First time overheating

[rfarey]

Hi All

My KZN130 has just overheated for the first time. Just driven 200miles in terrible spray so didn't notice anything coming out the exhaust. Now have a hot truck (just under red), no coolant visible in the rad, cold heaters, coolant in the expansion bottle and signs of coolant in the battery tray next to the expansion bottle. It had a new rad about 20,000k ago....
I have noticed a puff of white smoke on a couple of recent start ups and it did have a bit of a chug on start up the other day, which I put down to it not having been started for a couple of weeks.
The thing that alerted me to it was a aircraft like whining noise when i came off the motorway.

Could this have been the rad cap blowing pressure? Water pump siezing?

Is it what I think it is?

CHeers
Rob

[rfarey]

Just noticed what looks like a pin hole in the top of the rad (red antifreeze mark). Haven't checked levels for about 6 months (oops).
Hoping its just general fluid loss untill overheat blew it out the header tank? Fingers crossed!!!!!

[Tallyman]

If the rad lost pressure via the pin hole then when the water exceeded 100C it would have boiled and escaped as steam, etc. It's only whilst it's under pressure that it can heat to more than 100C without turning to a gas. That's probably what you heard. I've got a separate water temp guage on mine and I've seen it hit about 115C when towing up hill in hot weather but it's not lost any water.

Check the "pin hole" and if it is a hole then it can probably be brazed or soldered over. However, if there's one hole there may be more, so it would be worth getting the rad pressure tested on its own and repaired or replaced if it's bad (not a Milner's replacement is it as it seems they may not be of OEM quality).

Remember when you refill the system to have both heater sliders on fully open to avoid air locks and make sure the system is fully bled before any long journeys.