bleed the system
 

OK let me start by saying, finished the head on the car, no leaks, now starts on the first crank, no longer have to hold the key for a prolong period to start the car, crank and cam TDC. Did the tensioner, the whole bit. The DAMN car runs HOT. :mad: . Does the system have to be bled after replacing the anti-freeze? If so, where's the bleeding screw:mad: .
Also, the car runs rough. WTF???

Let me say this, you will have to have a lot of air in the cooling system, for your car to overheat.

Allowing for the fact, that unless you can drain both the block, the radiator, and the heating system, you may not get all the old coolent out, HOW MUCH coolent did you have to put in, compared with the systems total capacity.

Bleeding the air out, can sometimes be a long time project, because there are so many pockets, that air can be trapped in.

The sign that all the air is gone, is if your car has one, the coolent tank level stops dropping.

If you do not have a tank, then the level in the radiator, stops dropping. To get all the air out quickly, you need to ensure that the heating system is full on. Make sure you remove cap, only when the engine is cool.

I suspect you may have a crook thermostat.

You can check that, by removing it, and putting it in a cooking pot, but you must suspend it on a piece of string, WHERE IT DOES NOT touch the sides or bottom.

When the thermostat is cold, it should be closed, and as the water temperature comes up, it should slowly open and at the temperature that should be stamped on it, the thermostat should be fully open.

Some tips.

Do not drill or remove the centre of the thermostat, because your car will run so cold, that performance will drop off, and premature engine wear will take place.

Inspect the thermostat housing or cover, for rust as this item often can fail, just at the wrong time. It is cheap, as is the thermostat, so when in doubt chuck them out.

Also is the ignition timing correct, too far retarded and that can cause overheat.

The radiator, have you had it cleaned, it may be even though the coolent may not indicate, be partly blocked with muck over the years.

When you are running the engine, and it gets to full heat, check that the hoses are not being crushed and restricting the water flow.

You can run through these problems one by one, rather than change and do everything, which may not be required.

Let me know if I can be of more help.

Regards

Col Tigwell Downunder

I just completed the cyl head gasket change on the E320 this past Sat morning and during the initial run it ran a little hotter than normal (got up to around 105 dC). This was with a fill of radiator flush and straight water. I ended up flushing the system with straight water three times. Fill with straight water, run the car to temp, let it cool, drain radiator and block and refill. The manual does say that the head gasket does not seal until it has been run to temp. Don't forget to turn the heater up wide open to insure water flow through it too.

Finally, I made up a mixture of one bottle of water wetter, approximately 40% MB coolant and the remainder distilled water. Made a trip to Atl on Sunday and it now runs between 85 and 95 dC (based on whether sitting in traffic or on the interstate). I do have a very, very slight miss when it is at operating temperature at idle and I am working through that issue but otherwise the car runs great and I am getting the gas milage I am supposed to be getting. Unless you were really "feeling" for the miss you would not even notice it.

Go to your local parts house and get a coolant mixture tester. It is way easy to have too much coolant in the mixture which will make it run at elevated temperatures.

Col Tigwell and Engatwork,

Flushed the radiator. bled the system and the car no longer is running hot:D . Although I do for some strange reason do feel a slight miss at idle. DAMN,DAMN,DAMN. I did have this slight miss even before I did the head. Was so much hoping that the head job:D, would take care of this miss. Changed the seals and the holders on the injectors also while I was doing this job. 205k mi., maybe it's time for new injectors or maybe some Techron poured into the next fill up.

Next project is to take the car to a good tranny shop that knows MBZ. I still have a leak from the tranny that the last shop jerked me out of $600. Tranny shifts fine but it has a leak that the other idiot didn't find. I figured he was pretty good since I always saw MBZ, Bimmers, Lexus and Infinitis in his shop. After doing a more thorough investigation, they were all call backs because he never fixed the problems with those cars:mad:.

Wish me luck...

To properly re-fill the cooling system, add coolant through the thremostat opening until it won't hold any more. Then fill the radiator. That should do it.

Bill

Richie:

I recall you saying that you had pulled the head recently and hadn't timed it correctly? One question... did you re-use the head gasket?

:confused:

~Paul

__________________
'91 300E, 212K miles

For future reference, to ensure no air gets trapped in your coolant system when refilling, remove the bleed screw shown in pic until water begins to overflow. Replace screw (14mm), then finish filling expansion tank to halfway mark.

http://www.members.aol.com/buckweeat/bleed.jpg

Paul,

I installed a new head gasket when I reinstalled the head. I hope that's what you mean and not did I repull the head and install another head gasket after the car ran hot. I didn't have it running that long. Once it started to run hot I shut it down.

Yep, that's the screw that I removed to bleed the system. Ya have me worried Paul. Post back :( . I 'm sure all is good though. Drove the car yesterday and except for the slight miss/rough idle everything seems fine. The rough idle was there before I pulled the head. Was hoping the guides and the seals were the culprit to thst symptom.

Rich..
 

The former is what I meant .... so it sounds like you're good to go. Nice job BTW! Pulling/replacing head and timing cover is a huge DIY job. I'm sure you don't wanna go through that again. :D

I learned the hard way that once you torque down a head, you cannot re-use the head gasket, no matter how long you ran the car:rolleyes:

~Paul

Whilst I am not an expert on MB injectors, I suspect you may have an injector hanging up.

You have rulled out the head with all the work you have done, but I expect if your car was using oil before you started, that the injectors need servicing.

If you were here, I would suggest you memove the injectors, and take them to a Bosch injector shop for servicing.

The problem with miss's, is the fact that there are so many factors that could come into play.

A simple suggestion, which may assist, is to run the car on a very dark night, with the hood open. This way if you have HT voltage tracking down say a plug lead, or the distributor cap, you will be able to see it. Try removing the distributor cap cleaning it with a rag with gasoline on it, and carefully look for scrathes or hairline cracks both inside and out. Pull the HT leads one at a time, inspect the terminal that goes from the HT lead into the cap, and clean both metal parts, of any rust or mould you see there.

With luck you can find that it is something simple.

Let me know if I can be of more help.

Regards

Col

Paul and Col,

Thanks again for the info and replys. Paul you are 100% correct. I hope I have to never do that again(but again, if it's going to save me in excess of $1k?):D .

Col, I've thought about the dist. cap, will look for any cracks. The wires are just about brand new, so I know that's not the problem. Also thought about getting new injectors altogether. I just need to take a breather right now :) .

Wouldn't be the worst idea in the world to check the mixture adjustment either.
Gilly

Gilly,
Mixture adjustment? What the hezey:confused:? Please explain. That could've gotten messed up durung the course of the head job?:confused:

OK, here we go..