Thermostat change

S.Speed

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Hi All..
I know its been posted recently about changing thermostats but I thought I would add my two penneth..
The Tempo gauge in my C270 CDI (2003) was showing a notch or two below the *) mark even after a long run.. I read a post on hyere about that being too low and have to confess to being a tad sceptical..
Anyway I ordered a thermostat (It comes complete with housing and temp sensor and O ring) and fitted it today.
I must admit it was more fiddly than I expected but its done now..
I can report that the temp guage sits around 90 or even very slightly above.
My fuel consumption was not as good as it used to be and I thought the overcool thermostat may be the problem... It was.
Just reyurned from a 20 mile motorway trip and my car averaged 53.5mpg (It was 45mpg for the same run last week).
Soooo if anyone out there suspects that their engine is running too cool then you know the answer..
A Big thanks to Malcolm for pointing me in the right direction via the original post on this subject. :)
 

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Hi All..
I know its been posted recently about changing thermostats but I thought I would add my two penneth..
The Tempo gauge in my C270 CDI (2003) was showing a notch or two below the *) mark even after a long run.. I read a post on hyere about that being too low and have to confess to being a tad sceptical..
Anyway I ordered a thermostat (It comes complete with housing and temp sensor and O ring) and fitted it today.
I must admit it was more fiddly than I expected but its done now..
I can report that the temp guage sits around 90 or even very slightly above.
My fuel consumption was not as good as it used to be and I thought the overcool thermostat may be the problem... It was.
Just reyurned from a 20 mile motorway trip and my car averaged 53.5mpg (It was 45mpg for the same run last week).
Soooo if anyone out there suspects that their engine is running too cool then you know the answer..
A Big thanks to Malcolm for pointing me in the right direction via the original post on this subject. :)

Simon

This is good to know as, weather permitting, I am doing mine tomorrow.:D

Out of interest, how much coolant did you lose? I asked a tech at a main dealer and he recommended I bought 3 litres! I queried this as the thermostat sits at the top of the engine ( I was expecting him to say a cupful) but he was adamant that that was how much they would have on hand if they did it.

Dave
 

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You will loose very little on doing this Dave,, you could buy 1 liter and use a little of it and keep the rest for later
 

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You will loose very little on doing this Dave,, you could buy 1 liter and use a little of it and keep the rest for later

Malcolm

That's what I thought. I bought a 1.5l bottle so we shall see tomorrow.

Dave
 

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The cool running issues along with hot running issues are all the more reason all cars should be fitted with temperature gauges, not just a silly bulb
 

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The cool running issues along with hot running issues are all the more reason all cars should be fitted with temperature gauges, not just a silly bulb

I just think of all of those not on a forum running around with cold engines wasting fuel, and not good for the engine either
 
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S.Speed

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Simon

This is good to know as, weather permitting, I am doing mine tomorrow.:D

Out of interest, how much coolant did you lose? I asked a tech at a main dealer and he recommended I bought 3 litres! I queried this as the thermostat sits at the top of the engine ( I was expecting him to say a cupful) but he was adamant that that was how much they would have on hand if they did it.

Dave

Hi Dave..
In my case I bought 3 litres of antifreeze and totally flushed my cooling system, but as Malcolm stated this is not necessary..
Dave.. I strongly suggest you look at your new thermostat housing carefully to determine exactly where the new bolts are.. This may sound a strange suggestion but because of where its located its very very easy to miss one of the bolts to remove (as I did initially). There are three which actually hold the housing onto the engine but there are 4 to remove.. The fourth holds a sort of double fuel pipe clip. You will find that the new housing isn't tapped for the fuel pipe clip bolt so you wont be putting that back. In other words you will have 1 bolt and a fuel pipe clip left over..
Once the three bolts that retain the housing have been removed you will find it comes away pretty easily as there is no sealant / gasket seal used... Just an "O" ring.
Dave.. Just take your time and slowly removed any pipe clips so that the fuel pipes can be eased out of the way to have access to the three retaining bolts.. Oh on the subject of bolts I strongly advise you get a 1/4" socket set with short extension bar The Merc bolts are a sort of star headed job.. I have to confess I used a 8mm socket which worked absolutely fine. But I was lucky in that I own a quarter inch drive set which is ideal for confined spaces.
As stated in the earlier post you will need to remove your oil filter cap / filter.. Please make sure you pack a clean rag into the filter housing to keep any muck (and bolts) from falling in there.
I would say the hardest part was to put the filter housing back whilst making sure the stubby hose was seating squarely. (I bought a new stubby hose)..In hindsight I would use a drop of washing up liquid to lube the ends of the stubby hose as its a friction fit into the recesses and there are no clips involved at all !!
Next tighten the 3 bolts evenly and gradually and I gripped the housing and gave it a firm push/pull so as to seat it squarly..You will find that due to the friction fit of the stubby hose and also the fact it is very stiff, the housing will do its best to go on out of true.. In my case the bolts tightened up before they had made contact with the housing..almost as if cross threaded.. I removed one bolt and re inserted it and tightened as I jiggled the housing, and it went in all the way.. I did the same with the other 2 bolts one at a time. Remember the housing relies on being sealed by an "O" ring and so it needs to be tightened square to its mating surface.
As I said in my original post it was a more fiddly job than I expected but definitely not beyond you if you take your time and be slow and methodical.
Good luck with it Dave.. Let us know how you get on when you have done it.
 

