Author Topic: Normal operating temperature (Read 6585 times)

Montanvs · « **on:** July 06, 2010, 09:40:29 PM »

Hi everyone,

Great board btw!

I just replaced by waterpump and thermostat with BMW replacement parts. Had the car anti-freeze flushed and replaced by a German car shop (reputable).

The car runs hotter now that it did before (always stayed a a couple degrees under 1/2)

Now the car runs at the 1/2 point or a hair over that.

Did something go wrong? or is the that a normal temperature for the car. Seems safer to run it cooler IMO....

I checked the brands on the thermostat and they were the same brand.

thanks!

Montanvs · « **Reply #1 on:** July 08, 2010, 10:17:15 AM »

when the car idles the temperature can reach 1/2 between 3/4 and the middle/1/2 mark. This seems too high. My auxiliary fan is not running (accept when the A/C is on), so I'm thinking that perhaps my temp switch is out....

locknload · « **Reply #2 on:** July 08, 2010, 09:59:36 PM »

Temp gauge should read 1/2 when up to running temp. You said "reputable", so I presume your mech knows how to properly bleed the cooling system? If the needle goes beyond the 1/2 mark and you haven't been sitting in traffic on a hot day, it can mean there is a problem such as air in the system or a faulty engine fan. Aux fan comes on when either the A/C switch is on, or the temp hits the 3/4 mark on the gauge. It's a 2 speed fan and IIRC, it should be at low speed when activated by the A/C switch and high speed if activated by high water temp.

And to answer your question, modern day engines were designed to run hotter as they are more efficient at higher temps and the engine programming takes this into account when metering fuel, etc.

Montanvs · « **Reply #3 on:** July 10, 2010, 08:03:01 PM »

Thanks for the info. So the auxiliary fan shouldn't come on unless it is at 3/4? The car does only creap up past 1/2 when idling in traffic on the hot day, so perhaps it is fine. I guess before it did not seem to do that, so I was somewhat concerned....

jscribble · « **Reply #4 on:** July 10, 2010, 08:28:18 PM »

It seems as though m42 thermostats like to fail in a stuck open fashion. I am also one of the many on this board who had their temps never quite reaching half, until replacing the thermo. Just my opinion. Verify your coolant level, and that your fan is working. Should come on anytime the a/c is on, low level at around 3/4, and high speed when the car is about overheating.

There is a temp controlled switch for fan activation on the upper right side of the radiator (from drivers position, 3 wire plug). It is 23.00 for a lower temp (activates at lower temps) from pelican parts.

Montanvs · « **Reply #5 on:** July 11, 2010, 02:24:27 PM »

ya the aux fan works when the a/c goes on, and the engine has never reached 3/4 to have the fan go on. I just thought the fan would go on before the 3/4 mark, but if that is not the case, then perhaps it is working just fine. I guess I was just taken aback by the higher temps AFTER changing the thermostat.

locknload · « **Reply #6 on:** July 12, 2010, 08:30:46 PM »

Just to reassure yourself, here's what I would do.

1. Check the operation of the aux fan by unplugging the temp switch on the right side of the radiator. With the ign. switch on, but not running, and A/C off, jumper the brown ground wire to one of the remaining wires. remove the jumper and then jumper from brown to the other wire. The fan should run in both cases; one jumpered pair should make it run at a faster speed than the other. If the fan fails to run for either test, something is wrong with it.

2. Check the operation of the temp switch itself. Remove the top radiator support bracket and slide a large piece of corrugated cardboard down in front of the radiator so that it blocks airflow across the radiator. You should be able to leave the support bracket off for the test. If the radiator will not stay in place, wire or zip tie it in place as,when the time comes, you will want to be able to remove the cardboard without delay. Now start the car, A/C off. While monitoring the temp gauge, run the car until the temp starts getting to the mid-zone and then start checking the aux fan to see if the switch activates it before reaching 3/4. Once it does, go ahead & pull the cardboard so the rad can cool back to 1/2 before shutting down. This will also confirm that the temp switch is properly turning off the aux fan as well. (If you wanted, you could take the temp to max to confirm the fan goes to high, but I don't think I would do that on my car. I'll just assume that if my gauge ever went past 3/4, I would be stopping the engine before reaching those extreme conditions and not risk breaking something during the test). Conversly, If you don't see any fan action by the time you hit 3/4 to 7/8, pull the cardboard and let the engine fan cool down the radiator, and go buy a new temp switch.