Twin cam - Coolant in engine oil?

[pboedker]

I was just checking/topping up the engine oil in preparation for a 500 mile weekend trip in the Europa with my lovely wife. Looking into the valve cover opening I saw a greenish color of the oil. And I know it's been millions of years since that particular oil was growing as a green plant.

So we took the daily driver, had a nice weekend and returned yesterday.

Removing the valve cover reveals the attached photo and the following facts:
Lots of green colored fluid on top of the exhaust valves for cylinder 3 + 4.
As far as I can see there's no coolant resting above the other 6 valves.
The oil hasn't turned into mayonnaise inside the valve cover or elsewhere. The cover looks normal oily in all places inside.
Looking into the coolant expansion bottle, the coolant looks fairly clear (i.e free of oil).

A mechanics colleague told me from the photo that it could be a small seepage/crack or a frost plug in the head and that it would probably be a fairly new fault. And that it didn't immediately indicate e.g. a head gasket failure and a pressure test of the cooling circuit might reveal further evidence.

So, any good ideas and comments from the collective are more than welcome.

I'm puzzled as to where and why the water enters the oil. The motor has been dripping oil and water for many years, so I'm used to topping it up from time to time. This is the first time it has been mixed.

Sigh!

[jbcollier]

I can't really see any signs of coolant.  Some oils have a greenish tinge.  Water/coolant emulsifies in the oil and forms a yucky, creamy sort of sludge.  Yours looks to be clear.

[TCS4605R]

Peter,

I'd suggest two things.  First, do a compression check.  Second, do a pressure test on the cooling system.  Either test should locate the problem.  Also, look at the spark plug electrodes to see if their color is correct.

Tom

[Stuleslie]

Peter, A similar thing happened to me. I would first suggest removing the oil from the sump and pour it into a clear vessel. Leave it to stand for a few hours and you will see how much water is in the oil (water on the bottom). My engin had stood for several years fully assembled and I was preparing it to run it by putting coolant into the system, I later found water bubbles on the dip stick. After a long think I thought the only place water could leak without pressure was around the water pump. There is a large o-ring around the pump that seals the water gallery from the timing chain cover. Fortunately the body was off the chassis so I had easy access to the timing cover which I could remove without taking the head off. You can also take the sump off in situ to clean out any residual water. A new o-ring and sealant later all was well. If you fix your fault may I suggest you flush the oil system with flushing oil by turning the engine over without the spark plugs.
Good luck Stuart

[EuropaTC]

Hi Peter,
Well, that is a strange one, just why only 2 valve pockets are affected is well beyond my guessing.  My first thoughts were that it was under the filler cap and you'd managed to find some very old Duckhams Q, that weird green 20/50 that was such a novelty in the 60s/70s ?

I can't get over how localised and apparently clear it is, the only experiences I've had of similar things were very messy. Firstly oil in the coolant after a failure of the cylinder seal which pressurised and rapidly started to throw out coolant within seconds of the engine starting. On that one the engine oil staying relatively clear.  I've also had the emulsion/condensation thing on Mini A series engines, very obvious and nothing like you have there.

My only suggestions are the same as have gone before, pressure test the coolant and then the cylinders although I'd be surprised if it's the cylinder seal. 

If there's a head gasket failure between water & oil then I would have expected to see both the oil contaminated (as an emulsion) plus an oil film in the header tank. When the engine runs the higher oil pressure pushes oil into coolant, when the engine stops the residual coolant pressure forces some back the other way ?

If you want blue sky (read "silly") ideas to pursue, are the head bolts tight, specifically that one with the neat blue droplet on top ? 

I shall look forward to your investigation Peter, this one has really got me scratching my head.

Brian

ps - I've got it, "Sabotage" !  Your wife couldn't face 500 miles in the Europa but didn't want to upset you so she sneaked into the garage, topped up with antifreeze and then suggested you check the car before leaving.....   

[EuropaTC]

Peter, A similar thing happened to me. I would first suggest removing the oil from the sump and pour it into a clear vessel. Leave it to stand for a few hours and you will see how much water is in the oil (water on the bottom). My engin had stood for several years fully assembled and I was preparing it to run it by putting coolant into the system, I later found water bubbles on the dip stick. After a long think I thought the only place water could leak without pressure was around the water pump. There is a large o-ring around the pump that seals the water gallery from the timing chain cover. Fortunately the body was off the chassis so I had easy access to the timing cover which I could remove without taking the head off. You can also take the sump off in situ to clean out any residual water. A new o-ring and sealant later all was well. If you fix your fault may I suggest you flush the oil system with flushing oil by turning the engine over without the spark plugs.
Good luck Stuart

Good one Stuart, a failure there would let water into oil without cross contamination of oil into water which had been puzzling me.  It sounds a very plausible reason although I'm still struggling with why it's only on 2 exhaust valve bays ?  That's still got me beat.

[4129R]

If the head gasket is going, the exhaust is very steamy.

I recently had a disgusting Vauxhall Nova with the head gasket gone, and clouds of steam filled my driveway on start-up. .

