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MG MGB Technical - All the old oil is out of the engine ?

My mg recently blew a head gasket, there water in the oil
Gasket now replaced , I’ve drained the oil do I need to make sure
All the old oil is out of the engine ? If so how ?
D J Joy

Don't worry about it, any traces that are left will evaporate out on the first good run. Make sure it IS a good run though, don't just leave it to idle up to temperature or you will be putting more condensation in the oil.

Unfortunately weather conditions at the moment are not conducive to good runs or getting it nice and hot. In past winters occasionally I've run it for 20 minutes at a fast idle - throttle wedged though, not choke pulled - and it'll get hotter like that than normal driving in low temperatures. You can also block off most of the rad and keep an eye on the temp to get the needle up higher than it would otherwise be. That should get things plenty hot enough.
paulh4

I suggest removing the oil cooler and draining it as well. Once disconnected, the oil cooler hoses will also drain.
Glenn Mallory

Having worked at a marina, I recall a few times when a boat was swamped, we had to change the oil out a few times before the crankcase was clear of water. You can tell quickly as the oil turns white. Once you've gotten a "clean" crankcase, run the engine for a period of time to ensure the oil is no longer contaminated.

Cheers

Gary
79 MGB
gary hansen

On say a standard oil and filter change there's a surprising large amount old residue existing oil left in the engine - and as Glenn has pointed out the oil cooler.

So for oil changes/drains I get the oil as hot as possible and leave to drain for as long as possible but in this case I'd also remove the rocker cover, oil cooler and sump to clean them all and get at as much of the top and bottom of the engine to remove and clean out as much oil and water as possible.

When I'd put all back together I might add or use a fresh filter and flushing oil/fluid (for cleaning) and/or use cheap oil for a limited mileage before hot drain again and change of filter to replace with cheap oil again for a limited mileage and if all seems well than I'd do another oil and filter change to refill with good quality oil.

Good advice too to not (ever if possible) do short journeys and make sure the oil in the car fully warms up as that can get the condensation and acids (probably technically incorrect words) in to the oil anyway so won't help your situation.

Good luck.
Nigel Atkins

All good advice--specially draining out the cooler if it has one, just pull the hoses off the engine and hold one up and pour some fresh oil in (funnel)till the old stuff is flushed through
If most of the water is out i use about half a litre of methanol in with the engine oil, The oil will go all milky and absorb any water but as soon as it's up to temp it just fumes off and goes clear, just go for a good drive and cook it out- 1/2 hour drive will do it
William Revit

I like Willy's idea of driving to clear this up rather than messing about on the car. I've no idea where to get methanol from and possibly here in winter you might need more than half an hour and need to get get the car warmer by more spirited driving - but that's a win, win, win, taking the car out for an enjoyable spirited drive instead of getting very oily and dirty - what's not to like(?).
Nigel Atkins

Nigel you can get Methanol on Ebay, or maybe a pharmacy?

Dont be tempted to drink it!!
Colin Parkinson

lol--we have it laying about in 200 litre drums here
Some of the racer guys over there would be running it--everyone that runs it would be happy to flog some off so they can get into a fresh drum, it goes off fairly quickly after the drum has been tapped--Sprintcar racers at your local speedway would be using it
Maybe you could use methylated spirits but the boiling point of that I think is about 75-80deg so you would need to get the oil fairly hot to cook it out
Methanol is lower at around 65deg----?? and cooks off easily at normal running temp.
William Revit

Methanol is dangerous - breathing the fumes or getting it on your skin will cause health issues, possibly leading to blindness or even death.

Methylated spirits is ethanol with dye and about 5% methanol - still not recommended to get it on your skin!

Ethanol is just as good as absorbing water but I think you are over worrying here, as long as the sump is drained then the fresh oil will cope with any small residual water.
Chris at Octarine Services

Thanks Coilin, now I see it's freely available I can;t think why I thought otherwise - I just did.

Chris's remark about meths pulled me up a bit, I just think of it as the purple stuff to clean glass and other stuff, I've never got me head round the difference between meths, turps, turps substitute and the other one I can't think of now. Always confused me as to which you use to clean what.
Nigel Atkins

You worry too much Chris
I consider myself fairly safety conscious but
I've been round methanol big time for probably 45 years, never had an issue with it apart from you can't see it burning in daylight
It might make your eyes and nose run a bit if you get a dose of exhaust from an engine running it but a bit of fresh air quickly fixes that--cures the common cold instantly
It's not carconegenic so it's my friend---

I have heard that if you ingest it it can cause a loss of sight, but honestly who's going to knowingly drink it---Although,there is a rumour round here that in Bali they use it to raise the alcohol level in drinks and people have died from that, so in that regard Chris's health warning has merit
willy
William Revit

I agree with Willy, methanol isn't that dangerous unless you drink it. Having worked in a lab for 42 years I have sloshed about gallons of the stuff with no ill effects at all. And yes we did do risk assessments on every blessed chemical we used. Methanol was classed as low risk.

