Blown head gasket! questions…. – mercedes-benz forum a gas is a form of matter that


Last summer, on the way to drop off kids at camp for the week, my (then) beloved 94 E320 crapped out. It had been running fine and during the 45 minute trip, I had plenty of acceleration and smooth power. However, as we got closer to our destination, the idle started becoming increasingly rough at stop signs and low speeds. Once we finally pulled into the long grass driveway/parking lot of the camp, the car was shaking and sputtering pretty badly but I could still accelerate. Once I parked it, it never started again. This was last July.

When I went to start it after getting the kids settled, the motor would make a violent ka-chunk ka-chunk noise and the motor would rock excessively. When watching it while my wife tried turning the key, it looked like the drive belt wasn’t advancing at all. At this point, the car began acting like the battery was dead and after failed attempts at jumping it off someone else’s car, we left it. Later that day, we brought back a brand new Bosch group 49 battery and found the car would do the exact same thing when trying to turn it over, just with much more umph behind it. At that point, I cut the drive belt right off to eliminate the possibility of a seized A/C compressor, water pump or the like. No luck.

I got the car towed home and it has sat in my driveway ever since. The winter took the newly pealing clearcoat issue to the max and now the car’s once gorgeous Imperial Red paint now looks like a bad case of herpes with huge sections of clearcoat now gone.

I had a couple of hours this week for the first time since last April when we moved into this money pit of a house and finally started checking out the Mercedes. I pulled the valve cover off and started looking around. My suspicions this past year were that the timing chain tensioner or a timing chain guide had broken causing the chain to bind while trying to turn it over. I could turn the crank by hand all the way around with no bad noises. Once I pulled the valve cover, I saw nothing obvious with the chain. In fact, my top end looked immaculate with only 118k on the clock and regular Mobil 1 oil changes.

From there, I decided to grab the ratchet again and try turning the motor over by hand. With the first quick turn, I saw a long squirt of coolant come out somewhere towards the firewall. Uh oh! This time, I started watching the last couple of cylinders and turned the crank slowly.

So, cylinder 6 is completely full of coolant. My reservoir is empty. I pulled the dipstick and the level was showing above the plastic section at the bottom, however, it looked and smelled only like oil, which is kind of perplexing. A friend at work pointed out that if my oil pan had been a mix of coolant and oil, it would have completely separated while sitting over this past year. So it is unknown at this time if coolant and oil was mixed up while it was still running. When I left that day, I had coolant in the res and my oil was recent and the level was correct; I would always check before trips.

That’s a lot of water and I think you don’t need me to think that. Sure a badly blown head gasket might cause something like that but it might be something worse (and I hate to advocate for the worst case scenario – but you should consider it and prepare accordingly). Consider getting or borrowing one of these

It will let you peer into the cylinders to see if the piston crowns in the affected cylinders look okay or not, or if you have cylinder wall failure. You probably could run it down the intake runner and look at the valves too. Not the easiest thing but it might tell you more than investing a lot of time in a tear down only to have a rude awakening. You could also pull the exhaust manifolds away from the head and look at the exhaust valves too. I hope its a head gasket rather than a broken valve seat or something like that. But the bottom line is you probably would be better off having an 80% sure idea of what you are tackling before you pull it apart. Best wishes with this; you are right, this is not a common problem and I really do hope its a simple fix..