2008 550i - 96K miles

NavyBeeker · 07-02-2016, 09:30 PM

So not sure exactly what root issue is yet... started a few weeks ago and thought I might have had a coolant leak... filled up coolant and it seemed to go away for a bit. 96K miles, it's been really pretty reliable overall for me, I bought it new in late 2007. No mods done by me, basic V8 360hp engine.

Then yesterday it was back.... yellow caution of engine overheating, "drive moderately...".... and then later a red caution of "engine overheated, pull over and let it cool..." along with a "coolant low" warning. Limp mode seemed active as I got barely any acceleration with mid-level throttle. Had some steam from evaporating liquid coming out as I got home in the next 5-10 mins.

Sure enough, reservoir (expansion tank) was leaking, as next morning I tried filling the empty reservoir and saw it dripping underneath within seconds. Had it towed to a local BMW Indy shop (lucky to get it serviced same day July 1st). They changed out the expansion tank to a new unit (and new cap) and charged me $650 total. Expensive but they were super nice, responsive, and even gave me a free loaner car for the day while it was worked on. But wondering if they filled up the coolant tank fully ?? (continue reading....) I should have checked it before I left the service shop but had 2 little girls with me, installing car seats, etc... and didn't think to check it....

Then while driving it home from the shop (95-100 deg F in TX), in slow bumper-to-bumper traffic, the AC vent air got warm/humid and the engine overheating cautions reappeared.... but not the coolant low one. I was able to get home okay, turned off the AC and when I was able to maintain 50mph or so the overheat warnings went away.

This morning I checked the coolant reservoir (brand new one) and coolant level seemed only about 50-70% full. Luckily I had some at home and filled it up to full level (engine was cold). Drove 35 mins with no AC on at all and no warnings. But later in afternoon, while driving back (95 deg again), while in a fast food drive-thru the AC air got warm again and the engine warnings reappeared..... again I turned off AC and other electrical loads and the warnings disappeared once I got back on the highway. Seems like its mainly a slow / idling RPMs with AC on that I get the problem.

Questions:
1. Does the $650 sound fair / appropriate for the coolant tank replacement?
2. What do you think is still wrong with the engine / coolant system?
3. Since I plan to sell the car in about 2-3 months (but not in next 6 weeks anyway)... what type of $$ will I need to sink into it to keep it going? It's my daily driver and I work 5 days a week and need a car.

Sorry if searching would find me more answers, I will do some later but don't have the time at the moment.... thanks for reading if you kept up this far!

napeHbNYC · 07-09-2016, 05:03 AM

As far as $650 for the tank it is a lot of money, it is a very easy job and if the coolant tank is OEM I think it is around $150 depending where you buy it. If your car starts to overheat with a load my guess is it is most likely to do with the cooling system efficiency, just need to diagnose. You also need to see where the leak is coming from(hoses?).

NavyBeeker · 07-09-2016, 02:32 PM

So I paid for the new coolant reservoir, no more leaks I can see. No more coolant low warnings.

But this week I will often see the engine overheat warnings (yellow) if I get stuck in bumper-to-bumper traffic or sit idling for more than 5 mins. The Air Conditioning air always gets warm & humid shortly before the overheat warnings come on... perhaps that is due to system automatically shutting off AC as temp gets higher?

I think there is another problem with the engine cooling system but haven't taken it in to get checked out yet. When I can maintain steady 40mph or higher it seems to not be a problem - and AC works fine.... only problem is when very slow / idling for more than a few mins.

NavyBeeker · 07-20-2016, 12:43 PM

Okay new update on same issue:
< 35 mph get the engine overheat warnings
> 35 mph do NOT get them
.... observed that the coolant fan just behind radiator has NOT been on (apparently in 2-3 weeks now)
.... observed a few days ago (ONCE) that the fan DID come on as I backed out of my driveway after a 1st (cold) start of the day. But the next day and since then it is NOT working again....

Took it to a reputable (I think) euro indy shop... they say they tested the fan via powering up separately from the system and it failed on 3rd try. Quoting me about $1000-1100 parts plus $300-400 in labor to replace the entire fan assembly (not sold in piece parts) and replacing the oil cooler seals that go along with it.... about $1400-$1500 before taxes.

What do you guys think of this? Any cheaper way to replace that? Seems a like a fairly involved project that I probably couldn't do myself... may have to suck it up but open to suggestions. Worst part is I'll be trying to sell it this Nov anyway....

