[will.c]

FYI, coolant has been changed at 80,000mi, which was 6,000mi ago. The new coolant only consists of 1 bottle of MoCool (500ml) and remaining distilled water. So no BMW coolant here.

Cooling has been great so far. Limp modes have completely disappeared at the track, etc. But I looked at the reservoir to check the level, and 2 potential problems:

1) coolant level(stick) was lower than the minimum by about an inch or so.
2) when I pulled the stick out, the yellowish crap was all over the stick and at the bottom where the floating mechanism sits.

So I put more MoCool+distilled water mixture into the reservoir (during which the crap mostly washed down easily, so it wasn't hardened crap) until the top of the stick stuck out by about quarter inch, closed the cap, then drove away.

Again, no cooling problems still. But what is that? Corrosion???? And why did I lose so much coolant?

[cleex024]

i cant tell what it is from the pictures but damn hope its not algae or something cause thatll cause restrictions in flow.

[ajsalida]

This is where a real dipstick would come in handy. Any chance you have a cracked head or head gasket leak and that is oil residue in the coolant? More likely if the car has overheated recently.

[Beemw335]

I would have gone bmw coolant.
Did thi happen with oem coolant?
Maybe this one isnt made to withstand the high temps of the n54??

[335okc]

that looks gnarly. i got waterwetter + distilled and i guess i better check mine lol

[will.c]

I haven't had any acute overheating. My temps have gone upto 108C in traffic, but that was it. No limp modes of any kind since last summer. (I don't hear my radiator fan turning on while it's that hot, but this may be an unrelated problem that I'll have to deal with the BMW dealer.)

I did a quick google search, and it generally seems that yellow residue on OIL caps = leaked coolant into engine (as bad as cracked head/block or blown gasket). Also, frothy yellowish top layer of oil also means the same. (We have no damn dipstick!) So I did check my oil cap, and it was perfectly clean. I will check my coolant reservoir tmr morning again, as my engine is still hot now. Another answer from the search is corrosion.

I might just flush it back to 50/50 OEM coolant/distilled water. This is creeping me out.

335okc,
please do check and let me know how yours looks.

[MrRager]

im pretty sure based on where you live its corrosion. but i think you should flush the system and get the bmw stuff in there whenever possible.

[335okc]

i just checked mine. it does not look like that. mine is red since water wetter is red, but no residue.

honestly i don't think it's algae or corrosion. what color is mocool ? maybe just get the coolant flushed. it might be oil, but it's not exactly that color.

[rader1]

You are right about that being indicitive of oil/coolant mixing. You should probably have you cooling system pressure tested to see if you have a leaking head gasket or some other failure.

[boostaholic786]

Summer time is here and my coolant light came on but after I turned the car off to eat lunch, I came back to start it and coolant light did NOT come back on. I still stopped in at the local Walmart and grabbed a gallon of distilled water and waited till I put my car in the garage and let it cool down just a bit. Added about half a gallon of distilled water and the little bobber thingy was at full. Honestly what I have heard from a couple buddies of mine that are BMW techs is that especially in the summer you can really fill most of the coolant up with Distilled water and it actually cool better and make the car run more efficient due to the lower engine temperature. The BMW coolant is basically made so the water doesn't freeze but Its summer right now so I dont think there is going to be any freezing going on anytime soon lol. Im going to leave it like that unless Im completely wrong and someone on here that knows more about engine cooling ect.. can chime in, that would be great!

[rader1]

Originally Posted by boostaholic786

Summer time is here and my coolant light came on but after I turned the car off to eat lunch, I came back to start it and coolant light did NOT come back on. I still stopped in at the local Walmart and grabbed a gallon of distilled water and waited till I put my car in the garage and let it cool down just a bit. Added about half a gallon of distilled water and the little bobber thingy was at full. Honestly what I have heard from a couple buddies of mine that are BMW techs is that especially in the summer you can really fill most of the coolant up with Distilled water and it actually cool better and make the car run more efficient due to the lower engine temperature. The BMW coolant is basically made so the water doesn't freeze but Its summer right now so I dont think there is going to be any freezing going on anytime soon lol. Im going to leave it like that unless Im completely wrong and someone on here that knows more about engine cooling ect.. can chime in, that would be great!

