Dry sump catch tank venting oil?

[Benton]

Apologies if this has been covered by a previous thread but I did try using search without success..

On an number of occasions I’ve found some oil collecting in the “grot” trap apparently having been pushed out from the dry sump catch tank (there are no other obvious signs of any oil leak from the engine etc). On each occasion however there has been no visible oil left in the catch tank itself apart from staining indicating it had “passed through” leaving about a 5mm “tide mark” at the bottom of the tank.

I’ve checked the oil level in the dry sump, using the “new” caterham dipstick just in case my earlier visual interpretations of  the oil level were incorrect but the level appears to be within the recommended guidelines. The oil pressure rises and falls with engine revs range  gauge reading approx 3.5 to 5.

Car is a 2018 420R with around 5000 road only miles and is booked into Caterham in the near future for its 6000 mile service, with this “problem” noted for investigation.

In the meantime any ideas as to what might be happening here, it doesn’t happen all the time having checked after numerous outings, I can only assume the catch tank must be getting pressurised somehow occasionally.

[rj]

Sorry to answer with a question, but:

Couldn't it be from the gearbox venting?

 

[Benton]

I didn’t even know there was a gearbox vent, I’ve a lot to learn

However the residual oil appears to be largely concentrated directly under the catch tank, i.e around the vicinity of the cutout in the skin for the front suspension, if this isn’t referred to as the “grot” trap then sorry for the confusion.

 

[SLR No.77]

The grot trap is actually the gap further back between the outer skin and the footwell box on each side.

If it was a dry-sumped K-Series, the area you refer to around the cutout for the suspension mounting can get sprayed in oil from a leaking dry sump scavenge pump, I'm not sure where the pump is located on current cars. Even refurbished pumps can be prone to spraying oil on the side skin, they're not the most "engineered" of pumps! Mine gets pretty grubby, I just give it a good clean down when I check the belt.

Stu.

[anthonym]

have you been caning it? If not why not?

I have had this trouble, what does the oil catch tank breather look like? Assuming there is one does it have some sort of spray cover to stop oil being sprayed everywhere? 

and are you sure the tank tower cap is on tight and any bits lower down (not sure what your looks like), my conning tower (forgotten the correct term) was loose recently and that had oil all over the place. 

no visible oil in my catch tank would mean I am not putting enough oil in - but mine's a K R500. 

Anthony

edit: show us some pics?

[Benton]

Thanks for the replies and clarification of terms, I’ll have a more thorough look and  poke around tomorrow weather permitting and report back

[Benton]

So this morning I took another look around, no discernible oil leaks. So I took the oil catch tank out to have a better look. I noticed its vent pipe of the catch tank was touching the bottom of the tank, I therefore decided to adjust it, rightly or wrongly, so that it’s end was about 1/3 of the way up the catch tank instead, in theory well clear of any residual oil that could appear in the tank. I’ve also temporarily attached a container (yogurt pot) to the other end of the vent pipe to stop any oil dripping on the chassis and to monitor if indeed this is the source of any wayward oil

Went for a “spirited” drive including deliberately exploring the upper rev range (sorry officer just testing  the car :-)), came back and checked, no wayward oil to be seen anywhere either on the chassis or in the pot.

Will continue to monitor....

 

[Geoff Brown]

My R400D has the Caterham issue rudimentary washer bottle catch tank.

Before I put a fine mesh on the inside of the removable top oil used to spew out of the breather hole on to the drive belt tensioner, engine front cover & the rear of the oil tank.

Not so bad now with the mesh, just a wipe needed from time to time in close proximity of the tank. No liquid oil any more just a slight residue.

[aerobod - near CYYC]

With spirited use I get quite a bit of oil vapour vented on my R400D. I think one of the issues is the Duratec design with limited size of the oil scraper ring and thin piston rings in general, that was designed for a lower compression and rev limit than Caterham use, leading to more oil blow-by with high rev use, which ends up as vapour in the catch bottle. The three small holes in the top of the bottle seem to spew the vapour around the top wishbone hole in the bodywork, leaving a slight oily film that I wipe off on a periodic basis.

[Benton]

In my case there is a vent pipe for the catch tank that is zip tied to the chassis and therefore i’ve temporarily attached the yoghurt  pot to see if any oil is being expelled from here.

[Benton]

Duplicate post