About 150kms ago I replaced water pump, radiator, top and bottom hoses, heater hoses, heater tap, thermostat and housing. Now I have mayo . Would any of the previously mentioned items bring this on?
The motor is an 1100 and pretty fresh from a rebuild (the previous owner tells me anyway). I drive it kinda hard (gear changes @ 6000rpm) and drive it very infrequently (150kms in 6mths).
I noticed the mayo when checking the engine oil, it was mostly under the rocker cover oil cap but the dipstick was not showing any signs. Went to the mini Muster yesterday (15km round trip) and today had a look at the dipstick to see signs of mayo there too.

Can mayo come from engine breathers taking in moisture/humidity?

Can you get it even with no failures between the cooling system and lubrication system?

I'm thinking I'll do an oil change and see if or how quickly the mayo comes back and if it is still bad pull the head and check the gasket.

Is there a good technique and/or product to flush the lubrication system?

What else should I be investigating?

Will do a search shortly for others experiences and anecdotes but thanks in advance for any advice and info.

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Steven

Give it a good HARD run. Get the engine nice and warm.
Do this, though, with a different oil.
What are you using right now?

Sorry forgot to mention, using Kmart oil KMX. No wierd combustion noises either. Will check the coolant condition shortly and report back.

Edit: Also might add that this is a 1979 leyland, all the pollution gear has been removed and the carb connection has been plugged up (carb to breather setup thingy). Currently the breathers on rocker cover, and block are entirely open to the elements, no filters, just the tube and pipe stub.

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Steven

A lot of cars always have some moisture under the rocker cover, I know that if I look under my oil cap there will be some drops of water there.

Things that contribute to mayo or moisture in the top of the engine...
Short trips.
Breathers not working.
Oil.
Weather.

Hook the breathers up properly and most of the problems will probably go away.

If the signs persist and your concerned, take the car to a radiator shop/mechanic and get them to pressure test the cooling system, and test the radiator for combustion gasses.

The old 1098 setup like M1100 has, or using plain breathers like you have it is prone to mayo, better to run a hose from the oil separator/canister to the vacuum port on the HS4 carb.
You then have Positive Crankcase Ventilation. It works, neither of my motors ever get mayo.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks all,
will shove a hose back on from the breather to the carb and give it a quick oil change. See how that goes.

Will the mayo have any detrimental effect on the oil filter? The moisture should evaporate out once it's nice and warm/hot and circulated around for a while..... right?

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Steven

Right.
Drive far enough, and the moisture will evaporate out.
If it's a spin-on filter though I'd fit a new one, they are cheap if you buy em in the right places (in Mini shops, not Supercrap etc).

[edit] detail added

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

To avoid this from happenning, I used to take a good long 4100rpm (110km/h) run down the freeway to penrith and back late at night, once every month or so.

I call it the Anti Mayo Fang

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Lillee - 1969 Morris Mini K

Bring it down to Mini King on Sat, via M4 then Northern Rd. I'm going too...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I'll be there sunday. And if I come I will bring the station wagon so I can fit lots of goodies in the back!

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Lillee - 1969 Morris Mini K

I had the exact same problem in my 78 leyland, hooked the crank case breather to the vaccum on the carb (which WAS blocked...) and the rocker cover breather to the inlet on the air filter cover, changed the oil and filter (why have a shower then put your dirty jocks on?) and went for a run. Mayo all gone

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78 Leyland Mini - Prince