Need help with cooling/overheating problem:

[E34 530]

i still think your water pump is boned.

I'm going to the guy who put the pump in one of these days to see how he put it in and see if he will replace it. How can you mess up putting a pump in though?? Wouldn't it overheat all the time if the pump was trashed??

[gale]

I'm going to the guy who put the pump in one of these days to see how he put it in and see if he will replace it. How can you mess up putting a pump in though?? Wouldn't it overheat all the time if the pump was trashed??

Could be the pump impeller is slipping on the shaft, anymore they come with plastic impellers these days. There are numerous brands of pumps: Laso, Hepu, Graf. Laso is supposedly one of the better brands but my new one (Laso) has a plastic impeller. I went ahead & used it anyway since the old one was rusty & the new one has a brass hub sleeve molded into the plastic with obvious signs of serrated "teeth" to keep it from spinning.

Also, thermostats are cheap. Could have gotten a bum one. At one time there was a batch of bad viscous fan clutches (Behr or Sachs?). If it's running hot while sitting at a light, you should be able to hear the fan kick in when you start off again.

[E34 530]

Could be the pump impeller is slipping on the shaft, anymore they come with plastic impellers these days. There are numerous brands of pumps: Laso, Hepu, Graf. Laso is supposedly one of the better brands but my new one (Laso) has a plastic impeller. I went ahead & used it anyway since the old one was rusty & the new one has a brass hub sleeve molded into the plastic with obvious signs of serrated "teeth" to keep it from spinning.

Also, thermostats are cheap. Could have gotten a bum one. At one time there was a batch of bad viscous fan clutches (Behr or Sachs?). If it's running hot while sitting at a light, you should be able to hear the fan kick in when you start off again.

Thanks man. Also thanks for the pm- very helpful. I think the pump has the metal impeller if I recall correctly. I can hear the fan form the light. It reminds me of a Jeep, their sound is identical from a stop. I don't think it's the the thermostat because the original one didn't seem to be broken. I'm guessing the water pump is also bad. I just hope the guy who originally replaced it will check it out for free and maybe throw in a new one .

[E34 530]

I brought the car back to the mechanic who originally installed the waterpump. He asked me to open my hood and he revved the car until it became vey hot in the engine bay. He then stuck his finger directly in the fan and was able to completely stop it and spin it the other way. Bad fan clutch.

[nuclearfusion]

...he revved the car until it became vey hot in the engine bay. He then stuck his finger directly in the fan and was able to completely stop it and spin it the other way.

Brave guy! ... Stupid guy? ... Lucky guy.

Don't try this at home folks.

Enjoy!

Fusion

[E34 530]

Brave guy! ... Stupid guy? ... Lucky guy.

Don't try this at home folks.

Enjoy!

Fusion

nah dude. He's a BMW master mechanic and knew what the problem was even before I opened up the hood, therefore he knew his finger wasn't going to be taken off when he put it in the fan.

[nuclearfusion]

nah dude. He's a BMW master mechanic and knew what the problem was even before I opened up the hood, therefore he knew his finger wasn't going to be taken off when he put it in the fan.

OK, OK, fair enough. There's lots of experience there and he'd already been through most of the other possible culprits so he was very confident.

Nevertheless, I'd personally never do what you describe, and I'd never recommend it to anyone regardless of how sure they felt about it. It's easy enough to keep your fingers out of the cooling fan and roll up some newspaper to stick in there if you want to.

In all seriousness, losing limbs or digits is serious business and lasts a lifetime. So, I think I'll stick with my original (good) advice, but let's add a caveat.

Don't try this at home folks unless you're a BMW master mechanic and you know without any doubt at all what the problem is before you even open up the hood.

(Even then some rolled up newspaper seems like a better plan to me.)

Enjoy!

Fusion