Hi all,

Got a 3.9 V8 in my Disco and it is fitted with a cone air filter, Will come back to that.

Problem is that when i start the car and leave to heat up all is fine, now over heating or or coolant loss ect ect.

I can then go out for a drive for say ten miles or so and park the car up the temp will then slowly rise. This also happens in traffic. once i start moving again the temp gauge goes right down. This happens when running on petrol and LPG. One of the core plugs near the starting motor then starts to drip coolant at a fairly constant pace.

After reading the forum I have noted that when the car is started the viscous fan should make some sort of woooshing noise for about a minute or so which indicates it is working properly. Mine does not so does this mean its fooked?

When the engine was warm but not been for a run, I tried to stop it, which I managed no bother and it took an age to start spinning fully again.

How do i test it? I have checked all the coolant pipes which are all warm and also the radiator is piping hot across all the cores so I dont think the radiator is the problem. No Oil in the water and no water in the oil and i cannot smell any fumes from the header tank.

Like i said when the car is moving again the temp goes right down. Any advice would be welcome which then leads me back to the air filter.

This is my first V8 and i have noticed that the temp under the bonnet is very hot to say the least, infact it is so hot i cannot put my hand on the slam panel after i have been out for a short run as it is that hot.

Obviously heat is not good for a V8 so i am thinking of ditching the cone filter and going back to a standard air box, but i don't know what the original one looks like. Is it the same as a 300 or a big metal one?:doh:

Apart from the dripping core plug (which will need to be replaced) I am struggling to understand what the problem is.

The temp goes up when you are not moving and goes down when you are. Unless the needle is pushing the 'red zone' this sounds normal to me. V8s do radiate a lot of heat.

The viscous fan is probably not working properly.

V8s get very hot under the bonnet, but the fan should be able to keep it cool. It's a big fan and shifts a lot of air, so if th temps are high at standstill, id suspect a fan straight away.

Like you say, if the viscous is very loose when the engine is hotter than you might expect, theres a good chance it is worn out.

The other option is that it's cooler than you think, but it probably ain't!

Viscous should be stiff with the engine cold and off, but then slacken up when running, and stiffen up again when hot.

Usually they just lock up so you get huge wind noise all the time, but sometimes they go floppy like yours.

Viscous unit is fairly cheap and worth replacing so give it a go I'd say.

Core plug is pretty simple too, just a bit awkward sometimes!

Cheers

blocked rad, dicky temp sensor, sticking state, failing water pump nothing to do with the cone filter

Mr Noisy said:

The viscous fan is probably not working properly.

V8s get very hot under the bonnet, but the fan should be able to keep it cool. It's a big fan and shifts a lot of air, so if th temps are high at standstill, id suspect a fan straight away.

Like you say, if the viscous is very loose when the engine is hotter than you might expect, theres a good chance it is worn out.

The other option is that it's cooler than you think, but it probably ain't!

Viscous should be stiff with the engine cold and off, but then slacken up when running, and stiffen up again when hot.

Usually they just lock up so you get huge wind noise all the time, but sometimes they go floppy like yours.

Viscous unit is fairly cheap and worth replacing so give it a go I'd say.

Core plug is pretty simple too, just a bit awkward sometimes!

Cheers

Click to expand...

Id agree with noisy if the car heats up when stationary and cools when on the move

Took it out for another run ysterday.

When i got back i checked the Viscous Fan and to be honest it feels no different whether the engine is hot or cold. The fan seems to rock slightly back and forth as if the bearings inside had gone.

Like I said the radiator seems to be hot across all cores and all the pipes are red hot.

I dont think its the water pump, as it only seems to happen in traffic or when stopped.

I have ordered a new one to see what happens.

When the temp rises it does go towards the red but I stop then engine before it gets to high.

Will report back when the new fan arrives!

I hope it goes well for you mate

My money is on the fan. They usually feel tight - if it's gone floppy it's gotta be shagged...

Thats a quote there anorl

Mr Noisy said:

My money is on the fan. They usually feel tight - if it's gone floppy it's gotta be shagged...

Click to expand...

Oooer Mr Grimsdale

:hysterically_laughi

why would the fan make a whoosing noise?And whats the air filter got to do with cooling?Test the fan from cold and see what resisitance is like.Sounds like ya need a new one, but a flush of the coolant and rad fins wouldnt hurt

and the starter motor wire on mine regualrly popped off, never fixed it as it was a cheap anti theft device but to refit it yer arms had to get quite close to the manifold.A bit warmer than elf n safety would like i suspect.