Reply With Quoteidle its spinning enough to move water and keep the engine cool , when the engine speeds up and more drag on the impeller ,it slips on the shaft and the engine heats up. You need to replace the water pump.
Originally Posted by rs4pro3
Temp creaps up...
Last Saturday my dad's 95 525i overheated while driving hard on a mtn. road. We got the car towed home, and ordered a new radiator(old had been leaking for a while). Threw the new radiator and thermostat in. I've bled the cooling system many many times, and it keeps creaping up to 3/4 on the guage after driving it around 5-6 mins. It has been idling perfectly at 1/2 for at least a 20min seg. with no problems. I did the rolled up paper trick on the fan, and it stoped with very little resistance at all. So I believe that's the culprit, I know the typical fan clutch failing sign is heating up while sitting in traffic or at a drivethrew. I was wondering if anybody else has had this issue or not? While bleeding I was getting a nice steady flow from the vent that connects the radiator to the overflow tank, so I'm pretty sure I got all the air out, both sides of the radiator were nice and hot after driving it around the subdivision.
Ely Wineland
Super Moderator
Water pump impeller is plastic and is slipping at higher rpm's , at
idle its spinning enough to move water and keep the engine cool , when the engine speeds up and more drag on the impeller ,it slips on the shaft and the engine heats up. You need to replace the water pump.
water pump is just barely one year old, there are no odd noises from the engine at all. Is there any way to test this theory?
Last edited by rs4pro3; 05-18-2006 at 01:16 PM.
Ely Wineland
bump
Ely Wineland
Green Beret Special Ops
water pump or clutch fan are the culprit, as Bill R says it's not overheating at an idle so I would also vote on a bad waterpump.
95 E34 530I V2.37
===========
Those who make peaceful revolution impossible will make violent revolution inevitable.
John F. Kennedy
I too believe it's your waterpump. Paper test on the fan clutch is not reliable....it's better to use your fingers ;-) Seriously, I have one right now on my 94 that I can stop with my fingers until the raidaitor starts throwing off some heat, then I wouldn't dare try it. Fan Clutch is a viscus coupling that get's tighter as the engine get's hotter. This allows the fan to turn more the speed of the engine, and slow as the temperature is cooler...I think it's around 120F. Anyway, look at the fan clutch and the fan itself. If you see a slight discoleration or oil that has some dust in it, then you know that there is probibly something wrong with the fan clutch. It would mean that the coupling is loosing the oil....you'll want to replace this then.
Super Moderator
Using your fingers to test the fan clutch is a good way
to get seriously injured.
The paper test and the finger test are both not very good ways to check if the fan clutch is working. The on temperature at which the fan clutch will engage is 180F plus or minus 7 degrees,
meaning that the air passing through the radiator when it hits the thermostatic coil on the front of the fan clutch has to be at least 180 before the clutch will engage.
The temp that the clutch disengages is 140F. At an engine rpm of 3500 rpm the fan is turning 2100+- 100 rpm. At higher engine speeds the fan clutch slips so as not to draw too much horsepower from the engine
Posting Permissions