overheated

[hammy67]

had to be recovered today after we heard gurggling noises whist driving coming from the expansion tank the temp gauge got to about the 1 or 2 oclock mark but the low water alarm didnt go off neither did the cylinder head temp gauge which was reading 7 degrees c over normal running temp but no where as hot as it normally gets when idleing in traffic
we pulled over very quickly and turned the engine off the cooling fans were running
the expansion tank was not too hot but on releasing the cap a lot of coolant did come out bottom radiator hose was cold and the top one was not very hot either
aa came out and were happy to just top up and send me home but i insisted on being recovered home which they did
fitted a new water pump about 3 weeks ago and a new thermostat 3 weeks previous to that and both times spent a good hour bleeding the air out of the system
water pump belts are both ok one of the first things i checked
and no coolant leaks

when the engine is run without the expansion cap on the tank the coolant level goes down but when engine is idling the coolant level rises the aa man seems to think this points to a blockage in the cooling system i.e thermostat stuck closed
if so i dont understand why the level in the tank would rise and fall depending on engine revs thoughts please

[the laird]

Hammy did the radiator feel hot top and bottom?did you notice the water circulating ie swirling in the header tank.if the rad is blocked it'll be cold either top or bottom

[hammy67]

no radiator was just warm didnt notice water swirling in the header tank it just pulled down when the engine was reved and rose up in the header tank when returned to idle

[mikeonb4c]

If you squeeze your top hose, is it hard, and does it have a crunching feel when you crush it?

[Northern Bongolow]

check the hose and steel pipe where it leaves the engine and goes towards the rad. when this is holed it may not leak much coolant, but may suck in air. this air stops flow of coolant, you may find that the front heater goes cool too.

get a good garage to pressurise the system with compressed air, to 1 bar, then look for leaks.

[hammy67]

all the hoses are in tiptop condition and were all replaced less than a year ago

[mikeonb4c]

all the hoses are in tiptop condition and were all replaced less than a year ago

Can you recall if the old hoses were crunchy due to rust coating. The point is that if they were, you quite likely have a poorly maintained system and clogged radiators, which would cause the problem you are having

[hammy67]

yes you are right they werent crunchy or hard but even though i have changed the thermostat with new coolant , water pump with new coolant and changed the cylinder head again all new coolant the coolant is still very rusty coloured

[mikeonb4c]

yes you are right they werent crunchy or hard but even though i have changed the thermostat with new coolant , water pump with new coolant and changed the cylinder head again all new coolant the coolant is still very rusty coloured

That's your problem then I suspect: restricted flow through critical channels. I never know how bad the channels in the head and block might have got, or if you could do much if they had, but a new main radiator might be in order. And my mechanic Adrian (Japan Direct, in Bury) was caught recently also putting a new front heater radiator in an afflicted Bongo.

[hammy67]

just removed and flushed out the main radiator lots of crud came out now for the rest of the system

[hammy67]

thermostat checked and is opening fine all hoses checked and no leaks and only a fine film of brown sediment on the inside about to flush engine and heaters to see how much crud come out of them
also loosened the belts to the water pump and spun that over by hand and all that seem fine

[hammy67]

right all the system has been flushed through
all bled and refilled with just plain water whist cold
bled using see saw method with engine running but still getting lots of air out after 2 hrs of bleeding me thinks head has gone AGAIN

[Driver+Passengers]

right all the system has been flushed through
all bled and refilled with just plain water whist cold
bled using see saw method with engine running but still getting lots of air out after 2 hrs of bleeding me thinks head has gone AGAIN

Boo... are you absolutely certain that the header tank level is never dropping out during the 2 hour bleed? Have you got another pair of eyes watching it?

[hammy67]

yes keeping levels all topped up

[Simon Jones]

Could just be the head gasket rather than the head, although it's tricky to be sure without taking the head off and getting it pressure tested (which is not 100% guaranteed to prove it is or is not the head).