2013 GLK 350 4Matic just shy of 300,000 km's

Hi folks,
Yesterday my battery died, luckily in the parking lot of a Canadian Tire store. Was getting the red battery warning just before in the display. Stopped the engine and went into the enginering menu (press and hold "end call", then press "OK" buttons on steering wheel, went into the display menu) and found the battery was showing 12.1 volts). Started the engine and noticed the voltage was dropping with a negative current draw. Was going to go home, but the engine started chugging, display showed various systems shutting down, and then the engine finally stopped. Luckily, I hadn't left the parking lot yet.

Bought a socket set, removed the battery (negative terminal first) then went into the store with the battery and tested it. One cell was bad in a genuine MB battery after 2 years and 10 months, only had 2 years warranty. There was slight bulging on the battery ends at the lower part of the case (sulfation, maybe?). Bought a new exact AGM replacement at Canadian Tire with 5 years warranty. Car started and works ok.

The display showed 12 .4 volts and it began dropping again with a negative current on the display.Decided to head home (20 minutes away).

On the way home, I began revving the engine (2000 to 2500 RPM) in the faint hope of getting a bit of charge. All of a sudden, it began charging at 14.5 volts with a Positive current value of about 35 amps. When I got near home (15 minutes away), charging stopped and the voltage was back down to 12.2 volts with a negative current draw on the dashboard display.

The connections are very clean; I twisted the connections back and forth a tiny bit as i was reconnecting to ensure good contact and then tightened up.

Any ideas where to check from here? The sensors on the terminal ends of the battery wires look good (doesn't mean they are though). Could they have been damaged at the MB garage when the original equipment ( ! ) battery was replaced?

Going outside to do a bit more checking. Will attach my charger. I forgot how heavy those batteries are, and how much fun they are to remove at -12°C (12 degrees below freezing). Yeesh.

1) Any thoughts on how to check the sensors and alternator output? I'm curious how it would charge the battery for that short time
2) Any ideas why charging worked for that short time?
3) Is it ok to run my charger's battery tests while the battery is still connected?
4) Is it easy to (gulp) replace the alternator?
5) Are there any rebuild kits available?
6) Are the alternators a generic fit part between variants of GLK350 and/or variants of GLK250 (found that to be the case for the heater fan).

Thanks for all insight.

 

The alternator regulator often lasts 120000 miles . I blew mine at 80,000 miles I guess with a better big stereo , you can replace the regulator it’s like 120$ and takes an hour or two. It is on the alternator and needs to be removed . The main unit is very reliable . My commutator was very worn, that’s another job I never did . Get the alternator tested . You might just want a full replacement. That’s what everyone pushes . Connections can corrode . Is it driven Dailey ? Maybe the regulator over charged it to ruin the battery, A bulge is not normal . To bad no V meter on display , but I guess we are not supposed to know anything, only mb mechanics . Get it tested , if you need it right away and are not DIY get alternator if tests bad. Don’t go to mb. It’s less less than an hour job . Or just a bit more . Most any auto parts store will test it free and tell you if alternator is bad . Don’t get an auto zone alternator. FCP euro has lifetime warranty and they stand by it. They can fed x but it’s Christmas and slow . I would text today and call FCP and see if they still ship today . But time might have run out. I’m no pro it’s just my thoughts

 

Judging from what the OP said, the alternator is intermittent. If the alternator is anything like the old Bosch alternators of days gone buy, it's almost certain the regulator/brush assembly is bad. FCP Euro has the OE (Valeo) for $85US. If you can find it, I'd replace it. Unfortunately, there was quite possibly nothing wrong with the old battery...

(I can't tell from the pictures if the brushes are part of the regulator. It's definitely different from the old school ones.)

 

But if commutator on main alternator is real worn the new brushes may not get into the grove left by the old regulator brushes, and no way to look, it’s sealed up . That was my issue for a month or so . Not fast charging . The worn commutator you can see , but not when the regulator is put on. So you can’t check it.

