My 84 300cd was starting to puff at the release pressure small hose at the over flow tank,right after start up ,I wasnt putting two and two together ,my thoughts were a thermostat ,which was done or a radiator needing service ,got that completed and decided to check the oil .It was way high on the stick.Not looking good ,any advice on head gasket replacement ,whats next in my big adventure? .Might go after a motor transplant.

so the oil is the color of a chocolate milk shake...

a head gasket... you can do it.. just keeping the timing will be fun. Some have rigged bungie cables to hold the cam gear and chain while removing the head

That sucks. I wonder how many miles the car has? If it's a keeper and the motor is running well otherwise, I'd really consider doing the head gasket. It's not that hard, but it is time consuming. Here are a couple of tips I'd pass along from my experience. Don't attempt to pull the head without a crane/hoist. That thing is heavy! Remove the head with the manifolds attached--forget what the FSM says about that. Don't forget to remove that little oil line tie-down in the back. I lifted mine 12 inches or so before I found something not letting go. Make sure you replace every little seal on the turbo drain and be certain it's seated correctly. I think mine is shoved in a little too far. Hmmm, anything else? Oh, as long as you mark the chain and the cam gear, don't worry about hanging the chain from above while you lift the head. It looks all dark and scary down there, but even if you get some slack in the chain, don't worry, it doesn't skip teeth. But do be very careful not to drop anything down the chain galley--those things are not retrievable without pulling the engine. Which reminds me of one more thing--make sure you put a block behind the cam when you release the cam gear. Especially in my case where the car was sitting slightly uphill, that damn cam slid to the firewall lickety-split and I damn near lost that cam washer down the galley. Anyway, you'll have fun doing it--I did. Stay close to this forum. There are some experts here that helped me beyond belief. Good luck!

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1998 E300D, 287k, barely broken in.

This motor will probably sit this one out ,it already had low compression when I bought the car ,I really would like to do a head gasket but Im perty sure this motor would be a problematic child in the future .I was considering a motor transplant with a car I had found ,the motor purrs with that slight ping of diesel ease when Id investigated it around 2 months ago.Besides ,I got
Jimmyl s post for step by step.
Last month this car drove me to Austin and back ,300 miles in the round,it had plenty of power ,started making a very noticable sign of dicontent back on arrival,not overheating ,but 2 miles from home and it had to take a piss like a race horse out the release hose.Kept it parked and began to go thru it little by little to get to the bottom of its issue.My mechanic ,after describing it on the phone ,made the diagnioses,but the oil was not clouded or milky."Just wait",he said.So the head gasket blew at a cylinder wall and gas pressures from the combustion was making it into the radiator.Makes sense ,the pressure in the radiator would be enough to test the overflow tank after just a minute after start up.