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MG Midget and Sprite Technical - Breather and oil and smell

Since road going at Christmas my rocker breather has continually had a steady oil flow to the carbs. As well as this I have a very 'rich smelling' exhaust. (top down driving can be a bit overpowering at times).

MPG is good, tick over when warm is good (its good generally anyways), no smoke, no condensation, no 'wrong putter' in exhaust emissions. Exhaust pipe is lined in black - not oily.
So I was wondering if anyone can suggest a way of reducing the rich smell (a bit like the choke is out but doesn't choke the car). Happens with all grades of fuel. Engine serviced 1000 miles ago by the way. (Second service since Christmas, rocker set, carbs redone when HGF happened).
And has anyone put a catch tank on a 1500 breather? and if so suggestions for what to use and where you put it would be most welcome.

It is a standard set up car with no mods in the engine bay (apart from an electric wash wipe :-)
Dave Squire (1500)

Dave

Prevention is better than cure. Why is it leaking oil? Have you over-filled with oil, dodgy rings/oil scraper on a piston - check the plugs - for easy elimination of possible causes and consult a manual thereafter.

If sooty deposits inside zorst and it stinks then could well be mixture/over fuelling somehow. Check every hose and pipe for leaks, check vac advance etc etc - there are entire books written on this stuff.

Catch tank - forget it. A bit of a gimmick IMHO. Stick to standard set up. For 1275 a vacuum is required (either direct to the carb or via a vac valve) to prevent back pressure and leaks at the carnkcase seal. Any catch tank will allow volumetric expansion and mitagate that effect. Not sure about set up on your Triumph lump.....



Mark O

On revs up to 3000 RPM (55 to 60 in top) the oil consumption is very small, almost nil. Over that, like quick starts in town and main roads at 60+ for bits, it is noticeable after a week (300 miles ish at the moment) - about 1/2 a pint.

The breather pipes always have some flow of oil in (only a drip type amount but still there all the time).

Earlier sump and pressure relief valve leaks now fixed and the bottom of the engine and floor of car are drying out. The whole car is continuing to sound better mechanically as the miles roll onto it. Amazing after an unprepared lay up of nearly ten years really.

Anyway a colleague just suggested taking the breather off, running the engine to warm, and seeing how bad the smell is then. He says he doesn't think its any worse than the smell from his 78 VW camper. I will try that next. I also need to make the effort to get to the MASC meet in Derby then I can compare motors and see one that's been running for a while.

Dave Squire (1500)

Penny just dropped about volumetrics, and yes I see the implication re the seals and internal pressures. In fact I need to make sure the breathers are attached and working with as little interference as possible methinks.
Dave Squire (1500)

Dave,
Are you sure the smell is coming from the exhaust? Sometimes the oil smell is a good deal more noticeable from under the bonnet area if there is a leak in the breather system. Especially on a 1500 where a poor fitting hose would drip oil direct onto a hot exhaust manifold and give your oil smell.

In "the day" my advice would have been to change to Castrol R, and enjoy it. Sadly those times are gone, but I can still recall the smell!
Guy W

Ah Casrol R. Reminds me of watching stock car racing. I love that smell more than napalm in the morning. lol.
Lawrence Slater

Yep, Castrol, Duckhams, and Fina to name a few.

No drips under the bonnet; top of engine all dry now since new HG and bottom of engine drying out so all happiness re external leaks. Not worried much about oil consumption at this point as I sort of feel its still wearing back in as it were.

On further reflection I reckon it is probably smelling normal like the colleague says and I am just not used to it anymore. Got 200 mile run tomorrow if I have changed nearside front shock in time so we'll see if it gets better. The engine is still improving and I'm still smiling.

Plan to service, retime etc. in another 1000 miles or so. Methinks I will review it all then.
Dave Squire (1500)

Dave,
it was specifically Castrol R - smelled quite different from any other oil for some reason, even other offerings from Castrol. Lawrence clearly remembers it!
Guy W

Dave,
the answer is obvious to me, it's the installation of the electric wash wiper

the rich smell (and possibly black exhaust) is possibly as simple as that, it's running rich, fine when it should be running rich but not when it shouldn't be - are you using the choke a lot say lots of very short journeys or perhaps leaving the choke out too far for too long - check the cable and links are fully returning to off and not catching anywhere

oil consumption could be engine wear or perhaps a bit of still settling in (if it's not also leaking of course)

as well as checking the breather pipes and connections I'd check the oil filler cap seal same way you would on the rad expansion tank cap and fuel filler cap

I expect I'm the only person on classic forms that doesn't like the smell of Castrol R, I think it's because I followed a mate a long way who was running it in his MGB (yes, I'm sure it was his B I think)
Nigel Atkins

just thought the oil filler cap is probably all metal but it must still seal
Nigel Atkins

This thread was discussed on 24/05/2013

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