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  #1  
Old 04-23-2011, 08:24 PM
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New owner/ 240D temp issue after t-stat change

Hi, guys need some help. I just got this MINT condition 83 240D with only 60K on it. The temperature seemed always high to me, so I ordered BEHR t-Stat and temp sender from AutohouseAZ. Tested the new T-stat in hot water it opened at 81'C. Friend put it in for me.. And my dilema started.
now .. when I drive on hwy the car runs on 100'C mark (on gauge) when I stop and use my IR thermometer it reads 90-92'C by the area of the sender on block engine.
So, I need suggestions guys. Do I drain by the block engine and re-fill it..
Do I have air lock ? I tried few tricks from this forum already, I put the car on ramps ( nose up ) and run the heater etc. no go same outcome.
- I am using correct OEM coolant (Mercedes )
- I am using correct radiator cap 1.2bar (Mercedes) should it be 1.4bar ?
Is the hash mark on gauge after 80'C ... 100'C ?

Thanks[IMG]file:///Users/Keram/Desktop/IMG_0152.jpg[/IMG]

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New owner/ 240D temp issue after t-stat change-img_0152.jpg  
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  #2  
Old 04-23-2011, 08:36 PM
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If your heat is OK, the cooling system is full. Verify that the t-stat was installed with the arrow facing up. Failing that, it could be the temp sender, I had to try three in my 300D before I got one that approxiamated the real temperature of the engine.
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  #3  
Old 04-23-2011, 08:39 PM
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Thank you

I will have to do that my self, I used friend .. so it is touchy subject.
I asked to replace T-stat and sender at the same time ( had no problem with them just the temp seemed to high to me ), should I put back the old one ? it was not bad, I just replaced it with new one just in case...

Where did you get your temp senders.. I used BEHR from Autohouse.AZ.

Thanks
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  #4  
Old 04-23-2011, 11:23 PM
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So if I read correctly, the photo indicates where the car is on the road, but it rises to the hash mark just above when you park the car idling. Does it stay there, or slowly cool down while idling?

I think you confused things a little by replacing both the T-stat and the sender at the same time. It is often best to take things one step at a time (that is, one component change at a time).

The sending units are notoriously inaccurate.

Check the wire that attaches to the sender for any signs of cracking or chafing; this will alter the reading.

Also if you are using a IR thermometer, I would point it at the upper radiator hose, not the thermostat housing.
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  #5  
Old 04-24-2011, 10:45 AM
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If you can get your hands on the old temperature sensor put it back in for a test. Simple change.
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  #6  
Old 04-24-2011, 10:49 AM
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I'd also check to be sure it has not burped and is low on water. You need to usually fill them and run them until the stat opens to get the air bubbles out of the system... this will take a cycle or two.
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  #7  
Old 04-24-2011, 11:40 AM
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Replay to Zacharias

When I am driving 60-65MPH, the temp gets to the hash mark and it stays there, when I stop the car and use the temp gauge it shows 90-95'C, when lelft idling it goes down to the the temp that pix shows in my original post.
Yes, now I know not to change few parts at the same time... you live you learn... I still have the old t-stat and temp sender... I may try to put it back the temp sender just to see what it does.
Q1. Now, here is the question, what is the function of the aux fan at front of the radiator .. I newer heard it on.. but when I get power to it.. it starts to work. How is this fan triggered.. by some kind of switch ? if yes, where is it located or if you know the name of EPC part number, so I can find its location...
Q2. when you drain coolant do you drain the block of the engine also... by the bolt on the engine...?

Thanks for all the help ...
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  #8  
Old 04-24-2011, 01:50 PM
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It sounds like you've got a few questions:

1) Is it running too hot?
2) If it is actually too hot, what should be done to reduce it?
3) Is the temp gauge in the cluster accurate?
4) If it's simply showing too hot, what do I do?

For #3 and #4, I think you're okay. If the IR sensor on the outside of the block shows just a few degrees cooler than the gauge whose sensor is inside the block/coolant, then you're probably okay. The Germans are methodical and the gauges are logical but not linear. 40-60-80-100-120 for the temp (just like R-1/4-1/2-3/4-1/1 - why not F? - for the fuel).

There are two p/n's for the sensors in the head: one for the gauge (0055422617) and one for the glow plug temp sensor (0055450324). I don't know the differences, if any, but if you're really concerened about accuracy you could double check you've got the right one. For the aux fan, ******** may have some bad info. They have an "aux fan switch" in the cooling section (0008208010) but I'm unaware of an electric "aux fan" except for the A/C system. They have the correct pic and p/n in the A/C section.

If in doubt, check EPC for the right sensor for your car and your cluster and match that against what you've got installed.

The thermostat might be installed wrong, or you may have some other issue. If the temps are behaving the same as with the other T-stat and the gauge, maybe they're correct. Or maybe the old T-stat was installed incorrectly and the friend simply put the new one in the same way. An incorrect install can make it run hotter.

