Tusc

These two have popped up in the past week.

1 - Low Coolant : Check Level

I checked the level and it is not low. Temp sits at 95*C and does not rise or fall. Fans kick into High mode once that temp is attained.

I have read that the temp sensor located in the (overflow?) tank could be bad, but I can't help suspecting that I need to replace the thermostat in this case.

Corroboration? Dissent?

2 - Misfire.

This was a one-time-only event. I keep a blown corvette at my dad's house and went down to work on it. I left the daily parked for a day or so. When I went to start it, there was a clear misfire and I immediately shut the car down. Veteran car guy idiot that I am, I then immediately restarted the car and the misfire was gone. It has not repeated. And I have never felt the engine falter prior to this.

Pulling the OBD2 codes revealed misfire on cylinders 1 through 6 (would that be driver side cylinder bank for Mercedes?) and a Map sensor error.

Note: I have yet to read anything about this engine or even break into it any farther than changing the oil as of yet.

That said, does this car run one Map sensor, or is there one per bank?

Given the low coolant issue above with the fans kicking on high, my secondary thought pops up: if the engine is running hot at 95*C, is it then also fouling the spark plugs by running rich and pulling timing to cool the engine and keep a safe detonation?

Whatever the answer is for the number of Map sensors, I'm definitely going to replace it to be certain.


So I'm thinking I need to order a new thermostat and map sensor. What else is advised?


Don't worry, guys. I figured out the Low Washer Fluid warning all by my lonesome.

Tusc

Ah! And let me also ask what the correct part numbers would be for these two, as well as where to find the best pricing.

In the five minutes I've searched, I've discovered that MB only sells the thermostat HOUSING for $390. Is this true? Fine if it is, but I'd be much happier if I could find the $20 to $40 thermostat which I know will be found inside.

tusabes

95 is the correct temp, do not buy a thermostat

yes if you do buy one you need to buy the whole housing

You did not post what year car or model S class you have but I'm assuming you have a 2003-2006 s600 since you mentioned "misfire 1-6 and same bank "

these may be simply random errors but most often they are signs of a failing coil or voltage transformer (that thing that sits top center of engine )

As far as what coolant is low I bet it is your intercooler coolant - it is a separate system from the radiator coolant , but they both trigger the low coolant dash error . If your intercooler is dry , then your car will pull timing and misfire

The fill cap for the intercooler is at the top back of the engine but do not open it because the system must be bled if you open it . Note however if you install an overflow then you can ensure it is always full . Here is how to install an intercooler overflow

https://mbworld.org/forums/m275-v12-...servoir-2.html

Tusc

Excellent write-up, and what looks like a dead simple and common sense mod. Already pulled the trigger.

Tusc

Update. Drove home tonight watching temp carefully. It jumped like a rabbit in just seconds. 95, 115, back to 95. It stayed there. Then hopped to 110 and started to climb. So I'm pulled over letting it cool. New change: the fan had been running at full tilt before when system read 95 since the weekend. Now no fan at all that I could hear when I showed down.

Relay? Fuse? Fan motor? Temp sensor?

I feel like replacing everything at once this weekend so it is all fresh and the problem is gone.

Any new thoughts given new info?

Tusc

Restarted to check temp. Going down. Fans kicked on heavy now. Temp gauge looks like it's having a seizure. Coolant overflow, upon checking, is empty. Crack the cap and it fills quickly.

There must be a leak. I could hear a faint hissing at driver front area. Coolant tube going down from there is limp and empty. I see no leak. When I changed oil last month, what came out was just oil. The car doesn't burn anything out the exhaust or sputter. Nor has there ever been a pool of any sort wherever I park it. And yet now I look in the engine bay as see white speckles across the front covers and belt area. I don't recall ever running through cement area, but maybe some gravel at one point with fine silt. I'm letting a drop of coolant dry in one spot now just to see if it dries white like that.

This will make for a fun weekend. =)

Give me all your parts suggestions and numbers so I can order and have them for the weekend. =)

tusabes

When it overheated that will cause coolant boil over and the white spots

with your new info it sounds like a bad fan controller , which is a very common issue

ItalianJoe1

All common issues on this engine. Fans are dying at this age, new aftermarket units are available for under $300 and easy to change, just replace the whole thing. It's a massive fan, with a brushless motor, so they rarely fail, it's usually the controller that fails.

When the fan is failing you will get the "Coolant ~ Visit Workshop" message, it's because the fan isn't sending signal back to the M/E and cluster properly.

