Thread: Defender Td5 thermostat

Hi Frenchie,

$3500 sounds pretty brutal.
I have noticed a similar change in temperatures on start up (just going off the dash gauge though). A large spike in temp (halfway position on temp dial) then gradually comes down over 5-10 min of driving at 70+ km/h. I have also noted that it seems to run way down in the blue bar of the temp gauge pretty much all the time after the initial start up spike. Even under high load aka long hill climbs (calcup hill) ive only noticed that temp gauge get colder, weirdly. I've mostly been told its just the pre-warm and then fan kicking in and that the thermostat is fine. I've only had the defender about a year now though so maybe someone more knowledgeable can tell us whats going on.

I changed mine last week
Take off the top shroud
Take off the fan
If you are using the original hose clamps one of the special tools from Snapon or the like will make life much easier.
Take off the 3 hose clamps and pull the thermostat out and replace.

Pretty easy really

Originally Posted by djam1

I changed mine last week
Take off the top shroud
Take off the fan
If you are using the original hose clamps one of the special tools from Snapon or the like will make life much easier.
Take off the 3 hose clamps and pull the thermostat out and replace.

Pretty easy really

Thanks for that. Is there any need to bleed the system afterwards? Can I avoid losing too much coolant?

I simply filled the system with the bleed screw removed from the top hose.
When the fluid starts flowing put the screw back in I had no issues this way.
I could figure out a way of saving the fluid I gave up in disgust and let it flow.

Originally Posted by Frenchie

Have an intermittent cooling temp issue, I'm using the Nanocom as a gauge as I don't trust the one on the dash! Temp will occasionally rise to 110-114C then drop to normal ~86-88C and be fine for a while. This normally (but not always) happens when first warming up. I thought maybe sticky thermostat and as it was due for a service took it to the local (Canberra) LR specialist. $3500 later (a few things needed doing and they charge more than my dentist ) they didn't replace the thermostat but reckoned it was the fan, which they did replace.

Okay they are the experts I think but it's still doing it. I'm not sure I can afford them anymore and am tempted to replace the thermostat myself. A search on here seems to indicate that it's a pig of a job but that mainly seems to relate to Discos. Any hints for a Defender?

TIA

I changed mine by accessing from underneath, it was a bit fiddly but can definitely be done without removing the fan.
Although If you can get the fan off easily it would be an advantage.
And take the top shroud off to let more light in .
It sits in a plastic bracket/clamp that it pops out of quite easily
A thin smear of rubber grease on the new thermostat also helps when fitting to the hoses.
And I found a good set of needle nose pliers did the job on those spring hose clamps.

Cheers,
Paul.

Frenchie,

If you REALLY want to save the fluid - and why not? You can get some thin tubing and siphon from the header tank, once that is empty remove the hose from it's base and insert the tube down that and syphon again, remove the top hose engine side, siphon again - generally chase the level disconnecting and siphoning to bring it down below to the top of the thermostat before removing it.

If the coolants new it'll save you money but cost a little time.

FWIW - the original symptoms didn't sound like a stuffed viscose fan to me.

Ian.

This is driving me nuts. I did replace the thermostat myself, was a pig of a job and took two people but got it done. Now she runs fine, normal temps, no overheating....but....for some reason when warm, coolant is being forced into the header tank as you would expect but doesn't flow the other way on cool down. So I end up losing coolant through the header tank as it overflows, get a low coolant alarm, refill and bleed, repeat. What is going on???

Fan, thermostat and filler cap have been replaced and I have had the head tested, it's not that. (Head was previously replaced and it has metal dowels).

Make sure the tank's cap is completely tightened cos if it isn't there will not be the required 1,4 bar in the system and it will overflow... did you lift the tank above the top hose when you filled the system?

undo partially the bleed screw, and rev it above 1500(as the mechanical bypass valve of the stat to open) and keep it so untill no bubbles are coming out there, maybe there's an airlock if it wasn't properly bled

are you sure the pump is working ok? you must have serious flow at the bleed hole with engine running even at idle

by the way, using a gauge is more reliable as nanocom doesnt actually read the temperature but the coolant temp sensor's input to ECM, and the temp sensor might be fubar'd