Hi Everyone
I own a Mercedes 2013 E350 4 matic, it has 120K, recently i noticed there was a slight leak from the water pump which was not over heating the car but the coolant level would drop ever so little and every month or so the light would come on and id top it off, keeping in mind it would never overheat and the temperature gauge was always in the correct position I believe at 90 or 100 degrees, However since the change of the water pump i noticed within the first 15 minutes of driving the temp gauge was flying around up and down to prevent overheating i stopped the car, took it back to the garage who removed the connectors not removing the water pump or thermostat but after removing the connectors and a few front parts to access the water pump and put it back together the issue was gone so it seemed, there was no error codes showing no check engine light and no sensor codes, the mechanic claims hes not sure what the issue may be however pointed at the thermostat might be sticking however it never had that issue before other than the minor leak in the water pump. there was no air leak and no coolant leak and all else was showing okay he said and claims it may not even be the thermostat but that what he would recommend to change i don't want to go around changing parts for no reason but otherwise i drove about 60 KM yesterday and noticed all was fine engine is running hotter than normal and the temp gauge did go back up to almost red. im concerned about this and was hoping someone with experience can let me know what the issue may be there seems to be no error codes but after driving now compared to before the water pump change the engine seems to be running hotter the fan kicks on more frequently and the gauge is higher a little than normal but it does not overheat right away the heating and cooling seem to be working fine. Please help!! anyone!

 

Perhaps a bad pump. This an OEM part or aftermarket? I can tell you that the default position for a failing thermostat is open, causing your 90-95 Celsius reading to drop (run cooler). It will also cause a CEL, not just a code. I doubt it is a thermostat issue.

 

The water pump was just replaced and it looked like its an OEM aftermarket as the mechanic mentioned, i requested an OEM part. however the warranty that was covering the part they mentioned they use aftermarket OEM and so i took the car back the mechanic mentioned its not the water pump that it only has limited things it can do and how it functions and claims it cannot be the water pump is there a chance from your experience it can be the water pump? i was skeptical about the thermostat as its been performing fine for over 60 KMS and then it just swings all the way up to almost red and then dropps as i turn the heat on blast. I don't want to change the thermostat seeing there are no codes and no errors. the car never overheated prior to the water pump change.

 

I posted a response if when you get a chance you can let me know what you may think, Thanks!

 

By chance was the cooling system flushed after the W/P replacement? Not judging anyone's work just trying to get a baseline. The following link is a quick but fairly detailed explanation on the operation of the cooling system. Good description with voice over and pretty good graphics.



I reread the post and outside any obvious recent updates he could be onto something with the thermostat. trust me I hate upsells and don't want to spend extra either but sometimes the old "As long as I am in the neighborhood" theory can be overall a money saver. My guess is unless there is documentation or proof of a fairly recent thermostat change with that mileage you probably wouldn't be wrong. Hear me out, First if all if they were full Mercedes certified or trained, then the thermostat replacement might have or at least SHOULD have been recommended. The Water Pump and thermostat are fairly close to each other and I believe that you either remove or at least pass over the thermostat on the way to the water pump. I get a headache agreeing with mechanics on this one but might not have been that far off. From what I can see there would be very little additional labor costs for the W/P and Thermostat at the same time. The new thermostat should have a new CTS so literally plug and play to the sensor wiring lead. Coolant flush would only have to be done once and saves the work of going back in later. You get piece of mind of new W/P thermostat, and cooling system flush . The System flush as a by product if done correctly can also help flush out the heater core and get some debris, scale, rust, sediment out of the heater core hopefully prolonging that life...Under the dashboard and usually a pretty major job to replace. Usually involves almost total removal of the dashboard. Depending on the engine layout there could be two fittings on the engine compartment firewall side, you can flush as part of a cooling system flush or as a separate project and force high pressure water, cleaner through one side until it comes out clean on the other and SHOULD drain to either a catch pan/drain bucket on the ground or if totally clear water then to the ground.

Probably too late for this one but check out FCP Euro (FCPEuro.com) they are a pretty good online retailer with US distribution centers and so far from what I ordered not overly excessive prices. They sell individual components or some items as a KIT with all components required. E350 is a good example. They sell the Transmission service kit (Fluid, filter, new pan bolts, stand pipe, gasket etc... and most kits are compatible to OEM specifications, or is the OEM vendor. Another example is drivebelt kit. Belt, Idler pulleys, tensioners and new bolts. Prices might be the same as retailers but as they say..."One stop shopping" and are pretty good about FREE shipping with purchases over a certain amount.

