01' 530i won't get up to operating temp

[ElkoCaballero]

Hey all! Couldn't find the info I was looking for in the forum so thought I'd make a post. About a month ago I replaced my thermostat after it got stuck on me. It worked great for about a month but now I think I have another problem.
On my way to work the other day the temp needle went into the red about 10 minutes after start up on a -28°C day. Pulled over and restarted the car to have it go back down to cold.
Before I changed the thermostat it wouldn't get above the blue in the gauge. Now the temp sits at the 1/4 mark.
Did my thermostat really crap the bed again this fast? Or is this something else?

[JimLev]

Welcome to the forum.
Could be a bad t-stat. Where did you buy it from, is it a BMW part?

[ElkoCaballero]

Thanks, appreciate the response. I bought from a Partsource store. Believe it's an OEM stat with the plastic housing

[Mike WW]

On my way to work the other day the temp needle went into the red about 10 minutes after start up on a -28°C day. Pulled over and restarted the car to have it go back down to cold.

That sounds to me like it's freezing up, the coolant, not a bad stat. I suspect it's very cold even for Canada, but to me -28 is just freakishly cold. Weird crap happens. Is the coolant mix good? Again, down here I don't have to worry except for some in there and corrosion protection, but at those temps if it's a bit too diluted it could freeze up. Typically I see hot, then cold shortly thereafter when it's low on coolant with air in there, but this sounds more like a coolant issue. Now I haven't had the best of luck with stats, but none that failed that quickly and always by not getting up to temp.

[ElkoCaballero]

We've had a pretty warm winter but there's a polar vortex sitting over us at the moment. Supposed to be -40 pretty soon lol
I've got coolant made specifically for BMW's. I'm hoping it's just too cold for it. For right now I think I'll keep an eye on it and see if it at all gets up to temp in the next couple days. I'm just worried as I don't really have the money to replace the whole cooling system. Thanks for your opinion!

[Dave Sal]

Suggest you run the engine while monitoring test 7 on the OBD so you can see exactly what the coolant temp is. The gauge is about useless since it's buffered.

[ElkoCaballero]

Not sure my scan tool can view live data. I'll check it out after work though.

[JimLev]

A 50/50 mix should be good for -37ºC, so it shouldn't be freezing up if he has a 50/50 mix.

[ElkoCaballero]

I'll also double check the coolant and make sure it's rated right. I have a half hour commute so you'd think it would be able heat everything up alright

[Mike WW]

A 50/50 mix should be good for -37ºC, so it shouldn't be freezing up if he has a 50/50 mix.

Yes. If it's 50-50. OP is more likely to be more careful than I am given +28 only occurs every couple of years where I'm at, but from what I'm seeing even 45% will up the freeze point to -25. And it's hard to be perfect on anti freeze mix.

I'll also double check the coolant and make sure it's rated right. I have a half hour commute so you'd think it would be able heat everything up alright

Not sure my scan tool can view live data. I'll check it out after work though.

Yes, but... It's not a big pot of coolant, it goes thru some small passages where it can freeze up easier. I think you need one of those anti freeze percent testers you can buy cheap at auto parts stores. You might want to open those bleeders too to make sure you don't have any air trapped in there.

On the actual engine temp, if you have the high cluster with the OBC you can get a readout on the cluster of an assortment of parameters including actual engine temp.

[edjack]

Get a coolant hydrometer and measure the mix.

[ElkoCaballero]

Looks like it may be the thermostat again. When the car is dead cold it will say it's overheating. When I restart the car it goes back to cold but won't get to op temp. How can i see what the actual temperature is on my dash?

[effduration]

Looks like it may be the thermostat again. When the car is dead cold it will say it's overheating. When I restart the car it goes back to cold but won't get to op temp. How can i see what the actual temperature is on my dash?

Let me search that for you.................

search on "E39 OBD unlock"or "cluster hidden menus" or "cluster unlock" it is test 7.