P38A Overheating

2000 V8 4,0 Thor 190k
Puzzled here
Rangie has been going just fine for ages.
Yesterday ( a warm day) going uphill temp gauge suddenly shot up and steam under bonnet colled down and filled her up and she only got about half mile (Uphill) before boiling again.
Today at home filled her up, got all air out system and she ticked over fine and go to normal temp no problems.
Fan turns by hand when engine stopped and turns with engine on.
Took her for a short run on level and no problems.
Took her up a wee hill and instant overheat. Water gushing out cap.
Not a gradual getting hotter but more an instant needle whanging against the stop
Oil is fine, no water.
Water is fine no oil
Where to next?
Thank you

Sounds like the viscous fan is not cutting in, you should be able to here it when it cuts in, time to test with a rolled up news paper if fan stops no good if it shreds the paper all good.

Thank you for reply.
Is that with engine at temp?
Or when overheating?

Don't forget the temp gauge isn't analogue, it will stay at normal '12 o'clock' over a large temp range then move 'suddenly' one way or the other.
When the viscous has sat cold for a while it should be stiff to turn. Start up and leave it a couple of mins at idle then stop, fan should move much more freely. When it's *hot* then it should get harder to turn, like when it was cold.
At no point should it spin freely by hand

Oh right I thought was good that it turns freely Ooooops cos it does turn freely when cold or at normal temp

By freely, when completely disengaged, you should be able to turn it with light (ish) pressure from one finger but it shouldn't keep spinning. When it's engaged, it should need a lot more pressure.

If it keeps spinning like a bicycle wheel then you need a new one!

If it's just not locking up, then check the curly spring on the front isn't gummed up with rust and nastyness.

If you leave it overnight, you should still be able to turn it, but should resist and stop as soon as you ease off

Over a certain temp 104C the Aircon fans should cut in to aid in cooling..

With Ram air going through the rad she shouldn't overheat, unless of course the VC is completely dead.

Henry_b said:

Over a certain temp 104F the Aircon fans should cut in to aid in cooling..

With Ram air going through the rad she shouldn't overheat, unless of course the VC is completely dead.

Click to expand...

104F is 40C

kermit_rr said:

104F is 40C

Click to expand...

oops.

yes 104c duh!

Thank you gents
I will try in the morning but methinks she spins like a bicycle wheel.
It could be that Ram air has kept it going for so long when the air has been cooler.
The hill yesterday and today were at relatively low speed

oakey said:

Thank you gents
I will try in the morning but methinks she spins like a bicycle wheel.
It could be that Ram air has kept it going for so long when the air has been cooler.
The hill yesterday and today were at relatively low speed

Click to expand...

I have a viscous fan in the garage that has done 4k miles.PM me if you need one.

Thank you Alan will keep that in mind

And Kermit I had no idea that gauge wasnt analogue thanks for that

tomcat59alan said:

I have a viscous fan in the garage that has done 4k miles.PM me if you need one.

Click to expand...

God on you sport

Update
This morning I can turn fan easily but stops when I take off pressure
After running a few minutes it is just the same
And when at temp still the same
No noticeable difference

Above a certain temp the VC should lock, you can usually tell but a change in engine note and a very audible roar from the front end
If she's overheating then it should of locked long before.

Working well the VC fan can pull a good amount of air, usually signs it isn't working is it'll be fine at 40+mph on a normal road, but once under load either going slow or up a good hill it'll start to struggle.

Thank you I reckon its knackered then
Then the VC locks will it start to turn faster then?
Yesterday when she was overheating the fan seemed to be going round at usual speed ie tickover

oakey said:

Thank you I reckon its knackered then
Then the VC locks will it start to turn faster then?
Yesterday when she was overheating the fan seemed to be going round at usual speed ie tickover

Click to expand...

When it locks yes it should spin faster to draw more air through the rad.

It wasnt lol
Knackered methinks

When the fan is locked it should run at 80% engine rpm