Cooling strangeness

[Henn28]

I took my X on an 1100 mile round trip hunting trip this week and just when I was thinking that she could be relied on, she threw a belt 60 mile from home.
Probably my fault somehow in the installation and tensioning of said belt of course. I was able to dribble off the highway and get it shut down quickly, but she did get hot for a minute or so. We'll see what the damage maybe when I get a chance to dig into it this month.

I did notice at a stop for gas an hour or so before that I had what seemed to be an intermittent coolant leak at the top radiator hose connection area. The belt issue seemed to prove that this was from the radiator where the plastic side meets the aluminium at the top, since this was where the steam was pouring forth from! At the time however I didn't know precisely where it was coming from, and it was intermittent. I cleaned it up and then checked again 30 or 45 minutes later and the area was still clean. As I was trying to coax her home, I thought that I must have an overheating issue that wasn't registering on the temp gauge but was over-pressurizing the radiator. Therefore, I put foxwell on it and put the temps on live view. 90% of the time the engine temp sensor was at 219 to 221 and the radiator outlet sensor was between roughly 95 and 110, depending on grade, trucks in front of me, engine speed, etc.

However, every so often I would see the radiator outlet temp rise quickly to 160, followed by the engine temp sensor dropping (!) to 180 or less. Perhaps I don't understand the coolant system, but I'm struggling to reconcile the engine temp dropping so drastically seemingly after the radiator temp increases so quickly. I would think that if the engine gets hotter, the radiator will reflect that same increase as the tstat opens and the coolant picks up more heat than it can shed perhaps. At first I thought it was only under higher load (long hills, etc.), but then it did it on a long flat stretch. Temp outside was 67ish and I was doing between 65 and 70 mph. Perhaps I cooked the water pump bearing, which then caused the belt to come apart. Strange that the temp gauge didn't move a MM beyond 12 o'clock until after it all came crashing down.

Guess I won't be moving on to the interior any time soon. Mrs. Henn28 was very, very excited to come and get me in Baton Rouge late last night. Good times with the X! In fairness though I'm grateful she didn't die when I was deep in the eastern Oklahoma woods looking for quail and a long, long walk from a paved road.

Lesson learned perhaps is that a bit more than 300 around town miles may be needed to shake her down! More to follow I'm sure as I get into it. Thoughts on the above temp strangeness would be appreciated.

[StephenVA]

Air pockets in cooling system

[LA02MAX]

So is the water pump pulley loose? And was the belt new? When my water pump bearing blew, it was wobbly and coolant leaked out of it. Without that or another one of the accessories shifting in place, I'm not sure how the belt would pop off (assuming the belt was in good condition).

Regarding the coolant fluctuation, it definitely sounds like there was an air bubble bouncing around in there. Try and re-bleed the system once you get the belt situation sorted out.

[Bmwe5320023.0]

So do you have a leak at the radiator hose?

I'd fix the leaks first, then remove the belt and spin all pulleys by hand, including the water pump. See if they spin freely, without wobble, squeaking etc. Put on a new belt. Make sure grooves match properly with each pulley.
Bleed the coolant system, take for a test drive and then bleed again.
Google how to bleed the system. On bmw it's different from other vehicles. There's an Auxiliary pump so you don't need to start the car.

[X5chemist]

Check the smaller upper neck connection. Mine had a small leak there. Water would leak onto the reservoir. The inside molded ring that holds the o-ring in place cracked off. Overtime, the loose o ring would leak water. The entire upper hose assembly was replaced to fix it.

[Henn28]

Thanks for the tipper guys. The hoses are all new, but I may have paid the price for reusing my radiator. New ones aren't too expensive, but I was looking to save a buck - although the motor could have just gotten hot and blown the radiator at the cheesy plastic side part. The thought of air in the system also crossed my mind. I bleed it for a 10 or 15 minutes with the aux pump when I put the car back together, but I've got to think that a big bubble of steam/air could lead to the wacky thermostat readings I was seeing.

It sounds like a vacuum bleeder is the best way to ensure all air is evacuated from the system? Probably a good tool for me to buy if so. None of this explains the shredded belt, but I'll report back on what turns out to be the culprit(s).

I had my problem child towed to a local indy BMW guy whom I've been meaning to look into for future use. Second time in 20 years the X has been towed, so I'll cut her some slack. Especially since the cars woes were likely my fault somehow. The tow truck couldn't drop the car in my driveway, and I refuse to be the guy who works on an broken-down car in the street. I also have a nasty work schedule this month so time to let someone else bust their knuckles on the X for a bit, especially that rear axle. The guy's shop was a wonderland of BMW cars that my wife would never want me to see. I saw what I think was a 3.0 CSI tucked in the back, and several E46 tourings in his lot, along with a Z3 M coup track car and various other fun cars I immediately could envision dumping lots of money and time into.

[LA02MAX]

I have a vacuum bleeder if you wanna use it.

Did you go to wedge kyes in Baton Rouge, or did you end up towing it back home?

[Henn28]

Originally Posted by LA02MAX

I have a vacuum bleeder if you wanna use it.

Did you go to wedge kyes in Baton Rouge, or did you end up towing it back home?

Tried to get it to Wedge Keys shop in BR, as he comes highly recommended it seems, but he's got a two+ week waiting list and didn't have room to store the car unfortunately. I had it dropped at The Bimmer Shop in Harahan. I've been meaning to give the guy a look, but not necessarily like this! My plan was to have him install some braided brake lines and do a full flush and bleed of the brake system and see how I liked his work.

I did get a good vibe from him yesterday, for what that's worth. He's built quite a few M62 powered custom cars and seemed to appreciate what I was doing and have done to my X. I'll keep you posted, and thanks for the offer on the bleeder. Unless he specifically tells me he used on, I'll take you up on it.

I was recalling your thread about our X cars not allowing us to complete long road trip without drama as I coasted down the off ramp in BR.

[Bmwe5320023.0]

You could also park the car on a steep incline facing up to help with bleeding