Grey Coolant, but no coolant in oil *Now, water pump shenanigans?

[lemoose]

My coolant is looking grey and sludgy and im not sure what could be the cause. Head gasket seems possible but rare? I understand head gasket failure on the s54 usually happens between cylinders and not between coolant/oil jackets- but then again, id also understand the contamination would go both ways, plus, the car runs strong with no codes otherwise indicating no leakage. Are there possible causes for grey sludgy coolant other than oil and if not, where else would this one-way mixing occur?

[maw1124]

How frequent are your oil changes and are you losing oil between changes? I'd suspect that's oil (gaskets) but slight enough that on frequent changes you wouldn't recognize it. The last question would be when were the gaskets last changed? If more than 3 or 4 years (in TX) that would be my suspicion. At least that one I can check easily by changing the gaskets.

GL, please keep us posted.

maw

[bmwfnatic]

I have also seen this happen if incorrect coolants are used, mostly if pink and blue coolant are mixed. I would flush out the entire system, also with the drain plug on the block, and then fill it up with the correct coolant, then drive it for a while and check again.

[bigjae46]

Are you using 50/50?

I used 100% distilled water and water wetter. My coolant gets grey and cloudy. Not sure if it's because of multiple water pump failures where the bearing explodes and leaks the bearing lube. I can't seem to get rid of it....flushed the system many times. Doesn't seem to affect cooling.

In case you're wondering...I've had multiple water pump failures because I had 6 used water pumps from dismantling many S54s. Figure I might as well use them...takes me 10 min to swap it out.

[lemoose]

I have also seen this happen if incorrect coolants are used, mostly if pink and blue coolant are mixed. I would flush out the entire system, also with the drain plug on the block, and then fill it up with the correct coolant, then drive it for a while and check again.

IVE always used the correct coolant but i did get the car back from the body shop a couple weeks ago. I dont think the scope of work wouldve called for them to touch coolant but i suppose it is possible they may have and just not said anything.

How frequent are your oil changes and are you losing oil between changes? I'd suspect that's oil (gaskets) but slight enough that on frequent changes you wouldn't recognize it. The last question would be when were the gaskets last changed? If more than 3 or 4 years (in TX) that would be my suspicion. At least that one I can check easily by changing the gaskets.

GL, please keep us posted.

maw

every 5-7k miles and yes i do lose a good amount of oil despite multiple shops confirming there is no significant seepage anywhere. I assume you dont mean its the head gaskets that need to be replaced every 4 years, right 😂?but then, not sure what other gaskets separate our oil from our coolant. Plus, again, there is no significant signs of seepage anywhere. I guess all this is in fact pointing to a head gasket issue but i must be the first person ever to experience this type of failure lol

[maw1124]

Yeah I was confusing head v valve cover… disregard that comment… how often do you flush your coolant system… any new pipes or other components lately? It may be a non-problem. Is it grey and sludgy after every flush (2 years), or just this first time?

maw

[lemoose]

Yeah I was confusing head v valve cover… disregard that comment… how often do you flush your coolant system… any new pipes or other components lately? It may be a non-problem. Is it grey and sludgy after every flush (2 years), or just this first time?

maw

Ive never done an actual flush but throughout my almost 8 years of ownership ive had to refill on coolant for just these jobs off the top of my memory and the coolant was always nice and blue:
1. New Radiator
2. upper and lower radiator hoses
3. New expansion tank

[maw1124]

I personally wouldn’t worry until it repeated itself. That could easily be internal residue off any of those components. But I also flush mine every 2 years, which I would also recommend. I have no idea what this book calls for. I treat them all loosely according to what MB specs for my SClass, so coolant and brake fluid get swapped every couple years, transmission fluid and Pentosin every 3/30k, oil every year or 5k, etc. But I’m also in a warmer, more humid climate than you (SoFL, coastal town).

maw

EDIT… 8 yrs in TX with this high a compression engine, I’m surprised the coolant isn’t flammable 😂

[Arith2]

Coolant flush is every 4 years if you don't do a coolant system repair. The minimum freezing point spec is -29 C. The sludge usually comes from mixing in an incompatible coolant. I've not ever seen BMW coolant sludge. Flush and see what happens. I would suggest popping the lower radiator hose and then applying so pressurized air to push coolant out of the system. I typically just put on a glove and put an air nozzle through my fingers. A vacuum fill tool will also prevent air in the system.

