Suzuki Club UK

My 413 is losing water from the reservoir causing it to overheat when idle or slow traffic but fine when at speed. There is light brown gunk in the radiator cap and it's spitting orange water all over engine area from the overflow pipe. Could this be thermostat or head gasket ? Thanks

It could be a stuck thermostat, what's the colour of the oil on the oil filler cap?

Oho don't know haven't looked at that, I'll look tomorrow, the dip stick oil is black though ??

That sounds ok but check the cap for any whiteish oily residue, if it is it's prob head gasket if not it's the stat, which is a fairly cheap and easy fix

Thank I'll check this tomorrow

Ok, let's us know how it goes.

Have had a look in oil and it's black and normal looking, have added a pic of the gunk in the radiator cap

It's the little bottle on the right of radiator that runs out of water, not sure how it works to be honest

Looks like the coolant could do with draining, flushing and re filling.

Sound like the thermostat is stuck closed. So when the engine is warm instead of opening and allowing more water to flow around the engine, its pressurising the radiator causing it to blow out the excess water.

The idea is as it warms up some water goes into the expansion tank and as cools it sucks it back in. If the system is blocked it spits out a lot more water than normal and doesn't have enough to cool it efficiently.

Its more noticeable stood still as there isn't enough air flowing through the radiator / around the engine to aid cooling.

New thermostat, flush the system and refill. Try it.

Hope that all makes sense.

Thank you, will order a new thermostat off ebay and give it a go