Coolant / thermostat issues

6333 Views 24 Replies 8 Participants Last post by jmc, 10 mo ago

nyc_renegade

Discussion Starter · Jul 6, 2021

For the most part MY2014 Is still rocking 59k miles in just minor issues another one I’ve noticed over the past couple days.

I got a check coolant level on a long drive (300mi) last week. No other problems and I didn’t stop to check because at the time I was driving on an overpass and figured it was cause the car wasn’t level for a period of time.

well I hopped in yesterday to run some errands and low and behold another coolant level check as soon as I turned the ignition. As well my thermostat started jumping up and down so went to auto zone and the reservoir was low. I topped up with some European blue formula (same as original) and left.

no engine issues or warnings but my thermostat still jumps up and down until settling just above 80 but creeping towards 10 and fluctuating in between.

So my concerns naturally are

A) any idea as to why I would lose coolant? Not white smoke from tailpipe, could the northeastern heat wave and my extra a/c use have something to do with it.
B) Should I be concerned with how much the thermostat in fluctuating? Honestly, it’s one of those things you don’t pay attention to until you do. The last time it started acting this crazy I had to have the water pump replaced. From my memory my engine would normally be just above 80 but it seems a tick higher than that. Could also be I really hadn’t noticed previously.

Any insight I’d appreciate

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Picard

· #2 · Jul 6, 2021

Common leak areas are at the bottom of the coolant reservoir and the turbo coolant return line. There are topics here in the forum discussed extensively.

Let us know what you find out. One or both may be the culprit of your fluctuating temps.

Sent from my SM-G998U using Tapatalk

Reactions: 1

jmc

· #3 · Jul 7, 2021

Air pockets / cavitation

Eclipse1825

· #4 · Jul 7, 2021

jmc said:
Air pockets / cavitation

I have never had anything done to my coolant system and I have the fluctuation in temp even after it gets up to operating temp. When I give it a good pull from light or spirited driving it will drop down to 80 then go back up. Then it repeats next time.

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Picard

· #5 · Jul 7, 2021

Yes the small fluctuations are normal.

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mav238

· #6 · Jul 7, 2021

Eclipse1825 said:
I have never had anything done to my coolant system and I have the fluctuation in temp even after it gets up to operating temp. When I give it a good pull from light or spirited driving it will drop down to 80 then go back up. Then it repeats next time.

Sent from my iPhone using Tapatalk

It might be a faulty temperature sensor in the coolant system or a flow valve. Why not just drop into a local shop that knows german cars and take a look?

Bahn

· #7 · Jul 8, 2021

When my 2014 CLA was brand new, the temp gauge needle would fluctuate more frequent than most cars. I did not exhibit coolant low warning whatsoever. Then at 24K miles I overheated from a 10 min commute at the Hutchinson parkway heading to Yonkers. I stopped for a couple of minutes at a gas station then proceeded to MB of New Rochelle. It was a failed water pump.
I hope yours is just some air pocket or benign symptom of something not as critical as my experience.

jmc

· #8 · Jul 9, 2021

... but the cavitation is coming from somewhere

though I do know when i punch it my entire water loop drops from 205F to 155F ... must be the added 60mph of wind

Geo K

· #9 · 10 mo ago

nyc_renegade said:
...I got a check coolant level on a long drive (300mi) last week...any idea as to why I would lose coolant?...

nyc renegade>
Note Comment #2 from Picard. Can you describe the outcome?

nyc_renegade

Discussion Starter · #10 · 10 mo ago

Thanks for reminding me I had a previous issue. I completely forgot. This issue kind of resolved on it's own after topping up however the current issue is that I'm losing coolant at a faster rate and when the car is parked. No thermostat gauge fluctuations.

This morning 7/23/22 I removed the expansion coolant reservoir and didn't spot any leak. I have hand traced the hoses and felt around behind the engine block and looking at the radiator and still haven't spotted the leak. Still looking but will report back with any updates/solutions.

Geo K

· #11 · 10 mo ago

Any gas station can put your CLA on a lift so you can exactly trace the leak. Maybe there was an error made in replacing the pump?

jmc

· #12 · 10 mo ago

if you have one snake a drain cam around the backside between the block and firewall
or just look from underneath
hunt for whiteish trails

nyc_renegade

Discussion Starter · #13 · 10 mo ago

Update: Took it to a local mechanic he identified the leak as coming from the intake manifold. Charging $870 to look further at the issue. He Says there may be hoses back there and one has busted.

Really frustrating as I’m away from home and can’t take a look at this myself. Will report back after he gets to the manifold.

jmc

· #14 · 10 mo ago

at the intake manifold??? weird
last place to run hot water thru …..

pa4ul

· #15 · 10 mo ago

i think the thermostat is located in that general area.

jmc

· #16 · 10 mo ago

yeah tstat is just underneath
but then there will be a dried up coolant trail

Reactions: 1

nyc_renegade

Discussion Starter · #17 · 10 mo ago

Thanks all latest development.

Mechanic (general) told me following needs to be replaced:

Thermostate housing / Thermostat
6 hoses (dry rotted)
vaccum intake hose (dry rotted)
clamps
coolant
Labor

Cost $3,500 really seems excessive as that's about 1/3rd the value of the car at this rate.

mav238

· #18 · 10 mo ago

nyc_renegade said:
Thanks all latest development.

Mechanic (general) told me following needs to be replaced:

Thermostate housing / Thermostat
6 hoses (dry rotted)
vaccum intake hose (dry rotted)
clamps
coolant
Labor

Cost $3,500 really seems excessive as that's about 1/3rd the value of the car at this rate.

I think you are getting ripped off there. When I repaired the cooling system in my CLA, it included the replacement of the thermostat and housing, some hoses, and also the water pump, total ~ $1600 (taxes and labour included).

Reactions: 1

mav238

· #19 · 10 mo ago

mav238 said:
I think you are getting ripped off there. When I repaired the cooling system in my CLA, it included the replacement of the thermostat and housing, some hoses, and also the water pump, total ~ $1600 (taxes and labour included).

Some unscrupulous shops will see you driving a nice mercedes in, and immediately think to themselves "okay, a nice fat fish to be scaled and gutted". that's why it's important to shop prices around. First find out about how much it would cost the dealership shop to fix, and then the local mechanic shop should cost less than that.

nyc_renegade

Discussion Starter · #20 · 10 mo ago

The saga continues. Visited the shop to get the estimate in writing and everything looked fairly reasonable except for a vacuum line for $1,600.

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Entirely put off. Having it towed to nearesr dealer (30mi) hopefully via insurance and will take it from there.

thanks @mav238 @jmc @pa4ul. Will keep everyone updated. I’m mainly salty because being away from home staying in a rental I have no place to work on this on my own

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