E30 Zone

Hi, got an overheating problem on my 1990 316i.
Basically, needle starts off on cold as normal, gets to midway very quickly and very soon gets to red.
I first noticed it after i did an oil change and was running the engine to get the oil through. After about 15mins i noticed there was water dripping quite quickly out from under the radiator somewhere. I checked the rad and couldnt see any cracks on the outside, checked the small pipe going into the reservoir (which is at the front of the engine attatched to the rad) and it could have possibly been coming from there - not too sure.
Thing is though, i've tried to recreate the situation, had the engine idling for about 20 mins but not had any water dripping. I checked the coolant level, it was fine. Pipes seem firm which suggests there is water going round...
Thing is, (which makes me think its the thermostat) i cant seem to get any hot air out through the blowers. The fan is going round, seems to be constantly on, but all i get is cold air, even when the needle is at the red.

Anyway, i've checked numerous posts and people are mentioning the Viscous Coupling on the fan, water pump, the Thermostat or an air leak, i was wondering if someone had the same problem so i could narrow it down before i fork out loads of cash for someone to look for me!!

Any ideas????????????

if you say that there is no water leak, then flush all the coolant out from the engine, change the thermostat and then make sure you bleed the coolant removing all air so you dont have any airlocks.

does your engine smoke when the needle is on red?

Cool, i'll give that a go, cheers.

Nope it doesnt smoke, havent let it get that far - ive had experience of an overheating engine before (in a MK3 Escort) so i'm wary of driving too much with needle in the red!! However, i did notice a bit of steam coming from one of the top pipes leading to the top of the engine the other day when i was trying to recreate the "dripping" i had before. I wouldve thought that the engine smoking would be because of a crack in the engine block - im pretty certain thats not the problem.
I've got it booked in for 2moro anyway so i'll mention the thermostat to them so they check it out first. Whatever the problem is i have a bad feeling it's not gonna be cheap!!

Bingo!! i've fixed it.
This is how it went....

I noticed on someone else's post (thanks bmwe30mtech!) that to fix an air lock (which is free!) "Park the car on a hill (bonnet end facing uphil). Cut a water bottle in half, and then wrap electrical tape arround the bottleneck untill its a tight fit in the header tank opening. Then pour coolant into the bottle (and fill the bottle above the level of the header tank) while the engine is idling, this will get rid of ANY air! Then undo the bleed screw on the thermostat housing while the engine is running untill water steadily flows out (not air). This will all make certain there is no air lock."

Unfortunately there aren't many hills around me close enough, so i kind of did my own thing. Instead of bleeding the thermostat i let the engine warm up slightly and very gently undid the cap on the header tank until all the pressure had gradually forced the air up out of the opening. this in turn made the water level rise in the tank. I then filled up the tank and followed the idea above about filling up the bottle so it was over the level. After starting the engine again the water level dropped suddenly suggesting that more water than i had originally thought had leaked out, so i topped it up a couple more times and lo and behold all is now fine.There must've been 1 major air bubble in the system somewhere but hopefully now it is all sorted.

Still doesnt solve the problem of how it started leaking in the first place. might have to invest in some new pipes methinks!!!