[Mcc420]

I've done it. It's about a 1.5hrs Max. And that's taking your time. I did it from up top. But I think it can be faster from the bottom but I didn't want coolant running down my arms lol.

[BMWDriverX]

Originally Posted by Mcc420

I've done it. It's about a 1.5hrs Max. And that's taking your time. I did it from up top. But I think it can be faster from the bottom but I didn't want coolant running down my arms lol.

What about the vacuum and all that so the cooling system works correctly after the thermostat install?

[Sophisticated Redneck]

Originally Posted by Mcc420

I've done it. It's about a 1.5hrs Max. And that's taking your time. I did it from up top. But I think it can be faster from the bottom but I didn't want coolant running down my arms lol.

1.5 hours start to finish taking your time? That would be an impressive sight to see this amount of work done & filling and bleeding both cooling circuits that quickly.

Here is a link to the full instructions for all that are interested:

https://www.newtis.info/tisv2/a/en/f...nes/1VncI3daZd

[Mcc420]

No need to vacuum the system. And you're only emptying the rad coolant not the ic's. Remove the front cowl , remove rad fan and it's right there.

[bm5bullit]

Originally Posted by Mcc420

I've done it. It's about a 1.5hrs Max. And that's taking your time. I did it from up top. But I think it can be faster from the bottom but I didn't want coolant running down my arms lol.

What is your experience with the claims about improved cooling and do you think it was worth it?

[Sophisticated Redneck]

Originally Posted by Mcc420

No need to vacuum the system. And you're only emptying the rad coolant not the ic's. Remove the front cowl , remove rad fan and it's right there.

Ok I can see how you could do it that quickly now, the official BMW instructions has you remove the passenger Intercooler.

BMW puts the fear of God in you though to drain and vacuum system or the engine will go boom and I have to agree, I think it's an important step and insurance that there will be no air trapped in the system, especially on such an expensive engine but to each their own on doing it or not.

[Used2be]

Both of you, Redneck and Mcc420, have more experience with this part of the car than I, but I still have some questions. Mcc, after removing the radiator fan, is there adequate space to remove the thermostat from the top without the removal of anything else? I can’t see the thermostat in your upper photo, but perfectly in the middle photo. Is the middle photo also taken from the same position as the upper? Looking down into the engine bay from the top? Or, is your slim phone lowered to the level of the thermostat with one hand, a perspective that can’t be had while you’re working? It seems it would be very difficult to get a socket on all three of the thermostat bolts with only the radiator fan removed. Any special contortions or tools needed to do that?

By removing the thermostat you introduce air into the cooling circuit, even if it isn’t into the intercoolers. Isn’t the purpose of bleeding the air out of the system to eliminate any bubbles that might obstruct water circulation inside the tight water passages in the engine or create hotspots? Wouldn’t it be prudent to do the recommended vacuum procedure?

I’m not clear how a lower opening temp for the thermostat keeps the engine cooler when it’s being driven hard. Both thermostats open fully and allow the same full flow when needed, don’t they? Under high demand, say for half an hour on track, wouldn’t the system provide the same cooling with either thermostat? A thermostat is used to bring, and maintain, the engine at the operating temperature BMW wants in a shorter amount of time. Otherwise, why have a thermostat at all? Does BMW perhaps use the higher temp thermostat for emission reasons? I certainly don’t think the 90c thermostat would hurt the engine, but it seems the benefit derived isn’t worth the effort needed to replace.

Good question from bm5bullit. I’m interested in your answer also.

[Sophisticated Redneck]

Originally Posted by Used2be

Both of you, Redneck and Mcc420, have more experience with this part of the car than I, but I still have some questions. Mcc, after removing the radiator fan, is there adequate space to remove the thermostat from the top without the removal of anything else? I can’t see the thermostat in your upper photo, but perfectly in the middle photo. Is the middle photo also taken from the same position as the upper? Looking down into the engine bay from the top? Or, is your slim phone lowered to the level of the thermostat with one hand, a perspective that can’t be had while you’re working? It seems it would be very difficult to get a socket on all three of the thermostat bolts with only the radiator fan removed. Any special contortions or tools needed to do that?

By removing the thermostat you introduce air into the cooling circuit, even if it isn’t into the intercoolers. Isn’t the purpose of bleeding the air out of the system to eliminate any bubbles that might obstruct water circulation inside the tight water passages in the engine or create hotspots? Wouldn’t it be prudent to do the recommended vacuum procedure?

I’m not clear how a lower opening temp for the thermostat keeps the engine cooler when it’s being driven hard. Both thermostats open fully and allow the same full flow when needed, don’t they? Under high demand, say for half an hour on track, wouldn’t the system provide the same cooling with either thermostat? A thermostat is used to bring, and maintain, the engine at the operating temperature BMW wants in a shorter amount of time. Otherwise, why have a thermostat at all? Does BMW perhaps use the higher temp thermostat for emission reasons? I certainly don’t think the 90c thermostat would hurt the engine, but it seems the benefit derived isn’t worth the effort needed to replace.

Good question from bm5bullit. I’m interested in your answer also.

Your right when being driven hard the computer opens the thermostat, what the 90c thermostat really makes a difference is in the daily driving commutes, stop and go traffic, part throttle performance around town, and preventing engine temps from hitting 225+. If your M doesn't see alot of stop and go traffic/daily driving, then benefits will be limited compared to someone who does. BMW runs them hot for emissions compliance only. 10-20 degrees may not seem like alot but it will give a mild performance bump, reduce intake temps, but mainly extend the life of the engine seals over the course of the life of the engine.

