear to be engine oil rather than one of the other fluids.

 

@oldbutnoslow - Indeed, block to bellhousing on a K (1.8 VVC). Flywheel face viewed through the gap on the other side of the engine is clean and dry. There is no corresponding weeping from the other side of the engine. Also no problems suggesting oil contamination of the clutch. I would have thought that, after standing for a couple of weeks, any weeping from the rear crank oil seal would tend to collect in (or drip from) the bottom of the belhousing which is quite a bit below the point where I find the oil, but the oil still appears on the bellhousing attachment lug.

 

To be honest as the oil loss is so little (not even really measurable) I'm not too worried, just find it a bit strange and would like to know what is going on. Thanks eneryone for your input.

[Brucey]

I believe I had a similar showing of oil when the rear Crank Oil Seal was leaking on my K Series. It was enough to leave a little spot on my garage floor each time I parked 😔

 

It's amazing just how far the oil can travel before it forms a drip! If you can, check the engine side of the flywheel for any oil residue.

 

Hope this helps,

 

Brucey

 

 

 

 

 

 

 

 

 

 

[JonL]

Following on from revilla's post, I too have a leak between the bellhousing and the block. After liberal use of talc I have now tracked it down to the near side between the sump pan and the bellhousing. You can make out the slight staining of the talc in the photo here. It drips about a dessert spoon a day when the engine is not running which enough to get me worried.

The car is in for a service next week about 20miles away. I was planning on driving there having topped up the oil first. Does this sound like a sensible idea, or will the additonal pressure of a running engine make a bad situation a lot worse?

thanks

Jon

[Birkin S3 ZA.]

If you block all the breathers and use a adjustable air valve to put 7 psi pressure in the block, then use a spray bottle with soap and water to spray where you think the leak is and it will blow air bubbles if its leaking.

works well on gearboxes as well.

[revilla]

A dessert spoon of oil is a LOT more than I was getting - mine was odd, it just seemed that oil was oozing out onto the surface all the time but there was only the occasional actual drip, probably one drip a week (but I didn't set watching it!). Tracking it with talc didn't really show where it was coming from, it almost seemed to be coming out of the metal itself; personally I wouldn't be surprised if I have a bit of porosity along the joint between the block and the crank bearing ladder.

 

If you do find yours please do report back as it may give me something else to look at.

 

Hope you get it sorted soon.

 

Andrew.

 

Edited by - revilla on 4 Apr 2014 14:24:18

[revilla]

Oil leak now found. I've started a new thread here to dicuss possible repair options. I'll close this one now. Thanks for all comments.