BIG problem - help please :\

[CHR1S1990]

so
i'm sat in the KFC drive thru and i smell something bad
i look at the temp gauge and its in the red and now smoke is pouring out from the bonnet
so i jump out pop the bonnet and find that steam is pouring out from the coolant cap
so i think shit try and tighten it - lukily enuf i make it out into the car park, with a 16 piece bucket
so i let the gauge cool down way into the blue, open up the coolant and slowly fill it back up - i thought i must have left the lid loose
so Im driving away and it gets up to just below half and i think few its alright!
2 minutes later it starts racing back up to red again!
so i pull in on Asda car park (lol) and again wait for it to cool down
after repeating I make it to my mates house where Im now asking for help!
what could it be?
perhaps the thermostat cas buggered up?
ive just gon out to check it and its been sat idling for about 5/6 minutes and it idles just below half so it seems ok.. for the moment!
any help would be much appreciated

cheers

chris

[maxfield]

Take the thermostat out and put it in boiling water to see if it is this?
You checked the oil cap for mayo?

[kipper]

when its hot, sqeeze the top house..it should be soft like bottom hose...if its hard there is built up pressure...( therostat not opening)..you need a new one..you can also check by tryingheater in car, if not hot air then its not circulating..prob thermostat. if car still starts first time like before then chance is heads fine....to bleed make sure you put heater on in car to hot and full blast whilst you bleed to make sure the matrix is bleed too...air should be hot..

[StuBeeDoo]

i make it out into the car park, with a 16 piece bucket

Good man! Priorities right there.

[CHR1S1990]

right - so its idling and still warm - air is blowing and nice and hot
also, when i squeeze the pipes theyre all soft so perhaps thermostat is fine?
and it started up okay
took it for a spin a couple of times round the block and it seemed to stay below half
worried as its quite a distance back to my house so cant rely it to be okay
any other ideas?
p.s. thanks for the help guys keep it coming!

[Jon_Bmw]

How was the bucket?

[CHR1S1990]

lol
besides the stress, it tasted good whilst i was sat on my red hot bonnet

[2_stroke]

take the stat out for the drive home as this will make it run cooler and ya should make it quite hapily and it wont cause any probs the stst is only there to let the car come to running temp quicker.
besides thatyou could check else where on the coolant sys for leakes as i had a merc with a small hole in the bottom hose and it kept overheating when i got a thrashing or was stood still the reason for this is that because the water in the sys is under pressure then it wont boil as fast but when u release the pressure it will boil and make steam pour out of the rad cap!! just think of kettles on planes and how the water boiles at a lower temp because of the lower presure well its just reversed in a coolant sys so pressure leaks make big steamy messes happen.

good luck bro

[cliffybabe]

just make sure theres no mayo in the header tank and theres no mayo under the oil cap. As already stated pull the thermo out put in a cup of boiling water and see if it opens up

did u get anyhting in asda to wash down ur bucket meal??

[Brianmoooore]

When the car is up to running temperature, all hose should be hard, as they should be under a pressure of 1.4 bar.
If the system is not pressurised, the cooling system will boil locally in the head and push the coolant out.
Check that the lower O ring on the coolant pressure cap is intact for a start.
If the stat is the problem, it's OK to leave it out for a short while, but don't leave it out for any length of time.
Turning the heater on to full hot with the fan on max will help.
You haven't stated the age and model of the car!

[CHR1S1990]

its a 1989 320i
it got me home okay which is about 10 miles or so, and the temperature didnt even breach half
just worrying as it seems to be on and off as of a few hours ago
i will check the thermostat tomorrow to be sure and get back to you
cheers for the help guys

[CHR1S1990]

and yes cliffy
a few beers and a tub of ben n jerries ice cream from asda i took to my mates

[t2g]

i don't think that thermostat is your problem here because if thermostat goes then warm air dont gome from heater anymore and temp will go up very quick. i would check water pump do if i was you.
sorry for bad english

[zaust]

Go and check the Viscous fan coupling. let it get to just under 3 quater's hot and put a rolled up paper in the fan. If the fan stop's then this is your problem...

[robbo86]

i'm sat in the KFC drive thru and i smell something bad

not unusual at kfc

[Brianmoooore]

Heater will still work with the thermostat stuck shut.
This problem could be as simple as a faulty pressure cap. IIRC, someone on here had his trip to the 'ring ruined recently by a fault that turned out to be as simple as this.
Has your pressure cap been replaced under the 1997 recall? I still find plenty of E30s still with the original cap!
Check with your local BMW dealer, and, if it's still the original, you should get a nice new one FOC.
Check that the small pipe from the top corner of the radiator to the neck of the coolant bottle isn't blocked.

[cliffybabe]

i had a simliar thing with a ecp thermo im now using a bmw one and its spot on

[Brianmoooore]

The genuine BMW thermostats are the one's I find faulty!

[CHR1S1990]

right so it has been running fine for the past day since the problem - i totally bled the water system and re filled so i thought it wos something trivial
now the problem is occuring again and no hot air is coming through the heaters
just about to take the thermostat out and check it - lukily no mayo anywhere tho (touch wood)

[cliffybabe]

sounds like the thermo, did u blead the system with the heating on full? theres a good trick using a 2litre bottle of coke

[CHR1S1990]

I did yeah, bled it a couple of times now "properly" lol
how long does it take to take the thermostat out?

[CHR1S1990]

so taken the thermostat out and tested it and it seems fine - starts to open after about 10 seconds or so at near boiling water (tried to get it as close as possible to about 80 deg) and opens up fairly quickly and fully
any other ideas?
just to refresh - overheating and getting no heat through heaters
a possible airlock? even though ive bled the system time and time again
perhaps Im doing something wrong?

[CHR1S1990]

p.s. whats the trick with the 2 litre bottle of coke?

[Jon_Bmw]

Perhaps pop to burger king for some inspiration!

Only kidding, chin up. Hope its nothing too serious for you. Search under bleeding techniques for the m20/325i etc. Find an answer by Brian and do it that way. Some people think using a slope is advantagous. In my experience some are easy to bleed, others not so. Random?

[Brianmoooore]

Overheating, and getting nothing from the heater, strongly suggests an airlock at the back of the head.
Fill the coolant tank right up, pull the top heater hose of for a second or so, to allow some coolant (and the air) to flow out, and put it back on.
This should clear the airlock. If the airlock returns after a while, you have probably cooked the head gasket.

[CHR1S1990]

thanks brian, legend as always
i'll keep bleeding it from the 8mm at the thermostat housing as air keeps coming out in splurts
i'll keep all informed

[Brianmoooore]

It's important that you don't run the engine in an airlocked condition! You are in real danger of cracking the head if you do.
You won't overheat a M20 many times and get away with it.

[CHR1S1990]

well the air seemed to have been removed once i took the top heater hose off, as no/hardly any air comes out when bleeding idling from the thermostat
also, the temperature hasn't even reached half
thank ****
thanks guys, hopefully this is the end of this matter