On the SDL, I didn't add the coolant to the head, as I advised you to do. The temp. ran right up to 110°C. sitting in the driveway.

So, I let it cool and then added about 1 1/2 quarts down the upper radiator hose. Started it back up and the temp stabilized at about 90°C. (normal for the SDL). Then I drove it. It also needed coolant every day for a few days.

On the SD, I added coolant directly to the head via the upper hose. It never had any temperature issues, but, needed coolant every day for about five days.

Apparently, you need to add a sufficient amount of coolant so the head is full. Then you won't get an air pocket in the head and cause the temperature sending unit to go off the scale. It does not mean that the system is completely full.........simply that the head is reasonably full to the point where it won't give temperature problems.

You will not see 110°C. on the first day, then 105°C. the next day.......etc. When it's "sufficiently" full, the temp. will stabilize at normal levels.

On some "difficult" vehicles, some folks have attempted to run the engine with the expansion tank cap removed with the heater set on "high" in an attempt to bleed the heater core lines of air. I haven't tried this approach, personally.

As Kerry mentioned, getting a "difficult" vehicle with it's nose up in the air can also be helpful.

However, take the easiest approach first.

now youre confusing my little brain, I thought you said to remove the upper radiator hose and pour in enough coolant until it is full, that is what i did.

unless you mean you advised me to add coolant to the head (via upper hose) if thats what you meant by your first sentence then im not confused.

__________________
1980 300D.

120,000

That's what you should have done. Add coolant to the head via the upper hose.

Now, was it successful??

Last we heard, you were going out to get a battery???

no, last we heard i was out to get a new battery, to replace my 1 yr old interstate which didnt hold a charge, (i got my new one for free since the "old" one was defective). I started her up before and she smoked(exhaust) like a mug, then after some trips around the block she stopped smoking (out of the exhaust).

__________________
1980 300D.

120,000

Yeah.......battery........I remembered it after I typed "starter"

So, correct me if I'm mistaken.........there has been no test of the engine for temperature after filling the head completely via the upper hose???

that "test'' has just begun. she is running.

__________________
1980 300D.

120,000

Excellent. Let's hope for the best. As PEH would say:

If it ain't broke, don't fix it.

Let it run in the driveway and watch the gauge. If it gets up to 110°C., shut it down and repost on the thread. Don't drive it.

I will put my car in your hands mister brian carlton I trust you.

She is slowly getting hotter...temp is rising, will report back in some minutes.

__________________
1980 300D.

120,000

............gets to 90° and holds there...................

..........25 minutes of running time............

It would have hit 110°C by now...........if it was full of air.

Well, after 32 minutes, I'll bet he took it out for a drive.

Goodnight.

noooo come back.

it capped out at 105. I had to drive it a tenth a mile away, and let it idle there since its 145 am here, it hit 105 just idling very slowly.

I'm assuming tomorrow morning I add coolant as some air shouldve left and cleared room for some coolant. Then let it idle and hopefully the temperature will go down?

__________________
1980 300D.

120,000

You can add more coolant in the morning. I presume that you have the heater controls on high.

But, I'm growing doubtful that the problem is air in the system. You had high temperatures before the radiator was changed and before the coolant was changed, correct??

If the temperature is remaining high after you have added most of the required coolant, we need to start looking at other things such as the thermostat.

Was the thermostat changed or checked during any time in this process?

If I'm not mistaken the 617 has a bypass thermostat system. Unlike GM on which the thermostat just stops most of the water circulation when cold, MB allows the water to circulate thru the block when cold then closes that circuit when warm and substitutes another circuit which includes the radiator. Am I right?
I think I have read on this forum that if the 'seat' of the engine circulation system is not good, the thermostat does not completely close that system and water still circulates mostly thru the engine block and not thru the radiator once warm.
Anyone know any easy way to check the volume of the circulation thru the radiator?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yep, that's exactly right. If the thermostat does not "open" fully and shutoff the bypass flow, the radiator won't get the full coolant flow and the engine will run warm.

We've been chasing a problem of air in the cooling system, however, he had the high temperature problem prior to changing the radiator and adding new coolant.

So, the problem may remain, even if the system is properly filled with coolant. I'm not so optimistic, at this point, that the problem will be solved with a new radiator and new, properly installed, coolant.