Hi, I have an M156 engine that me and my friend took apar...


Hi, I have an M156 engine that me and my friend took apart replaced the faulty cylinder headbolts and other gaskets and now that we've put everything back together the oil is mixing with the [coolant](/topics-coolant-mercedes/) an...

Hi, I have an M156 engine that me and my friend took apart replaced the faulty cylinder headbolts and other gaskets and now that we've put everything back together the oil is mixing with the [coolant](/topics-coolant-mercedes/) and producing chocolate milkshake kind of fluid. When we pour approximately 1 liter or more of water into the coolant holder thingy (forgot the name) it pours out the oil pan in the bottom after 10 or 20 seconds. We've tried to narrow down the problem and found out that it is probably from the water pump entry. We disconnected the hose that goes into the thermostat and it still leaks but when we remove the water pump hose from the radiator it doesn't leak. We took out the water pump and it looks fine and also has a new gasket and when we pour water right into the water pump opening it comes right back out and doesn't go in, so it looks like a mystery to use but maybe someone more experienced can help us out. Mechanic's Assistant: What part of the car is the leak coming from? And are you sure it's water? Its leaking from the oil pan and we are 100% sure its water Mechanic's Assistant: What is the make/model/year of your car? Mercedes w204 C63 2009 Mechanic's Assistant: Are you fixing your vehicle yourself? What have you tried so far? Yes we are fixing it ourselves, we've replaced every gasket on our way to the cylinder headbolt, including the h3ad gasket and others Mechanic's Assistant: Anything else you want the Mechanic to know before I connect you? No thats it

Automotive Expert
Hello my name is\*\*\*\*\* will be assisting you today. I hope your day is going well so far. May I ask your name?
Automotive Expert
there are 2 places that water will mix with coolant. the timing case cover to the engine sealing or the head gaskets. see photo of the timing case cover. but those are the only 2 points of entry. I hope this works out for you, this is going to be difficult to determine which , you will have to reseal the timing cover and if that does not work then reseal the head gaskets. I hope this information helps. I have submitted this as an "ANSWER". If you need further help please copy and paste this link to request me further. https://www.justanswer.com/car/expert-lou-p/ If you feel I earned one, BONUSES are ALWAYS appreciated. Thank you for choosing JustAnswer. Lou

Hello and thanks for your help, you can call me Meosh. We suspected that it might be the timing cover, but I don't think it is the head gasket because we are filling a little amount of water that won't reach the head gasket I think. We wil be looking for other possible cause and might start working to replace the timing cover gasket hopefully soon, once again thanks for your help.One more question, how does the gasket for the timing cover go bad? Before opening the engine everything was running fine, but after the rebuild it started mixing coolant and oil even though we didn't even open the timing cover?

Where can I send photos? I want to show you the engine before we put it back together, there were rubber gasket parts hanging in the water pump in the timing cover space.
Automotive Expert
if the right bolts were not used you can punch holes into passages, but those are the only two points of entry, I cannot answer why its happening, you will know that when you find the issue, all I can do Meosh is tell you the possibilities.

Bolts for what? The timing cover or the water pump?
Automotive Expert
both, the bolts need to be put back in the right spots or you can punch a hole into the block. but you are on to something if all you have to do is pour a little water in and it runs out before making it to the heads, you might be able to fill it quickly and then do a pressure test to see if you can hear air escaping or see the water gushing out. but that is the best I can advise. best of luck. I hope this information helps. I have submitted this as an "ANSWER". If you need further help please copy and paste this link to request me further. https://www.justanswer.com/car/expert-lou-p/ If you feel I earned one, BONUSES are ALWAYS appreciated. Thank you for choosing JustAnswer. Lou
Automotive Expert
You'll need to pressure test the cooling system to see exactly where the leak is coming from.

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