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1997 S600 Coupe
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Discussion Starter · #1 ·
My thermostat is sticking open, preventing the car from reaching operating temp (97 600 coupe) and the age of the coolant is unknown anyway. I also bought a repair kit for the duovalve (a/c not as cold as it should be, which could also be the refrigerant as the climate diagnostics show 4 [and read it should be around 7, psi I think]). I was looking at also doing the double "T" while the coolant was drained. However, it appears it may have been "taken care of" by a PO. What do you think based on the pics? Sorry for the quality, not much room, as you know, and they're from above. (The burnt stuff is gas that had leaked from the FPR hose and has since been fixed, just hard to clean there.)


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600 coupe, one of the very first built
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2681030


This to me looks like some butchered job on the replacement "TT"
May want to consider doing it right. The V12 part is not the same as the V8 or I6 and considerably more difficult to do (due to lack of space to put a wrench in there)
Good luck.
 

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86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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Definitely cobbled up from household plumbing department offerings. As mentioned, it needs to be done correctly.

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1997 S600 Coupe
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Discussion Starter · #4 ·
Yeah, I've read up on it here quite a bit. I'll get the correct part. From what I've gathered, which took some digging, this is the part number for the M120: 1408302696. Please correct me if I'm wrong.

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1997 S600 Coupe
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Discussion Starter · #5 ·
And thank you for taking the time to answer.

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93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
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Only buy it at the MB dealer(A fresh tee)-No aftermarket, or used/craigslist/offerup/ebay/aftermarket. Change it every 70k to 80k miles because at 90k miles to 100k Miles you are in the danger zone. When that tee blows on the highway you got roughly under one minute to stop the engine before it welds itself together.

Change the thermostat every 5 to 3 years on these cars, so you are at optimum cooling and fuel mileage. Again, factory thermostat-No Stant or gates thermostat...

Martin
 

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1997 S600 Coupe
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Discussion Starter · #7 ·
Thank you MAVA for the info. I ordered the t-stat from FCP (along with a few other things) and found a "TT" at ECS tuning, but will probably get it from the local MB dealer (which I actually used to work at years ago).

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600 coupe, one of the very first built
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this is the part number for the M120: 1408302696.
The M120 engine was used in sedans and coupes. The part number you have, I believe, is for the sedan.
Coupe part number for the "TT" should be 1408303696.
 

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'97 CL600
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3,112 Posts
I have the same car and it is the best car I have ever owned. The first thing we did was change out the dreaded "T" fitting. Just out of curiosity I put it in a vise and took a hammer to it. It would NOT break. Apparently they changed the plastic formula on the 120's or on all '97's. Don't know which. If I were "carguy140" I would find a GOOD indie and tear out the homemade stuff and return the car to Benz original. However, there are 6 GOOD Benz indies within 5 miles of my home but 2 of them won't touch a 12 banger. 😵
 

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600 coupe, one of the very first built
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Again, factory thermostat-No Stant or gates thermostat...
I am the minority here. The OE thermostat is Wahler. Any of the replacements I've seen are also Wahler (regardless of what's stamped on the box, the part inside is identical).

Also, if the housing is not corroded, there is a much cheaper option for the T-stat. P/N 1430602
RockAuto has them for less than $15.

 

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1997 S600 Coupe
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Discussion Starter · #11 · (Edited)
I'm a hands on type of guy, so I'm going to be doing it all myself. Thank you TimeCapsule for the part number, I hadn't seen that one before. At least it's cheaper than the one for the sedan ($37-41 vs $60-65).

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'97 CL600
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I have the same car and it is the best car I have ever owned. The first thing we did was change out the dreaded "T" fitting. Just out of curiosity I put it in a vise and took a hammer to it. It would NOT break. Apparently they changed the plastic formula on the 120's or on all '97's. Don't know which. If I were "carguy140" I would find a GOOD indie and tear out the homemade stuff and return the car to Benz original. However, there are 6 GOOD Benz indies within 5 miles of my home but 2 of them won't touch a 12 banger. 😵
What I forgot to mention was that while the TT fitting was indestructible on my '97 CL600, the hoses connecting to it were NOT!! Be sure you change out the hoses with the valve or else you will lose the engine in a couple of minutes if you don't spot the rising temp. 🙃
 

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1997 S600 Coupe
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Discussion Starter · #13 ·
I ordered the TT hose yesterday from my local MB dealer, the 1408303696. About $50 out the door. Just a heads up though, he said there appeared to be only a couple left in the US (one being mine now). I'm in NC and the part is coming from CA. Just need to get the rest of the coolant and some distilled water to do the flushes. I have all the other parts waiting. As I tackle this connection itself, I'll check the remaining hoses there to see if they also need replaced or were when the last person was back there.

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'97 CL600
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Rare parts? Don't forget Thomas Hansen at The Classic Car Center in Irvine, CA. It is a Benz operation that only works on older Benze"s. Everything I have bought from them was discounted, unlike my local Benz dealer.
 

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1997 S600 Coupe
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Discussion Starter · #15 ·
They must be getting that way. Thank you for reminding me of them, too.

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Discussion Starter · #16 ·
Ok, I got the new TT connection. Which side does the curly hose go? Driver or passenger? I'm only asking since the original isn't in there now (as stated above) and I can't find a good image online. The parts diagrams aren't any help either.


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The long curved part goes to the back of the engine, the short thick 90 degree bend goes to the duo valve.

The best picture I have saved on my computer (sorry, I didn't take any from my own car, which BTW is also with a metal TT) is this one:

2684087


This is a bit more complicated than what you have since this early 600SEL has the option with front and rear climate control, thus, a lot more hoses.
 

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1997 S600 Coupe
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Discussion Starter · #18 ·
The long curved part goes to the back of the engine, the short thick 90 degree bend goes to the duo valve.

The best picture I have saved on my computer (sorry, I didn't take any from my own car, which BTW is also with a metal TT) is this one:

View attachment 2684087

This is a bit more complicated than what you have since this early 600SEL has the option with front and rear climate control, thus, a lot more hoses.
Thank you. So looking at that, the part of the junction where my thumb is attaches to the heater core hose. It would obviously be extra work, but what are your thoughts on pulling the intake while doing this job? I'm not saying in will, but it's crossed my mind.

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So looking at that, the part of the junction where my thumb is attaches to the heater core hose.
Correct!

It would obviously be extra work, but what are your thoughts on pulling the intake while doing this job? I'm not saying in will, but it's crossed my mind.
You'll need to decide for yourself. There is not much space to put a wrench in the area between the engine and the firewall. Pulling the intakes is one option, opening the access plate in the firewall, another.

2684102


This image was cropped from an old thread:


Looks like, if you don't have the hands of 5-years old, some extra work will be needed.
And should you decide to pull intakes, then, you are likely to be doing valve cover gaskets and a few other things "while in there" :))
 

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1997 S600 Coupe
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Discussion Starter · #20 ·
Sooooo, slightly related to this thread. Car started running rough yesterday on acceleration. Got it home, popped the hood and noticed this. Am I right in assuming this piece missing could cause the car to run like it's having a misfire?


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