[sapote]

1. My coolant is looking grey and sludgy

2. Ive never done an actual flush but throughout my almost 8 years of ownership ive had to refill on coolant for just these jobs off the top of my memory and the coolant was always nice and blue:
New Radiator
upper and lower radiator hoses
New expansion tank

3. yes i do lose a good amount of oil despite multiple shops confirming there is no significant seepage anywhere.

1. Post a picof the sludgy coolant in the tank
2. When was the last time you checked the tank and saw blue coolant?
3. This could mean engine oil leaking into coolant via the head gasket. The high oil consumption didn't happen before the sludgy coolant symptom?

I would drain flush the coolant, refill with proper mix, drive a week or two and check for sludgy again. If it appears then pull the head off.

[mrgizmo04]

Do you get any bubbles when car is running and coolant tank is open? Or steady stream?

Easy to test with a kit you can rent from autoparts store, it would change color is you are getting combustion gases in coolant. Had a video on YouTube I posted.

Sent from my SM-S911U1 using Tapatalk

[Cronenberged]

It's probably overkill but I did the Chris Fix super flush, it's very time consuming but it did pull a lot of stuff out my system.

[lemoose]

Hey all, thanks for your input and sorry for not being responsive after asking for help lol- i took off on vacation for the week. Ill try to address the gist of the general suggestions and share some further findings below.

I think the grey coolant (it was not sludgy after all) is a symptom of a greater issue. Background i now realize might be consequential: I picked up the car from the shop the day before i made this thread and they had mentioned to me the coolant color- i declined their flush service and figured id do it after checking the coolant out for myself. Upon picking up the car, i did notice the coolant gauge reaching the 3/4 mark (this car has always run on or to the left of the middle point on anything less than a 100 degree day) on the highway and at home i did confirm the coolant was off color so i ordered supplies for a flush.

Today after doing said flush (removed lower rad hose and block drain plug + ran distilled water until it came up clear) the car still runs hot- going past the 3/4 mark while standing still after a heat soak. Also, I get no heat from the vents once the coolant gauge moves past about the 3/4 mark*EDIT: AT IDLE*. It's hardly my first time bleeding air on this car so I doubt this is due to air in the system (nose up, bleeder screw open, heater full on and fan on low- although im not sure what the consensus is regarding auto/manual vent section and the strat dial, but regardless, never been an issue)

I’m a bit at a loss but I think all the variables only leave one possible culprit- the water pump. My working theory is that the impeller has shredded itself into my coolant (causing the color) and therefore isn’t moving enough coolant at idle to keep the car from overheating or move it through the heater cores. Also the car is at over 190k and it seems to me most people have serviced this part by this mark. The only thing that doesnt seem to corroborate this is that my clutch fan has no play at all and that the pump would go out overnight without warning?

What do you all think? Are these symptoms consistent with a failed s54 water pump? Is there any way to isolate the water pump as the issue other than throwing the part at the problem?

[sapote]

Today after doing said flush (removed lower rad hose and block drain plug + ran distilled water until it came up clear) and the car still runs hot- going past the 3/4 mark while standing still and after heat soaking. Also, I get no heat from the vents once the coolant gauge moves past about the 3/4 mark.

At this temperature, grasp the rad lower hose to check if it's cold or luke warm; it should be hot to your skin. If cold, then no coolant flowing and this means either Tstat didn't open or water pump is bad.

[bigjae46]

Probably a water pump. Pretty easy to check, just pull the thermostat off although that can be an exercise in frustration at times…🤣