Nissan Patrol 4x4 (Africa)

Good afternoon!
Yesterday, 4th gear, very low revs, the temperature climbed close to red.
Just by adding a touch oft thrust it immediately went back to normal and stayed there.
Today I checked the coolant level - that was ok.
But the radiator looked strange, there was kind of lime or grease on it.
Does anybody have an idea what to do? Is a radiator cleaner a good idea?

Florian, looks like your radiator can do with a flush and some new anto freeze. I think it is recomended to change anti freeze every 2 years.

Is it oily where the cap sits?

Hi Florian
I think there is amixture of different types of antifreeze and radiator sealant been thrown into that radiator
Would advise to flush and do a cylinder leakage/radiator pressure test

There are some really good aftermarket radiators avalible from tombo automotive a lot of us have them if your radiator is blocked ect get a new one its
Like 3.5k

Thanks a lot for the replies!
It actually is an aftermarket radiator, fitted by Graham 3 years ago or so.
I'll do the flush and have the system checked and do follow up here as soon as I know something.
Have a great weekend!

Do you loose any water ?
What does your engine oil look like?

Sorry, I didn't have time to write before.
Problem solved: it was a mixture between a technical issue and stupidity.
Stupidity was me checking the coolant fluid level only in the expansion container when the temperature rose.
Technically the cap of the cooler was not sealing correctly. So the pressure didn't build up as it's supposed to, water was able to boil / evaporate in small quantities until it just was not enough to cool the engine.
In the end the radiator cap was replaced, the cooler cleaned where the cap is located and everything is fine and running again.

Oh, and five liters of coolant where missing - as I said, stupidity.

Did you use anti-freeze/coolant??

Looking at the gunk on the pic I would use a radiator cleaner as per the recommended instructions on the bottle and then flush it out with clean water, and use a GOOD QUALITY (expensive) antifreeze/coolant diluted to the specific instructions of that product. Too much antifreeze will damage the motor, and too little will just make it an expensive bit of inefficiency.

A clean radiator give piece of mind !! Mine after 4 odd years was still clear and the blue colour ( same as when I poured it in ) and when looking down the radiator cap opening, the metal still looks shiny and clean.

Ok, I got some news: all was good, at least there was never any leak again.
I wanted to have a look if the coolant level is still ok and a few minutes after opening the cap it began to drop again.
A quickblookbunder the radiator showed that the rubbers around the alignment pins where wet.
So I went to the garage, we did a pressure test - nothing.
We came to the conclusion that it might be a hair cut which closes when the system is hot and that was the correct guess: around both alignment pins there were hair cuts you won't see with your bare eye.
The radiator is just now at a guy who can weld aluminium.

Sure I was using antifreeze, I think the radiator looked so bad because the cap was not closing properly either and therefore coolant evaporated.
It would be good to know, what came first: the faulty cap or the hair cut. But as both now will be sorted I hope it will be ok again afterwards.

Awesome find!!
Small cracks like that can make your life a nightmare because it is very rare that one manages to find them and usually you assume that the car is using water and think towards head gasket or cracked head