Low coolant can be a faulty level sensor in the bottle but is most often a leak. On the turbo cars, the lines can leak at the turbos, the o-rings harden and fail with age. Engine out job to replace though, despite the simple parts.

Also, there is NO warning for the I/C system being low, there are no level sensors. You will find stored codes for intake temps too high and pump failures, but no lights will come on, the car will just be down on power when in boost. If it's always been like that most owners will not know, and will be amazed at how fast the car is once the i/c system is bled and working properly.

Tusc

SO.

She drank 2 full gallons of coolant. Where the heck did the rest go?

I'll have to do some hunting for leaks. If it were consumed, I'm sure the engine would act up and/or I'd see a cloud out the exhaust - which I don't. The oil came out clean. These two facts make me happy and hopeful for the head gaskets, btw. Yet I see white spatter around the front of the engine. Likewise, still no pool of liquids anywhere.

For now, I'll have to keep diagnosing. But I'll say this... with 2 gallons in her, the temp went from 95*C (3/4 from 80 to 100) down to just a hair below the midway, so about 88*C. And it stayed there faithfully.

I'll leave it parked until the weekend when I can get some time in the garage. For now, I think I'll swing down and pick up the stick shift car for the commute over the next few days.

Recap:
Low Coolant Warning was CORRECT.
White spatter at front of engine.
2 gallons coolant consumed
Fans functioning intermittently - (if the system was low on coolant and had air pockets, doesn't it stand to reason that the fans and control module may simply not have been getting a correct temperature feed?)
Erratic temp gauge was likely due to air pockets, low coolant.

At the moment, I'm not sure where to go next.
I should think not the thermostat at present.
Likely need to locate a leak.
Unsure about anything else beyond that.

ItalianJoe1

Pressure test it and check for leaks. The system capacity if 4 gallons. It's huge.

AlexMercedes

lol this is the most true statement ever when it comes to the TTV12. I was so wildly shocked at the acceleration after fixing my IC system and installing an overflow reservoir. The car was always fast, but when I fixed the system 3 years after I bought the car without even knowing about it failing, it felt like I gained 300hp. It's stupid.

Tusc

I swapped it out last night for the other car. On the half hour drive down the temp stayed dead on at 80*. Then a mile from destination it hopped to 95 again. I'll diagnose the leak when I can. Might take Friday off.

TenZero

I would add that at the age of these cars, the plastic tanks on each side of the radiator are susceptible to fatigue and cracking which will result in leaks. The radiator in mine just recently developed a small crack just above the coolant outlet on the driver's side. This resulted in the 'white specks' you describe in my car as well. Mine would intermittently leave a small puddle, or sometimes not. The nature of the cooling system operation means that the system is more likely to leak during driving (under pressure) and then possibly self seal when stopped. (especially if the cap is loose or doesn't seal completely) Keep in mind that the actual crack can be very difficult to find, and the fan can also distribute the leaking coolant around the engine compartment, frustrating your attempts to locate the leak. Because you say it doesn't leave a puddle, my money is on the plastic radiator sides. If you can't find it yourself, pay for a simple pressure test, like Joe suggested. That will find it for sure.

ItalianJoe1

I have seen it first hand, a car comes in for plugs or oil leaks or whatever, in the process I find a degraded cap that hast allowed the system to boil off fluid, so I fill and bleed and replace the cap. The customers never come in with a power complaint, but they always notice that the car is more powerful afterwards.

Sadly, most V12 owners are not enthusiasts and drive quite slowly. It's a shame, as the engine is really a sweet unit when it's working as it should. The car is just stupidly powerful everywhere and still totally silent and smooth.

ItalianJoe1

Yes, very accurate info. The radiator tanks fail on all the older benzes, and the leak can be very high in the tank so once the level drops a little, only air comes out, and you have a hard time finding it unless the system is full and pressurized.

TenZero

"Low Coolant Warning was CORRECT.
White spatter at front of engine.
2 gallons coolant consumed
Fans functioning intermittently - (if the system was low on coolant and had air pockets, doesn't it stand to reason that the fans and control module may simply not have been getting a correct temperature feed?)
Erratic temp gauge was likely due to air pockets, low coolant."

Remember, coolant temp sensors do not measure temperature correctly on steam. In the event your coolant level is low enough to expose the sensor to "air" or "steam", then you have a significant leak indeed. Large fluctuations in the coolant temp reading on the gauge point to this. A leak this big should be large enough to find easily. Price the cost of a blown V12 head gasket if you're tempted to 'let it ride'. EEEK!

Tusc

Ha, no.. Definitely have her parked until I can chase it down.