Methanol and water love each other and will combine readily, so mixing some with the oil to eliminate water makes sense to me.
Mike Howlett

Many years ago I used to licence manufacturers etc to use denatured alcohol and ANY use that involved contact with humans was restricted to ethanol denatured with bitrex - methyl denatured ethanol (methylated spirits) was not allowed.

Methyl alcohol DOES get absorbed into the bloodstream through the skin.
Chris at Octarine Services

ETA: Mike and/or Chris (I was typing when Chris posted).

Mike, to take advantage of your knowledge - and imagine you're addressing someone with the understanding of a ten-year-old (but without the memory retention so will need reminding or get mixed up again!) - what's the difference between meths, turps, turps substitute and the other one I can't think of, please?
Nigel Atkins

Turps is processed pine resin, Turps substitiute & white spirits are the same thing - produced as a by product of petrol distillation.

They do not mix with water and are used as a general solvent, used mainly in paints.

Alcohols (ethyl & methyl or mixtures) mix readily with water but not with mineral oils.

So cleaning down an oily surface is a job for turps / white spirits (or diesel / petrol) or a soap product that breaks up the oil and makes it miscible with water.

Alcohol is used for cleaning, drying and disinfecting non oily surfaces.
Chris at Octarine Services

Nigel, what Chris said.
Mike Howlett

Hey D.J., did you get the water out of your crankcase yet?

Cheers

Gary
79 MGB
gary hansen

That's the go Gary--
Back to D double J's question
That's the last time I'm going to suggest a simple safe fix, wasn't suggesting a methanol bath party
William Revit

You could use ethanol instead - but that's also toxic......
Mike Howlett

What ratio of methanol to oil do you use ...
paulh4

It'd be a struggle to get the oil hot enough to boil off ethanol I reckon Mike, don't know never tried it,,I think it's about 80deg for eth. while methanol is a lot lower in the mid 60s and steams off fairly easily
The fun bit is methanol doesn't mix with engine oil so it goes milky/frothy just like water does but as soon as it gets hot enough there's just a little steam and magic clear oil.

Sorry DJ, we've nicked your thread a bit here
How's the new headgasket going----?
William Revit

The whole point of using alcohol is to drain it out after it has mixed with the water - carrying the water out of the sump.

Just boiling it off would leave the water behind!

Anyway, as the oil hits the underside of the piston it will be way over the boiling point of water, let alone alcohols ....
Chris at Octarine Services

Thanks, Chris, Mike and all, I now at least have a (copy & pasted) note to refer to as a reminder for me.
Nigel Atkins

If parts of the engine didn't get hot enough to dissipate water with a boiling-point of 100C you would never get rid of the natural condensation from each cold start.

This is another one that's being way over-thought.
paulh4

Lol---The only ones that are overthinking it Paul are those that are over thinking it and won't accept a proven simple remedy---it works, full stop, been doing it for years

How's the car going DJ, seeing as you started this thread a little feedback wouldn't go astray
William Revit

Not as simple as simply driving it ...
paulh4

Having done quite a number of MGF head gaskets that have resulted mayo in the sump for some time before the owner noticed, I am amazed at the almost complete lack of bottom end damage in such cases. I suspect that it does affect the VVC mechs as I have found some which are prematurely noisy but don't know the history of them so have just joined the dots. Maybe correctly, maybe not.
But any crank bearings I have seen appear surprisingly unaffected.
Paul Walbran

We just kept changing the oil until there were no signs of "mayo" in the crankcase. It could take several oil changes to accomplish it.

Cheers

Gary
79 MGB
gary hansen

I'm.with Paul on this, just drive the car and the water will boil out.
Obviously drain and replace first and make sure you get engine up to temperature. I have no idea how long it would take but an hour should go a long way.
Stan Best

Since the water would displace the oil, how long would it take before the engine packed up?

Cheers

Gary
79 MGB
gary hansen

doubleDJ hasn't been back since his first post
Bit of a p.o. when there's no feedback
--or maybe he's stuck out on the side of the road somewhere with a seized engine running on water-?
Or still looking for some methanol to cook it out with--------lol

willy
William Revit

It all helps the sum of human knowledge I suppose!

In terms of getting all the water out, if you've completely drained the sump, fitted a new filter, got the oil out of the cooler, is what's left hugely worse than the amount of condensation you'd have inside a cold engine anyway? Apologies for long rhetorical sentence and if this has been said already.

I've happily, well not exactly happily, driven vehicles with water in the oil and oil in the water and what has eventually stopped the vehicle has not been bearing failure.
Peter Allen

This thread was discussed between 10/12/2019 and 07/01/2020

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