Water temp hit 300. How screwed is my engine?

[TheObjectivist]

Did I destroy a head gasket or warp something?

Be me:
Get car back from body shop and (somehow) the computer began acting up. e.g - As im driving, everything went completely dead, (dash gauges off, idrive screen black)
It seems the alternator to ecu connection failed and the car wasnt getting sufficient voltage so it went haywire. I had no indication what was happening

I decide to keep driving home since it felt fine.
On the way, it lost all power, and I had to floor it in 4th to maintain speed.
Nervous, and still on the highway, i plug in MHD and pull up gauges. See water temp 279, oil temp 250 and climbing rapidly. May (prob) have hit 300 water temp
About 10 secs later, the mickey mouse clamp on the water hose blew and all coolant shot out grille. I pull over immediately and get a tow.

Car is now at home and I havent done any diagnostic. Feel sick that I may have destroyed the engine


Can anyone shed light how sensitive temps are for the N54s?

Just spent 10k on bodywork and if the engine is gone, I dont know what to do

 

[johnnyd40]

Depending on what you have available you can do a few basic checks to see if there was any damage done, mostly just visual inspection if you are limited in the tool department.

I'd start with removing the cap on the expansion tank and just seeing if anything looks melted in there, see any evidence of coolant mixing with the oil, remove the oil cap and give it a whiff, if it smells like something is burnt- that is usually a bad sign (but does not always mean its toast)

since the cooling system has a blown hose you cant pressure test it, unless you replace the hose and refill with water. the next thing to do that would tell you if you did any major damage would be a leakdown test.
Hope its ok, let us know how it goes.

 

[rac]

Did I destroy a head gasket or warp something?

Be me:
Get car back from body shop and (somehow) the computer began acting up. e.g - As im driving, everything went completely dead, (dash gauges off, idrive screen black)
It seems the alternator to ecu connection failed and the car wasnt getting sufficient voltage so it went haywire. I had no indication what was happening

I decide to keep driving home since it felt fine.
On the way, it lost all power, and I had to floor it in 4th to maintain speed.
Nervous, and still on the highway, i plug in MHD and pull up gauges. See water temp 279, oil temp 250 and climbing rapidly. May (prob) have hit 300 water temp
About 10 secs later, the mickey mouse clamp on the water hose blew and all coolant shot out grille. I pull over immediately and get a tow.

Car is now at home and I havent done any diagnostic. Feel sick that I may have destroyed the engine


Can anyone shed light how sensitive temps are for the N54s?

Just spent 10k on bodywork and if the engine is gone, I dont know what to do

next time the engine losses all power, dont floor it. pull over or drive at low speed in that limp mode state. speaking from experience engine will survive quite some distance with a lack of water in limp mode / light engine loads so long as your moving getting fresh air through the system.

i doubt you will have an internal leak and the limp mode will have prevented high boost environment. at 300f your probably borderline on the coolant seals which might recover and re-seal or might need replacement, that's quite a number of hoses or individual o-rings to check out (but practically just replace the one you blew and run it up again) to test.

lots of n54s have ran routinely up to those oil temps so dont stress about that. can dump the oil and check for water.

if i had to bet the only thing you destroyed was what was already destroyed to cause the issue in the first place.
ultimately what's done is done, no point in killing yourself stressing about the possibilities. good luck.

 

[TheObjectivist]

I appreciate the advice.

The Expansion tank appears flawless inside (was replaced not long ago so easy to see if any melted bits)
The back of the oil cap has a bit of white on one edge but could have been normal residue

I hadnt thought about other cooling components being compromised. Thats a good call. Hopefully theyre built with a lot higher temps in mind and that the excess pressure blew out the flange before anything else split.


Agreed that I shouldnt have floored it. The strange idrive/computer behavior hit right as I was on a freeway overpass merging onto another. Stopping would have been bad, and even floored I dropped to less than 40mph nearly causing a rear-end so I pushed on.

I assume when the ECU's voltage went, the water pump stopped along with everything else. Surprised the entire car didnt die TBH. Still cant explain all that happened. I had no instruments to tell me the car was overheating. The thing was utterly possessed and then black

 

[rac]

yeah understand sh8t happens in the wrong place at the wrong time.

 

[Sava666]

I appreciate the advice.

The Expansion tank appears flawless inside (was replaced not long ago so easy to see if any melted bits)
The back of the oil cap has a bit of white on one edge but could have been normal residue

I hadnt thought about other cooling components being compromised. Thats a good call. Hopefully theyre built with a lot higher temps in mind and that the excess pressure blew out the flange before anything else split.


Agreed that I shouldnt have floored it. The strange idrive/computer behavior hit right as I was on a freeway overpass merging onto another. Stopping would have been bad, and even floored I dropped to less than 40mph nearly causing a rear-end so I pushed on.

I assume when the ECU's voltage went, the water pump stopped along with everything else. Surprised the entire car didnt die TBH. Still cant explain all that happened. I had no instruments to tell me the car was overheating. The thing was utterly possessed and then black

Lol. I remember the first time I encountered this. The first thing you have to deal with is the BSD line. The alternator voltage regulator is probably dead. Try disconnecting all the equipment on the BSD line (water pump, oil level sensor, alternator, etc.). If you can't do it yourself, tow the car to the nearest BMW indie.

You'll know the engine is dead by shaking and smoky exhaust. The worst thing you can expect is that the head is screwed on because of the high temperature.

 

[fmorelli]

Here's the bottom line. You're not going to know.

First you need to read codes and see what they tell you. Next, fix your cooling system. You have two separate (maybe related issues) - whatever happened to your electrical system, and why did you cooling system blow a leak.

This is the part you'll like less - if you overheated the car, the head gasket might be just fine. BUT BMW's are notorious for warping the head just enough that, over time (like 10k miles) the head moved enough to start having the head gasket start to leak just a bit, then a bit more, then a bit more.

 

[rac]

This is the part you'll like less - if you overheated the car, the head gasket might be just fine. BUT BMW's are notorious for warping the head just enough that, over time (like 10k miles) the head moved enough to start having the head gasket start to leak just a bit, then a bit more, then a bit more.

haha, his stressing enough already!

she'll be right mate, put it back together and fkn send it... lol.

 

[Msoden82]

When my water pump went and coolant boiled out of the res and blew all over the engine bay, my car went into limp mode and I got the red oil light and all power shut down.

Waited on the side of the road for 20 mins, filled some of the res with water and got it home which was 15 miles away. No issues besides the aux fan blowing like crazy to keep her cool.

I’d say your fine. Do an extensive check and a leak down to confirm, and if the head is warped then cross that bridge when you get there down the road.

These cars are pretty resilient.

 

[TheObjectivist]

Not going to lie: your words give me hope. If the head can take a beating, Im hopeful. I ordered the replacement bits and am inspecting now

Note: seems the mickey mouse flange didnt break, the hose blew off.
I love it: the only reason I may not have blown the engine is that the hose failed

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[TheObjectivist]

And for laughs: the reason im in this mess, (and why I paid nearly $10k USD in body work):

Some rub-a-dub lost their stove top (out the back of a pickup truck) on the freeway and hit my car. At 75mph, it bounced up and destroyed the entire passenger side.



Long story, short: the work was so expensive, I eventually had the body shop halt and I took the car home unfinished.

I think (now that I reflect), what happened is I took the car home with the passenger door panels disconnected. The disconnected airbag killed the BSD line, and the ECU refused to charge the system. The lack of power then led to the systematic failure which killed the water pump along with my instruments