Tusc

I haven't had time to breathe. But I did stop down two nights ago. Haven't got it on jacks or dug around yet, just eyeballs it with a flashlight.

​​​​​​It appears the leak source is localized to the driver front area. The car has previously not leaked at all. Can anyone suggest possible / likely sources in this area for me to start looking?

ItalianJoe1

Radiator usually, check for cracks at the tank/by the upper hose.

Tusc

Would anyone here have the service manual in .pdf format, or be able to share the step-by-step to change the radiator on the car?

With such close proximity under the hood, I want to read ahead on this one before diving in. It's not an old Chevy, after all, so I doubt this is a 30 minute job.

Edit: of special attention would be any key parts I should buy ahead of time (things that break or are hard to reach otherwise and this is the right time to replace them) and/or any special tools needed to facilitate a .... well..... less of a bang-your-head-on-the-wall experience if I can avoid it. Doubly so since I've been working around some health problems recently.

Edit 2: is the factory MB replacement radiator the best bet, or is there an upgrade which will is plug and play?

TenZero

I just replaced the radiator in my S600 a couple weeks ago. I found a couple of write ups using forum search, and some of these had some good info. Something I did, which no one else mentioned, was to remove the top cross brace across the front of the car. Theoretically, it's maybe not necessary to do so, but removing it makes everything SO much easier. It's only about a dozen bolts to remove it, and you have to take your time to align it properly on reassembly, but I would do so. There are several bolts which others have reported they struggled with, that I found are fairly accessible with the crossbrace removed. Downside: Removing those bolts disturbs the paint, and may make the car appear to have been damaged and repaired to a prospective buyer. I didn't care, because my car *has been* damaged and repaired, but you might.

This would be the time to replace your serpentine belt and tensioner pulleys if necessary, and you'll want to have 2 gallons each of coolant and distilled water on hand. I found a new coolant recovery tank available on Rock Auto for only 30 bucks so I replaced my old one, which was in sad shape and had a lot of dirt and sediments in the bottom of it.

For my new radiator, I went again to Rock Auto, and got an APDI replacement for about $110. This unit fits many W220 applications, and has a fitting that needs to be blanked off in the S600. The rad comes with the necessary rubber cap and clamp to blank off the unused outlet, but you should know about it in case that bothers you. I'm guessing the $850 factory radiator is a more exact replacement. Other than that, it bolted right in with no problems, and everything fits perfectly. Having the cross brace removed made lining everything up on the install much easier. Do yourself a huge favor and tape cardboard to both sides of the new radiator to protect it before you try stuffing it in there. And be warned: the oil dipstick tube will do its best to stab a hole in your new rad during the install. Plan on unbolting the bracket, and bending it back toward the engine for clearance. The rubber intercooler lines can be tucked back out of the way for enough clearance that you don't need to remove them, or drain the IC system.

I ended up with a new radiator and catch tank from Rock Auto, and new coolant and a new upper hose assembly from Mercedes, for about $240 all in. I was able to do everything in about 4-5 hours from start, so set aside a day. My car actually runs measurably cooler with the new APDI rad, as it is touted to be a new 'high efficiency' design, with more coils and thinner tubes. Where it used to run down the highway with the needle steady at 95 deg, it now hovers between 85 and 90 in most driving. I'm very pleased with it, and I'd use one again, especially for the price.

Tusc

I thought I had scored a deal on rad and hoses until I realized I had ordered the charge cooling system radiator and hoses. Doh!

Cancelling that one and moving on to find something else available before this weekend.

TenZero

Rock Auto took 2 days to get the radiator to me. Another 2 days for the catch tank, but you can pay extra for expedited shipping. I bought new upper hose from the dealership for almost $80.

Welwynnick posted some good tips in this thread, at post #58.

https://mbworld.org/forums/s-class-w...ted-you-3.html

The only thing I would add to his instructions is to remove that top cross brace, as I explained. Once you have the parts in hand, you can do it in a day, easy.

Tusc

Thanks for the link.

​​​​​​Finally diving into the car today.

Beginning the radiator project and I notice the layers of dried coolant on the base of the thermostat housing.

Not sure if it is from spray or is its own leak.

Replace thermostat housing?

If it leaks, then I feel this is still a secondary issue. The radiator had only about a gallon to drain after sitting for two weeks leaking in the driveway. Likewise, when refilled two weeks ago the thermostat itself appeared to function properly when driving. If anything, if it leaks when done with the radiator then I think I'd want to remove the thermostat housing and refresh it's connections.

tusabes

I would leave it alone at this point , keep driving and see if you notice any further puddles first or if your problem was fixed