Thread: Cooling - what's the problem ?

Viscous fan was gone on mine.

Symptoms were more occasional overheating - especially fully loaded up hill at highway speeds.

Slow going/low range never seemed to cause a problem.

temp sender carked it?

have you got an actual read of the temp at the thermostat or top of the radiator?

Apologies if you've done this first and it seems over simplified. I've had two '96 and one '98 300Tdi in the past. All three of them displayed "hot" readings at some point of my owning them.

The first one had all the regular things replaced same as you chasing the problem. After LRSA spent a fortune on warranty replacement bits an old chap collecting his son from a service drop walked over. It turns out that 300Tdi's for some inexplicable reason builds corrosion under the main earth tab on the chassis close to the battery box. LRSA did not believe him and ordered more parts to replace.

When I got home, I undid the earth tab, sanded it clean as well as it's mounting point and reconnected the tab. Problem completely solved with nice low readings. I am no mechanic and purely followed advice on this one and it worked for me. I did the same with the other two the moment their temp readings started to go up and the problem went away.

Hope the problem turns out to be this simple!

Cheers!

I was about to suggest - earthing problem. Probably engine/chassis earth, possibly chassis/instruments earth. A giveaway would be if the reading changes when instrument lights are on/off, remembering the gauge has a response time of a minute or so.

John

Again, possible earthing issue Vlad, I have seen this on several Defenders, Especially those in damp and humid areas....Try a cable between the battery earth terminal and a seat rail attaching bolt under the passenger seat, it will help any poor body earth problems.

JC

I would check the earth like posted above but if you haven't done a cooling service,rad rodded,paint brush on the fan check,clean A/C condensor core if fitted and then flush and pressure test now would be a good time to do it.I would suggest getting the bypass hole in the tank baffle blocked off too,that alone makes a huge difference. Pat

Originally Posted by PAT303

.I would suggest getting the bypass hole in the tank baffle blocked off too,that alone makes a huge difference. Pat

what's this mean ?

The rad has two tanks either side,the LHS one has a baffle half way down it to sent the coolant across the rad to the other side where it then comes back across again and out,the coolant goes throught the core twice.The baffle has a 20c piece size hole in it so the coolant can bypass the core completely and not be cooled.Get the rad shop to solder a piece of copper over it so all the coolant goes through the core. Pat