over heating at speed

jerrytlr said:

how can it be the fan if the car overheats at speed? Fans do nothing once the car is moving at more than 20ish mph.....

Pump and rad both new

The only thing I can think of is that the new thermostat is not working properly (did you test it as there are lots of reports on here of faulty new thermostats) or there is a blockage somewhere that is restricting flow.

Odd one this.........


Cheers

Jerry

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the viscous coupling relies on heat. the hotter it gets, the more it works. if the coupling is duff, it wont spin as fast as it should, therefore not pulling enough air through the rads to cool the liquid inside them.

the newspaper test as mentioned is about the only way to test them. start engine, wait till it gets hot, put rolled up paper into the blade. if it stops, fooked. if it keeps going and shreds the paper, all good.

you can also tell if it works by hearing a loud WHOOOOSHING sound as you rev the engine and a lot of hot air coming at you.

sas1810 said:

you can also tell if it works by hearing a loud WHOOOOSHING sound as you rev the engine and a lot of hot air coming at you.

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Correct me if I am wrong.

Viscous fan engages gradually (that is my theory ) with the rise of the coolant temp. Also, engine ECU turns on AC fans to aid cooling. I think this WHOOOOSHING comes from AC fans as they are turned on/off ( not gradually).

qwertz said:

Correct me if I am wrong.

Viscous fan engages gradually (that is my theory ) with the rise of the coolant temp. Also, engine ECU turns on AC fans to aid cooling. I think this WHOOOOSHING comes from AC fans as they are turned on/off ( not gradually).

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The viscous lock up is effected by a bimettalic mechanism on the front, It locks up pretty quick when hot. The AC fans rarely if ever come on on the V8 due to engine temperature as there has to be a considerable overheat to trigger them. They never come on on the diesel unless called for by the aircon which on mine has only happened in stationary traffic with an outside temperature of around 40C

I've got a diesel that does the same its had new rad fan water pump and stat water was leaking from stat housing but isnt now but using water also took vacc housing off for easier access to stat now got an oil leak too changed oring but still leaking oil there is another seal in rocker cover anyone know the part no and please tell me the head isnt going starts and runs fine only gets hot when waterlevel drops, just darent go very far in her

Steve Elliott said:

I've got a diesel that does the same its had new rad fan water pump and stat water was leaking from stat housing but isnt now but using water also took vacc housing off for easier access to stat now got an oil leak too changed oring but still leaking oil there is another seal in rocker cover anyone know the part no and please tell me the head isnt going starts and runs fine only gets hot when waterlevel drops, just darent go very far in her

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If the water level drops of course it will overheat, keep doing it and budget for a new head.
Find out where the water is going, check for damp carpet in drivers footwell.

Hi
I have drained off a bit of water and topped it up with another 2 litres of anti-freeze so im at about 50 % , I have checked the fan as advised and that all seams fine . when I took the cover off to get to the fan I did not put it back , I have noticed that the temperature gauge although still goes up , does not as quick and seems to come down a bit. Although I replaced the rad it was for a recon one , is there any way of checking to see if it’s a dud? How do I check that the temperature sender unit is also not a dud ? I am still not losing any water

you were told how to check the rad with a marble in the header. if you havent checked it go back and do it. no point chasing your tail if you havent checked what people have told you check from previous posts.

sas1810 said:

you were told how to check the rad with a marble in the header. if you havent checked it go back and do it. no point chasing your tail if you havent checked what people have told you check from previous posts.

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Not sure when I was told that about the marble in the header , please explain , I did check the weight of the old one against the recon one and it was a bit heaver but not a lot.
And as I had brought the new one thought I would change it any way.
I have tested the thermostat on in a pan on the stove and that looks good . just not sure how to test the rad and temperature sender unit

gazzatops said:

Not sure when I was told that about the marble in the header , please explain , I did check the weight of the old one against the recon one and it was a bit heaver but not a lot.
And as I had brought the new one thought I would change it any way.
I have tested the thermostat on in a pan on the stove and that looks good . just not sure how to test the rad and temperature sender unit

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sorry my bad wrong post. someone else had same issues after changing the rad. we never knew if the new rad had the baffle in the header of the rad or not. put a marble in 1 side, if it rolls to the other, the baffle is missing. it needs to have 1 fitted or the water wont follow the correct route.

Have given up on this , cant find any thing that’s wrong I have had a sniff test done and that shows no leaks
So I have taken the thermostat out , pain getting it out the housing and all is good again

Have you replaced the pressure cap yet? On my first LandyZonoe International rescue, I stopped to help a RRC on the side of the road overheated, and it turned out that his expansion tank cap was letting off pressure and boiling up the coolant.