Thread: Coolant slow leaks

From a bit of reading, the housing for the top hose is a known corrosion issue at the hose end there on the TD5.
Brother had it too(D2). We changed most of his rubber hoses with silicon types, and as reiterated by others the housing end had some corrosion on it. The new hose did stop it tho.
If you do remove the hose to inspect, of course you would also check the condition on the inside of the hose too.

ps. the main reason for going with silicon hoses was the option to find a metal bleeder T piece section that splits the silicon hose into two smaller sections, and also the bypass hose too(rather than all one unit).
The primary concern was the fragile bleeder screw which is easy to break on the standard hose(after much aging) replaced by a nice beefy bleed nut.

Also, and again from reading. Have you at some point recently changed coolant?
Many people use glycol coolant, but the TD5 requires OAT(or HOAT).
Again, brothers came to him with (most likely) glycol based, even tho the sign on the fill cap says OAT is required.
Anyhow, after a flush and then refill with HOAT, I warned him that very likely it will start to leak a bit here and there(from reading here).
And sure enough it did .. which confirmed my guess that previous owner(s) had used glycol. Some seals were changed(I think water pump also leaked) .. and been perfect ever since.

So if you think or did yourself that it previously had glycol and then OAT(or HOAT) coolant was used for replacement, they don't like each other and can cause small leaks(until they are fixed).

The expansion tank is either over pressurizing, actually getting hot .. irrespective of what your standard temp gauge is telling you!! .. or cap is old and tired allowing pressure leaking past it.
Easy way is try a new cap, if you can pressure test the old one to confirm .. saves wasted $s

A more experienced member will probably chime in on how to diagnose if you have head gasket issues .. ie. over pressurising the system.
Do you have access to an honest mechanic that could do a compression test on it?

Hi mate,

Thanks for the reply, Jip got one that I can trust with my life! yes it is possible and will get him to check it all out. The seal on the cap seems well worn s I have bought a new one. I'll check on the type of coolant just to make sure we are using the right one. I do remember some time back I cleaned the top hose. There was quite a lot of build up of coolant around the male inlet where the hose fits over. Looks like it time for a new pipe and good clean up of the inlet. The madman reports a consistent 85 degrees C, that would be the temp of the water at the front right of the engine (standing in front of the car).

cheers

J

If these hoses need replacement, is it worth while going to silicone hoses like these on evilBay or is it best to stick to the rubber ones?

ps, just about to click over to 260 000km's

Cheer

So far my experience is either.
Some don't like silicon, other swear by them.

My only reasoning for silicon, which by default = aftermarket .. is really only for the non moulded multi octopus designs(which you can get in silicon too.

Two late LR vehicles I have(D1 tdi and D2 V8) the vulcanised join seems to be a weak spot.

On my Tdi, I got the particular silicon hoses that have the metal(IIRC aluminium or aluminised) T piece sections.

On brothers Td5, the metal t piece houses the bleeder nut too.

Like this type

link to ebay above is not a recommendation of product or seller, just the first search of that t piece type.
You can get alternate types with moulded t-piece sections too, with bleed screw designed into it, like the standard type, but that was the primary issue with the brothers(as well as a leak).

One note on silicon hoses. If you search for info on them by members, almost all the negative comments seem to centre around the fitment of them.
Appears that many don't realise that most if not all these aftermarket kits may require some trimming.
That's what I found with my kit, that's what I found with brothers kit. trimmed properly, they fit like standard hoses.

How interchangeable is the discovery TD5 hose set with the Defender hose set, the on evilbay is for the discovery and all the rest seem to be located in the UK.

Originally Posted by TheEntertainer

How interchangeable is the discovery TD5 hose set with the Defender hose set, the on evilbay is for the discovery and all the rest seem to be located in the UK.

Its not

Originally Posted by TheEntertainer

How interchangeable is the discovery TD5 hose set with the Defender hose set, the on evilbay is for the discovery .....

oops! sorry, I did notice yours is a Defer(overflow tank) ... I just typed in TD5 silicon hose in ebay, and the most common are for D2s.

Could it simply be that the pressure relief thingy in the cap or the rubber cap seal are defective and it's a simple leak? RED OAT has a tendency to fund a way out anyway.

Originally Posted by TheEntertainer

Hi all, hope your doing great!

Got a couple of slow leaks in the coolant system thanks to the Low Coolant alarm in the EMS3.

1.) at the expansion tank cap
2.) top hose connector into engine. See below picks.

Replace both I guess is a good start but I was wondering what the ROOT cause could be.