Evening lads,

I know im not a regular poster on here but, have used the search function and had a good read of various posts relating to this inconvieniant problem! It's just pin pointing it to the exact culprit. So any of you seasoned Disco TD5 owners had this problem?

Took the car for a regualar service/check before winter and the mechanic said he put 2 litres of top up coolant into the radiator expansion tank- filling it to the cold mark level where it should be. Before this it did take a while to get warm and blow warm air through the vents, after it was amazing and almost instantly gave hot air when wanted....

I checked this again as it started to take abit longer to get warm air through the vents, low and behold the overflow tank for the radiator was empty (checked when cold of course). So i topped this up again (2litres ish again) to the cold level mark where it should be the other day. Now at least half must have gone..........but gone where?

I can't see any leeks, there's no puddles when i've parked up and no steam when i drive it! It just can't hold it's drink!!

Where would you look first as the culprit-water pump seal?

Aside from this problem it drives fine-no loss of power and does what i ask of it, just componants are not up to the job. Cars only done 120K, 7k of which i've put on it. It did have a sniff test done and that came back fine also no mayo under oil cap and no sludge/oil in the coolant system..

Also has power steering pump leaking so if things need repalcing they will all be done at the same time, read that the water pump is behind the power steering one? Correct me if wrong please...

Im used to Jap reliability from my other car and it's making this much newer disco look like a pup.. Got to say i think i should have bought a hilux . Sorry but im getting annoyed with these niggling issues on the TD5 every month or so....

Cheers in advance anyway...

Check header tank cracked, tank cap or head gasket/head if there are no external leaks

Thanks Fanatic, when i last checked in daylight the header tank seemed fine with no sign of fluid running away from it will double check if i have time when still daylight. Would the seal on the tank cap cause fluid to evaporate if it was worn and not sealing it properly?

I don't want to check the headgaskit/head incase it is this, i heard the cost involved, though a new head would maybe mean the plastic dowls could be replaced with metal ones mmmmmmmm

A big problem is that the expansion tank is too small. With two litres missing there is nothing left in the tank.
You should bleed the cooling system properly as a first try.

Then fix a small pet bottle on the overflow pipe. If the system is pressurized due to head basket failure the water will disappear on that way.

Also check all the hoses for leaks and also the fuel cooler and the radiator.

Regards Markus

Thanks Ahaggar, i'll try that bottle idea. I did check that pipe to see if there was any sign of fluid leaving it and it looked dry. Will have to get under it on my day off with a torch and have a look at all radiator joins and hoses

#Side note when i checked under the bonnet after getting home from work after it had stood for abit i could still squease the radiator pipes easily. Even though they were bloody hot they wern't hard/pressurized so i hope this is another sign as to no headgaskit problem?

I've seen the screw bung on the top rad hose that goes to the block- must be highest point of the system. Take it you undo this whilst the engines running, fill header tank then tighten the screw up once all bubbles/air has left the system and a steady fluid stream is running from it?

Markus, luckily my parents drive way is on a slope so i'll use that to get the front end facing the sky and try and move the reservoir off it's mounting point for this bleeding process...

With it being on a slope is there a danger of over filling the reservoir? I don't mind guessing as anything above minumium i'll be happy with. Will definantly try this technique over the weekend.

Funny you should say failure of the tank cap is a common fault as this crossed my mind on the drive back from work. Simple loss of pressure could cause coolant to evaporate through the slightest gap- i can make a gaskit to sort this though. Also looked at a replacement reservoir incase there's a hair line crack somewhere in mine

I will try the headgaskit test you describe haha, i've a feeling it will be fine if not it's going to be moved on for spares/repair and i'll replace it with something else!!

Makes perfect sense in English to me!

you dont want to make a gasket to seal expansion cap, it is designed to be a pressure release valve, so at preset pressure it will release some, if coolant system is working properly none should be released.
Just buy a new cap, around £3 so shouldnt be a deal breaker.
check all hose connections for staining, look at drain hole in waterpump, any steam from the rad. are the mats wet,
If no external leaks, prepare for the worst, head gasket/cracked head

Fair enough Johnlad i'll not do that if it's a pressure release valve...there for a reason!

Thats just it there's no steam from anywhere once up to temp or puddles once parked. Mean the mats inside the car in the footwells, if there wet? Will check this next time im out..

Yeh i'll prepare for the worst with a bottle of liquid gaskit sealant!haha

Had much the same symptoms, are you sure you don't have any leaks.

I removed the engine cover and top cover over the radiator and lo and behold there was a bit of dried pink staining around both ends of the radiator hose at the temp sensor elbow and also the radiator. There was no puddle under the Disco as the coolant was evaporating with the heat before reaching the ground.
At some point someone had replaced the spring clip at the elbow with a jubilee clip and over-tightened it which had caused a tiny split in the pipe.
I replaced the pipe (which comes with the correct clips) and this seems to have cured the problem.

Looks like im going to be stripping plastic covers off everything tomorrow aswell then!

I don't have the engine cover on as some muppet (previous services) filled the engine with oil and let some over spill onto the block which the foam absorbed, so when this gets hot dumps oil onto the block making things dirty/grubby.

The radiator and connections will be checked looking for pink stains..

My plan for tomorrow from cold;
1) top coolant reservoir up to the cool level indicator..
2) idle or drive up to temp,
3) put heaters on full hot setting,
4) loosen bleed screw on top pipe to see what escapes, tighten soon as liquid flows out. See what happens after the above....

5) Start to strip plastic covers off see if there's leaks on joins and hoses, water pump, crawl all over and under it!

Have i missed anything apart from the petrol soaked rag and a match?

Here's the correct way to bleed the system