The original N63 and S63 were notorious for fried engine and valve guide seals popping up around 60-80k. Next gen TU & TU2 had improved cooling but you are starting to see this pop up again on engines that are getting up there in Mileage.

[Mcc420]

No special tools needed. All pictures were from the top. I did this within owning the car for a month so no before data. If anything this thermostat will open to the full position quicker since it's designed to open at 90. As for bleeding it almost self bleeds like any other car. Fill up until no more bubbles let run for about fifteen minutes with the cap off and just keep topping it up. Drive for a day or two check again top up if necessary. I also added two bottles of redline to the rad and one bottle for the ic's. If you remove the bottom skid plate you can save some of you coolant.

[Used2be]

Originally Posted by Mcc420

As for bleeding it almost self bleeds like any other car. Fill up until no more bubbles let run for about fifteen minutes with the cap off and just keep topping it up. Drive for a day or two check again top up if necessary.

I suppose you're right. BMW wanted the same procedure done for their liquid cooled motorcycles too, and all the shops I knew of didn't bother. Let it run, watch the bubbles, and add as needed.

Different subject. How do you like the F90 as opposed to your very fast modified F10? More potential?

[Mcc420]

Originally Posted by Used2be

I suppose you're right. BMW wanted the same procedure done for their liquid cooled motorcycles too, and all the shops I knew of didn't bother. Let it run, watch the bubbles, and add as needed.

Different subject. How do you like the F90 as opposed to your very fast modified F10? More potential?

Yes definitely more power. I've broken all my old records already lol with stg2 ots e30. The best thing to say about the f90 is useable power all the time 👍🏾. If you're addicted to torque like I am then awd is the way to go. It's my first awd powerful car. It's almost comparable of going from the e60 to the f10 lol. Almost.

[Mcc420]

Originally Posted by bm5bullit

What is your experience with the claims about improved cooling and do you think it was worth it?

I did more for peace of mind. And also I didn't have to pay anyone to do it. I'm also running redline 5w50.

[bm5bullit]

Yeah. I would be doing it for the same reasons and because I have not finished my other mods on the car.

[Used2be]

Originally Posted by Mcc420

The best thing to say about the f90 is useable power all the time 👍🏾. If you're addicted to torque like I am then awd is the way to go. It's my first awd powerful car.

Mine also and I love it. Peace of mind for me. There were a couple of situations on the street where I forgot myself with the 2wd of the F10 in first or second gear and the fishtailing was more than I'd bargained for. My F90 is still stock engine wise, but I feel even with a tune it'd be more well mannered.

Congratulations on the F90 times! AWD sure helps the et, doesn't it? But now you're lusting after the 9s! Good luck with it.

[Mrbig]

What coolant are u guys adding to the car ?

[Used2be]

Originally Posted by Mrbig

What coolant are u guys adding to the car ?

I used the same stuff I had on hand from the 2013 F10 M5 I'd owned. Never thought to check to see if BMW has changed the formula. 50/50 mix BMW antifreeze/coolant from a one gallon container I bought from the dealer. Not sure if this is a part # or not, 82 14 1 467 704.

[IancoleTX]

Originally Posted by FloridaM5

Thank you for that; appreciate it. Some conflicting points of view and/or assumptions being made. Not atypical.

Well shit, just checked at 8800 miles and I’m well below min. Wtf.

[SatinblkF90]

Any updates on what to do about this? Literally freaked out reading about this ridiculous coolant issue the f90 has.

[brad65ford]

purchased one of theses today. curious how much of a bitch it is to install. If found it funny how someone lists/states 6-7 hour job and two other guys finished theirs in 1 1/2 lol. We'll see what happens, looks fairly easy....

[pbonsalb]

I installed the 90C thermostat today. Definitely took my more than 1.5 hours but it was my first time on this car. One of the thermostat bolts was hard to access. The fan came out slowly. There are about 3 hoses you need to unclip and 1 wire and of course the harness. I massaged the upper radiator hose to get the fan to pass by but disconnecting the hose from the radiator may be better. Also had to move the front connector bar and air box tops and braces.

I’d say I lost about 1.25 gallons of coolant doing the job. Replace with the new green coolant. Not sure about the benefits of the lower temp thermo but some say it is a good idea including one drag racing member who is in this thread and one engine builder. The gauge in the car is oil not coolant. I could plug in a scan tool — probably should so I can see oil and coolant temps.

[Maverik259]

Lol so many opportunities for someone to document a DIY and yet nothing. Y'all are killing me.

Ok I guess I'll have to do it once I get around to this myself. Ugh.

Glad it seemed at least straight forward. Did this on my AMG back in the day and they was super easy. Didn't have to remove anything but some hoses.

[pbonsalb]

It’s a little more work than that. I am not good about taking pictures though I do like to ready a DIY before doing a project when one is available. I have done oil, braided brake lines, brake flushing, Dinan monoballs, competition motor mounts, H&R springs, charcoal filter delete, drop in filters, JB4, water/meth, flash tune, trans tune, downpipes, turbo blankets, coolant tank, coolant thermostat. Next will be front diff, transfer case, rear diff, rear subframe bushing reinforcements, Dinan rear toe link kit, and Dinan turbo inlets.