1. Electric water Pump: Some recent vehicles.....(BMW appears to be the major one.) take the water pump off the drive belt system and use a electric water pump. Two VERY OBVIOUS holes in this operation. 1. Electric pump with no temperature indicator provides no warning and unlike a mechanical water pump which as long as the engine is turning and the coolant is flowing, you are getting a closed loop system with normal cooling and the cooling fan operates as necessary AND outside RAM air across the radiator helps to maintain operating temperature. 2. Electric pump no matter how allegedly reliable they are claimed to be can FAIL at any time and sometimes without warning or at least no obvious. Wire gets cut, corroded, insulation get stripped, loose fed or ground...etc.... Electric Motor gets damaged, you get the idea. Next thing you and your family are sitting along a sun baked Interstate in the middle of July with possibility of no exit immediate waiting for AAA or whatever Roadside Assistance plan you have.

2. Internal Water Pump: Again at least one obvious flaw. 1. Little or NO external warning of impending failure. The pump may be impeller driven but without the serpentine belt there is no obvious external indication of operation impending failure. Modern day Fords are at least one example.

The reasons for the design are simple.....at least to the designers and manufacturers. Every manufacturer is so paranoid about meeting fuel mileage requirements that they are tweaking every last drop of energy to gain that extra .005 miles per gallon and saying they are more efficient with total lack of regard to how they work in practical application. The other part of this is if pump fails they get to soak customer for even more outrageous labor and pump prices, also banking that the failure will last until about five miles past the warranty end. The other part is they exclude common failure items from the warranty even if they fail early. The customers are just as guilty for buying them, especially BMW with the electric pump.

Rant complete

My vote would be thermostat you get a new W/P, thermostat, CT sensor and should get a cooling system flush and after proper servicing will have any air pockets bled out of system. The previous recommendation was made possible in part by a grant from the University of YouTube helping and occasionally hurting automotive, household and life's DIYers since around mid 2000's

 

KEY is correct about the thermostat fail theory but partial disagreement. Yes he is correct about the modern design thermostats are designed to fail open but other parts come into play.

Thermostat failing open YES. The CEL not 100% on that one. Hear me out..... I know from believe it or not about three winters in the North Texas area (DFW Metroplex) Let me run the scenario and this can help explain why the CEL may not always be a factor.

Winter of 2016 and 2017. Previous vehicle was 2014 Ford Taurus SHO. 3.5 E/B V6 Twin Turbo. Livernois Motor Sports Stage 1 tuning kit. The normal stage one tuning components, ECU tuning profile, new plugs, CAI kit and 160F Thermostat. The 160F Tstat is the key here.

Around December-January time frame I was getting a CEL. Cleared codes the first couple if times but after that read the Code. (P0128....Coolant temperature not within specified range) Wording not exact but same concept and understanding. Summary, the 160F Thermostat combined with low Outside Air Temps (OAT) also add in cooler RAM air across the hood and radiator. Combined to make the engine....believe it or not running too cool. Warm enough for heat and driving but below the minimum temp range that the CTS can read....could be one degree, cold be 5 could be 30 you get the idea. I didn't change TSTAT but after clearing and driving on warmer days the MIL didn't illuminate. I had another vehicle at the time so kind of kept in the garage to help reduce mileage. Called LMS to see if there were previous notes from other customers with same tuning profile and said very isolated and usually went away with OAT got warmer. Tried to follow the common denominator which became the following conditions. Dry Air, Low OAT, and the 160F thermostat. Fast forward to winter of 2017-2018. Same deal on a few events......Having the previous information I monitored and as before around February, March when weather started warming up MIL was non existent. The P0128 is a fairly common MIL Code and for the most part is standard. A P0128 on a Honda, Chevy, Ford, and Mercedes pretty much means the same thing. the only exception could be BMW since for a while they removed the CT sensors or at least the gauges but that's another story.

TSTAT Failing open is a self protect feature that I can understand and be on board with. What I am getting at is the TSAT might be failing open but Coolant temp might still be warm enough to NOT trigger the CEL/MIL. Example if I had the 180 TSTAT it would open at a higher temp so even with low OAT and arm air cooling across the radiator might still keep the Coolant temp Above the lowest value that the CT sensor is able to read.

Based on the information and feedback presented I still say TSTAT. Either way I don't think you would be wrong its not like you are going to remove a perfectly new thermostat just because the problem was elsewhere right?

 

I think 2011E350 was referencing burping the system for air bubbles. Air bubbles can cause overheating and swings like you are having, but this is basic auto repair 101. I'm sure your mechanic properly let the air out of the closed system prior to sending you on your way. Thermostats for these cars are a little pricey and you don't hear of too many failures on this site. Indeed the CEL will come and go as the thermostat is failing. When it goes completely the CEL will illuminate constantly.

