Ok, so after have the head replaced and valve job done on my '05 MCS about 2 weeks ago, I've been having the fish tank coolant noise coming from behind my dash ever since. It is scheduled in for a Friday to have the system bled.

However, my car also seems to be using coolant now. I've put about .75 of a quart in since last Friday. My question is could the air lock that is causing the noise be causing the coolant level to fluctuate?

I drove to the mountains (about 1.5 hrs each way) to go skiing on Friday and put about 1 pint in before I left as it was well below the minimum line. When I got home on Sunday night, I needed to add about the same amount. Monday I drove to work & back (40 minutes each way...15 minutes of which is city driving...an easier drive than to the mountains & back). Car wasn't cool enough to check Monday night, but Tuesday morning I checked and it was down again slightly...not enough to add. Drove to work & back yesterday, checked the coolant again this morning and it hasn't moved from the level it was Tuesday morning.

There was no coolant on the ground during any of this that I could notice. So if it is using it, I'm a little concerned that it could be going into the engine since I had all that head work done.

So do you think this is all because of the air lock, or do you think I could have 2 separate issues going on?

Thx! Kim

 

Hey there,

If you just replaced the head - I would expect to have to "top up" the coolant several times until you get all the trapped air out of the system. If you are not blowing steam ( white vapor - smells like anti-freeze - sweet ) out of the tailpipe, and there is no water in your oil - then I would just top it up and watch it very closely for a few days. If you are really worried you could pressure test the cooling system and see if that generates any leaks??


Good luck Hope this helps

 

Most likely air in the system. Hopefully they'll bleed and fill it correctly this time.

 

Sounds to me as if you have entrapped air in the cooling system. This should be purged via the air bleed screw in the upper radiator hose. If air continues to find it's way into the system, there is a chance that the head job has gasket issues and needs to be redone.

 

Thanks for the replies, they definitely help. I'm keeping an eye on it (and mixed coolant in the boot) 'til the car goes in on Friday.

 

Bleeding it yourself is not hard at all. Just set the thermostat to full heat and with the car running, use a big screwdriver to open the bleed screw on the upper radiator hose. If there is air in the line, you will notice it bubble out of the loosened screw. Once solid coolant flows out, air should be purged.

 

LOL...not hard at all to you who knows something about working on a car. I'm a woman and basically the only thing I understood about what you wrote was "big screwdriver" . Ok, that is a slight exaggeration, but I think it would be best for me to let the shop do this...

 

What exactly is the fish tank coolant noise?

 

Sounds like gurgling water behind the dash...like a fish tank has been installed. Water seems to run left to right, present when the car is first started and less so as the car warms up.

 

weird, my wife complains of the exact same thing. we took it to the dealership and they said its fluids and they couldn't do anything about it. what's the way to solve it, bleeding the coolant of air?

 

A short burst of gurgling when first starting up and revving the engine is normal and is caused by the heater core being mounted low and far into the dash where it's easy to hear any noise it makes. There is also a 'hump' in the pipes that connect to the core that will accumulate dissolved air bubbles present in the coolant in the high spot. Dissolved air is normal in coolant, and will settle out after the engine is stopped for a while. The gurgling you hear is the pockets of air getting pushed through the core. The air will eventually make it's way into the surge tank. The surge tank in a MCS should never fall below the minimum level or else air will become sucked back into the cooling system. The MCS has a continuous flow of coolant through the surge tank, where the MC is a more conventional 'overflow' tank.

 

Mine is definitely not a short burst.

 

To restate the procedure stated earlier, have at least a half gallon of 50/50 coolant water mixture on hand, after the engine has cooled completely or the first start of the day, open the cap on the "surge" tank, un-screw the bleeder screw (it’s located in front of the intercooler on the heater hose and has a cross slash top), turn the heater on all the way, and start the car. Watch the coolant through the bleeder hose, when it begins to move (this may take more than five minutes) wait for it to reach the top of the hose, if you are lucky the fluid will begin to escape with some air bubbles, I say lucky because this is not always the case, as coolant evacuates replace the lost coolant in the surge tank. Once fluid escapes without bubbles then close the bleeder. If the coolant does not rise enough to come out of the bleeder, close the bleeder when the coolant comes as close to the top as possible. Hopefully, and this has worked for me, enough air will escape in the overflow tank and through the bleeder hole to reduce the fluid noises without coolant flushing the air out. I have experienced both the evacuating fluid and no fluid exiting the bleeder so it can happen either way. The local MINI tech told me the way he does it is with a vacuum pump.

As others have said, fluctuating coolant levels in the surge tank is normal after coolant replacement, until all stabilizes. Avoid the urge to over-fill in compensation because the increased pressure will send fluid out the cap if the surge tank is healthy.

 

There are actually two vent screws. One on the upper hose at the front bumper and one tucked between the t-stat and intake manifold (it has a gold head). Look straight down into the obyss at the top driver side of the intercooler cover. If you are having trouble bleeding the system be sure to try the second one.

My directions are basically the same but, don't open the vent screws while the engine is running, especially with the cap on. It will release pressure and spray coolant. If you still can't get coolant to flow out of the vent screws then pour some water in (the vent hole). Once it tops off the hose, put the screws back in. DO NOT over tighten the plastic screw. There is an o-ring on it so relax. Just check for leaks when your done. If you over tighten the screw you can crack it enough that it won't brake for while, then blamo, it over heats. I then run the car with the cap off, topping it up until it warms up. Put the cap back on and check the level in the morning after it cools completely.

 

haha yeah....I did that. cleaning up coolant isn't that fun

 

im the wife mentioned above
i've had the water sloshing noise for awhile now, my coolant got replaced about a month back. i took it to the dealership for an oil change and asked them to bleed the coolant and they said "thats probably something someone just told someone to do and it wont do anything"

so..they wouldnt do it. bums.

i drive away and 5 miles later my temp needle is almost at the red line, and the fans are going crazy.
drove back, and they checked the fans and coolant level, everything seems fine.

i'm going to try to bleed the system myself this weekend and see if the noise subsides. will also be watching that needle......