help.. cooling system goes pop!

[L18M]

this is  a long one, but fully \'documented\'
[ATTACH]42640[/ATTACH]

SITUATION: so driving up to gloucester for the mini meet, after an hour and bit driving my stock temp is horizontal, greddy temp jumps to 100C ish, then bit high to 110C so i pull over n let it cool.
thinking it might be low on coolant (the rad light pops up every now and again even if the level is full) i take the rad cap off when cool and add water. was only a cup full or so, which replaced some coolant that came out the reserve tank earlier in day.

so after the meet i was on my way home when the temp rose to about 100C quite quicky and i was only doing 60mph. so driving along at 60mph, all of a sudden i see my screen covered in water*
pulled over to hard shoulder n turned engine off. opened hood and the rad hose had literally split in 1/2!

**jus something funny but can skip this if tis too much to read**
traffic officer (to) arrives to see if everything is ok
to: we saw the water back there.. blown headgasket?
me: eh.. :3Confused scratched head... lol
***

VITAL INFO BEFORE POP: driving along at 60mph, stock temp was horizontal, greddy temp 100C, coolant level was full when i started car.

i thought it was just a weak hose but that wouldnt make the temp hot unless there was a leak n loosing coolant. after talking to chris he mention the system was pressurised. i then did some research n came up with either of the following 3 causes.

1) the rad cap is faulty. coolant was able to leave the system and go to the reserve / expansion tank but i nvr noticed coolant going back into the system from the reserve tank.

2) faulty thermostat. maybe the thermostat sensor was buggered and closed causing the system to be over pressurised? i thought that this would cuase the stock temp sensor to increase, but then the greddy temp was only 100C so still withing the stock \'normal\' temp range

3) all of the above

so, can any gd engineering place pressure test a rad cap?
is it best to replace the thermostat with a brand new one or is 2nd hand ok? ( i got a spare 2nd hand one kicking about from when my water mump broke)

anyone got any ideas what else it can be?
lastly, replacing the rad hose (upper part) would it be best to keep using stock hose or go for shiney hard pipe? thinking if i went for shiney hard pipe then if this happens again then the tube wont break n it could damage the seams in the rad instead thus being a more expensive fix?!

*on a side note, the vented bonnet does actually work at pulling air out from engine bay! this was tested / proved as my water pipe broke n all the water came out the vents and only about 30% (if that) of the water stayed in the engine bay

[grinder]

100 - hummm i very rarely saw those figures on my gauge - i used to panic around the 95 mark

it used to sit around 85-88 ish

could be the thermostat is a higher rated one ??

must be some pressure to blow a hose in half though

[ashc]

? stuck thermostat or blown water seal pressurising the system?

[L18M]

Blown water seal? Where about?
Its usually 80-90.
Sat at 100 for bout 15min prior to breaking.
Will try put pic of blown pipe tmr. It is literally blown in 1/2.
Still, better that than rad breaking.
Will play with thermostat tmr.
How do i test if it works? Stick in hot water with DMM attached?

[C-Rex]

Is there a way of testing the water system on a FC would like to know mine is ok before I go trashing it around a track..

Like water seals etc if it is pressurised??
Would be interested to see the out come of this too since my temp gauge rose on the drive home from collecting it in heavy traffic, but I think this was due to a faulty therostat the fan didnt kick in:(

[pdtaylor18]

The 1st thing you want to do is to drain the system fully.  Put a hose in the top of the rad and pressure wash the internals out through the lower hose connector. It might be a blocked rad.  Next flush the engine and see what comes out.
Replace your thermostat
Replace or check your rad cap
Check your water pump or replace

For something to blow your hose apart means you must have a blockage, these standard hoses are dam fine bits of hose and very thick, I can send you another one if you want it, i have several, just PM your address again, just pay for postage.
Anyway you may want to fiund out what is blocked or causing too much pressure within the system.

[m1tch]

The problem in the winter with old hoses and high temps is that they can split due to the temperature difference, perhaps your rad hose was starting to go and just happened 2 go as it got hot? I think it might be a faulty thermostat as they are rather old! hope you get it sorted!

[pdtaylor18]

easy fix is to take the thermostat out and see what happens (after you have flushed your system)

[antnicuk]

it sounds like your water seals have gone in the engine and are pressurising the water system.  Sorry to be the bearer of bad news but exactly the same happened to me. Thats why you also blew the seal on your water pump. It will just continue to blow the weakest link.

[pdtaylor18]

Carl is the man for a rebuild if you are not doing this yourself, he has given me a very good price and far cheaper than i thought.  That was for an engine block only delivered. He actually stripped mine down in front of me to show what was wrong. Thankfully if its just a water seal then everything should be in good condition if you have lowish miles then a refresh only might do the trick.

[C-Rex]

Whats the approximate cost of a cooling system overhaul??

[m1tch]

sounds like time for.....heavier porting

[L18M]

it sounds like your water seals have gone in the engine and are pressurising the water system.  Sorry to be the bearer of bad news but exactly the same happened to me. Thats why you also blew the seal on your water pump. It will just continue to blow the weakest link.

thanks.. i was hopeing no-one would say that
fact of life i guess

it was behaving fine aft i got the waterpump replaced. only little anoying thing was the rad light came on once in a while and lost a tiny amount of coolant. tiny as in 1/2 a cup or so

[L18M]

The problem in the winter with old hoses and high temps is that they can split due to the temperature difference, perhaps your rad hose was starting to go and just happened 2 go as it got hot? I think it might be a faulty thermostat as they are rather old! hope you get it sorted!

the pipe was good condition from what i can make of it. it wasnt brittle n looked fine on outside.
i could be wrong.

[L18M]

The 1st thing you want to do is to drain the system fully.  Put a hose in the top of the rad and pressure wash the internals out through the lower hose connector. It might be a blocked rad.  Next flush the engine and see what comes out.
Replace your thermostat
Replace or check your rad cap
Check your water pump or replace

For something to blow your hose apart means you must have a blockage, these standard hoses are dam fine bits of hose and very thick, I can send you another one if you want it, i have several, just PM your address again, just pay for postage.
Anyway you may want to fiund out what is blocked or causing too much pressure within the system.

thanks pete. how are you ment to pressure wash the rad? as if u put a hose in the rad n turn up the water then it\'ll squirt out the side as theres nothing sealing the hose to rad.
where to stick the hose when you flush the engine?

i got spare thermostat but nt sure how gd that is.
i did coolant change not long ago, was b4 water pump was replaced.. maybe when he changed the pump he got some crap (sealant) into the system?!