Coolant leak and slow speed fan not working

[SD1too]

Originally Posted by Mr Toad

The mayonnaise is confined to under the cam covers.

Thanks for this Martin. I think the question should be asked: why? If oil and coolant are mixing, wouldn't you expect the valve gear to be covered in it as well? Wouldn't this be a virtual certainty if, as you surmise, there's a crack in the head as opposed to the cam cover?

How has this car been used? Does it stand for long periods outside? The cam covers are probably the coolest part so I'm wondering whether it's condensation mixing with oil vapour. Are your breather tubes intact or have they fractured recently?

Originally Posted by Mr Toad

I have not fully drained the oil but I can see it is black no doubt coolant mixing with the oil.

Regarding this and T-Cut's post, you will need to drain the oil since he specifically states that ....

Originally Posted by T-Cut

.... it will take days to empty due to the high viscosity.

So if yours doesn't, could the black oil simply be a sign that a change is overdue?
By the way, if you have a black tipped dipstick as I do, that can mislead. Wipe it on a sheet of kitchen paper to obtain a true indication of the lubricant's colour.

As you can probably tell, it will take a lot to convince me that a head has cracked. There's always a temptation to follow a very complicated diagnostic path when most faults turn out to be very simple. Think of garages looking at a 75/ZT which overheats and convincing the owner that the head gasket has gone and the car's fate is sealed. We all know that the fan is the most likely culprit.

Simon

[marinabrian]

Martin, coolant emulsified lube oil looks like butterscotch Angel Delight, however if left long enough, it will separate out.............

Here is Kaiser's picture of the cracked block with the liner removed.



I've seen cracked liners on a couple of occasions, and also failed head gaskets, and while certainly much less common than the four cylinder engine, not unheard of and definitely not to be dismissed as never happening ever as a lot of people will have you believe

As you've now got the heads off, drop the sump remove the pistons and liners ad take a look at the block, also it may simply be a matter of resealing the liners, as it's possible for water to track between the liner and block, ending in the sump

Best of luck

Brian

[kaiser]

Thanks MarinaBrian.
For some reason I can't get that link to take!
Anyway, looking at the picture, I actually think that water stain is from a leaking head gasket, if I have to be honest.
I cannot see how the grey plume on the wall comes from that crack. It could well have caused a problem, but I cannot see water having run down between the liner and the block, there is no corrosion further down, from what I can see. I didn't remove the liner, maybe it was also cracked, I don't know.
It looks to me as if the gasket has been breached at the corner where the waterway is, and the marking is from that, rather than the crack itself.
Ah well, assuming, and all that jazz.
And, upon closer inspection, the next cylinder, no 4 below, has also cracked! Which I can't remember to have noticed before. But there definitely appears to be a small crack on that as well.
This is the block I use when I make the thermostats, and I got it in 2008, if I remember correctly. It comes in handy for making sure all measurements are correct. But there you go. Two cracks, at least.
I wonder what actually happened to that engine, to cause this. I will have a closer look tomorrow. Now it is dark, and the temperature here in Africa drops like a lead balloon after sunset in winter. no cloud cover and the heat just oozes out into the dark night sky, where, high enough, you have -270 oC.

[T-Cut]

Originally Posted by marinabrian

Martin, coolant emulsified lube oil looks like butterscotch Angel Delight, however if left long enough, it will separate out.............

Not in my case with a 1.8Turbo at 32K miles. It had full synthetic engine oil and a standard 50% OAT coolant charge, when the latter was effectively dumped into the former over just a few miles. I was seven miles from home and stationary when I noticed the cooling fan running. Soon after that, the gauge went asymptotic and the red light popped on. I stopped to check and found the header tank empty. Luckily, I had some coolant in the boot and after cooling down and topping up, cautiously returned home. It was very clear that the sump was full of coolant-oil mix. I saw a pale coloured emulsion around the top end. On draining down next day, there was no butterscotch mousse. It released a jet black, viscous fluid resembling tar or molten bitumin. Obviously cold, it took several days to empty.

I was therefore intrigued by the observation made by Martin about his V6 oil after only 2500 miles. However, he has yet to drain the sump to enable us compare notes. It's apparent though, that given the right conditions of oil type, coolant type/concentration, plus the homogenisation of the running engine, something rather different from the typical mousse can be produced. The cause was catastrophic delamination of the rubber seals on the OEM gasket. The gasket shown here had been washed/cleaned.



As can be seen, the fire rings are perfect and the head surface was mechanically perfect. Only the seals were faulty. Most interestingly, there was a distinct pink 'staining' on the metal around some of the seals and on the corresponding areas on the head. It appeared to have been deposited by the coolant flow around the seals and the hot fire rings



The OAT coloured stains wiped away with a paraffin damp rag. I suspect this is a typical example of the head gasket failure that's characterised this engine since birth. My personal opinion is that this particular gasket was not fit for use with OAT. The rubber to metal bonding also looks inferior by today's standards, but is clearly adequate. I have replaced it with a Payen type elastomer of similar construction and refilled the cooling system with 25-30% OAT. In fifteen years ownership, I've not had any other OAT implicated failure.

