Thread: 300 tdi Defender overheating ?

Thermostat jammed shut or not opening up enough?
I've had my D1 for about 18months now, fitted a temp gauge about a month after I got it. Normal running temps have been about 83-85 everything working well ... no A/C on.

I recently changed my thermostat(mistakenly diagnosed) and while the original Waxstat thermostat did work, it it opened much higher than it's supposed 88°C and when it did open at 100°C(in freshly boiled and topped up water), it barley opened up more than a couple of millimeters.

I got a couple of Tridon thermostats from my local parts store, and the 88° version started to open much earlier, and at approx 88-90°C had about a 10mm or so opening .. far larger than the Waxstat version.

The major difference in how the two react(or operate) is, with both thermostats in the same bucket, I pour freshly boiled water till they're submerged, The tridon starts to open with the water filling the bucket and is fully open before it's submerged.
The Waxstat takes a long time to finally react maybe a min or so after it's been submerged by the boiling water.

I'm assuming that better flow is helping mine now.
I used to get 95-100 temps when running the A/C at highway speeds and on slow twisting steep roads, I've seen 105°C .. had to back off, turn off A/C and managed coolant temp with slowing down A/C off .. etc, prior to changing to the Tridon.
Haven't had enough time to test in the recent 30-ish degree temps we've had if this Tridon actually helped yet or not. But so far it hasn't gone past about 87-89 degrees on the two days I have had a chance to run the A/C on.
We've got a few days of 30-ish degree temps coming so I'll go for a bit of a drive to test a bit more.

Another thing I had to do with all that above was to remove my fan cowling(cos I broke it) .. and that may have helped in some small way too.

The other thing I've changed recently is my water pump(this last Monday).
my normal running temp has been 83-85 on the highway after about 1/2 to 1 hr of running.
Just this morning I did a freeway run, ambient at about mid 20's and my temp maxed at 83(I thought normal) .. but settled back down to 81 towards the end of the freeway drive.
ATM, I reckon the new water pump may also be helping a little now.

How is the viscous fan clutch ? - scrap that just read that its fairly new, still worth considering if it was a cheapy.

Interesting point doesn’t one of the falcon viscous fans fit?

Originally Posted by djam1

Interesting point doesn’t one of the falcon viscous fans fit?

EA to ED 6 cylinder ones fit clockwise rotating applications, V8 ones fit anticlockwise applications, e.g where a serpentine belt runs smooth side around the fan pulley. The threads match the correct rotation type boss. I've not replaced a 300TDi fan myself but have fitted a Falcon 6 cylinder water pump bearing and drive flange to the front cover of a couple of them, same fan clutch thread.

X2 for the Tridon thermostat.
Buy an new 88deg version and test in in a pot and boil the water before you fit it.
I've had one that didn't open brand new out of the box.
Phil

Thanks for the replies
I ventured to the nearest town today to be stuffed around by every auto shop at the end of the day I ended up getting the Dayco equivalent to the Tridon TT388-180
this is a 82 Degrees thermostat that fits perfectly .
We had limited success with temps being slightly lower but still up to 100 degrees on some hills not sure if this is normal for a 300 tdi but I know its not for a TD5.
The last thing is the radiator but as I said its not that old and it looks perfectly clean internally.

If 100 degrees is normal going up a hill at 100 km/h I would hate to tow something heavy through deep sand

Did you test the new thermostat to see how much it's opening becomes at 100°C?
If you still have the old one try that as well.

You say you fitted a large thermo fan in place of the condenser(I'm assuming the A/C condenser that is).
If so, then there's no point mentioning a blocked A/C condenser(dirt/build up in the fins).
But what about the radiator? Have you tried spraying it with tap water(not high pressure) just to be sure no grime is blocking it up.

I suppose the other things to look into would be flushing the small hoses. Other than time taken, they're probably worth looking into.
The three small hoses from thermostat housing to bleeder thingie, bleeder thingie to coolant reservoir, and bleeder to radiator.

ps. many moons ago I had an RRC that had hot running conditions. First thing looked at was radiator of course. Just the visual inspection. Looked clean inside and out.
For about 2 years I ran the RRC with the temp gauge(dash gauge) just at the start of the red zone. Gauge and sender were both electrically tested to be OK.
Other than very hot running, it never actually overheated, steamed up or lost coolant .. just ran hot. But I drove it into many trips up into central SA in the heat.
So about 2 yrs later .. or so .. I was mucking about and rubbed my arm hard up on the inside fins as I slipped and the fins crumbled, almost into dust. No leaks and whatnot .. just looked pretty sad.
So I sourced a new rad .. and wouldn't you know it .. the temp gauge settled to normal temp operation!.

Like you said tho .. it can probably take that kind of operating temp for a while .. but you wouldn't want it to for too long.

Try running it without the fan shroud for a run to see if it makes any difference, either hotter or (hopefully) cooler.
I'm guessing that any difference could be a clue as to where to best direct your efforts.

Originally Posted by djam1

Interesting point doesn’t one of the falcon viscous fans fit?

Yep,been running one on my Tdi for over 15 years. Pat