coolant Problem ajp

[Jackal83]

I have a small Problem the header tank keep blowing off when hot.
I'll tell you the whole story.

I've had to take the header tank off to get to the wiring loom grommet under neath it... It was letting water in so managed to do that... Today i've put it all back together and followed the manual to sorting the coolant out.

This is what i done.

1. Filled the header tank up with coolant half way.
2. Loosend the nut on the rad to let any air out... there was'nt any.
3. loosened the two taps on eather side of the engine to let air out... Passengers side had abit of air in but not much at all.
4. Then started the engine with the header tank cap off and reved it to around 1500rpm just like the manual says
5. The header tank was getting hot and steaming and sometimes bubbling over tock ages to get to temp
6. The Fan came on at around 105 on the gauge and the water in the header tank droped... so i filled up with coolant to the joint line.(max)
7. Put the cap on and the cap keeps blowing off...

Anyone got any ideas of what i'm doing wrong?

Jack

[al 350i]

you could still have an air lock, did you put the heater on hot? trying running the engine and undoing the bleed valves in turn and allow the water to seep out for a while. check to see if the top and bottom coolant pipes on the rad are getting warm, if one is cold then the water is not circulating.

[Extra 300 Driver]

I am sure its just air. My old cerb would take a few cycles of hot/cold to get all the air out.

[Jackal83]

had another go with it!!

left it for abit withthe cap on just tock the cap off and the header tank had gone down so topped it up again
went for a spin and brought it back and let it come up to temp.
fans come on and i waited for them to go off turned it off again.

Looking to be getting better know so im letting it cool again and see if it wants any more water.

No air is coming out of any bleed screws

Jack

[tvrgit]

I would still go with the air lock theory.

Also - I wouldn't be too worried about the actual water level. I was in the same boat as you a few months ago with my Cerb, and found that if I bled it thoroughly (many many times over!) and then let the water find its own level, it seems to be fine.

Another cerb I know had no water visible in the header tank at all! I asked him how often he tops it up and he said "never have"! Yet it runs fine.

My S series also runs well below the handbook recommended level. I've had that nearly 7 years so I know now where to fill it up to (ignoring the header tank altogether). I only put water in it once a year or something - if I put too much in, it loses it very quickly, back to the level it likes. So that's the level I top it up to!

[Jackal83]

Suddenly the inside of the car has started to steam up when left after a run... Only says one thing to me...
somethings gone wrong with heater matrix... Can i cry!!!

looked at the workshop Manuals online and my cars diffrent..
Any idea how to get at the early 1996 cerbera matrix??? My to water hoses go thought the firewall near the exhaust manifold not under the header tank like the workshop manual says.

Jack

[Ireland]

Is the stat ok?

I got all sorts of weird stuff happening when I had a dodgy stat.

[tvrgit]

Good point - a lot of my troubles were associated with a sticking stat and seemed to stop after I changed it.

[Jackal83]

All seems to off settled down now.... temp gauage seems fine and first time yesterday eve that i saw both fans come on after each other...
Cheers

Jack

[Allandwf]

Thats good, be careful cap doesn't cross thread , as can look ok, but will boil over, I've had this so I double check as easy done.

[M3John]

Jackal83 said:

... so i filled up with coolant to the joint line.(max)
Jack

Oh so is that the max mark on the expansion tank. Not the small line around 15-20mm below this join line that is visible on the off side of the tank?

[M3John]

Just to add to your story/problem. I've recently changed the rad in mine and when bleeding the system to get rid of the air the first time i ran the car up to temp it gave two puffs out of the expansion tank cap. Once cooled down, the following day i put a bit more coolent in there and run it back up to working tempature again. Checked that there was no air in the system again (there wasn't), this time it was all fine and has run ok since.

[FarmyardPants]

M3John said:

Just to add to your story/problem. I've recently changed the rad in mine and when bleeding the system to get rid of the air the first time i ran the car up to temp it gave two puffs out of the expansion tank cap. Once cooled down, the following day i put a bit more coolent in there and run it back up to working tempature again. Checked that there was no air in the system again (there wasn't), this time it was all fine and has run ok since.

How's your car doing John, all sorted?

[M3John]

FarmyardPants said:

How's your car doing John, all sorted?

Picking it up on Friday matey !

[Jackal83]

M3John said:

Just to add to your story/problem. I've recently changed the rad in mine and when bleeding the system to get rid of the air the first time i ran the car up to temp it gave two puffs out of the expansion tank cap. Once cooled down, the following day i put a bit more coolent in there and run it back up to working tempature again. Checked that there was no air in the system again (there wasn't), this time it was all fine and has run ok since.

I'm going to do it this way straigh away next time... Worked for me the second time... warm up to temp leave it to cool.. then top up.