What would cause a pungent fish smell from car radiator?

[stu]

I took the cap off my car radiator to add some 'K' seal to the water & there is a very noticeable fishy smell.

What could cause this, is this a sign that the car has no anti-freeze present or that the water has never been flushed or changed out throughout its life ?

When I removed the radiator pipe briefly, the water appeared to be of a dirty brown colour ?

I don't really know the full history of the car, but I know I've never smelled anything quite like that before.

The car is a 'M' reg Toyota Diesel & the temperature needle always stays steady at the 9 o'clock position whilst driving , so I know its not overheating.

I've heard that its ok to add a crumbled dishwasher tablet to the contents of the radiator or to the expansion tank, drive around for a
few days then flush out the system with fresh water to get rid of all the old crap thats built up inside the pipes.

Will that be ok to do, will it get rid of that smell ?

Has anyone had the same experience & sorted it out ?

Also if I do have to flush out the old water, will all the 'K' seal be flushed out too ?

Thanks in advance.

 

[First L]

sounds as though some other **** has tried using a non descrpt treatment.
Why not spend some money and buy the correct flushing agent, we are talking pennies!