Water pump attack

[Thys]

What attacked my Discovery's water pump? My 300 Tdi blew the head gasket between no 1 and 2 and a water jacket. The coolant mix was as per specification. The thermostat was as clean as new. The pump was in service for about 2 years.

It looks like Microbes, but how can they survive with the coolant mix?

Can the coolant mix have a high sulpher content as a result of the combustion leak (I use the standard diesel)?

Is the pH level messed up as a result of the carbon content in the coolant?

Has some one added Bars Leak or some other gunk to try and stop a slow coolant leak?

What scares me is that the innards of the cooling jackets inside the block may look the same?

Could this condition be the cause of gradual over heating, resulting in the head gasket eventually leaking?

Lots of questions, but I am very concerned.

[BogMonster]

Looks like pretty patterns of rust to me

[Les Henson]

The impellor blades are originally zinc plated and rust has burst through the plating in what looks like little balls. No doubt the restricted oxygen supply has caused the rust to form in the way it has. In a minimal oxygen environment rust can appear black, and the more oxygen present - the more orange the rust becomes (what most people are more familiar with). Anti freeze not only prevents the coolant from freezing in cold conditions, but also raises the boiling point - so your coolant is more efficient in the warmer weather. Anti-freeze is also an an anti-oxidant, and the correct concentraion of it in the engine will prevent steel and alloy components from corroding. Strange that this has happened if you have always used the correct concentration of anti freeze in your engine.

Les.

[ThreeSheds]

Just an off-the-wall thought - it looks a bit like salt water rust* to me - but why it's like that? I'm stumped...

TwoSheds

*there is probably no such thing as 'salt water rust' but you do see a lot of this sort of thing on ironwork on or near beaches...

[JimAttrill]

Maybe your coolant had become acidic, especially in view of your gasket problems. We test coolant in two ways, the first is the strength of the anti-freeze, preferably 40% to 50%, but we also have an electronic ph meter. Pure Antifreeze has a ph of 10 or slightly higher, and when diluted the ph should be 8.5 or higher.

I recently changed the coolant in my Defender as the ph was 8, and it had been in for 18 months.

I do remember from the short time I worked on Rolls-Royce Griffons in the Shackleton 2 that the coolant was tested with litmus paper after every flight. If acidic, it was changed. The litmus paper was specially made, so I don't know what ph we were actually looking for. Certainly anything lower than neutral at 7.2 is way too low.

[Thys]

Maybe your coolant had become acidic, especially in view of your gasket problems. We test coolant in two ways, the first is the strength of the anti-freeze, preferably 40% to 50%, but we also have an electronic ph meter. Pure Antifreeze has a ph of 10 or slightly higher, and when diluted the ph should be 8.5 or higher.

I recently changed the coolant in my Defender as the ph was 8, and it had been in for 18 months.

I do remember from the short time I worked on Rolls-Royce Griffons in the Shackleton 2 that the coolant was tested with litmus paper after every flight. If acidic, it was changed. The litmus paper was specially made, so I don't know what ph we were actually looking for. Certainly anything lower than neutral at 7.2 is way too low.

Thanks Jim,

I made allowance to replace all the coolant, thus also draining the block, and flushing

[Thys]

The impellor blades are originally zinc plated and rust has burst through the plating in what looks like little balls. No doubt the restricted oxygen supply has caused the rust to form in the way it has. In a minimal oxygen environment rust can appear black, and the more oxygen present - the more orange the rust becomes (what most people are more familiar with). Anti freeze not only prevents the coolant from freezing in cold conditions, but also raises the boiling point - so your coolant is more efficient in the warmer weather. Anti-freeze is also an an anti-oxidant, and the correct concentraion of it in the engine will prevent steel and alloy components from corroding. Strange that this has happened if you have always used the correct concentration of anti freeze in your engine.

Les.

Les,

Thanks for the reply. I bought the Discovery one year ago, and the coolant was OK. However, based on the previous owner's admitance that the Discovery overheated, and was nursed to the nearest town with a LR Dealership, the enjine may have been run on pure untreated water. As replied to Jim, I will replace the coolant after flushing the block, with a 50% concentrate.