 

Thank you so much for your very thorough response, the water pump was not recommended to be changed infact i was told since there is a gasket that is included changing that alone would do it and so yes the thermostat would have had to be removed to change the water pump as it sits on the water pump and is connected via the water pump. otherwise the mechanic that changed the part was just a mechanic i was referred to from this third party warranty company called A protect here in Canada. they specialize in german cars apparently i cannot say for sure whether the did the flush but i did see a bucket with some of the coolant from before, however as mentioned it was all fine until the water pump was changed and now its acting up but again no codes and no check engine light and seems like the overheating issue doesn't occur until the car is on for about an hour or so

 

Thanks for the update and yeah i don't think unless once the thermostat is removed that it requires a mandatory change however im still unsure what the real issue is the mechanic who did the change is not sure either as there are no codes and everything seems okay, they did change the gasket that connects the thermostat to the water pump, but i will have it all looked at locally by my own mechanic and see what his opinions are i really respect everyone's feedback here Thanks Key this information all really helps and thanks 2011e350 for your help also!

 

No problem. I'm sure you will get it sorted out quickly. Your car is not acting normal and you know it. Please let us know what the final outcome is. It always helps others in similar situations.

 

I will be sure to post an update once this gets resolved, Im planning on taking it in today or tomorrow at some point to have it further assessed so far no codes no engine light .

 

I hate to say it but the warranty company will probably nickel and dime every drop of coolant and every gram of gasket sealant. I didn't catch the warranty part until now that could change everything. I am not sure what part of the country you are in, but strongly recommended to get it taken care of soon. If it is overheating now imagine how much damage it can be in the summer. If it was a leak that might be easier at least to diagnose. Good luck, and if you do decide for the Thermostat R/R might e a good time to consider new hoses, since they would be disconnecting for thermostat R/R anyway.

 

^This - air in the system is the most likely scenario - temperature may seem fine for a minute until the next air bubble(s) slowly makes it way through the system and stops the flow somewhere along the way. I would sincerely hope the people who did the water pump let the air out, if they didn't and this ends up being the cause I would be very hesitant to use them again.

 

I ended up driving the vehicle home with the heat on max and the temperature gauge was in the right spot the whole way which is about 60 KM however i did notice the needle would go down every little while a few degrees perhaps when the thermostat opens and its flowing the coolant. Im in Toronto Canada and so hit the usual traffic back home i would not have been revving high rpms or going over 60km/h. I ended up driving straight to a shop i was referred to the guy there specializes in german vehicles he did a few tests here and there no codes popped up nothing seemed unusual he thought it might be air in the system however under further inspection while the car was on and idle and he was revving a little to see if the needle would move which it didnt it was in the right spot on the temp gauge, the radiator fan did kick on and in idle with no revving you can hear it get faster and then faster, his conclusion was that the aftermarket water pump just isnt circulating the coolant hard enough and that it may just be faulty and not right for the vehicle. otherwise he ruled out it being the thermostat as it wasn't showing any real sign of problems just that the engine was still very hot due to the poor circulation of the coolant with this yet to named brand of water pump, ill find out tomorrow hopefully when the shop who puts it in can tell me as they apparently dont know which i find hard to believe, either way lets see where this goes hopefully the warranty company GM who claims wants to see me happy and satisfied does about this when the mechanic forwards his assessment otherwise what do you guys think crappy aftermarket water pump not circulating the coolant hard enough?? issue yet to be resolved and will keep posting updates. mentioned something about water pumps having different material and type of circulating fins that may not circulate the coolant as well as the engine needs any thoughts on this Thanks.<br /><br />ish

 

posted 2 pictures of the temp gauge but cant see it on the post is anyone able to see them thanks.

 

Air bubbles should work their way out eventually without any kind of intervention, they just needed some time to make their way to the coolant overflow reservoir. You may have gotten all the bubbles out just driving along so it may be fine moving forward. I wouldn't think the fans increasing in speed while idling for long lengths of time would be unusual, there is no air moving through the radiator while sitting still so the fans kick into assist.

May just try driving it a few more days to see how it does, but like earlier if the needle starts shooting up definitely pull over and stop.

 

The car doesnt seem to overheat right away but i know the moment the engine is running long enough or im driving local traffic the temperature will start to shoot up its already running hotter a few degrees than it normally does, if you can see the two pictures i attached you can see the gauge at 2 different temps and so from the looks of it and also i noticed my self the fan is on more often then it normally is i can almost say for sure if i turn off the heating and just drive normally for like 30 mins or so the temp will go back up its been like -15 degrees Celsius here and so that im sure helps to keep things cool but as its warming it will i feel give more issues but lets see tomorrow i will have it diagnosed yet again by the mechanic who changed the part still unsure of the real cause of the engine running hotter than it normally does and why the fan is kicking on more often its noticeable more also.