TC

[kaiser]

That type of failure is a catastrophic mix of oil and water. That is not the same as a smaller amount ending in the oil and "burning" off.
The smaller amount will actually evaporate off the oil in the sump, and lodge itself as "mayo" in the colder areas of the engine, notably under the oil filler cap and other colder parts.
I have little doubt your fault was the OAT attacking the silicone seals. However that type of gasket was never (to my knowledge) used in the V6.
These are multi layer gaskets, and they are not prone to this type of failure.

[T-Cut]

Originally Posted by kaiser

The smaller amount will actually evaporate off the oil in the sump, and lodge itself as "mayo" in the colder areas of the engine,

Coolant is typically 50% water and 50% ethylene glycol. It's the water that evaporates. The glycol mainly stays put. A slower leak over a long period will generate a similar system to the one I experienced. That's what I was hoping to confirm. With sufficient homogenisation, the coolant is incorporated into the oil phase as a water=in=oil emulsion. This type of emulsion is invariably of high viscosity. In my case (and perhaps the current subject) it produced a black and highly viscous combination. I suspect the strange colour change is related to thermal and chemical effects on the OAT dyestuff and the active ingredients in the antifreeze. I've not read of a similar effect from non-OAT type antifreeze, so I assume (sorry) that this case also involves OAT coolant. However, that hasn't been reported. In my case. what little water evaporated over the short journey produced the typical upper end condensation emulsion/mayo you describe. In other areas, a less viscous greyish emulsion was also evident (see second photo above).



TC

[marinabrian]

Originally Posted by T-Cut

Not in my case with a 1.8Turbo at 32K miles. It had full synthetic engine oil and a standard 50% OAT coolant charge, when the latter was effectively dumped into the former over just a few miles. I was seven miles from home and stationary when I noticed the cooling fan running. Soon after that, the gauge went asymptotic and the red light popped on. I stopped to check and found the header tank empty. Luckily, I had some coolant in the boot and after cooling down and topping up, cautiously returned home. It was very clear that the sump was full of coolant-oil mix. I saw a pale coloured emulsion around the top end. On draining down next day, there was no butterscotch mousse. It released a jet black, viscous fluid resembling tar or molten bitumin. Obviously cold, it took several days to empty.

I was therefore intrigued by the observation made by Martin about his V6 oil after only 2500 miles. However, he has yet to drain the sump to enable us compare notes. It's apparent though, that given the right conditions of oil type, coolant type/concentration, plus the homogenisation of the running engine, something rather different from the typical mousse can be produced. The cause was catastrophic delamination of the rubber seals on the OEM gasket. The gasket shown here had been washed/cleaned.



As can be seen, the fire rings are perfect and the head surface was mechanically perfect. Only the seals were faulty. Most interestingly, there was a distinct pink 'staining' on the metal around some of the seals and on the corresponding areas on the head. It appeared to have been deposited by the coolant flow around the seals and the hot fire rings



The OAT coloured stains wiped away with a paraffin damp rag. I suspect this is a typical example of the head gasket failure that's characterised this engine since birth. My personal opinion is that this particular gasket was not fit for use with OAT. The rubber to metal bonding also looks inferior by today's standards, but is clearly adequate. I have replaced it with a Payen type elastomer of similar construction and refilled the cooling system with 25-30% OAT. In fifteen years ownership, I've not had any other OAT implicated failure.

TC

TC that is a classic example of a post 1998 HGF model, so nine years after the engine was originally launched

This is the exact reason I use antifreeze with silicates used in the role of corrosion inhibitors

It goes to show after replacement with a BW750 (identical to the factory fit BTW, as Federal Mogul supplied Powertrain) and a 25% mix of OAT, that there has been no repeat failure.

That ratio of coolant is advised by Jules, and he has done for years, it would be interesting to compare the hybrid OAT silicate coolants to see how they stacked up against the pure OAT formulations, in terms of elastomer seal damage.

Brian

[kaiser]

Classic anti freezes have proved their worth for the last 100 years or so. It is well know they work, and also that they need replacing at 2 to 3 years.
If you do that, you have perfect protection against both corrosion and also freezing, provided you don't dilute the mix.
If that has been good enough for my grandfather who drove Fords, Taunus, Fiat and Austin, and my dad, who drove Fiat, Alfa, Mercedes, then it is good enough for me.

I have never used OAT, and I never will.

[Mr Toad]

Brian I'm afraid I have no intention of removing the liners especially not with the engine in situ.

I haven"t yet had a change to drain the oil but propose to do it tomorrow. In the meantime I have had the heads pressure tested, no leaks found. I have also had the heads lightly skimmed to ensure they are perfectly flat and i have ordered genuine MG Rover head gaskets.

The head gaskets I removed were MLS and I could find nothing wrong with them. How does OAT coolant react with MLS gaskets.

Could there have been a failure of the MLS gaskets even though a chemical test proved negative?

[marinabrian]

OAT antifreeze won't have any effect on a multi layer steel gasket Martin

Why not fill the jacket water spaces in the block, and see if the level drops through leakage, while you have the heads off, just a thought

Brian