[Gmg31]

I'm not convinced that where the water is in the photo is relevant. If the car was parked pointing up or down a hill then the water would settle at the lowest point. I think we may be overthinking that part of the puzzle. None the less the testing suggested above would seem to be a starting point.  The fact that it hasn't emulsified suggests it has only just happened. and you haven't run it for long since the the "contamination event".         

[pboedker]

Thank you all for your comments and suggestions! It gives me some ideas for what to try looking for

I will try to arrange a pressure test of the cooling system in the hope that a leak will reveal itself. It has to be near this place, to distribute the fluid so concentrated on only these two valve tappets. My first bet is on a head gasket leaking between a water channel and the hole for the bolt. I hope it's not a crack in the head connecting the bolt with the water channel.

Second step would be to do a compression test, but since the engine was not blowing white smoke and the oil otherwise looks fresh and clear, I doubt that the head gasket has failed between a water channel and a cylinder to a degree that a compression test will show a clear difference across cylinders. But I could be wrong, and the leak is just a new development that hasn't mixed up the oil very much yet but could be found in a compression test.
Having removed the valve cover, I am a little hesitating about rotating the engine. Maybe at cranking speed the sloshing is minimal. Hmm, wouldn't hurt to try.

I will wait to drain the oil until after I have either done a compression test or decided not to do so. Should be interesting to see how much of my oil is actually oil.

Brian, you seem to already know my wife? Or are they just all like that? 

[Bainford]

If it is un-emulsified water, why has it pooled on top of the oil?

[BDA]

I don't have a whole lot to say about what you're seeing on your cam, but if you can, I would think a leak down test would be preferable to a compression test.

[EuropaTC]

Having removed the valve cover, I am a little hesitating about rotating the engine. Maybe at cranking speed the sloshing is minimal. Hmm, wouldn't hurt to try.

Peter, as one who has started the engine without properly fitting the filler cap after topping up and successfully washed the rear of the engine bay in oil (Elan) I'd suggest at the very least you drop the cam cover back in place, the amount of "splash" defied belief !

I like Stuart's idea but I'm really beat as to why there's no emulsifying or why it's just collected at that point on the exhaust cam.  I'll be interested to see what you find when you drop the oil out.

Brian

[pboedker]

If it is un-emulsified water, why has it pooled on top of the oil?

As far as I can see, it has filled the pockets around (under?) the valve tappets with water and the lighter oil has then escaped and drained to the engine bottom. I plan for some garage time tomorrow and wil try to suck up some of this fluid for further examination and comparison with fresh oil.

[buzzer]

Been reading this with interest and 3 things strike me.
1. As you say it is just pooling by the rear exhaust valves.
2. It’s not mixed with the oil
3. It is very difficult for the coolant to get there without getting all over the engine.
Is it a coincidence that this is under the oil filler? Could someone have mistaken the oil filler for the water filler
Have you jet washed the engine with cleaning fluid, was the cap on properly?

Just an alternative thought before you strip out the engine!

[pboedker]

Okay, so the puzzle is solved. I found the explanation. I'm not needing an engine rebuild this time. But I might owe a beer or two.
 

I went to the garage and sucked up the green fluid with a syringe and put it into a glass jar. It didn't separate in water and oil as I was expecting it to, but I put it aside and thought it would probably do so overnight.

Since I couldn't borrow a coolant pressure tester until the day after, I was left to thinking a lot more about the ideas and questions in this thread:
Nobody has put oil into the oil filler (I'm the only one working on it).
Engine hasn't been jet washed. It's leaking oil from the cork gasket, but even though I have washed it with a brush before going to the MOT test that was all a month ago, and if water would be sucked in, it would have been mixed a lot more.
The green stuff was only in the valve parts close to the oil filler. And very strangely on the top of a bolt as if only this part of the engine had been flooded with water.
And as several suggested, it just didn't look like normal mixup of engine oil and water.

I then realized that the engine had in fact been flooded, but it was with oil as I was topping it up. Reading the dipstick I knew that it could take about half a liter and that's what I poured into the oil filler. It always almost blocks the hole so I always wait a couple minutes for it to drain to the sump before taking a new reading of the dipstick. I also did that the week before.

What if the oil was somehow bad?, I thought, and went into the workshop and poured some oil into another glass jar. No, it looked perfectly normal, brown and clear as new oil does. I went to the garage, still with the jar in my hand, and couldn't believe my eyes: The fresh oil now had a green color just as the color I saw through the oil filler the week before.

Then it dawned on me:
Above the engine was hanging my powerful LED work light. I was using a LED flashlight to shine into the oil filler. Pictures was taken with my phone, using the LED flash...
And I have neon lights in my workshop.

What I thought was coolant fluid was in fact the LED light making a green reflection of the fresh oil. I don't know what it is, it must be one of the unmolested additives that does it. So the green fluid in my initial photo is fresh oil and that explains why it was only in the oil filler area.



The first photo below shows what I initially saw through the oil filler. The other two are of the fresh oil, one with and one without light from my LED flashlight. I guess you could call this some kind of a light-bulp moment.