Coolant temperature review
 

Hey Guys,
2003 X5 4.6 engine.
I had my ODB plugged in while driving
Around. The temp stays very steady. It is
Very stable at 223. That seems too hot to me.

What is the temp supposed to be on the X5 M62?

questions: what, when, how much? keeping it cool
 

Of course you mean in Fahrenheit, don't you? In our current N.Texas weather, where the afternoon ambient temperatures are at or above 100F, I think that 223F is a bit on the high side, but only a little. If you're in traffic, creeping along and you've got a mechanical fan (depends on the model BMW), then it'd be normal. My 3.0, using a 3000cfm aftermarket electric fan, stays around 194F (+/- 2F) in the same circumstances.

My wife's been driving my '09 HHR Panel around town, and it had a near-overheat incident last year that makes me wary of re-occurrence (low coolant level caused the A/C to shut-down at 242F, and brought the low coolant situation to my attention). After I corrected the situation, with proper coolant level again, thermostat checked, and A/C function restored, I advised my wife to always watch the Dash Info Center coolant temperature, just in case, with these instructions:

• 1) the normal temp for the thermostat to open is 180F, so it should remain nearly that or rise to around 195F in normal traffic/weather, so not to be alarmed,
• 2) in hot weather, or in heavy traffic, w/o using the A/C first, the temp could rise to 217F, upon which the electric fan should start (no mechanical fan on this engine), but if it doesn't by 224F, switch on the A/C (even if heat is needed), and the fan will start up, and
• 3) if for any reason, the coolant goes to 240F, pull over, shut off the engine, and call me.

She's been dutifully watching the readout, day-in or day-out, night & day for 1.5 years now, and I've been keeping the fluids maintained as well, so it's been OK. She learned her lesson, I guess, after driving her '88 Fiero until it stopped, though the oil pressure gauge had read zero for several minutes before she tried to pull over (the oil pump failed).

Similarly, I had an electric fan relay fail on my '66 Chevelle, and barely made it to an auto supply house (to get another relay) before the temp rose past 225F (iron block, iron heads, tough old 327!); I've always carried extra relays and fuses for my electric fans, ever since, and always had an accurate temperature gauge to read, also.

I'm not sure how hot the M62 should run, but I've always tried to keep my vehicles running just under the manufacturer's "normal" preferences, whether by using lower-temperature T-stats, water-wetter-type coolant additives, adding extra or high-powered electric fans, and/or larger/better/supplementary radiators, too. It gets hot here in Texas, so more is better when trying to keep the engine/tranny cool.

I think the V8 has a much higher Thermostat.
A 105C factory Thermostat is 221 F.
So I guess I’m on target?

Yeah. It's working as intended.

should be at 190 degree F. Throw in a low temp thermostat in there. The higher temps are only for a marginal fuel economy and emissions crunch that Euro-Union regulated since the late 1990's which causes rapid acceleration and wear of all gaskets and seals and reduces peak power output and increases chances of misfiring.

Boy-O-boy, sure a lot of discussions on that topic.
Let’s talk about Roe vs. Wade instead….

lower temps are better, from a performance view as well
 

I've not changed my X5's T-stat, yet, since the electric fan is keeping my M54 cool enough, but I've always changed my T-stats to lower opening temperatures, for added performance or trying to avoid head gasket problems (particularly on iron block/aluminum head combinations).

My '04 Silverado 2500HD has a 6.0L iron block/aluminum head combo, but the viscous fan, large radiator and oil cooler have kept running temps below 210F, so I've not put in a low-temp T-stat yet, while my '98 GMC 5.7L iron/iron engine runs cool, using a 160F T-stat. All my previous trucks got the same T-stat as well, with E-fans and oil coolers too, while the '66 Chevelle got the full-race treatment, with multiple fans, coolers, electric high-volume water pump, and tuned (for best flow) water restrictor instead of a T-stat. Conversely, I kept stock temperature T-stats on all my last fuel-injected engines, since they were all 4-cylinders, and economy vs performance won out.

I've not driven the X5 enough to see if it even needs a different T-stat or any performance boost as yet; with 10+ compression and 4:10 rear gear, it seems spry enough for a 4600-lb truck to be. I just don't need any overheating problems, and will address them if they crop up (Stewart pump, and perhaps modifying the T-stat with drilled holes would be my first set of solutions). A Zionsville "BMW M54 Competition Thermostat Plate Kit", or a " Competition Thermostat Kit, AAF 80C" might be good to add, but not if the M54 might have emissions problems afterwards. My first instinct (as a former hot-rodder-racer) is towards the performance side, but my septuageneric-retiree side is leaning towards reliability, at a reduced cost.

Furthermore, with the N62 and newer engine variants with the aluminum piston sleeves, they expand at a rate faster than they should be due to higher temp thermostats and the engineer's (more like accountants who only want engines to last within the warranty period and then start encountering failures) opted for a lower weight oil again to save in fuel economy at the expense of drastically reducing engine life.
Running a low temp thermostat and some heavier oil like 10W40 is a very common sense solution to a more reliable, dependable BMW engine.

Mine has a new thermostat. The removed replacement lasted about 2 years. The PO changed it out according sale records. Where do ya'll buy performance lower temp thermostat housing? I'm keeping the mechanical fan for city driving cooling. New clutch and fan work great.

lower temp-opening thermostats
 

Racing Thermostat, fits BMW M52, M54, M56 Engines https://www.bimmerworld.com/Cooling/...saAv2pEALw_wcB or
https://www.mishimoto.com/bmw-m52-m5...kaAvV3EALw_wcB

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