Water loss
 

I am having to constantly top up the water in my diesel 75, there is no sign of any leak. The oil on the dipstick looks fine so hopefully it won't be the head gasket. Any suggestions please.

I've owned diesel 75's for nearly 20 years and they normally don't lose a drop. When they have, they tend to lose it from the radiator cap due to worn seals but the evidence will be antifreeze showing around the top of the expansion tank.

The next most common area is the O ring failing on the metal pipe going into the thermostat. I found mine leaking after pressurising the system then shining a torch around the area. They are a bit of a tinker to change as I've done it on both of my cars.

The next could be the water pump as mine failed earlier this month at nearly 197,000 miles ! Found water on my fan belt !

Commonly, an area that leaks is the 'Y' branch beneath the engine cover. You can't see it until the cover is removed, and of course, it will evaporate before it hits the ground. They tend to crack, and can be purchased widely, maybe use the Land Rover one.

Hi Terry.
When you say constantly top up the water, how much are we talking about and over what period of time.

How much do you have in the header tank? is it at the top of the fins or at the bottom of the fins in the tank, can you see the max & min step in the tank if you shine a torch into the tank?

this is to much coolant
https://i.imgur.com/DkqpGf1l.jpg1

https://i.imgur.com/35LMW0yl.jpg2

https://i.imgur.com/FNwNhjBl.jpg3

https://i.imgur.com/pvCdIGCl.jpg4

Are the O-rings on the car ok not flat but as these below.
https://i.imgur.com/7X8KZZql.jpg5

The above is the best starting point, making sure the level is correct and the cap is in good order.

After that as above check the Y unit connector the the head, look for red/pink deposits around that area, what happens over time the plastic unit can go brittle and then leaks.
https://i.imgur.com/18MJJGwl.jpg6

If there is any sign of leaks there then it will need replacing, removal of the manifold is required to do so.

This is what happens the internal lip breaks and the seal no longer works.
https://i.imgur.com/I9Cewxyl.jpg7

https://i.imgur.com/E6zGrw6l.jpg8

https://www.island-4x4.co.uk/water-h...0l-p-8085.html

Also inspect all water coolant hose for security and little splits etc.

From there the next place would be as mentioned above the O-ring on the thermostat.

Thanks for that Artic, I have just done 200 odd miles Norfolk to Burbage Leics and it needed a cup full to bring it up to the fins. I shall check all of your suggestions and go from there.

Terry was it a cupful to the bottom of the fin or to the top of the fins, if the later then you are putting to much coolant in the tank ;) and most likely losing it through the cap because you have no expansion room in the header tank. ;)

It was to the top of the fins so you could be right as there is no room for expansion. Thanks for that.

I've always filled mine to the top of the fins mistakenly thinking that was the level and it never dropped to below that point . When I replaced my water pump earlier this month, two days later with the car loaded to the roof with camping gear, we headed to St Austell and it never dropped below the fins even 1500 miles later when we returned home.:cool:

Hi Pete.
Even so you still know it's the wrong amount in the header tank, maybe your cap is ok O-rings sealing properly, secure and tight, but the day will come when you need that expansion and it will not be there :shrug:

I /we don't know the state of the OP header tank cap, or it's O-rings, at least if he drops the amount to what it should be and then see if it needs topping up or not he as eliminated the expansion being part of the fault.

The cap must be tight and able to seal correctly, if not and to much coolant is in the tank then there will be a loss.

[QUOTE=patrolman pete

The next most common area is the O ring failing on the metal pipe going into the thermostat. I found mine leaking after pressurising the system then shining a torch around the area. They are a bit of a tinker to change as I've done it on both of my cars.

How much of a "Tinker" is it to do? I have a small weep of coolant from this area.. More annoying than anything..