Ok guys figure this one out

[DRKREVRND666]

Ok here i am again still battling the cooling system on my 1996 318is. I have replaced the radiator ,thermostat,hoses, water pump, coolant, fuses, temperature switch , and i am still having problems . Ok first the dam cooling fan still isnt working i replaced the switch made sure i filled and bled the system,changed the fuses,tested the fan(and it works),tested the ground and the fan still dosent come on when the car starts to get hot. The only thing left is the relays. Does any one have any other ideas? Also here is the kicker. i just bought a new radiator and was driving about two weeks ago and pop the side of the radiator (expansion tank side) seperated from the aluminum part, so i returned the radiator (with a big fight because the guy wanted to blame a bad thermostat or blown head gasket on the blow out) and got a new one. I installed it and the car was fine except the dam fan issue. Then yesterday i went to get in the car and there was coolant all over the ground, so i filled it and didnt drive it. When i got home from work i looked and it was still full, so i bled the system again (yes i turned the heat on) and then pressure tested the system and it held pressure @ 18lbs so i figure it was good, but when i tried to get it up to temp to test the new temp switch it was taking a long time in idle so i put it in gear as soon as i did it started leaking really bad from the bottom of the expansion tank where it meets the radiator plastic housing . WHY WOULD IT HOLD 18LBS OF PRESSURE AND WATER UNTIL I PUT THE CAR IN GEAR NO MATTER IF ITS HOT OR COLD IT HOLDS IN IDLE ALL THE WAY TO OVERHEATING BUT THE SECOND YOU PUT IT IN GEAR IT LEAKS . Im very sorry for the long post but i am really at the end of my rope with this cooling system and my wallet is really hurting. and help is grealty appreciated. thanks

:mad::mad::mad::mad:

[suntex01]

check all your hoses to the expansion tank real quick. It might be one of the overflow lines that fell or came loose. Atleast that's what happened to mine.

[DRKREVRND666]

No thats not it i can actually see the fluid coming out of the bottom of the expansion tank and i removed it and checked the gasket and its fine so are the hoses and the tank its self

[strogg]

does the expansion tank leak if you just rev the engine? could be the gasket is strong, but just not strong enough. otherwise... wow. you have quite a unique engine. and a boatload of patience.

[Bartman619]

Your're talking about the electric fan in fron of the radiator right ? If you are, this is what I got from my independent BMW mechanic. The electric fan only comes on when you have the A/C on or when the car is getting close to overheating. Hope this helps.

[DRKREVRND666]

The expansion tank holds until you put it in gear you can rev it ,pressure test it what ever as long as you dont put it in gear .i bought some black silicone and took the expansion tank off the radiator and the gaskets looked good so i put some silicone around the bottom of the tank and between the two gaskets then i put it back togeather it has to cure for 24 hours so when i get off work im goingto try it. I am talking about the electric fan in front of the radiator . The fan wont come on with the ac or if th ecar overheats this is why my car is overheating . This is why i am tring to fix the fan.

[E36youngster]

my fan wouldnt come on either, so i just hard wired it and put a switch in the cockpit. whenever i am in traffic or something i flip the switch and the fan kicks in. i have no idea what can be causing your expansion tank to be leaking like that...its ridiculous

[DRKREVRND666]

I was thinking of doing that im gonna re install the radiator today make sure its filled with coolant,bled,im also replacing the relays for the fan that should fix it if not im going your route

[bimmerblack]

If you can do what youngster has done, man i'd skip it all and run with that idea...damn all that, sorry to hear about your 318, hope i NEVER have to run through the same

[DRKREVRND666]

Ok, heres the latest on the car, the car doesn't want to start now, smoke pours out of the exaust when it does start, then it runs ok( other than the over heating). I cant get it to stop overheating. If you're familiar with my cooling system issues you will know this is probably post number 20 on this issue. Now the car when i try to start it first thing in the morning is ver hard to start it takes like 5 or six tries then when it starts it runs bad really bad like its missing a cylinder or two. Then when it finally starts it blows a big cloud of white smoke that lasts till the car warms up, and when ever you try to start it even if i only get out to pay for gas its hard to restart . Also i just had to replace the expansion tank on the radiator ive only had two weeks (and this is the second time it sprung a leak) i also put black silicone around where it meets the radiator. Well today as i was driving i got stuck in traffic and the car started to over heat so i pulled over and let it cool well after it cooled i drove around 65mph and it didnt cool down as usual (because the fan dosent work for some unknown reason( i have explained this in detail in previous post explosion under the hood) i have bled it properly, checked fuses, replaced the fan switch, checked the fan, checked the ground. i am having that problem diagnosed by a mechanic tomorrow, but now the radiator cap has sprung a leak due to overheating . i have replaced every part of the cooling system except the two fan relays which will be replaced tomorrow, and something keeps making the system build up enough pressure to blow some part (whatever is the weakest part of the cooling system at the time) . i have done tests to see if it is a blown head gasket, compression test was 150lbs on every cylinder, i checked coolant for oil and vice versa , and theres no sign of any thing where it shouldnt be . theres no coolant loss (except for random explosions).i also see no visible leaks from the head. so i dont want it to be the head gasket. but i also have the white smoke , hard starts , overheating, and pressure build up in the cooling system. so what else can i do besides tear the head off to see if i have a blown head gasket? by the way thank you every one for all your help. sorry this post is so long im just really frustrated and i figure its better to just rant than answer other peoples question with smart ass remarks.

thanks all
jesse