07-02-2016, 09:30 PM	#1
NavyBeeker Second Lieutenant 97 Rep 275 Posts Drives: 2017 M3 SS/SS - 19SepED Join Date: Jun 2014 Location: DFW TX iTrader: (0)	2008 550i - 96K miles - getting engine overheat warnings So not sure exactly what root issue is yet... started a few weeks ago and thought I might have had a coolant leak... filled up coolant and it seemed to go away for a bit. 96K miles, it's been really pretty reliable overall for me, I bought it new in late 2007. No mods done by me, basic V8 360hp engine. Then yesterday it was back.... yellow caution of engine overheating, "drive moderately...".... and then later a red caution of "engine overheated, pull over and let it cool..." along with a "coolant low" warning. Limp mode seemed active as I got barely any acceleration with mid-level throttle. Had some steam from evaporating liquid coming out as I got home in the next 5-10 mins. Sure enough, reservoir (expansion tank) was leaking, as next morning I tried filling the empty reservoir and saw it dripping underneath within seconds. Had it towed to a local BMW Indy shop (lucky to get it serviced same day July 1st). They changed out the expansion tank to a new unit (and new cap) and charged me $650 total. Expensive but they were super nice, responsive, and even gave me a free loaner car for the day while it was worked on. But wondering if they filled up the coolant tank fully ?? (continue reading....) I should have checked it before I left the service shop but had 2 little girls with me, installing car seats, etc... and didn't think to check it.... Then while driving it home from the shop (95-100 deg F in TX), in slow bumper-to-bumper traffic, the AC vent air got warm/humid and the engine overheating cautions reappeared.... but not the coolant low one. I was able to get home okay, turned off the AC and when I was able to maintain 50mph or so the overheat warnings went away. This morning I checked the coolant reservoir (brand new one) and coolant level seemed only about 50-70% full. Luckily I had some at home and filled it up to full level (engine was cold). Drove 35 mins with no AC on at all and no warnings. But later in afternoon, while driving back (95 deg again), while in a fast food drive-thru the AC air got warm again and the engine warnings reappeared..... again I turned off AC and other electrical loads and the warnings disappeared once I got back on the highway. Seems like its mainly a slow / idling RPMs with AC on that I get the problem. Questions: 1. Does the $650 sound fair / appropriate for the coolant tank replacement? 2. What do you think is still wrong with the engine / coolant system? 3. Since I plan to sell the car in about 2-3 months (but not in next 6 weeks anyway)... what type of $$ will I need to sink into it to keep it going? It's my daily driver and I work 5 days a week and need a car. Sorry if searching would find me more answers, I will do some later but don't have the time at the moment.... thanks for reading if you kept up this far!
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07-09-2016, 05:03 AM	#2
napeHbNYC Captain 242 Rep 997 Posts Drives: 2007 e60 550i RWD 6MT Join Date: Feb 2013 Location: NY,NY iTrader: (7)	As far as $650 for the tank it is a lot of money, it is a very easy job and if the coolant tank is OEM I think it is around $150 depending where you buy it. If your car starts to overheat with a load my guess is it is most likely to do with the cooling system efficiency, just need to diagnose. You also need to see where the leak is coming from(hoses?).
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07-09-2016, 02:32 PM	#3
NavyBeeker Second Lieutenant 97 Rep 275 Posts Drives: 2017 M3 SS/SS - 19SepED Join Date: Jun 2014 Location: DFW TX iTrader: (0)	So I paid for the new coolant reservoir, no more leaks I can see. No more coolant low warnings. But this week I will often see the engine overheat warnings (yellow) if I get stuck in bumper-to-bumper traffic or sit idling for more than 5 mins. The Air Conditioning air always gets warm & humid shortly before the overheat warnings come on... perhaps that is due to system automatically shutting off AC as temp gets higher? I think there is another problem with the engine cooling system but haven't taken it in to get checked out yet. When I can maintain steady 40mph or higher it seems to not be a problem - and AC works fine.... only problem is when very slow / idling for more than a few mins.
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07-20-2016, 12:43 PM	#4
NavyBeeker Second Lieutenant 97 Rep 275 Posts Drives: 2017 M3 SS/SS - 19SepED Join Date: Jun 2014 Location: DFW TX iTrader: (0)	Okay new update on same issue: < 35 mph get the engine overheat warnings > 35 mph do NOT get them .... observed that the coolant fan just behind radiator has NOT been on (apparently in 2-3 weeks now) .... observed a few days ago (ONCE) that the fan DID come on as I backed out of my driveway after a 1st (cold) start of the day. But the next day and since then it is NOT working again.... Took it to a reputable (I think) euro indy shop... they say they tested the fan via powering up separately from the system and it failed on 3rd try. Quoting me about $1000-1100 parts plus $300-400 in labor to replace the entire fan assembly (not sold in piece parts) and replacing the oil cooler seals that go along with it.... about $1400-$1500 before taxes. What do you guys think of this? Any cheaper way to replace that? Seems a like a fairly involved project that I probably couldn't do myself... may have to suck it up but open to suggestions. Worst part is I'll be trying to sell it this Nov anyway....
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