1996 BMW 328is/having temperature fluctuation issues

[Jonnycash22]

Hello, i have a 1996 BMW 328is. It was running rather well as far as i could tell until a few months ago when one of the hoses for the radiator blew. 700 dollars later, i had a new radiator (and an oil change). Everything was fine and dandy until one day i was doing about 150km on a highway stretch of road by my house and i saw my temperature gauge was in the red so i immediately slowed down and about 20 seconds later, the dial had made its way back to the middle. When i got a chance i turned the car off and let it sit for a little bit. I was alittle confused, as i expected the new radiator to work a little better than it did on this occasion. As the weeks went by i started to notice the gauge would move beyond the mid-point here and there, and i'd have to slow down to let it go back to the middle. This was when i was goin speeds of only about 80kms. Eventually, i got fed up and went back to my mechanic again, and told him what was wrong and he looked at it and then told me it needed a new thermostat housing unit and a new fan clutch, as the old one wasn't engaging the fan properly. He said this was what was causing the temperature fluctuations. So, about 530 dollars later, i have new fan clutch, and new thermostat housing unit. But, for some odd reason, the temperature still fluctuates above the mid point and to the 3/4 point from time to time, when i'm going about 80km+ (meaning highway driving is out of the question) and its a hot sunny day out. I am trying to figure this out because i dearly love my car very much, i just wish i could drive it the way BMWs are meant to be driven. If you have any input as to what can help me solve this dilemma, its would be highly valued and greatly appreciated. Thank you.

[Mike328i]

Maybe a weird question...but did your mechanic let all the air out of the system...can be a real pain in the a$$ to get it all out
If all the stuff above is fixed/renewed.(visco-fan?)..have a look at your waterpump

[Jonnycash22]

Yeah thats a good question. I'll ask them and see if they fully bled the air out. Yeah i was thinking it could maybe be the waterpump. I vaguely remember having my mechanics fix that already in the past. Which leads me to possibly believe they probably just don't want to admit that the waterpump they installed is faulty. I'll give it a look. Thanks for your input, i'll keep you posted.

[Jonnycash22]

Yup, so finally after all this time, you were right Mike328i. They looked at the water pump and as it turns out, seems theres a piece on the back of it that is usually made of metal, but BMW and Volkswagen for a year or two, used plastic on a few of their models instead. The problem was that whenever i got up to speeds of 60km+, this piece was slipping meaning that the water wasn't properly circulating through the coolant system. I am very happy to have this issue fixed, it was definately a pain in the ars.