Just bought a 96 328is for my wife with 90k miles on it. Drove it for a week with everything ok. Took my brother for a spin showing off getting on it a little but not too bad and overheated it. Pulled over let it cool then drove to the nearest gas station and it overheated again. Had a little coolant overflow, let the thing cool for a couple hours while I called a mechanic and read the Chiltons on it. Checked all the fuses and hoses ele fan etc, everything ok. Started it back up to make sure the Elec fan was ok and it was. let it idle to normal op temp and it stayed in the middle. Drove home and it stayed in the middle. Wife has been driving it for past week and everything a ok. No leaks. I have read about water pump impellers and plastic housing but all seems ok. I figure it was a sticking thermostat. no engine lights came on or are on now. Any suggestions that won't cost me an arm and a leg. A BMW mechanic said if everthing seems ok just drive it until it happens again. I guess I'll let my wife have her car and if I want to go hot rodding drive my car. It's not a BMW. any suggestions would be greatly appreciated. It's our first BMW.
Sounds like a sticky thermostat.. like you said... get that thing changed... a thermo will run you around 30 bucks... a gal of coolant... about 20 bucks... and two gals of distilled water.... 2.5 bucks... and a drain pan.. maybe 10 bucks.. and some tools... its not hard... go to pelicanparts.com for a do it your self page on this... good luck
check the fan clutch, the car will likely overheat driving small trips compared to long trips, since the air flow at higher speeds is keeping the engine cool,
they are about 130$ to replace and an easy job so get it checked out could save you an engine
a few things to be mindfull of. first is that once you fix the problem , try to diagnose if anything else may have suffered damage due to the overheat. once the car overheats it can cause damage to all the other essential working parts of the cooling system.
1-rad-usually an overheat will cause the spigots (where the hoses connect to the rad) will weaken and become brittle from the excessive heat.
2- the waterpump (depending on what type you have) can actually eat the blades on it.
3- hoses- can also become brittle and crack.
4- thermostat housing- can crack and wear
5- all seals - same as everything else....crack and or break.
Just for peace of mind I would get a pressure test done. All these suggestions are very plausible and hopefully it will be something this simple but you can never be sure and it wont cost you the earth, Wheras if you don't a new head gasket or head will cost you an arm or leg.
Yea.. I'd also say get a compression check done on the cylinders if you feel the need to make sure you dont have a head gasket leak.. and take the oil cap off and make sure there is no white milkey stuff on it... and your good for the gasket... as for the pressure test.. that is a good idea.. but if I was you.. I'd replace it either way.. as the water pump it self it not all that exspensive... and in the long run it would probably be worth the replacement...
Ok, Finallly got the time to do the job. Ordered the pump and got the car ready for the job. Wife has been driving the car for a few weeks now. Everything ok but just I just want to be sure so I decided to do a new water pump, thermostat, elect fan switch, etc. First, I sliced my finger to hell trying to get those plastic bolt and rivet crap off for the fan shroud. Snapped all them off. Then go to take off the fan and figure out you need that damn fan tool to remove it. So I had to order it. Then I go to get the new Pump and yes it is the one with the plastic impeller. So I had to reorder another one which should be here today. But I cannot get the fan tool untill friday so my wife's car now sits in the garage. Could BMW make this any more difficult!!! I have also seen that a company makes an aluminum thermostat housing. Is it worth getting over the stock plastic one?? How about the damn coolant. Does BMW coolant really have something in it better than the off the shelf stuff? If so what?????? The stuff I took out this weekend was blue but I do not know how old it is so I will replace it.
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