Cracked head or Dodgy Thermostat

[bornwina]

Firstly hi to everyone, ive been a Hilux surf owner for 5 months and up until now ive really not encountered any problems with the vehicle apart from having to put a new Rad in about 3 months ago. To cut a long story short i was driving home last night and seen the temp guage fire right into the red. Lucky for me that i was relatively close to a garage so pulled in and lifted the bonnet. There was a bubbling sound coming from the expansion tank and also a lot of steam, i grabbed a couple of old towels i had in the back of the motor and undone the Rad cap, the steam literally filled the forecourt of the garage. I let her cool down and then proceeded to fill her up again with coolant. All was fine driving her home the rest of the journey. This morning however i noticed the expansion tank was filled with brown fluid as opposed to being the usual clear bluey colour. Before this all happened i was getting no hot air coming through the heaters therefore after reading some threads ive come to the conclusion ive either got a faulty thermostat or an air blockage. Took the rad cap off today and it was frothy like the head of a guiness pint but after squeezing some pipes it settled down. Ive ordered a new rad cap and thermostat as of today. My question is could i now have a cracked head?.

[Koi]

Hi and welcome

Its possible but theres a few things I would do first.

On my old Surf I got brown sludge water in the coolant, this I think was the stuff in it previously.

Flush out the system fully, take off hoses at the bulk head and put a hose on them flush right out, be surprised how much crap comes out.

Fit your new cap and stat and refill the system, they can be a bit of a pig to fill so take your time.

Make sure both heaters set to hot setting before refilling and flushing out.
Fill via the rad cap until full, start it up couple of blips of the loud pedal and switch off, top up. Repeat that a few times then whe it wont take no more I took mine for a short drive round the block and topped up if needed.

Also check the hose from the rad cap to the expansion isnt perforated if it is it wont suck the expanded coolant back in the the system.

I think the fact you never had the heaters working properly there was an air lock, it may have moved now causing not enough coolant in the system.