Car running hot and cold spots on radiator?

[Munch92]

I picked up a Suzuki Grand Vitara 2l petrol 2001 a few days ago, I test drove it and everything was fine.

After driving it home I noticed after going up a steepish hill the temp gauge was about 80%, very very close to the red line.

I have flushed the coolant, removed thermostat and the water pump appears to be OK because coolant is flowing well. The car can be driven all day around town and idle for 20minutes+ with no issues. The problems start when you are going up a hill or giving it high revs for a period of time (e.g 4k revs for 1min) then it starts to creep up.

I noticed the radiator isn't warm everywhere, it has random areas where it's stone cold. I would say about 40% of the rad is cold but it's in completely random spots. Does this mean the rad is buggered and needing to be replaced? Is it a common problem? Could it be causing my issues?

[Trevor555]

If your oil and water is clean I'd start with changing the water pump.

Edited by Trevor555 on Wednesday 11th July 23:32

[Mignon]

Trevor555 said:

If you're oil and water

I very much doubt if the OP is oil and water.

Sounds like the rad is blocked with debris and while this may be flushable if you take it to a specialist it's probably time for a new rad.

[Munch92]

Oil and water is not mixing. I think waterpump is fine as coolant is flowing well and car is fine idling and doesnt get any warmer

[Kccv23highliftcam]

I would say from what has been stated that a replacement Rad rather that flushing attempts would be better..

[Munch92]

I agree. Will be replacing rad tomorrow but wondering what happens inside ras to cause cold areaa

[Trevor555]

If it idles ok for 20mins the I can't see it being a blocked rad unless your thermostat is stuck open.

You say you've flushed the system so surely you'd know if the rad was blocked?

If over heating at load and higher revs then almost certainly points to weak flow from water pump.

By all means put a new rad in if it looks old and ropy but I'd do the water pump first.

[Mignon]

Munch92 said:

I agree. Will be replacing rad tomorrow but wondering what happens inside ras to cause cold areaa

The internal channels in the cross fins are very narrow. They can block up with limescale if distilled water wasn't used or machining debris if for instance a cylinder head was skimmed but not cleaned properly. Or gunge from radweld and other nasties that may have been poured in at one time.

[Munch92]

Thanks for the replies. Will replace rad and see how I get on.