You might have air in the system making it run hotter. Search for "burp". Although it sounds like you've done that.

You might have a partially blocked radiator or debris between the condensor and the radiator.

Your fan clutch might be iffy (does the 240 have the viscous clutch?)

You might be running the A/C and your temps will be a bit higher.

Or maybe it's hot where you are and you're driving the car hard and the temps are accurate, just a bit above what you'd like.
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  #9  
Old 04-24-2011, 07:46 PM
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Thank you Yak

Yak, Thanks a lot for your time and willingness to help... below are few answers...

T-Stat - Iam going to try to drain the system using the bolt on the block, and put new T-Stat ( I will make sure I put it in right way ).
Temp Sensor - I will use another one just to make sure to eliminate hardware failure.
Coolant - I have used Mercedes OEM coolant and will stay with it.

What do you think about this modification ? R U for it or against it...
http://www.dieselgiant.com/thermostatreplacementandmodif.htm

Q1. When filling the cooling system with new coolant, do I put front of the care up on ramps ?
Q2. Some people suggested to fill the engine with new coolant via upper house ( disconnect from radiator and put it up and fill it up ) put it back on the radiator and fill the radiator full.
Q3. At this point do I run the car with heat on and top it off the difference with coolant to full ?

Thanks,
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  #10  
Old 04-24-2011, 11:32 PM
Yak Yak is offline
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Looking at the pics, it appears that the holes allow more coolant to flow from the radiator to the block. The "in all directions" thing makes no sense.

But, like it says, until you've done everything else I wouldn't try it.

First I'd make sure the T-stat was installed correctly, to include the arrow in the UP position like Tango said and like the FSM says, but is conspicuously absent in that DIY. You can see the arrow in the pic of the undrilled T-stat, so maybe worth a mention.

Look at 20-005, page 5. If you're going to pull the T-stat housing maybe see if you can check if that "integrated vent" is clear. Low pressure air to check it?

My thinking is that if you replace stuff (correctly) and the same symptoms re-appear, then they're not the problem so you need to look elsewhere.
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  #11  
Old 04-25-2011, 01:18 AM
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Apparently the only time the Aux Coolant Fan goes on is when the A/C Reciever Drier Thermal Temp Switch reaches 126 degrees F and that turns the Fan Relay on and turns the Fan on.

See post #6 it has a wiring diagram.
http://www.peachparts.com/shopforum/showthread.php?t=297551
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Last edited by Diesel911; 04-25-2011 at 01:30 AM.
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  #12  
Old 04-26-2011, 12:21 PM
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Quote:
Originally Posted by Yak View Post
>snip

You might have a partially blocked radiator or debris between the condensor and the radiator.
This was mine. New 'stat and pump did not completely fix. Removed the radiator and there was a wad of fluff, bugs and hair and debris, between the rad and the cond. You could not see thru the radiator there was so much dirt in it.

Hosed it out, reassembled. Heating issue is completely gone, regardless of outside temp, speed, or with or without air.
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  #13  
Old 05-08-2011, 10:36 PM
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Temp Issue is gone

Hi, guys.. Thanks for all of the help and suggestions. Actually it turned out to be the temp sensor. The brand new one ( UroParts ) was off by 7'C from the actual temp of the engine. We put the original back in, and temp stays at 85'C all the time regardless of the speed or outside temp. My next step would be to run it with AC on.. I will let you know what I find...

Thanks again to every one who tried to help..

Mark
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  #14  
Old 05-08-2011, 11:44 PM
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Quote:
Originally Posted by keram69 View Post
Hi, guys.. Thanks for all of the help and suggestions. Actually it turned out to be the temp sensor. The brand new one ( UroParts ) was off by 7'C from the actual temp of the engine. We put the original back in, and temp stays at 85'C all the time regardless of the speed or outside temp. My next step would be to run it with AC on.. I will let you know what I find...

Thanks again to every one who tried to help..

Mark
Engine temp measured where? At the stat or the top rad hose?
So... Which sender is correct? Just because the old one indicates a number you "feel" is more accurate, does not make it so... It amazes me how many owners of MB get so concerned about engine temp as it approaches 100C... Chill Out, guys (pun intended)... Are the engine temps of diesels that much different from gassers?
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  #15  
Old 05-09-2011, 07:57 PM
Yak Yak is offline
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Quote:
Originally Posted by keram69 View Post
Hi, guys.. Thanks for all of the help and suggestions. Actually it turned out to be the temp sensor. The brand new one ( UroParts ) was off by 7'C from the actual temp of the engine. We put the original back in, and temp stays at 85'C all the time regardless of the speed or outside temp. My next step would be to run it with AC on.. I will let you know what I find...

Thanks again to every one who tried to help..

Mark
Not trying to exonerate the Uro part, but since they work on measured resistance it may have been corrosion on the connector at the wire. The act of installing/uninstalling/reinstalling may have cleaned it up.

Or it may be a bad part.

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