c63er

A week ago I got the coolant message in the morning when the car was cold. It never came back that day. I've gotten it a couple mornings in the last week. I checked the coolant level in the reservoir and it's spot on, never went down one bit and I've never had to top it off since i've owned the car for the past 40k miles. The car has 95k miles and has been Eurocharged tuned for the last 25k miles with no issues.
My idle is a bit rough as I can feel slight vibrations inside the car, that has been the case for the past 6 months.
I have replaced the plugs already but that didn't help much. The old plugs looked clean and dry.

The fact that my coolant hasn't gone down makes me think it's an intermittent coolant level sensor. I just don't know why the idle is slightly rough, other than a bad coil. Performance feels the same. No smoke under WOT.

I don't have a software to diagnose anything with. I have left messages at both dealerships near me but still no response. I just want to get ideas on how else to diagnose and rule out head bolts stretching. Anything other than a compression test?

I spoke with a guy that owns a MB shop who had worked in the local MB service dept for 24 years. He said that if coolant gets in the oil there is usually bearing failure within 10k miles even if the bolts and gaskets are replaced because the coolant stays in the bearings. Not sure how true that is.

Any suggestions are very welcome, other than "take it to the dealer".

AMG3.2

Have a shop perform a leak down test.

BLKROKT

Either take it to the dealer, or drive another 10k miles and see if the engine fails.

c63er

So very helpful.

bhamg

If your coolant level really is spot-on then you have nothing to worry about. But here's something you might try to make monitoring the level easier and more consistent if you're concerned about it going forward. When the car is cold (ambient temp cold) draw out coolant with a turkey baster until you can see the coolant level just under the black reservoir top front to back. (Maybe 2 or 3mm below the black top as seen from the front of the car, you should be easily able to see a full line of coolant through the white reservoir body). Mark that level with a black dot from a fine point permanent marker. That is your new reference point and any variance when cold will be obvious. Your actual level as seen inside the reservoir with the cap off will be maybe a half inch below the black marker so almost full. When your motor is cold the coolant should stay rock steady on that dot.

c63er

Thanks for the advice. I will do that.
I also ordered this kit:
https://www.amazon.com/Lisle-75500-C...s=block+tester

I will also do a compression test.
If all results from all these tests are good then I will probably just take the car to a local shop that has done quite a few of the "one by one" bolt swaps on these engines and have them do it that way as preventative maintenance.

AMG3.2

I'd do a leak down test over compression.

m a x i m u s

Sounds like a sensor if the level isn't changing. Good luck.

Jasonoff

A compression or leak down test won't tell you if your HG is compromised since bad values could also point to the valves, piston rings, etc.

That tester you ordered will be good enough to let you know the state of your HG. You can also do a cooling system pressure test as well to be 100%.

c63er

Thanks for all the input, everyone.
I have an appointment scheduled to drop off the car at the dealership Thursday morning. The block tester kit arrives tomorrow and therefore I can do that test myself.

I was a bit discouraged by the service advisor I talked to at the dealership. He said that in the 15 years he's worked there they have never done any engine work on a C63. That has me a bit worried about the quality of work they will do if it gets to there. He said that these engines are bullet proof and he hasn't even heard of any having bolt problems. Anyways, the diagnostic will be $210. We will see what that will get me at the end but it sounded like they don't even know where to start diagnosing it.

AMG3.2

To be just as fair though, the tester that I just used, and you both will be using shortly will not give us an indication of a cylinder to cylinder head gasket breach nor a cylinder to atmosphere breach. But then again, I don't think either of those breaches would equate to an increased consumption of coolant. Right?

c63er

If the coolant is dropping that means there must be a path to at least one of the cylinders from that reservoir, so it should detect it.

c63er

I just took this picture literally ten minutes ago. The car is pretty much cold at this point. You can see that the coolant is covering at least half an inch over the black area, I think it's actually more and it's just the angle. The message only appears in the morning so tomorrow morning before I start the car I will check the level first and then will see if the message appears. If it does then clearly this car is messing with me and my paranoia about bad head bolts.

c63er

Holy cow, it was not supposed to cover the entire screen.

I also added half a gallon of window washer fluid in the washer reservoir. I read somewhere that being low on washer fluid sometimes triggers the coolant message. That's pretty damn weird but I still topped it off. Who knows, the message might not show up tomorrow morning.
I am still replacing the bolts though, but it will be one by one and for a lot cheaper.

Jasonoff

There's an issue with the level sensor.

Jasonoff

Unless you had some sort of catastrophic failure, or someone didn't machine a deck properly, or the HG was damaged before install. I'd say it's impossible to have a compromise between cylinders and not coolant with loose/compromised head bolts.

AMG3.2

Okay - now that I actually look at the block, I see that a cylinder to atmosphere compromise would equate to a water jacket seal compromise.

Yes, what you're saying makes sense to me now.

m a x i m u s

Interesting, bc when I went to the dealership for a coolant top off they also topped the washer fluid. I thought they were being nice, but maybe your statement re low washer fluid somehow affecting the low coolant message has some merit?

c63er

Well this might be completely unrelated but I used to have a Nissan 350Z and when the washer fluid was low it would also give me a low coolant warning.

A quick update, this morning I checked the coolant level and it was exactly where it was yesterday, as shown in the picture. Yet I still got the low coolant message. Seems like it's just a bad sensor in the expansion reservoir. I will order a new reservoir today and see if it goes away. At least I am not loosing coolant, which is a huge relief. I still plan on replacing the head bolts after this scare but it will be at a shop that does it one by one for about $1k, instead of $5500 at the dealer where they remove the heads.

AMG3.2

Not a bad price. You doing tappets as well?

c63er

Yep, definitely.

AMG3.2

The revised M156 or M159 ones?

c63er

I am not sure which ones were included in the quote I got from that shop.Most likely the revised M156, in which case I will tell them to put the M159 and pay the extra.

c63er

So I just received the block tester in the mail and immediately did the test. The fluid stayed dark blue for all of the 5 minutes I kept doing it. If this test is the best and most accurate indication of a bolt issue then I guess my car doesn't have it, at least for now. My coolant is consistently at the same level for the past 2-3 days that I have been watching it closely.
I will order a new overflow reservoir now and hopefully that will make the coolant message go away every morning.


On a possibly related note, I got a "Check oil next fill up" or something like that today while driving. Not sure why as my oil level was just perfect when I was checking my dipstick yesterday for any milky oil in the engine. I think this car is trying to make me paranoid and is playing some nasty tricks on me.

Vader27

I know I am rehashing an old thread, but the link seems to be to a tester for motorcycles. Does anyone have a good link to this tester that you all have used successfully?