Signs of a blown headgasket - PeachParts Mercedes-Benz Forum

300SD81 · #1 07-19-2008, 07:58 PM

I significantly overheated my new car on the way home with it when the water pump blew. It still seemed to start and run fine when I moved it off the tow truck and onto my driveway. I just got the new water pump installed, and while doing a citric acid flush, I noticed the upper hose was pretty hard, I let it cool and it was still kind of hard, I might just be imagining it since the engine was still pretty hot, and I have no idea if citric acid will release any gases while its in there... Anyway.. what are the signs of a blown headgasket? And if I have one, how much is it going to cost to fix it? (parts/tools only).

79Mercy · #2 07-19-2008, 08:00 PM

White smoke out the rear is a sign that there is water in the combustion camber. Oil in the coolant, or visa versa.

uvula · #3 07-19-2008, 08:07 PM

If your oil & your coolant mix together for a while, both sides (the oil system & the cooling system) will start looking like a mint-chocolate milkshake which, as you can imagine, isn't good for anything. Before that happens, though, your coolant will look and smell really oily which is a pretty darn good sign that you've got a headgasket leak.

Cervan · #4 07-19-2008, 08:15 PM

if there is water in the oil, dont drive it you will spin bearings. theres no way to tell if anything is damaged without taking the head off. Then you will beable to see if you scored the cylinder walls or warped the head. if its a simple headgasket failure, nothing more. Maybie 70$ in parts. if it warped the head, then your out about 50-100 dollars in milling to get the head flat again. If it overheated to the point where you scored the cylinder walls, thats an overhaul 1000+

Oracle12345 · #5 07-19-2008, 11:14 PM

Loss of power, low compression readings,

Doing the head isnt too bad but you will need new head bolts and whatever else got damaged in the head

yellowbenz · #6 07-19-2008, 11:24 PM

Is this a common mode of failure for the headgasket on an om617? I thought these iron head engines where more resistant to damage from overheating.

uvula · #7 07-19-2008, 11:56 PM

Quote:

Originally Posted by yellowbenz

Is this a common mode of failure for the headgasket on an om617? I thought these iron head engines where more resistant to damage from overheating.

I don't think that it's common - the engines are pretty damn solid - but as car guys, you and I both know, anything can happen & usually it'll be when we're least prepared for it.

Cervan · #8 07-20-2008, 12:43 AM

metal is metal, the 617 engine will warp just like anything else if its overheated.

300SD81 · #9 07-20-2008, 01:05 AM

I don't think its blown anymore, drove it a bit and there doesn't seem to be anymore pressure in the hose, oil/water are separated, and the only smoke the car is making anymore is black when I hit the accelerator.

Cervan · #10 07-20-2008, 01:28 AM

Quote:

Originally Posted by 300SD81

I don't think its blown anymore, drove it a bit and there doesn't seem to be anymore pressure in the hose, oil/water are separated, and the only smoke the car is making anymore is black when I hit the accelerator.

If i were in your position, i would still remove the head just to make sure everything is in good condition. Would you rather spend 4 hours or so, and know the condition of your engine or just chance it blowing up when its most unconvienient.

Hatterasguy · #11 07-20-2008, 02:00 AM

Send a sample of the oil out to a lab. If they flag it for coolant than you know it needs a head gasket.

barry123400 · #12 07-20-2008, 03:48 AM

There are different levels of getting hot. If you did not loose pretty well all your coolant in the engine chances are everything will be okay. The diesels seem to develop less head temperatures than gas engines. Plus the mass of the cast iron head is a plus if a little coolant is still flowing.