Yep. Water does a lot better job of cooling than BMW coolant, which is basically there to keep the water from freezing. Products like water wetter also aid in cooling.

[acdHQK713K]

Originally Posted by 335okc

i just checked mine. it does not look like that. mine is red since water wetter is red, but no residue.

honestly i don't think it's algae or corrosion. what color is mocool ? maybe just get the coolant flushed. it might be oil, but it's not exactly that color.

MoCool is red. I have the same mix and those pictures are definitely not normal. I highly doubt its a head gasket. I don't think there has been a documented head gasket blown on this car yet, so that would be at the bottom of my list.

Do you have the stock oil cooler or an aftermarket one? The gaskets in the oil filter housing have been known to leak. Theoretically oil and coolant could mix in this area. Some people have found small amounts of oil in their coolant after changing the gasket or going with an aftermarket oil cooler setup. But with that said, nothing as extreme as this.

Does it have an odor? Can you fill up the expansion tank and see if oil is floating? How about dipping a piece of paper in there and seeing if it comes out oil covered.

[venom3469]

I had this happen to me on my first car..well I think. The owner before me some how chanced the coolant that was normally green and used on that was pink. So the two formed together to make the nasty brown sludge..the only thing to do is flush the whole thing out and stick to one coolant.

[will.c]

Originally Posted by Stangorang

MoCool is red. I have the same mix and those pictures are definitely not normal. I highly doubt its a head gasket. I don't think there has been a documented head gasket blown on this car yet, so that would be at the bottom of my list.

Do you have the stock oil cooler or an aftermarket one? The gaskets in the oil filter housing have been known to leak. Theoretically oil and coolant could mix in this area. Some people have found small amounts of oil in their coolant after changing the gasket or going with an aftermarket oil cooler setup. But with that said, nothing as extreme as this.

Does it have an odor? Can you fill up the expansion tank and see if oil is floating? How about dipping a piece of paper in there and seeing if it comes out oil covered.

Hmm, weird... I'm pretty sure my MoCool was purple. Maybe I bought a batch that expired?

Stock oil cooler. Oil filter housing gaskets (there seems to be two of them actually) have also been replaced by the dealer under warr. 9,000mi ago when I complained about small smudges of oil around the housing. So I'm gonna put "faulty oil filter housing gasket installation" as one of my diagnosis.

I'll smell it and dip some paper tmr morning and post pics.

Thanks guys, you guys are extremely helpful!

[R1000K3]

I would flush the system ASAP and revert to BMW coolant or Water Wetter, which I use.

I've had a car with a quite similar look in the coolant. I flushed it several times and it became better but always returned to some degree. One theory was a previous owner had mixed something that was not compatible into the coolant by mistake, e.g. topping it with engine oil or some other type of antifreeze than recommended.

The car always consumed some coolant and there was coolant odor in the car during winter time. The problem disappeared completely when the heater element was replaced.

[STONEY_M5]

Originally Posted by rader1

You are right about that being indicitive of oil/coolant mixing. You should probably have you cooling system pressure tested to see if you have a leaking head gasket or some other failure.

Originally Posted by Stangorang

MoCool is red. I have the same mix and those pictures are definitely not normal. I highly doubt its a head gasket. I don't think there has been a documented head gasket blown on this car yet, so that would be at the bottom of my list.

Do you have the stock oil cooler or an aftermarket one? The gaskets in the oil filter housing have been known to leak. Theoretically oil and coolant could mix in this area. Some people have found small amounts of oil in their coolant after changing the gasket or going with an aftermarket oil cooler setup. But with that said, nothing as extreme as this.

