2.8i Oil in water

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Oipallett
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2.8i Oil in water

Post by Oipallett »

Hi all want to pick some brains as always

I’ve a 2.8 I’ve been doing what seems like forever now and had a rebuilt engine had head skimmed new gaskets everything prior to being put in last year

Finally got it all running coming to MOT stage and I noticed oil in the radiator so assumed the head could be at fault even tho Itd barely ran and covered no miles I did a compression test and the left bank one was at 100 the rest were about 140

So I went ahead and changed the gasket on the side it was low I didn’t think it necessary to do both sides as it’s basically new and compression was good

Nothing major looked out of place in gasket and head there was no marks

After all that the situation was the same after flushing out many times and refilling by the time it ran for a bit the oils back

I bipassed the oil cooler to see if it could be leaking but it still looks like Mayo in the rad after that so I’m scratching my head what to do now don’t want to start ripping the engine to bits for the sake of it

Is there any where else the oil could sneak in

The oil is Cristal clear not a sight of water in the engine oil so I’m confused to say the least

Thanks so much for any advise to to ramble on
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Noel
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Re: 2.8i Oil in water

Post by Noel »

Read this about 3 times and struggling to think of any other entry point for oil into coolant if the oil cooler has been taken out of the equation.

But, if I had one new head gasket that had caused low compression on a fresh built up engine, I would not trust the other one either and replace them both.
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Peter-S
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Re: 2.8i Oil in water

Post by Peter-S »

Have you done another compression test on the pot that was only showing 100 since changing the gasket? If its still low I'm thinking cracked cylinder :(
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Bug
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Re: 2.8i Oil in water

Post by Bug »

I'm trying to get my head round viscosities, capillary action, temperatures, pressures etc.
No matter which way I look at it I still feel I would expect water to get into the oil, not the other way around?? :headscratch:

Is it even remotely possible that oil somehow got into the waterways while the engine was being worked on, and is now being flushed through? It takes a miniscule amount of oil to create the mayonnaise effect you are seeing.

Would it be worth thoroughly flushing out the coolant system a few times just to eradicate that possibility?
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stevemarl
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Re: 2.8i Oil in water

Post by stevemarl »

Martin,
I`m thinking that the oil in the galleries IS under pressure so if you had a crack twixt oil passage & waterway, it could conceivably pass into the water (which, even hot, has a fraction of the pressure)?
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Bug
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Re: 2.8i Oil in water

Post by Bug »

stevemarl wrote: Thu Jun 03, 2021 5:28 pm Martin,
I`m thinking that the oil in the galleries IS under pressure so if you had a crack twixt oil passage & waterway, it could conceivably pass into the water (which, even hot, has a fraction of the pressure)?
As I said, I was head scratching and second guessing myself for a while. You could be right. Depends where the crack is I suppose.
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Re: 2.8i Oil in water

Post by Mc Tool »

I would want to confirm that the gasket was the cause of the low comp . Why was the engine rebuilt and is there a possibility that the oil is from the previous version of the engine and no one cleaned out the coolant system, ( or as Bug says got in whilst engine being worked on )it doesn't take a lot of oil to put a head on the coolant . My take on the transferance of fluid ( stevemarl says 🙂 ) is that the oil pressure is higher than coolant pressure so oil would flow to water in a gasket failure or cracked block ( are they known for cracking blocks ?) , but when parked and cool I guess it could go either way.🙂
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