Thermostat opening temp 105c?

2000
318ci
M43tu engine

I replaced the thermostat recently with a Topran. Apparently all thermostats for this engine (PN 11531437085) state that they open at 105c, that seems very hot to me.

I replaced the water pump and thermostat. While flushing I used the digital dash temp gauge to keep an accurate eye on engine temp. Needle temp gauge stayed in the middle the whole time but the engine went up to 115c after 15 minutes of fast idle which I feel is hot, most thermostats should open at 85ish no? At 115c the bottom hose felt only slightly warm and nowhere near a hot as the radiator top hose.

Engine seemed ok but I think there was air in there after draining the old coolant and filling up with the flush, I bled it but no hot air was blowing though the heater.

Does anybody know about the specs on this engine and what's considered "normal" I know they run hot but is that normal? Thanks.

Sounds like air in the system. Not sure on M43 engines but M54 cars normally run between 95-105 C.

Radiator should feel hot and if not then Tstat didn't open.

If car runs fine and temp needle stays 12 o clock, dont worry too much.
Temp should go little bit down when thermostat opens. Just be sure car is blowing hot all the time inside cabin and temp needle stays 12.
I have 316i with N46 engine (valvetronic 4 cylinder), and if i remember correct it runs much hotter compared my M54B30.

Check the water pump. If coolant is hot but heater and radiator are not, there may be a coolant flow problem.
Also, is the electric fan operating properly?

Water pump is new. The fan didn't come on which is another issue.

The installation of aftermarket cooling system parts is strictly verboten. 105*C is too high.

If you follow the link below they are all rated to open at 105C, even the Mahle which I though was considered good to use in these cars. Every manufacturer wouldn't use the same rating unless specified by BNW for this engine surely?

https://m.autodoc.co.uk/car-parts/oe...caAs1DEALw_wcB

I recently picked up a E46 Wagon with an over heating issue that has since been fixed (torn lower radiator hose).

Living in the southwest, I have been monitoring temps on the regular utilizing the Torque Pro app and have seen as high as 221F (105c) on a handful of occasions. Current ambient temperatures this week are 110-115F degrees. From my research, the thermostat is a 207F (97c), so should hover around that area majority of the time. When driving my car, anything light throttle or idling is staying around the 205f area, with creeping upwards of 221f when accelerating, such as getting up speed on the on ramp of a freeway. Majority of cruising appears to hover from 205-210f area. Mind you all of this is with AC running full blast. Both of my fans are functional and no known issues with the cooling system. Freshly flushed with BMW blue 50/50 mix.

That said, I don't think that 221F (105c) is any concern as my other vehicles (Audi and a sports bike) both have thermostats that open at 221F and have no issues even with these excessive ambient temps.

Originally Posted by Chrisbish2000

If you follow the link below they are all rated to open at 105C, even the Mahle which I though was considered good to use in these cars. Every manufacturer wouldn't use the same rating unless specified by BNW for this engine surely?

https://m.autodoc.co.uk/car-parts/oe...caAs1DEALw_wcB

According to realoem.com for your vehicle that link is for the correct thermostat part number so I'm thinking that 105C is correct for your car. Granted we still need to figure out why you're getting to 115C.

Have you been getting to 115 at idle or at speed on the highway? If it happens at idle I'd suspect your fan isn't working properly, especially given your note that it wasn't working properly. I believe you can force it to come on with A/C

Yes I think it is correct, I thought I would check if anybody knew exactly.

Thermostat is new, as is the water pump but at 115c the bottom hose should feel as hot as the top no? I took the bottom hose off the Thermostat this morning and water flooded out so it's obviously circulating but still overheating.

115c was at fast idle when flushing the coolant system, not driving. The fan did not come on by itself but if I spin it by hand it starts up for for a while then stops again. I tried unplugging the coolant hose temp sensor but nothing.

Today it won't start. I've got fuel pressure at the rail, spark, air. Car cranks but want start, crank sensor is fine,p. I get an occasional pop noise which sounds like it's coming out the intake if I crank long enough :/. It was running fine the other day, did I over heat it? Maybe it's lost compression.

The issue I'm having is no code reader I own works on this 2000 model. I've heard I need PAsoft v1.4 but I need a windows XP laptop to run it which in 2019 I don't own anymore.

This car is starting to frustrate me.

Get the OBD Fusion app for your phone and the proper dongle for your phone. It can track your coolant temp among other things and read codes for emissions faults.

I've gone with the ipasoft 1.4..It looks the most versatile for coding.

Im at the point now where I need a good code reader for this car. All sorts of strange things are happening.

I'm sure I'll be posting a new thread later in the week after I've had a look at the DME.