Radiator pressure.

Post by **dalahare** » 07 Dec 2006 01:36 pm

We've had a few warm days here and i notice the car (85 360 glt) was starting to overheat, so i checked the radiator water which was low, it took about a litre!, now i can't see a leak anywhere external and no water has mixed with the oil, where did it go?

Also to fill it i took the radiator cap off whilst the car was still warm, slowly to let the pressure out, but there was stuff all pressure behind it, I tried again today after a 25 minue drive when the car was at it's normal temperature (just below halfway) and i can just take the cap off with the tiniest hiss, any other car that i have owned would have gushed out hot fluid everywhere. Is this normal or is it the begginning to the end? ( i'm thinking head gasket leaking into chambers?)

Post by **pettaw** » 07 Dec 2006 02:39 pm

You've most likely got a leak somewhere, a fairly large one so that the pressure can't build up in the system.

I doubt its the head gasket, cos otherwise you'd notice either mayo in the oil, mayo in the water or excess pressure in the cooling system from cold.

There is one other thing, have you checked the radiator cap to make sure its sealing properly, a leaky radiator cap can cause low pressure and unexplained coolant loss, but it would be slow.

Post by **Ronnie** » 07 Dec 2006 02:46 pm

Try changing your expansion tank cap. It's designed to vent under high pressure as a blow off mechanism. If it's failed it could have lost all it's resistance.

The next thing to try is replacing the rad itself. If you have an original rad (which is likely) it's been working hard under the oz sun for over 20 years, fair enough that it's quitting now!

In the absence of mayo in the oil or other overt horrors, I would thing it's unlikely it's your HG. B19, B200's are pretty bullet proof and I'm not sure I've ever heard of a HG failure on one (although there's bound to be a few experts on here who have)

Post by **dalahare** » 07 Dec 2006 02:59 pm

Well it's diue for a 180K service, so i'll give it a new cap whilst i'm at it and see how it goes, might flush the whosle system too, i know there is a stack of corrosion in there, when i first bought the car the heater wouldn't work, traced it bak to the heater tap, which was jammed open, but completely clogged, with rusty deposit. the car sat unused for three years before i bought it which i don't think helped...

The cap makes sense i suppose, slowly venting vapour would explain why i cannot see collant loss and the very slow depletion of fluid.

Post by **5lab** » 07 Dec 2006 03:46 pm

i'd not worry too much - its an old car and it's going to use a *bit* of coolant - just keep an eye on it and worry if it starts dropping too fast

Post by **pettaw** » 07 Dec 2006 05:43 pm

5lab wrote:i'd not worry too much - its an old car and it's going to use a *bit* of coolant - just keep an eye on it and worry if it starts dropping too fast

Ignore that advice

Post by **classicswede** » 07 Dec 2006 08:15 pm

I would say you probably have a leak as well as possibly a jammed thermostat or it could have even possibly been removed.

Post by **dalahare** » 08 Dec 2006 02:02 am

I replaced the thermostat when i bought the car (>20k klms), and the temperature stays constant when the right amount of coolant is in there, so i presume it is still working ok, i'll try the cap first.

Thanks for the advice.

Post by **dalahare** » 08 Dec 2006 04:46 am

Well after my post this morning i went out to find some coolant leaking under the car

top radiator hose between the temp sender and the thermostat, no shops carried it so i went and got a secondhand one and second hand cap, from a wrecker, $10 with a few other bitts and pieces, some fresh coolant after a flush and away we go, we'll see if all is good after i drive to work.

Post by **dalahare** » 11 Dec 2006 01:20 pm

Well i still have no pressure, and car is running a little warm at times, so i'll fork out for a brand new cap. (pain in the arse is the 45 minute drive to the nearest shop that has one)

Is there a trick to bleeding the system in a b200e?

The odd thing tha i've never seen before, car runs slitghly warm, just past halfway on the gauge, when i turn the car off the coolant raises in the expansion tank and pushes its way past the cap.

Post by **sven360** » 11 Dec 2006 05:40 pm

dalahare wrote: when i turn the car off the coolant raises in the expansion tank and pushes its way past the cap.

Airblock in system I would say

Post by **fume** » 11 Dec 2006 09:40 pm

I had the same problem in my 1.7 after i had flushed the system, there was a flake of rust in t joint under air cleaner it had the effect of a one way valve causing an airlock in system. In normal running though the gauge still sits quite high (past halfway mark) summer should be fun!

Post by **classicswede** » 11 Dec 2006 09:49 pm

Best bet would be to fluch the system out with a hose pipe.