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-   -   Overheating (http://www.peachparts.com/shopforum/diesel-discussion/102133-overheating.html)

Veloce300DT 08-24-2004 07:33 PM

Overheating
 
Hey guys!
Im having a power/heating/cooling issue. But before I describe the specific probelm in question, let me lay down the conditions of the car. The following is a complete list of what the car needs in terms of repair. Some I know are not related to the specific problem im questioning.

-Needs Engine Mounts
-Small Power steering fliud leak
-Coolant resivoir leaks: needs to be replaced due to cracking.
-Bad Thermostat
-Battery holds low charge (old old battery), needs to be replaced.

Car runs hot, typically running right above the 80 mark on the temp gauge, and rapidly rises once the car is shut off. (due to bad thermostat & coolant leak)
With that said I know why it overheats, and how to fix it; Replace thermostat, replace coolant resivoir, flush, and re-fill coolant.
But heres the main problem I am having:

Lastnight, the car was running hotter than usual, so I started running the heater to bring the temp down. I turned the temperature control up on the climate control, and it started blowing very toasty warm air immediately, without a problem. The temp gauge dropped, and that was that.
HOWEVER, I had to run some errands today. I stopped once for about a minute or so at a grocery store. Car started right up upon return.
Then I stopped by my friends house a couple of blocks away. When I returned to the car about 5 minutes later, it wouldnt start. So, knowing that the battery NEEDS to be replaced, since its holding a very low amt. of power, I got a jump start, and the car started right up. Then i got on the freeway and drove a good 3 miles, and the engine was running hot as usual, so I again, turned the temp dial on the climate control to the max heating position. But this time NO warm air would come out. The air that was blowing into the cabin was the same temp. as outside.

So here are the official questions I am asking:

-Why wouldnt any warm air come on when i turned the heat up, even though it worked fine lastnight? (everything related to the climate control system is new, except for the main thermostat and coolant resivoir as mentioned above)
-Could the fact that the battery is holding such a low charge and died today, make the heater not work since theres not enough power?

- Should the problem go away when I replace the thermostat, coolant resivoir, and battery?

Any help is VERY appreciated.
Thanks so much!

Wasuchi 08-24-2004 07:48 PM

If the coolant level was low that might explain the no heat issue...... otherwise it could be the monovalve.

Veloce300DT 08-24-2004 07:52 PM

I just ran out to the garage, checked the coolant level. It was about 1/4 of an inch low, but its mostly water anyhow with all of the intemittne fill ups ive had to do.. i ran out of my last coolant jug recently. Id say tis time to get this stuff fixed!!!!!!!

Im crossing my fingers that the monovalve is fine, i dont want to have to add another repair to the list!

boneheaddoctor 08-25-2004 03:15 PM

Quote:

Originally Posted by Veloce300DT
I just ran out to the garage, checked the coolant level. It was about 1/4 of an inch low, but its mostly water anyhow with all of the intemittne fill ups ive had to do.. i ran out of my last coolant jug recently. Id say tis time to get this stuff fixed!!!!!!!

Im crossing my fingers that the monovalve is fine, i dont want to have to add another repair to the list!

Isn't there a auxillary water pump for circulating hot water to the heater core like a W116 has? I am pulling threads here but if it has one and it froze up you would have little heat on hiway and more at idle.

Veloce300DT 08-25-2004 03:28 PM

When the heat was working it was working full blast on and off the highway
when it wasnt working it wasnt working both on and off the highway.

Filled up collant resivoir, and am getting a new battery today. I'll see if the heat comes back with a full resivoir on while im going to get the new battery.

TwitchKitty 08-25-2004 03:30 PM

Quote:

Originally Posted by Veloce300DT
Id say tis time to get this stuff fixed!!!!!!!

I am not trying to be mean but when cars are not properly maintained they are more problematic and their lifespan is shortened. It is past time to get this stuff fixed. It is time to familiarize yourself with the term preventive maintenance .

Veloce300DT 08-25-2004 05:04 PM

Just went and got my battery, filled up the coolant resivoir and there ya go. Heats returned.

Twitchkitty-

I completely understand the term PREVENTATTIVE MAINTENANCE.
In the past year I have spent $7k+ on this car, on everything from rebuilding the fuel system, drive lines, belts, hoses, all of the pumps, front and rear suspension, Climate control unit, climate control system, A/C rebuild and conversion to R134A, transimssion components and much much more!
I have done so not only because of my love for the car, but also because I average at least about 25K miles per year!

The car is in AMAZING condition. It runs like a champ, transmission shifts promptly and smoothly, perhaps the smoothest tranny I have experienced in a W123 300DT. And theres nothing comparable to driving a car like this with all of the major mechanical compents in as new shape! Im sure you know what im talking about if you practice what you preach.

These little snaggles, small problems, that I am having are the last of anything on the car which needs tending to, and have only begun to show in the past week or so as I have begun driving the car after a summer trip in Miami. I DONT EVER drive my car more than necessary when it is in need of things. But when it is, I like to turn to the reliable, good ol' mercedesshop, to post my problems, and in doing so can get diagnostic comments, and therefore make an educated visit to my shop of choice for... lets say, PREVENTATIVE MAINTENANCE.

Next up this month:
Engine mounts
Power steering fluid leak correction
Coolant resivior replacement, flush, and refill
Thermostat.
Battery taken care of today!

No harsh feeling twitchkitty, but dont assume somones car care repitoire without knowing the whole story.

cheers!

dieseldiehard 08-25-2004 05:34 PM

Why wouldnt any warm air come on when i turned the heat up even though it worked fine
 
-Why wouldnt any warm air come on when i turned the heat up, even though it worked fine last night?
You have discovered the MB climate control brain, it is pretty smart, you know. What it did was it determined for example that the temp that night was below the temp threshold it has set in its "brain" and it put the heater to "work".

OTOH, the day you selected heat, was it warm, or much warmer than it was the previous night? I bet it was, and that explains why the thermal differential was not met that allowed the heater to come on.

BTW, you said over 80 degres is too hot. The last time I looked at my '85 300TD it was running the normal 83 degrees it is supposed to.

I am not convinced you have a problem other than no pressure in the cooling system - fix that tank and it will probably be OK, unless the radiator is crudded up inside (try a proper flush) or has lots of stuff in the fins and is plugged up form the outside.

You say you have several indy shops, why didn't you just take the car to one of them for a diagnostic instead of risking a warped head or something?
DDH

Veloce300DT 08-25-2004 05:47 PM

Thanks for the info DieselDiehard!
The car has been "sleeping" in the garage for most of the summer, while ive been traveling. It was only on my return trip to SF that the overheating prob. surfaced, which was also the first time the car was really driven since my trip. Yesterday, only upon running my short errands, did I become more concerned with it since the temp gauge was showing much larger variations in temp. So today I dropped by my indy here in the city and had it diagnosed, along with getting a new battery. Your assumptions on the problem are correct.
99% of the time I know whats wrong with the car when somthings not running right, however, I like to be sure by using this forum, to at least gather info before I lay down money on a repair or fix somthing myself. I trust my indys, but I also like to be informed. In this case ive been informed, and my assumptions before posting this thread were confirmed. Thanks guys!


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