W204 OM651 Thermostat

[AsifS]

Hi

I have C220 CDI W204 Om651 car.

I Noticed my temperature is only going up to 30-60 degrees on the motorway and it will eventually get up to 80degree going up hill on the motorway, it use to stay at 85-90 degree before so sounds like a dodgy thermostat.

Anyone have a guide on how to change it? If not how many hours should a mechanic charge for labour

 

[grober]

Could be your water pump-its switchable- it can be switched off when the engine is cold to help it heat up more quickly- either the pump or its switching mechanism can go faulty. Its a common fault
Coolant Pump - Mercedes-benz OM 651 Service Manual [Page 42]

 

[AsifS]

Thanks I will ask the mechanic to check it.

Although the water pump was replaced by the previous owner by a specialist 15 months ago.

 

[grober]

The waterpump is operated by engine vacuum directed by an electrically switched solenoid valve. Vacuum line or valve might be faulty?
https://forums.mbclub.co.uk/attachments/install-coolant-pump-switchover-valve-pdf.64172/

 

[OneForTheRoad]

I changed my own ln less than an hour .

 

[AsifS]

Thanks for all your replies.

Graeme you have made some interesting points especially about the Vac pipes - could it be another blockage?

There are no fault codes showing on Diag system at the moment!

The Merc Independent in Oct 2017 replaced the following and I've just checked the paperwork (previous owner):
Water pump A6512000300 - which Is the metal one rather then the plastic one, which I've heard are supposed to be better.

He also replaced the Boost sensor and Map sensors at the same time and I know this caused some issues.

When I purchased the car I noticed it went into limp mode when I put my foot down on motorways on the hills.
earlier last year I took the car to a specialist and they found a broken piece of Map sensor in the Vac pipes which was causing the car to go into limp mode (badly fitted by the previous specialist). I wonder if there is a similar issue with the vac pipe near the water pump or as you have suggested near the solenoid.

Will speak to my local garage soon, but not sure the best way to test it myself.

 

[AsifS]

Local garage confirm with a quick look it looks like a classic thermostat issue, I'm not totally convinced so might have to try another place. I know on another thread someone replaced the thermostat and still had the same issues?

Do you know what the part number is for the Y133 switched solenoid, I can't see one ebay and would this throw out a fault code?

 

[grober]

Switchover valve for coolant pump (Y133)
The switchover valve is located at the front of the
engine, on the left of the throttle valve actuator.
The position of the regulating valve (open or closed) in
the coolant pump is controlled by the switchover valve
of the coolant pump. When the regulating valve is
open, the coolant can circulate in the coolant circuit.
In the rest position, the regulating valve is open.
The coolant pump is switched off during a cold start
for max of 500 s if the following conditions are fulfilled:
• The limit values stored in the control unit for intake
air and coolant temperature and for the total fuel
injection quantity have not yet been reached.
• The engine speed or injection quantity has not
exceeded the specified limit value.
• "Heat" has not been requested by the automatic air
conditioning control and operating unit.
Sorry I don't have a part no to hand. A fault in any electrical circuitry would be flagged as a fault code but a vacuum failure would not unless there was a vacuum transducer monitoring it.

 

[grober]

I believe the part no may be A0025407097------this valve may be used in other parts of the cars systems as well as the water pump.

 

[HITECH]

Replace the thermostat. For goodness sakes stop complicating the matter and reading online. You will find asking the ones who suggest this that and the next thing have never actually done it themselves (no offence grober, u prolly changed 1 or 2 in ur day lol) but good at talking the talk. The answer is in the comment ...."classic thermostat issue". If it has been checked and flushed and new coolant replaced mixed to the proper mix and it is still the same. Replace the thermostat.

 

[pembssurf]

As above.... CLASSIC Thermostat issue. It’s the most common issue of these engines. Currently on stat no 3 here (all genuine) and all on OM651.

 

[AsifS]

thank you all for the feedback, thermostat changed today and it's looking good.

 

[Gazwould]

As above.... CLASSIC Thermostat issue. It’s the most common issue of these engines. Currently on stat no 3 here (all genuine) and all on OM651.

If the genuine are poo poo ,what aftermarket make is recommended ?

 

[DieselCovert]

Hello All
I have the same thing however there are some points which makes me think it's the car doing what it is suppose to do and the temperature gauge is a guide.

The car never did this until two years ago when I had to have the engine ECU software updated to clear a DPF fault and Throttle actuator teaching problem. There were a couple of things I noticed after this. The engine took an age to reach operating temperature of just above 80. If I cruised on the motor way at 60, it rarely hit 80, normally just below it. If I boot the car then it hits 85 - 90. Drop down to 60 and temperature drops to around 75 - 80.

I had some DPF issues and had the laptop plugged in. I watched the coolant temperature. During a DPF regen, the laptop said the temp was fluctuating around 100 - 103 deg, yet the gauge indicated just above 90. Once the regen was complete the temp on the laptop dropped back down to 85 and the temp gauge was at 90. I am fairly certain the software update has affected how the temp is controlled. The update also allowed the DPF regen to start when the engine was virtually cold (temp goes up very quickly). In the past I had to have the car hot and above 2000 rpm before a regen started.

In short, it depends on the software in the ECU. For me the car operates fine, heater works, fuel consumption is better since the update and if there was a real problem, the car will tell me. They are clever bits of kit.

 

[classiccarzone]

My temperature has always sat at 80c. It gets up there reasonably quick.
When it is doing a passive regen it will do it at 1100 revs-no need to go to 2000- and the temperature gauge will creep up to 85c.

It has never gone past 3g of soot before returning to zero and ash is at zero.
As far as I am concerned it is performing as it should.

 

[AsifS]

If the genuine are poo poo ,what aftermarket make is recommended ?

Thats a good question, I went for the genuine as there wasnt much difference in price.

I know the housing has the temp sensor and historically when I've replaced sensors on my previous cars e.g Vauxhalls BMW and Peugeot in the past with after market sensors they usually throw up fault codes or go faulty quickly.