 

 

Sounds like you got a second opinion and good move...getting a assessment that YOU are getting the recommendation from. With the potentially bad pump already I would be hesitant of the warranty companies choice of mechanics....Sounds to me like Strike one already against the warranty company and mechanic they recommended/authorized. Personally I would put another claim against the warranty company and have mechanic that IS NOT in the warranty companies pocket for full repair or have the existing mechanic Start over AGAIN and insist that they use OEM Water Pump AND Just to be safe and peace of mind new OEM Thermostat AT THEIR EXPENSE. The obvious Cooling system flush, drain, bleed and fill after W/P and TSTAT replacement. Another possibility is independent shop but that could be at your expense.

Warranty company probably won't go for the independent repair and will either try another shop on their approved list or have existing shop REDO the process all over again. Insist on NEW OEM parts including coolant, gaskets, sealants etc...

With all the above stated, it would not be the first time that a brand new part, water, pump, motor, thermostat, sensor could be as they say...."Bad from Stock" definitely want to get it taken care of before it gets too much warmer and monitor closely.

 

Hi everyone

Thanks for the responses I just wanted to post an update, I ended up getting an OEM benz water pump installed and the aftermarket removed and the problem still persisted, i ended up getting the thermostat replaced as well as the mechanics kept insisting that was the issue, however turns out that it wasnt as the issue still remains, at this point im so frustrated and have no clue what the issue could be, when the heat is on full the car does not over heat however the moment its turned off the temp gauge starts to climb beyond where it should remain at, at this point im not sure what the issue could be anyone have any insight, i had a friend mention the only other thing could be the rad is clogged and not circulating the coolant properly could that be one of the issues based on the information i provided? also what else could it be seeing the pump and tstat were both changed and that there are no error codes showing?

Thanks

 

Also not loosing any coolant its all sealed and vacuumed the correct way, Im starting to think since the heater core is working and its blowing hot air the way it should that perhaps there may be something clogging the main radiator? i have read that plastic materials used like the propeller in the oem water pump can dislodge and create blockages, would you think that could possibly be it and most likely the radiator and not anywhere else in the cooling system?

 

Sounds like your troubleshooting is coming along. New W/P and new TSTAT even if not the cause in this scenario, again not a bad idea at this mileage and model year. Radiator is the next easiest next step. You really want to pray that it is the radiator and ANYTHING BUT the heater core. Can you say pull the entire dashboard apart... Heater core itself may not be expensive but labor even at independent shop. If you are going this far might as well replace the hoses yet especially if radiator removal is involved. Don't forget that the transmission fluid cooler lines run through the radiator so be prepared to lose some Transmission fluid. Engine does not have a engine driven fan so that rules out the fan clutch. If you have R/R the pump, thermostat and bled the system aside from clogged radiator and heater core that's the major components. Not much else. If you have to go the radiator and heater core route, me safe and replace ALL of the radiator hoses, upper, lower, bypass and heater hoses at the same time....especially with heater core. You can pretty much rule ever component of the cooling system out provided the system flush and service is done correctly with proper fluid and system bleeding procedures.

A outside chance of the cooling fan relay but probably not.

As for the engine temp coming down with heater applied, that is or should be normal system operation. Think if the heater core as a pressure relief valve which in hearing new symptoms could me more inclined towards the radiator. If the system pressure is reduced with heater applied that could be the smoking gun on the radiator. I would say on outside chance that I could be right try the cooling fan relay. After that be prepared for radiator and heater core in that order. Whatever the next step is be safe and R/R the hoses either radiator hose and or heater hoses.

 

Remember the MIL code is a electrical signal/sensor problem not necessarily mechanical. Yes it could register overheating when actually not but my guess is most likely a mechanical problem not electrical. If the temperature wasn't registering or registering too low of a temp, then the MIL P0128 should pop up.

 

Thats gives me alot to think about thank you so much for the insight. Im praying its not the heater core but all right now is pointing at the radiator, i will also look into the cooling fan relay and see if that has anything to do with it, however now that i come to think of it, i dont believe this shop did a complete flush of the cooling system, i dont know if its a mandatory step but ive read alot about always doing it , i dont believe the folks at the shop did a full flush of the system and im starting to think if they did perhaps i wouldnt be in this situation as this is the second pump install and now today also a thermostat boy im praying its some blockage in the rad which may have also caused the initial pump failure to begin with but who knows i just pray its the rad and clearing the blockage will resolve the problem ill be sure to post more updates. Thanks for your repies.

 

You said its running a few degrees hotter.... how many degrees is 'a few degrees' ?

As I mentioned before somewhere else, it sounds like your rad is beginning to clog or there maybe an outside chance of a small head gasket leak.
Also, on a previous car of mine when the rad began to clog up, the temp would climb past normal 10 or 15 minutes after starting the car and then begin to settle back to its proper range.

Its really cold in Toronto. If its getting to hot initially and then settling to the proper range, blame some of it on the cold and a rad that isn't flowing 100%.