Running hot. Heaters are fine. Dodgy thermostat?

Post Sun Feb 22, 2015 6:38 pm

My 318i runs with the temperature gauge at about 3/4 and I run with the heaters on max as a precaution to keep it there as it's quite hot. I'm yet to try it in traffic as I only bought it yesterday. The previous owner said it was burning a bit of oil too but I don't know the cause of that so I don't know if they're related.

I'm assuming it's just the old thermostat is just not opening fully - is that a reasonable assumption? I'm assuming it's either that or just some air in the system so I'll bleed it tomorrow.

Post Sun Feb 22, 2015 8:53 pm

Is the heater producing good amount of heat? If so bleeding won't be needed

There is a test of the viscous fan with a news paper it's in the wiki somewhere.

Any mixing of oil and water anywhere?

Post Sun Feb 22, 2015 9:38 pm

Yeah the heater runs fine. I'll have a look at that newspaper thing!

Not that I can see.

Post Sun Feb 22, 2015 10:37 pm

First thing to mention is that the centre section of the gauge is expanded, covering only a few degrees in the complete middle section of the gauge. As long as the needle doesn't get close to the red, then the car won't be overheating.
Turn the heater off and keep an eye on what happens to the needle when idling and under normal driving conditions - does the gauge rise? Does it fall? Does it remain stable?

Post Mon Feb 23, 2015 8:45 am

Brianmoooore wrote:First thing to mention is that the centre section of the gauge is expanded, covering only a few degrees in the complete middle section of the gauge. As long as the needle doesn't get close to the red, then the car won't be overheating.
Turn the heater off and keep an eye on what happens to the needle when idling and under normal driving conditions - does the gauge rise? Does it fall? Does it remain stable?

Cool, will do. I guess if the temperature continues to rise when idling it's probably a fan issue?

Post Mon Feb 23, 2015 7:37 pm

The temperature doesn't really go past the 2/3 white line. If anything, it's hotter at 80mph on the motorway than it is around town.

Post Tue Feb 24, 2015 10:36 am

Ideally, you need to get an accurate thermometer onto it to check that it really is overheating, and not just a gauge fault.
Failing that, you could either just replace the thermostat as part of a new purchase service (check that the bleed valve works while the outlet elbow is off) and take it from there.
You could also remove the instrument cluster, and check that the nut on the back of the case behind the temp gauge is tight, or even there. (Check fuel gauge nut, all bulbs, 220 ohm resistor soldering and condition of SI board batteries at the same time.)

Post Tue Feb 24, 2015 12:54 pm

If your gauge is reading right, running hotter on the motorway indicates a blocked radiator

Post Tue Feb 24, 2015 1:06 pm

Okay cool, so how would I check/fix a blocked radiator? I'll have a quick Google.

Post Tue Feb 24, 2015 1:21 pm

Flow test by running water through it
You fix it by fitting a new one

Post Mon Mar 02, 2015 8:47 am

Didn't have a chance to check the radiator but I did go through the paperwork and found a new radiator and thermostat installed 10/15k miles ago. Also had the head reconditioned - not sure why you would do this?

Post Mon Mar 02, 2015 10:01 am

ACJJ619 wrote:Didn't have a chance to check the radiator but I did go through the paperwork and found a new radiator and thermostat installed 10/15k miles ago. Also had the head reconditioned - not sure why you would do this?

There's only one likely reason for this - an expensive last ditch attempt to sort out the overheating problem that you have inherited. The attempt failed, so the car's been punted on.
Have you checked the accuracy of the gauge yet? There's nothing in your posts so far that suggests the car is overheating, other than a gauge that says so.

Post Mon Mar 02, 2015 10:03 am

How would I go about checking the gauge is correct?

Post Mon Mar 02, 2015 10:22 am

Brianmoooore wrote:Ideally, you need to get an accurate thermometer onto it to check that it really is overheating, and not just a gauge fault.
Failing that, you could either just replace the brown sensor. They are normally very reliable (much more so than the blue ones), so a second hand one would do.
You could also remove the instrument cluster, and check that the nut on the back of the case behind the temp gauge is tight, or even there. (Check fuel gauge nut, all bulbs, 220 ohm resistor soldering and condition of SI board batteries at the same time.)

Post Mon Mar 02, 2015 1:04 pm

Ah, of course. My bad!

Post Mon Mar 02, 2015 11:42 pm

I'm not going to be able to check the gauge until Saturday now as it's dark by the time I'm home from work, but in the meantime, it does smell like it's very hot. You know that hot oily smell? Yeah it's that.

I'm not too concerned about fixing it as I'm planning on popping an M52 in soon, but it would just be a nice sense of achievement. My first E30 repair

The oil is like thick tar too, so I'd love to give it a good service. I just can't justify servicing it only to take the bloody thing out!

It does seem like a fundamental overheating issue though. As I said, there are recent records for a new thermostat, radiator and head conditioning. I've now also found a new fan bought recently.