what is going on with the cooling system

[OhOh7]

Broke down on the motorway a week ago as engine was dangerously overheating steam pouring out the back and the heater wasn't working at all. Have fitted a new thermostat and water pump, flushed out the system with a hose and then tested the system with water before wasting new anti freeze. Followed the wonderful bleeding the coolant thread on Brikyard http://www.brick-yard.co.uk/forum/bleed ... page1.html" onclick="window.open(this.href);return false;. All seemed well and truly fixed. The coolant warning light didn't come on revved it as advised and bled at the radiator, radiator got warm, the heater was working the fan cut in when it should, no visible leaks. So let it all cool and then drained the water and added the antifreeze, the warning light came on and didn't go off, the heater didn't work and the fan didn't cut in but the engine was getting seriously hot. decided to switch off before something went bang. The coolant level in the expansion tank did go down a little but not much- also sprung a slight leak at the metal water pipe to the thermostat housing so have ordered a new o ring and a tiny drip from metal distribution pipe on top of the engine, neither of these were evident when it was successfully filled with water.
aargh, what am I doing wrong???? Why did it work for the water fill and not the antifreeze???
PS I have been trawling through all the archived and current stuff on here but can't find a similar problem to offer any comfort:-(
Forgot to say the van is a 1.9 petrol early 1985

[Eloise]

Hi, you don't mention it, but you did re bleed after adding coolant?

[mark]

how long between coolant changes?
did you have k-seal or the like in it?
what the new coolant is doing is cleaning all the rubbish out of the system so all the gunk that was stuck in there is being cleaned off and revealing all the little weakness'............regular coolant changes.......its the future

mark

[OhOh7]

Thanks Guys, attempted to bleed after adding the coolant but it seriously overheated before completing and sprung the two small leaks. Have received the new O ring today so hopefully will try again this weekend. Have had the van three years - a recon engine that has only done 30 thousand ish. I admit I haven't changed the coolant before, any guidelines as to how often this should be done? Cheers

[kevtherev]

I admit I haven't changed the coolant before, any guidelines as to how often this should be done? Cheers

Every two years.

[California Dreamin]

I admit I haven't changed the coolant before, any guidelines as to how often this should be done? Cheers

Every two years.

Evert 5 years with modern G12+ (OAT) ...2 years for the old type.

Martin

[kevtherev]

Thanks Martin

[OhOh7]

Well, bled the system apparently successfully, heater working, fan came on when left revving for quite a while, first test drive fine although coolant indicator light still flashing away merrily. Second longer test drive which involved standing traffic - temperature needle went way up, heater stopped working and the fan didn't come on - eeek, stopped, allowed to cool and a slow cautious drive home. Have replicated the problem again out on the drive (bet our neighbours love us) - light still flashing although coolant level is completely topped up, heater works initially then stops working and cooling fan stops working too. No air present from rad bleed valve.

have been reading Tobyn's thread with interest, could our problems be related?? xhttps://club8090.co.uk/forum/viewtopic.p ... 1#p8017475

Have taken off the connection from the coolant level sensor and the connection from the heater thermoswitch and the light is still flashing....

Am fed up as wanted to go to the seaside

[CovKid]

If you don't rev it high enough during the bleeding process, it can still have trapped air in it and it'll overheat soon after. Sometimes the air will make its own way out via the header tank overnight, but not always. I see no reason why it should do this when you bled it fine with water - other than there being a pocket of air somewhere. I had similar issues and slightly higher revs helped. Best with two people anyway, to keep header fully topped up.

Well, thats just one potential cause.

[Ralf85]

Yep air still in the system. It takes a long time to fill the system up and get all the air out. I get my garage to do it cos they know what they are doing. Even when this is done properly and seems to be full of coolant you will find that after a bit of driving it will need topping up as the last of the air is pushed out.

[silverbullet]

If a previous owner has used k-seal or similar to mask minor coolant weeps, then there is a good chance that one or more of the bleed hoses will be clogged. I have removed a thermostat bleed hose (on later coolant systems) that was completely blocked with silt and cork gunge for the entire length. The tiny bleed hole under the 'stat top bonnet screw cap can get blocked too: use a drill around 2mm to clear it.

[marlinowner]

If the coolant level sensor is disconnected, then the light will flash all the time. Pull out the relay marked 42 or 43 to disable the coolant level warning. Overheating will still show on the gauge and flash the light.

[OhOh7]

So .... new thermostat, new water pump, new thermo whatsit, new dalek cap - first replacement form JK didn't quack, got a VW one from Brikwerks which quacks beautifully. Flushed out hoses (again) quite a lot of rubbish in heater ones which didn't come out first time- coolant in, revving all the time, burping all the relevant bits, short test drive followed by another radiator burp, am now keeping fingers crossed that it is fixed. Will take it out and check burping on return for a while. Many thanks for all the advice so far, hopefully we will get to the seaside before too long.