MM63

Hey everyone i hope you guys are doing great, so i’m basically a new 2009 c63 w204 owner who is living in Pakistan where there is no official MB dealership or Workshop though there are a few hundred C63’s that are maintained by performance shops mostly so i got my ride a month or so ago and so far i’m loving it but there are some issues that are not letting me sleep peacefully.
So basically on the very first day the low coolant light turned on and i’m a ex evo owner so i was pretty familiar to forums so i just came to mbworld and i was bashed with headbolt issues and i thought okay maybe i’m the unlucky one and headbolts are gone. My car is Japanese Import 09.

Next day i went to the workshop and and they pressure tested the cooling system and found out that the thermostat was leaking, as i mentioned there is no official dealership so we have to order parts from Uae or USA which take time to arrive like 20 days easy.
So by chance the shop had an Used Thermostat which they put on my car and i went home.
Since that day i’ve noticed my car is still losing coolant like 50ml or so every 100-150kms there is no white smoke, No misfires, No milky oil cap, changed the oil too and the oil is still as good as new, the oil level is fine too.
The only code the car is throwing is that both the banks are running rich and has a little lumpy idle i dont know if that could be related to bad headbolts as this is my first ever Mercedes or German Car, i’m more of a Jdm guy since a few years.

Anyhow, i hate taking my car to the workshops here as they are total rip offs and one can’t trust them, i’ve ordered a block tester fluid too that will take around 20 days to arrive - So can anyone guide me please that it my headbolts are gone or have i compromised the gasket? The oil temp is fine, the water temp is fine too no over heating and i’ve driven my car 1100kms since i got it and i’ve topped coolant every second or third day as the level would come down, i even overfill it a bit so that it does not go very low. - The other day i was changing the coolant i saw they had put silicone on the radiator drain plug and we had to reseal it with silicone after changing the coolant as it was dropping a lil drop when we started the car.

I’m sorry for such a long paragraph but i’m very worried and i would like you Pros to guide me that how can i make sure my bolts are not bad, i cant see any visible leaks too.

please kindly help a brother, you can ask any further questions and i can even post videos or photos aswell if you guys say so.

thankyou.

GarlicBread

Odds are your bolts are bad regardless since your car is an 09 and you have no official MB personnel actively replacing or informing their customers of service updates/problems.

You can check them by looking at them, there is a different bolt head design between the two if im not mistaken but again more than likely they were never changed since no one either knew about this or noticed.

You can find the pictures between the two different head bolts somewhere in this forum.

MM63

Anyone?

BLKROKT

If there’s no coolant under your car or collecting in the underbody trays under the engine, there aren’t many places left that it could disappear to. Sounds like headbolts, coolant is likely leaking past the head gasket and evaporating in your cylinders. Sorry.

roadkillrob

Ya I am with the others probably headbolts, let is sit, pull the plugs and look for signs of water in the cylinders or plugs or really clean pistons. I would stop driving it if you loose that much coolant and it isn't obvious on the outside of the engine as it is likely going into the cylinders and that can end in a costly way if it gets enough to hydrolock.

Diabolis

+1 from me as well on the head bolts, which has now resulted in a leaky head gasket.

What you'll need to order (if it's coming form the USA) is this: https://www.fcpeuro.com/products/mer...ing-1560160769. I'd also get a new timing chain tensioner (p/n 156 050 06 11) and get that replaced as well while they are in there. It's a ~$5K job in the US.

roadkillrob

The worst part of the job is pulling the heads which isn't particularly difficult unless a head bolt breaks, if the head gasket is leaking then likely one is broken or has gotten longer to reduce the force on the head which means it will probably break when you try to remove it.

Diabolis

If the coolant level is decreasing at the rate it is and there is no external leak, the head gasket is leaking internally and coolant ends up in the cylinders. There's nowhere else for it to go.

MM63

Can i confirm this with a block tester kit? Is that accurate enough?

BLKROKT

Waste of time IMO