Two days ago, there was a slimy residue inside the coolant tank, so i cleaned it with brush and changed the coolant. Today, it’s back. What am i looking at here?

 

Look like you have oil in you coolant. Not good.

 

Yep, you have oil in the coolant. Probably either the head gasket or the oil filter gasket.

 

Agree with above. You can do a compression test to see if the head gasket is bad. Most likely it is either that or the oils filter housing gasket. I would do both for piece of mind and the “while your in there” thing.

 

After some brainstorming, we were almost sure that it was either the head gasket or oil cooler, then a friend of my guy said it might be freeze plugs (i dunno if it’s the right term considering i am turkish, he said something with plugs behind the engine). He is currently doing the job, what do you guys think, could that be the case?

 

If he is telling you it's a Freeze Plug, I would get someone else to do the work.....Get a Mechanic that knows how to troubleshoot and work on these cars. (Head gasket or Oil Cooler)

 

Freeze plug

 

there is definitely a contaminant (most likely oil) in the coolant expansion tank. And coolant level is decreasing at crazy levels without any visible leaks. But there aren’t any visible head gasket problems like white fumes out of exhaust or rough idle and even though the oil inside the engine is pretty old (about 6 months), there wasn’t any indication of coolant inside the engine oil at dipstick. There was some milkshake under the oil filler cap but he said it is caused by short distance driving. He also said that he saw the same problem at couple of thp peugeot engines in this year. So i trusted him and gave him a go. We will see the results tomorrow.

I know it might not be the case and i am not keeping my hopes up. But if it is, it’s gonna be hell of a lot cheaper than the other possibilities.

-after doing further research, oil cooler failure seems to have the same signs with my problem. but nkfry here points that it might also be the freeze plug too.

 

https://www.northamericanmotoring.co...ml#post4141048

He does mention that, however you would have coolant in your oil if that were the situation.

 

Like i mentioned in the thread the gasket might have failed and the coolant and oil is mixing. I would check that gasket first.

 

It's been 1 full day and almost 200 kms and it seems that the issue is completely fixed now. coolant level is steady as rock, oil is shining like a morning in Hawaii and the engine is smooth as silk.

There is this new small issue though, there is a minor chain noise at startup that comes just after pressing the start stop button for about 1 second. It also comes randomly when driving the car but it disappears after about 5-6 seconds of driving. It feels like the timing is off somehow? Guy said to drive the car around for sometime at 2.5k rpm to clear the remaining deposits, maybe it's related to that?

But the main issue is definitely fixed after the new core / freeze plugs and 15 or so liters of oil and coolant change.

 

Apparently the freeze plug failure thing is not that uncommon in the R56. Just another thing to worry about failing!

 

He said mine was corroded but in it’s place. Whole block is Aluminium but they’re something else. Also, valve cover was full of milkshake even though there wasn’t any visible oil from the oil filler cap looking down.

 

Well all be damned. Who knew..

 

just changed one more freeze plug because of a similar issue. this time the one between the block and the chain was corroded. the probable cause is out spec coolant. this meant, at 220k kms, i had to change all of the freeze plugs inside the head at different times.