E320CDI cooling temp.

[clive williams]

Hi all,

I been playing with the wife's 2001 320CDI Estate this week and noticed that the temp gauge moves up the scale quite quickly to 60 deg C and then stops It stays at 60-65 deg C most of the time in varying road conditions including motorway blasts and only gets up to 75-80 deg C in stationary town traffic. The temp of the top hose confirms the gauge is reading about right. I presume that this is not the correct normal temp. and expect that this should be around 80-85 deg C.

I suspect the thermostat but on enquiring about a new one was told only supplied by main dealer and the cost is £30+ for a complete thermostat housing - what a rip off!!!!

Questions - Am I right re the temp? Can the thermostat only be changed and not the housing as well? If not where can I try to get a reasonable priced stat - I've tried Euro Car Parts but they said Main Stealer only.

Please help! My wife and children are only getting 75% of the heat they need and its getting colder.

Clive

500E
E320CDIT210

 

[television]

In Sweden we used to put a piece of cardboard, blanking half of the rad.

The most efficient running temp is 90

Malcolm

 

[maddog]

Normally a faulty thermostat either stays open so the car never warms up or stay closed so the car over heats.

The fact the car warms up quickly indicates to me that the thermostat may be fine i would check to see at what temperature the cooling fan cuts in as it may be cutting in too early and not letting the car get hot enough

 

[clive williams]

...............The fact the car warms up quickly indicates to me that the thermostat may be fine i would check to see at what temperature the cooling fan cuts in as it may be cutting in too early and not letting the car get hot enough

All the indications are that the stat is functioning but opening early. At the end of the run with the gauge at 60 degC the top hose is comforably hot to touch and not too hot as would be the case with 80+ degC. Hence why I think the gauge is working. The cooling fan will have little effect as the stat will maintain the temp in the engine until it opensat the preset temp and allows flow (thro' the top hose, hence sampling the temp at this point) thereafter modulating the flow to maintain the temp in the engine. The rad is obviously working well to keep the temp down on the motorway and other roads by the flow. The fan is I believe, a viscous unit which is not adjustable and will flow air irrespective of temp albeit not as efficiently as when hot.

As you have the same vehicle what temp do you see most of the time?

Clive

500E
E320CDIT210

 

[maddog]

As you have the same vehicle what temp do you see most of the time?

Clive

500E
E320CDIT210

no idea i dont make a mental note

 

[malcolm E53 AMG]

I think the indication you are seeing on the gauge is correct and normal. My X plate 320CDi readings are the same as yours. I put it down to the size of the engine, its a big lump and consequently absorbs a lot of heat. I'll check the readings again this weekend and report back but yours seem perfectly normal.

 

[tamrsoft]

I have the E220 CDi and I get exactly the same readings, 60-65 deg.C on a run and upto 80 deg.C in heavy town, I even had it upto 90 deg.C on mountain roads in the summer. I phone MB and they say it's normal for diesel engines. I believe my stat is OK since the guage stays at zero after starting and stays there for about 5-10 mins (depending on outside temp), it will then suddenly move up to running temperature indicating that something is suddenly opening. However I plan to remove and test.

 

[Dunhamkid]

I had similar temperature readings, changed thermostat and effect was dramatic. Temperature now at 90°C, better fuel consumption. Engine retains its heat better between start ups so heater works better.

If you do the thermostat change yourself, which I did, don't forget to order the gasket and watch out for the bypass pipe which can drop out.

Mercedes thermostat housing contains thermostat and temperature sender. Doesn't appear that thermostat alone can be replaced

 

[tamrsoft]

Dunhamkid
Interesting reply. You didn't mention whether yours was a diesel or not, my old C200 certainly went upto 90°C. I would be interested in any detail you can provide on the job (especially on this bypass pipe ?), I assume stat housing is at the end of top rad hose at RH side of engine and not by water pump.

 

[clive williams]

I think the indication you are seeing on the gauge is correct and normal. My X plate 320CDi readings are the same as yours. .

Thanks Malcolm and Tamrsoft, the readings still worry me as I was under the impression that diesels had to maintain reasonably high temperatures to burn the fuel efficiently and minimise the contamination of the oil. Temps at about 85-90 degC are normal elsewhere and usually higher than comparable petrol engines.

