N62 Tune up - Tips, Tricks, and Info

[SeanC]

All installed and no issues. Also replaced the vacuum pump o-rings (factory one that mates the head is a joke), and the oil pressure switch.

I found out that the hose sticking out on the driver's side is a transmission vent line. It needs to be tucked in under the engine cover, but comes out when you're doing work there. It can really get in the way of the valve cover installation and get stuck in the cylinder head, so I suggest taping it somewhere while seating the valve cover. It happened to me twice.

Running temps are around 100 degrees on the highway with a 1.4 bar cap, a 6-8 degree improvement over the stock 105 degree thermostat. Thanks OP for the tips!

[BustedKnuckles]

Glad to hear it came back together well. That's unfortunate that you had to replace the valve cover but "better safe than sorry" is always a good policy. Especially when considering the amount of work involved in removing the valve covers.

[byM5]

Where do you get the coolant system o-ring kit?

[Thecastle]

Originally Posted by SeanC

All installed and no issues. Also replaced the vacuum pump o-rings (factory one that mates the head is a joke), and the oil pressure switch.

I found out that the hose sticking out on the driver's side is a transmission vent line. It needs to be tucked in under the engine cover, but comes out when you're doing work there. It can really get in the way of the valve cover installation and get stuck in the cylinder head, so I suggest taping it somewhere while seating the valve cover. It happened to me twice.

Running temps are around 100 degrees on the highway with a 1.4 bar cap, a 6-8 degree improvement over the stock 105 degree thermostat. Thanks OP for the tips!

Good to hear, I just replaced my 105C thermostat with a 90c one. I thought something wasn't right when I was seeing 97-100c on the highway. But this is expected?

[SeanC]

Originally Posted by Thecastle

Good to hear, I just replaced my 105C thermostat with a 90c one. I thought something wasn't right when I was seeing 97-100c on the highway. But this is expected?

I got mine in Houston from the owner of bmwlogicseven.com. On their website, they advertise and sell what they call a 90C thermostat, but when I met with the owner, he told me that it will go up to 98C. Apparently, they have two versions, a 90C one, and a higher temperature one. He told me that the 90C thermostat would throw a low coolant temperature code, confirming my earlier research (BMW 90C Thermostat For N62, N63, N73 Engines - Bimmerfest - BMW Forums). That was the reason why I didn't want to purchase the HT 90C thermostate from esctuning (it has also been reported to fall apart).

So I was looking for a ~95C thermostat, and I'm happy to get the one that I currently have. It runs slightly hotter with no codes. Highway cruising temperature is a stable 99C, with stop-and-go temperatures up to 102C. Both with A/C on, but my experience has been that A/C doesn't make a difference. Much better than 105-108 range before. I noticed that it drops down to about 90C when the car needs extra cooling.

[Thecastle]

Perfect, the thermostat I purchased a Mahle "90c" is doing exactly the same thing as yours. I was just surprised it wasn't as cool running as i expected. I too live in the houston area, League City to be exact.

My thermostat is 98-101 around town, the old one was 106-108 just like yours. I run my car a lot at full throttle so I was hoping the extra cooling might improve performance slightly and engine seal life. BTW what I mean a lot at full throttle is full throttle for 100's of miles at a time. When you tow you are probably running full throttle about 80-90% of the time while driving.

[BustedKnuckles]

Originally Posted by Thecastle

Perfect, the thermostat I purchased a Mahle "90c" is doing exactly the same thing as yours. I was just surprised it wasn't as cool running as i expected. I too live in the houston area, League City to be exact.

My thermostat is 98-101 around town, the old one was 106-108 just like yours. I run my car a lot at full throttle so I was hoping the extra cooling might improve performance slightly and engine seal life. BTW what I mean a lot at full throttle is full throttle for 100's of miles at a time. When you tow you are probably running full throttle about 80-90% of the time while driving.

What do you mean by "full throttle"? When I hear that I think gas pedal mashed all the way to the floor.

[BustedKnuckles]

Originally Posted by byM5

Where do you get the coolant system o-ring kit?

Below is the kit I got. Everything I used fit right. No issues and no leaks yet. Let me know if the link doesn't work.

BMW Cooling System Heater Radiator Hose O-Rings: X3 X5 2.5 3.0 4.4 4.6 4.8 | eBay

[Thecastle]

Originally Posted by BustedKnuckles

What do you mean by "full throttle"? When I hear that I think gas pedal mashed all the way to the floor.

Yes! though this is way off topic.

I drive the car floored 80-90% of the time while not on cruise constantly for hours while towing. The x5 with my travel trailer takes full throttle to keep the vehicles going 70-75mph in 5th gear on a level surface, any inclines or head winds and its 4th gear (sometimes 3rd). Can't use 6th and maintain speed even floored unless your doing >80mph, it just looses speed and bogs, not enough torque from the engine at low rpms to keep it moving (i'm thinking of getting a tune for another 20-25lbft). BTW I average about 7-8mpg while towing. I also keep the transmission in manual mode (to keep it from constantly hunting) and keep it floored even on cruise it runs full throttle, according to torque, the instant fuel economy almost never leaves 12mpg ;-)

Trust me when you have 5000lbs 11 foot high 8 foot wide barn door behind the X5 she is working hard. I'm not worried about driving like this, think about the engine working on the autobahn, in an x5 you'd probably be running it all out too. The engines are fine done it for 10's thousands of miles. The v8 lacks a bit of bottom end when its towing, wish I had a turbo. BTW my friends X5M gets the same fuel economy while towing. BTW towing at full throttle is common.

0-60 I would estimate to be in the 15-20 second range while towing.

[Thecastle]

I'm looking for advice bustedknuckles I just replaced my 105C thermostat with a "95C" thermostat to improve engine longevity.

I'm planning on taking the X5 to Banff next September about 2400 miles 1 way from Houston. I plan to tow my travel trailer, so I'll be putting considerable stress on my 2008 N62 X5 with 96K miles.

I was thinking of doing a cooling system refresh before the trip to ensure reliability while I still have cool weather in houston. What parts should I consider replacing? My X5 does not look to have its original water pump or upper radiator hose, so some parts have been replaced.

I've personally replaced the thermostat, heater control valve and radiator cap (still 2 bar). I've ordered a new expansion tank....

Do you think I should preventatively replace anything else before this road trip?