Plastic Radiator plug - yes they fail

There's a few threads mentioning to replace the plastic thermostat and radiator bungs with brass versions

I can confirm the plastic bungs can fail catastrophically! Replace them now!

My 96 300tdi had got a bit hot a couple of times when towing home the wifes new 1100 kg horse trailer up long 2nd gear (auto) hills and so A few days after getting back I was testing out that a new thermostat had fixed the problem and half way up a local "major" hill the plastic rad bung burst (hex bit split off) and dumped most of the coolant on the road. It took quite a while and a lot of water to get the few km home.

Lesson learnt ;-)

Don't put these things off...

Off topic but the the disco did 9.5litres per 100km going the 600km to get the trailer and 13litres per 100km coming home with it.

Pretty good I thought my hilux surf 3l turbo diesel used more fuel without a trailer in tow.

i would also check rad is hot all over when engine up to temp may be reason why plug failed

Hi James, yep the rad appears to be ok eg hot all over but although a new stat has improved the overheating it still got a bit hot towing during a retest with brass bung and I suspect when summer hits and there's a 600kg horse in the trailer it will get too hot. I'll try a new water pump next.

It's a bit annoying as I sold the surf as it overheated when towing and i thought the disco was "over cooled".

I found the 2 into one bleed valve was blocked last night, in the connection to the 6mm pipe that leads to the stat housing and so I've cleaned that out, I'm not sure what that valve does (it does not appear to be a one way valve more if a 2:1 connector) but I suspect it keeps the system free of air?

are you 100% rad is fine have you felt it all over core ,ive found its a very common failing not that others dont either but very important to be sure

Hi James the rad was pretty much the same temp all over after a 10 min drive, maybe a bit less hot in the bottom right looking at the screen but not much in it.

I spent quite a bit on surf to stop it overheating and sold it before the head cracked

The disco is not as bad but I need it to be better so the wife does not blow it up!

the one way bleed valve can be an issue might be your issue worth replacing

KiwiTDI said:

Hi James, yep the rad appears to be ok eg hot all over but although a new stat has improved the overheating it still got a bit hot towing during a retest with brass bung and I suspect when summer hits and there's a 600kg horse in the trailer it will get too hot. I'll try a new water pump next.

It's a bit annoying as I sold the surf as it overheated when towing and i thought the disco was "over cooled".

I found the 2 into one bleed valve was blocked last night, in the connection to the 6mm pipe that leads to the stat housing and so I've cleaned that out, I'm not sure what that valve does (it does not appear to be a one way valve more if a 2:1 connector) but I suspect it keeps the system free of air?

Click to expand...

I can tell you what that does it ain't working right - it causes over-heating, that's what.

My wife's TDi300 Defender started over-heating so I replaced the water pump, then the 'stat, then the rad all to no avail.

Checked that 2 into 1 pipe and it was blocked so not allowing the circulation of coolant. As soon as I replaced that, all was and remains perfect.

Wish I done it sooner


Dave