Dunham Kid, I see you've done the same job - was it to the MB large diesels? I've checked the manual and I've noted the bypass hose, which is cautioned. (This is shades of old A series engines and bypass hoses to the thermostat housing).

I can't find the thermostat temp specs in the manual so how are we/MB fitters supposed to check their function? Is the temp setting stamped on the new stat? I might have to buy a new stat, check its opening temp and reject it if its still only 60-65 degC as it means mine is still working.

Clive

500E
E320CDIT210

 

[television]

Clive My MB 300TE never got hot enough to get warm in winter, it would seem that the spec for the visc fans is quite wide as the fan would run. I noticed that other MB in Sweden had radiator blinds fitted, me being a poor OAP put some cardboard in blanking half the rad verticaly so as not to blank any oil cooler. I had it there all winter even when I was back here in the UK.
I was not happy using the car at 60 degrees knowing that it is only effifcant at around 90.
It was cheap and cheerfull but it worked,

Malcolm

 

[tamrsoft]

The irritating thing is that if you ask an MB Service technician (which I have done) they all seem so vague on the operating temperature characteristics of the thermostats on the diesels. If you test your own and it appears to work (ie open and closes) how do you know if the temp range is correct. When you buy a stat at Halfords, it has the operating temp stamped on it, but apparently not those from MB. Is it meant to be an MB secret ?

 

[Dunhamkid]

My car is 2001 320 CDi The temperature gauge very rarely went above 60°C but now it is at 90°C

The housing is attached to the top hose and by 3 bolts into the cylinder head. As the housing is removed be careful that the bypass pipe does not drop down the side of the engine(!) I should have replaced the seals on this pipe but didn't know it was there when I started the job but they looked OK so I refitted the pipe. I think this pipe links the housing to the water pump.

Job took about 45 minutes but I took my time, also changed antifreeze at the same time

 

[dogsbody]

E320CDI cooling temp

Two components comprise the temperature sensing circuit. The sender and the gauge.
I would firstly try the cardboard blank on half the radiator, before changing the thermostat, as if either of the components is reading low, you will get a shift in temp .
I once had a Jag which habitually read 10 degrees low. If it read 105 degrees (with 12 psi pressure) it boiled! ( it should have boiled at 120 degrees)

 

[Dunhamkid]

Just a comment, the auto gearbox cooling pipes and A/C condenser are insatlled in front of the radiator

 

[television]

By blanking half the rad verticaly you do not restrict the cooling to these parts its just an easy way to increase the temp.
I will have a look to see if there are any mods on this subject.

Malcolm

 

[television]

Cant find any mods for this, cars with electric fans the switches cut in at 100
I liked the warning page do not take off cap with gauge over 90. if I find anything else I will put it up.

Malcolm

 

[malcolm E53 AMG]

Checked the temp gauge when the engine had fully warmed today and it read approx 65 degrees. I've noticed the gauge occasionally goes higher but that is in very hot weather or crawling around town.

The user manual gives an explanation for what might be conceived as a low reading:

"There will be a delay in the indication in a rise in temperature if the coolant temperature is above 60 degrees. This ensures that an excessively high temperature is not indicated due to heat dissipated from the engine when the car is stationary or moving very slowly".

I quess the temp gauge would therefore be up and down like a yo-yo without this electronic damping effect. I must admit that I had noticed the low temperature indicated but have run other engines with similar readings and put it down to the tolerances of the temp sensor. Anyway your question has led me to learn a little bit more about the engine as I've never been one to scrutinise every line of the owner's manual. The info is on page 91.

 

[tamrsoft]

I have noticed a similar effect, the temp guage rarely indicates above 60°C in the recent weather conditions. I guess the only answer is to take an external reading on the engine body/head and compare with the guage reading. Can anyone confirm which part of the radiator area is used for tranny cooler, I assume at the bottom but is this correct. I am currently blanking off the top part of the radiator (about 25-30 cms of the top area)
Dunhamkid (thanks 4 the addtional info), I noticed the bypass hose from the exterior of the housing, is the part you mentioned on the inside of the housing and was the risk due to its possible falling inside the engine block. I will check the stat out this w/end, I assume you can test the stat/housing assembly in a saucepan of hotwater using a regular thermometer.

 

[television]

You can, but don't boil it.

Malcolm