300 TDI getting hot?

[malsgoing130]

Hi All,
Over the week end took the Defender 130 TDi for a drive up the coast , towing a trailer approx 700kg plus may be 150kg in the tub, the temp guage started to warm up to just over half way and at the sign of the first hill really started to head towards the red, dropped my speed to 90km/h and it returned to a bit above 'normal'. On the way back home the (ambient temp approx 30 deg) temp guage was much hotter at sat just bellow the red, in fact at 1 point I pulled off the road to let it cool down with the motor running. After that drove the rest of the way with a much more normal temp and with the heater on to help with the cooling. Is this normal????? the motor is 40k old looks as though the previous owner who put the motor in had the rad flushed (I hope so) What do I do, I plan alot more long distance travelling maybe towing, surely this is not right?? Please help.:confused::confused::confused::confused::conf used::confused:

Thanks
Mal

[Chucaro]

Have a look at the belt (if loose), the radiator for air lock and if it is clean.
I tow 1 ton trailer with my Defender Tdi300 in a hot day (30 to 35) and the temperature is normal. The sensor mounted on the back engine lifting point shows 82c.

[BilboBoggles]

I would say - No that's not normal. There's a long list of things that can cause this but in my experience overheating when under load is a issue with

1 - Blocked radiator.
2 - Corroded water pump impellor
3 - Worn out Viscous fan
4 - Corroded or blocked fins on the radiator.

I've seen this happen most commonly due to a faulty viscous fan coupling. For example on my Defenders if I hit a long hill on a hot day you can watch the block temp edge towards 93- 94C, and then you can hear the viscous fan lock up and start making a lot more fan noise. It stays locked up until the block temp reduces below about 95C. Where the viscous fan has failed it does not lock up and the water temp keeps going up until it overheats or I ease off.

Is it losing water?

[malsgoing130]

Thanks Bilbo,
Its not loosing any water and I assume the water pupmp should not fail at 40K, driving around town the gauge is rock solid with normal all the time. Concerned about the Rad, is it worth replacing as a precaution? vehicle has done about 215K. How does one test the viscous coupling on the fan?
Thanks
Mal

[BilboBoggles]

There are many theories out there about testing viscous fans, but it should be obvious from fan noise when it's fully locked up - For example if you get it good and hot and then thrash it on a long hill - by the time you get to the top you should be able to hear a lot of fan noise when the engine is revving. They fail in a variety of ways - from lost fluid to leaking or stuck thermostat valves - personally I would replace it given it's done 200,000 k's.

Radiators do clog up - and given yours is a decent metal job not the bonded plastic types fitted to later models - I'd be tempted to just get is stripped rodded and cleaned - should not be overly expensive.

Might also be worth getting one of those block temperature gauges to measure accurately what the temp is doing and also guard against any nasty accidents.

[rick130]

Were you using your wipers and/or lights during the trip ?

Defender instrument earths and temp gauges are notorious for giving false (and high) readings.
A mechanical gauge is a good investment IMO, eliminates a lot of variables, otherwise, yes, viscous clutches can and have given problems, and don't discount the head gasket either. A combustion gas test of the cooling system would be a good idea.

[jimbo110]

Yours is doing exactly the same as mine, no problems when running empty, gauge heads for the red when towing up hills. I found running the heater on full would get mine through to the next downhill, which if I forgot to turn it off would over cool the engine till the guage showed cold! I have replaced my viscous coupling, but haven't towed since to try it out. At just under $300 I sure hope it has worked! The silicone oil in them does "wear out" over time.

[camel_landy]

Before you embark on changing & swapping... Get hold of a laser thermometer & double check the temp independently.

As has been mentioned, poor earthing and other connections can easily give you incorrect readings. I've been there... Changed head gaskets, new rad, thermostats, etc... only to find that it's a poor earth. Had I checked the temp using a laser thermometer, I would have seen that there wasn't actually a problem!

HTH

M