 

Some more info.

1) Old battery was tested as having a bad cell. Maybe that damaged the alternator?

2) I disconnected the battery and cleaned the cable connectors even though they looked really clean. They were quite tight before changing the battery. No difference in starting the car.

3) I charged the battery using my conditioner. It charged it to 14.3 volts and indicated 90% capacity - likely due to it being at a temp of -16°C. When I monitored it in the car after reinstallation, it showed it as being at 12.2 volts and having a -31 Amp current draw. I'm guessing that one (or more) of the diodes in the regulator are leaking or bad.

I dont think there should be a heavy current draw from the battery when the car is on but isn't running, and also when it is on. I'm thinking that this means that the electrical system (radio, GPS, lights, etc.) is pulling current from the battery (thus the negative value) instead of it being delivered from the alternator, and this is why the battery voltage drops so quickly.

It's too cold (-12°C and the younger days of doing this in the cold are over, lol) to fool around with removing the alternator, so off to the local trusted corner garage on Monday. I'll see if they can order from fcp euro or another similar place in Toronto (https://germanparts.ca/?gad_source=1...RoCLC4QAvD_BwE). They have a 3 or two year warranty policy.

Hopefully they can float me the warranty these places provide.

What a pain at Christmas, hee hee!

 

You are better off ordering from fcp , you own the warranty not the garage . If garage own warranty you have to go back to them to get it honored . Im no mechanic but fcp is easy to deal with and get warranty honored. Also it’s at your schedule, not the shops . What they sell is good quality. Check out prices and different alternators - regulators online. At a shops labor cost just get a new one. But knowing milage and how my commutator was worn a new alternator for you is probably best . FCP is Lifetime warranty. For everything they sell. Oil , brakes , batteries, rotors , hoses , etc .

 

Sounds good Mmr1, the only difficulty is getting it across the border. We'll have to check on shipping time, exchange rate, customs duty, excise tax, & sales taxes, then compare it to the Toronto option. Extra costs might offset the excellent value provided by fcp euro in comparison to the Canadian option.

 

I just had mb wheel center cap emblems shipped from Canada to Chicago , it should be no different the the other way ?

 

I suggest That you either buy a new alternator (in Canada), or have your alternator rebuilt. Ascot Alternator in Ottawa has good reviews for a rebuild.

Shipping anything from the US is way more expensive than it used to be. The current exchange rate is terrible, you will still pay tax and possibly a customs brokerage fee.

 

Check the brands FCP and other reliable places sell. In the US auto parts stores have a lot of cheap , or defective Chinese stuff . There are quality without mb prices , (I think ) 😬

 

That's the "go-to" answer but a typical test won't prove it.
" It didn't pass"

"Why?"

"Bad cell."

 

Everything you’re saying indicates bad diodes. There’s nothing in the GLK except the starter that can draw 31 Amps. That’s a bad diode back feeding into the alternator winding. But with 300,000 km I think I would just replace the entire alternator.

 

31 amps was his total draw with the key on, engine off, not a single system. Not unreasonable unless we know more specifics.

 

Maybe. I don’t have my GLK any more to check. So more diagnosis? Looks like he’s headed to a shop because of temperatures anyway.

 

If you work on cars think about keeping the old alternator and get a Regulator, you probably need a commutator also , you won’t know until you remove the old regulator. The main unit is well made. FCP euro is the place to shop.

 

Hi all,
The final solution was to replace the alternator. It was just too cold to do any further work on it myself.

Summary:
As I stated above, the slight bulging of the battery case indicated internal damage...testing proved it. It's possible that the bad battery might have fried the alternator, who knows. Replacement of the alternator was the final piece of the puzzle, providing good output voltage and good battery charging current. The battery charging current began to reduce as the battery charged up to full capacity as expected and is now stable at a low value.

Many thanks to all for your insight.

 

Thanks for the feedback - it's always good to know the final fix. Very beneficial for others in here 👍

And those lurking