TD5 got hot or did it?

[crump]

Coming back form a run to Brissy this arvo, about 750kms round trip and as I was pulling up a small range I felt a miss and then started losing power, temp gauge started climbing into the red quickly as I was watching it. I drove about 200m and pulled over, thermo fan running. Switched off, fan still ran for about 5 minutes. Coolant full, no leaks, no sudden increase in oil level. had a sandwich and and a head scratch. Started it up and drove another 60 kms home at normal speed and it didnt get hot or miss a beat. I did notice the temp needle had a slight back and forward movement, which is different from its normal rock solid position it has held for the last 17 years, once at operating temp. Could it be a faulty temp sender telling the ECU it was hot even though it wasnt or how can I diagnose a head gasket failure? cheers .

[Tombie]

When did you last fully service the cooling system?

[crump]

new hoses, thermostat, belt, coolant about 3000 kms ago. motors done 100 000 since new (2003). had coolant changes every couple of years in that time. Had fan off a few times while messing about getting the right size belt, bearing felt smooth.

[scarry]

HAd a good look at the viscous fan?

Does it seem to be cycling and spinning like it should, that is moving heaps of air and roaring like they do when needed?

[PhilipA]

You could have a look at "instruments" on a Nanocom which will tell you what the sensor says, then compare with the head temp next to the sensor. ( with maybe an infrared sensor)

That should tell you if the sensor is faulty.

Usually if the sensor has a bad connection the gauge will under read and tell the ECU the engine is cold..

I have a digital gauge attached to a dry sensor on one of the bolts next to the wet sensor and it reads within 0.5-1C of the sensor.
Maybe have a look at the red plug.

Regards PhilipA

[Tombie]

Some options:

Radiator is likely around 30% blocked internally by that time.
Water pump
Thermostat getting lazy
Viscous Fan
Mud / muck build up in radiator core or between radiator and condenser.

The jolt you got was the “protection” fuel cut.

[crump]

thanks for the info. at this stage of the vehicles life, I'm happy to replace pump, fan, radiator etc.. for the sake of reliability.I'll check sender, but it sounds like thats not the issue. Not really worried about the fact I'm "throwing" parts at the problem without knowing the problem, as it were. As stated, the gauge went from its usual position mid way, to just before the red before I could pull over and shut it down. Its fitted with a working coolant alarm on the high point of the top hose, which didn't activate. So, all things being equal, if the fuel cut out activated due to temp, should I be prepping for a head gasket as pretty much a given due to the TD5's known dislike of overheating?

[Tombie]

I had the same issue years ago after a lot of mud holes in a Vic state forest.

Just flushed my radiator clean and it was all good.

At the age of the vehicle there will likely be a large sediment build up in the lower core of the radiator. Causing it to suffer the same fate on hills.

I’d say you may be very lucky this time and it’s just got warm for a fraction of time. However. Plan for a head gasket in the future if a new radiator etc doesn’t fix it.

[crump]

Just to close this one out, Hawkeye showed over temps all over the place, replaced water pump, radiator, viscous fan and found no culprit in the cooling system, so decided to pull the head. No obvious signs of HG failure and head was sent away to be tested, no issue found. This puts you in that wonderful place where you have to decide how much you like the vehicle!! Decided to replace head with a new one for piece of mind., hey, its only money! Ended up costing about 7K all up, but essentially a new engine. Vehicle has done just over 100 000 kms since I purchased it new in 2003, only use it for trips, been overserviced if anything. You have to question your sanity when I had to rebuild the gearbox at around 50 000kms due to a layshaft bearing letting go and now this. Hopefully the next 100 000kms will be less eventful.

[Tombie]

Hawkeye showed temps all over the place..

Did you replace the sender as part of your work?
Sounds very much like a faulty unit.

[muddy]

Check the temp sensor using a multi meter across the signal terminal and earth near the sensor ,start the motor and check the resistance /ohm reading and see if it comes down to a low figure

Secondary did you use thread tape on the sensor this will cause an insulation between sensor and head giving a faulty result

[Tins]

If the TD5 Defender temp gauge is anything like the one in the Disco then it is a lying POS. That 'rock solid' halfway indication is totally not true. The gauge functions more as a warning light when the engine overheats than a reliable indication of what is actually happening. Do not trust it. The low coolant alarm is a good idea, but a proper gauge that shows real time temps is pretty much a must. Small price to pay yo protect the $7K you just spent.

[Tombie]

I partially agree/disagree.

Normalised gauges are fine and a majority of punters prefer them as they don’t cause panic.

As an example - what do you think too hot is when it comes to coolant temp?

Where it all goes wrong is the lack of coolant level alarm - once you drop coolant the gauge doesn’t function correctly and we see the results of the coolant loss overheating event over and over.

If there isn’t coolant loss, but a conventional overheat eg. Blocked radiator. Then the system works very well, inducing a cooling routine to protect the vehicle.

[Tins]

Normalised gauges are fine and a majority of punters prefer them as they don’t cause panic.



Until you look and find the needle has gone from rock solid in the middle to the very top of the red in what seems like seconds, by which time it's usually too late. You are correct, it's personal preference, but the TD5 gauge is far too binary for me.

[Tombie]

Under normal overheat it’s far less binary, elevated then hot, then light on…

It’s catastrophic coolant loss that bite quickly!

[skidrov]

Must admit I got panicked, err, motivated to buy one of these products: Low Water Alarm Sensor (https://www.enginesaver.com.au/)

...after reading a few threads on ruptured hoses being noticed too late, with catastrophic results [read: new engine required]. No interest or affiliation.

A little over $200, pretty easy to install, shrieks at you when not happy, good insurance. But, doesn't replace standard maintenance of course!

[Tins]

Under normal overheat it’s far less binary, elevated then hot, then light on…

It’s catastrophic coolant loss that bite quickly!

My experience with an admittedly unrecoverable HG failure ( plastic dowel head movement ) says otherwise.. well, there was far less warning of trouble than I got with my 300TDi. That one lets me monitor fluctuations, which gives me the chance to catch something before it is unrecoverable. A climbing temp gauge gives me options that the on/off style of the TD5 does not. That one is either cold, normal, or way too hot.
For me, the choice is easy.