Does it have an odor? Can you fill up the expansion tank and see if oil is floating? How about dipping a piece of paper in there and seeing if it comes out oil covered.

Originally Posted by wonho

Hmm, weird... I'm pretty sure my MoCool was purple. Maybe I bought a batch that expired?

Stock oil cooler. Oil filter housing gaskets (there seems to be two of them actually) have also been replaced by the dealer under warr. 9,000mi ago when I complained about small smudges of oil around the housing. So I'm gonna put "faulty oil filter housing gasket installation" as one of my diagnosis.

I'll smell it and dip some paper tmr morning and post pics.

Thanks guys, you guys are extremely helpful!

My coolant looked exactly like this, the dealer did a compression test and a leak down test found no prob.... Ended up being oil in the coolant from the oil filter gasket. try doing a coolant flush drive for a couple hundred miles, if the symptoms persist then you know you have to move on to the next step... i.e. comp & leak down test...

[ajsalida]

Several things.

1. Coolant does more than act as anti-freeze. It raises the boiling point of the mixture over that of of water. A lot. Water alone does not have the needed heat capacity (esp on track days) and you will overheat easier without proper coolant. It also does a lot of other stuff WRT deposits and so forth. Legend has it that you never should use anything other than BMW coolant in BMW's. It is cheap insurance so why not.

2. See if the residue is greasy to the touch. If it is, it is almost 100% that it is oil from somewhere. You need to track this down right away.

3. Based on what you've said so far it is very likely you've got at least a small leak somewhere allowing oil into coolant and so maybe vice versa. Let us hope it is not a warped/cracked head or similar.

4. See if you can look at your plugs, and maybe change the oil to see if there's coolant in it. If there is park it til you figure it out.

5. Oh and put some real coolant in there.

[MDORPHN]

Originally Posted by ajsalida

Several things.

1. Coolant does more than act as anti-freeze. It raises the boiling point of the mixture over that of of water. A lot. Water alone does not have the needed heat capacity (esp on track days) and you will overheat easier without proper coolant. It also does a lot of other stuff WRT deposits and so forth. Legend has it that you never should use anything other than BMW coolant in BMW's. It is cheap insurance so why not.

2. See if the residue is greasy to the touch. If it is, it is almost 100% that it is oil from somewhere. You need to track this down right away.

3. Based on what you've said so far it is very likely you've got at least a small leak somewhere allowing oil into coolant and so maybe vice versa. Let us hope it is not a warped/cracked head or similar.

4. See if you can look at your plugs, and maybe change the oil to see if there's coolant in it. If there is park it til you figure it out.

5. Oh and put some real coolant in there.

At 15 psi, boiling point of water is around 265 F. If you're seeing temps that high, you've got problems regardless of whether you are with or without coolant.

Water is a more efficient heat transfer medium than coolant -- one of the reasons most track junkies use it.

Add some Mocool (sp?) or Water Wetter and you further aid cooling and provide the lubrication needed for the water pump.

Neil

[ajsalida]

Originally Posted by MDORPHN

At 15 psi, boiling point of water is around 265 F. If you're seeing temps that high, you've got problems regardless of whether you are with or without coolant.

Water is a more efficient heat transfer medium than coolant -- one of the reasons most track junkies use it.

Add some Mocool (sp?) or Water Wetter and you further aid cooling and provide the lubrication needed for the water pump.

Neil

I would never run pure water alone in any car's coolant system, track or not. Except for emergencies. For a lot of reasons. Water wetter, above freezing, yes of course. Great product. Closed coolant system under pressure with a thermostat + radiator + expansion tank is a very complex thermodynamic system. Good discussion of it here:

http://www.newton.dep.anl.gov/askasc.../chem03987.htm

edit: I would add that my layman's understanding of why track folks use water is because coolant leaks + race tires = bad. If I remember correctly it is for that reason you are not allowed to run coolant in SCCA (water wetter is OK). Having had a street car blow a radiator hose in front of me while we were both flat out downhill into carousel (turn 5) at summit point on an open track day, I can vouch for that. So it may be that track safety req. has morphed to street lore on track days w/o any engineering principles behind it. I think you need to have higher pressure system to handle it properly in any case.

