Losing coolant again!

Hi all.

After several attempts at sorting my overheating Disco 9 (see http://www.landyzone.co.uk/lz/f8/overheated-300tdi-264599-2.html), I thought I had sorted it out. I eventually replaced the thermostat and water pump, bled in several different ways as advised on here and she seemed to be rock steady at just under 1/2 on the temp gauge. After a few shortish trips and around 150 miles, all seemed well. But last night after around 20 mins, the temp started to climb again :angry2: :angry2: . I stopped before she went too high, opened up the cap and there was much knocking and burbling, so I assumed low water and air in there again. I let it cool a little and put about almost a gallon of coolant back in and the temp seemed to stabilize at very slightly higher than normal. She got us home OK and when I popped the bonnet, I noticed that there seemed to be a fair bit of water around the front and side of the expansion bottle. It also seemed to be hissing around the seam so my guess is that the bottle is leaking under pressure.

Has anyone had this happen before?

I am now looking for another bottle and hoping this will get rid of the issue once and for all!!

Any ideas/suggestions gratefully received.

Gotta love Discos!! :unsure: :glare:

If your expansion bottle is the black type, there's a fair chance that the seam is split. Replace it with the white opaque type and see how it goes. Also check the bypass hoses (thin hoses going from the bottom of the expansion tank into the top of the radiator (oil cooler side) and onto the top of the thermostat housing for any blockage.

If its bubbling back through the coolant tank it could be a fault with the head gasket or even cylinder head and pressure might have cracked coolant tank, if the cap didnt release it.

Did you change the P gasket at the same time as the water pump? If not I'd guess that was your problem there's only around a 5% success rate of no leaks without doing it IMHO
Sam

Thanks for the replies guys. I have replaced both expansion bottle and cap as there is definitely staining around the seam of the old bottle.

I bled the system by filling the radiator through the top cap, replaced the cap then filled the thermostat housing until the expansion bottle was showing the correct level. I then ran the engine with the radiator cap off for a few minutes, cracked the thermostat housing cap open until water came out then nipped it back up again. Then I put the expansion bottle cap back on and went for a short drive. All this done with the heater on max heat.

The temperature was rock steady at the norm (just under half way), and the water level looked OK. I left it for about 15 minutes, checked the water, and it had risen by about 1 1/2 inches. I checked it again when the engine was fully cold and the bottle was almost full! I assumed some sort of air lock causing the water to back up in the bottle, (the radiator was still full). I drained the water to the fill level, ran the engine with the cap off and cracked the thermostat housing cap again until water ran out then re-tightened. Ran up to temp and then a short drive, the heater was hot, the water in the bottle dropped by around 1/2" and the top and bottom hoses were hot. The radiator was mostly hot, but only warm at the offside end (I assumed this was because I only went for a short drive rather than a blockage in the radiator?)

I could smell no trace of diesel etc. in the coolant nor any steam or smell of antifreeze in the exhaust.

Anyhow, checked the water the following morning and it was back to the fill line, and no signs of any loss that I could see.

I will have to keep an eye on it for now and hope that all is well :scratching_chin:

@Sam: I did replace the P-gasket mate, and made sure all surfaces were Uber clean and applied a smear of Blue Hylomar to all surfaces

Well, I thought I had sorted it out after replacing the expansion bottle and cap. After a couple of shortish runs, the temp was rock solid, and the level in the expansion bottle dropped by around 1/2" or so once the water was up to temp then returned to the fill line when cool.

But after a run of around 60 miles today, although the temp was solid, the heater worked fine once warm, but after I stopped for about 10 minutes, when I restarted, although the temp was showing just a little under 'norm', the heater was almost cold, but after around 3-4 minutes of driving the heater was hot again. Once I stopped, I checked the water level, but this time it was up by around 1"!?? So I am now even more confused than before

Can I assume it still has an airlock and hence the varying level of coolant in the bottle and heater slow to react? I cannot see any signs of leaking around the system.

I am going to get an adaptor and try the method Boydie has suggested and see if that does the job.

Any ideas gratefully received.