But there may be other solid reasons water alone is good that I am not aware of.

[JamesM3M5]

Originally Posted by ajsalida

I would never run pure water alone in any car's coolant system, track or not. Except for emergencies. For a lot of reasons. Water wetter, above freezing, yes of course. Great product. Closed coolant system under pressure with a thermostat + radiator + expansion tank is a very complex thermodynamic system. Good discussion of it here:

http://www.newton.dep.anl.gov/askasc.../chem03987.htm

edit: I would add that my layman's understanding of why track folks use water is because coolant leaks + race tires = bad. If I remember correctly it is for that reason you are not allowed to run coolant in SCCA (water wetter is OK). Having had a street car blow a radiator hose in front of me while we were both flat out downhill into carousel (turn 5) at summit point on an open track day, I can vouch for that. So it may be that track safety req. has morphed to street lore on track days w/o any engineering principles behind it. I think you need to have higher pressure system to handle it properly in any case.

But there may be other solid reasons water alone is good that I am not aware of.

Then how does one explain the reduction in coolant system temperatures once the concentration of coolant to water is significantly reduced in every case, every track and racecar, BMW or not? I know that ethylene glycol has its benefits, but aside from the pump seal lubricants and anti-corrosion additives (present in coolant additives such as WW and MoCool), why run ethylene glycol in high concentration if it does a poorer job of shedding heat?

And that link has some mis-information in it, along with typos that one guy said his Honda coolant system runs over 200C. I'd like to see an engine that can run at 200C. They're talking about boiling points, completely ignoring the fact that the coolant system IS a closed, pressurized system, and heat exchange is the main function.

[rader1]

Originally Posted by MDORPHN

At 15 psi, boiling point of water is around 265 F. If you're seeing temps that high, you've got problems regardless of whether you are with or without coolant.

Water is a more efficient heat transfer medium than coolant -- one of the reasons most track junkies use it.

Add some Mocool (sp?) or Water Wetter and you further aid cooling and provide the lubrication needed for the water pump.

Neil

Originally Posted by JamesM3M5

Then how does one explain the reduction in coolant system temperatures once the concentration of coolant to water is significantly reduced in every case, every track and racecar, BMW or not? I know that ethylene glycol has its benefits, but aside from the pump seal lubricants and anti-corrosion additives (present in coolant additives such as WW and MoCool), why run ethylene glycol in high concentration if it does a poorer job of shedding heat?

And that link has some mis-information in it, along with typos that one guy said his Honda coolant system runs over 200C. I'd like to see an engine that can run at 200C. They're talking about boiling points, completely ignoring the fact that the coolant system IS a closed, pressurized system, and heat exchange is the main function.

+1

[ajsalida]

Again I may be wrong but my limited understanding of how this works is the following:

Water only works great as coolant until it doesn't. It begins to boil in pockets near combustion chambers where metal is hottest. It has a higher vapor pressure than water/coolant mix so this can cause leaks/overflow. Once level gets low things cascade quickly and you end up with a lot of air pockets around the combustion chamber, things then go bad real fast.

On a turbo car esp w/tune & higher boost I personally would not run pure water in my own car. As I said water wetter is fine.

There was an SCCA tech bulletin out a while ago about one spec class engines melting with only water as coolant. This was on very hot days and racing conditions.

I am curious to find out what the OP's car has going on, maybe this will shed some light.

edit: a system designed for higher pressures a water-only coolant system would generate is fine (like in NASCAR, say). I do not know what the design limits on a stock BMW coolant system are, or when you might exceed them.