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simon, what is the purpose of the stubby hose ? I understand its just blanked off so does not supply anything ?
My car does take time to warm up but does reach 80-85 after about 10-15 mins - depends on driving style and speed - If idling then it would be more than this i guess.
 

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simon, what is the purpose of the stubby hose ? I understand its just blanked off so does not supply anything ?
My car does take time to warm up but does reach 80-85 after about 10-15 mins - depends on driving style and speed - If idling then it would be more than this i guess.

It should open at 92º C and that is the start of the opening
 
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S.Speed

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simon, what is the purpose of the stubby hose ? I understand its just blanked off so does not supply anything ?
My car does take time to warm up but does reach 80-85 after about 10-15 mins - depends on driving style and speed - If idling then it would be more than this i guess.

Ho Wardpaa,
The stubby hose is definately NOT blanked off..
I would guess its some sort of bypass hose. Its about 2 inches long with a metal lining. The rubber is flared at each end...Imagine a miniature dumbell and you have the idea what it looks like.
 

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Hi Dave..
In my case I bought 3 litres of antifreeze and totally flushed my cooling system, but as Malcolm stated this is not necessary..
Dave.. I strongly suggest you look at your new thermostat housing carefully to determine exactly where the new bolts are.. This may sound a strange suggestion but because of where its located its very very easy to miss one of the bolts to remove (as I did initially). There are three which actually hold the housing onto the engine but there are 4 to remove.. The fourth holds a sort of double fuel pipe clip. You will find that the new housing isn't tapped for the fuel pipe clip bolt so you wont be putting that back. In other words you will have 1 bolt and a fuel pipe clip left over..
Once the three bolts that retain the housing have been removed you will find it comes away pretty easily as there is no sealant / gasket seal used... Just an "O" ring.
Dave.. Just take your time and slowly removed any pipe clips so that the fuel pipes can be eased out of the way to have access to the three retaining bolts.. Oh on the subject of bolts I strongly advise you get a 1/4" socket set with short extension bar The Merc bolts are a sort of star headed job.. I have to confess I used a 8mm socket which worked absolutely fine. But I was lucky in that I own a quarter inch drive set which is ideal for confined spaces.
As stated in the earlier post you will need to remove your oil filter cap / filter.. Please make sure you pack a clean rag into the filter housing to keep any muck (and bolts) from falling in there.
I would say the hardest part was to put the filter housing back whilst making sure the stubby hose was seating squarely. (I bought a new stubby hose)..In hindsight I would use a drop of washing up liquid to lube the ends of the stubby hose as its a friction fit into the recesses and there are no clips involved at all !!
Next tighten the 3 bolts evenly and gradually and I gripped the housing and gave it a firm push/pull so as to seat it squarly..You will find that due to the friction fit of the stubby hose and also the fact it is very stiff, the housing will do its best to go on out of true.. In my case the bolts tightened up before they had made contact with the housing..almost as if cross threaded.. I removed one bolt and re inserted it and tightened as I jiggled the housing, and it went in all the way.. I did the same with the other 2 bolts one at a time. Remember the housing relies on being sealed by an "O" ring and so it needs to be tightened square to its mating surface.
As I said in my original post it was a more fiddly job than I expected but definitely not beyond you if you take your time and be slow and methodical.
Good luck with it Dave.. Let us know how you get on when you have done it.

Oh how I wished that I had logged on and read this through this morning :(:(

You're right, it is very very fiddly to fit the housing back on with the pipe square etc, trying to slide it under the other pipes etc. Much swearing was had, along with several cups of tea and re-thinking. Eventually, like you, I worked out that the oil filter cap had to come off (which, if you think about it, is ridiculous - oil and water housings so close is just an accident waiting to happen).

In the end, I managed it and everything is back together OK. Except for one thing: jiggling all the pipes to get the housing back in, I think I may have cracked a seal on the fuel pipes as it was a b*tch to restart. Eventually it started but I will see in the morning if I get the cold start symptoms. Might be another job to do, although I'm hoping that I just disturbed rather than knackered the fuel pipe seals. :(. I did, though, manage to re-fit the pipe holder as the bolt self-threaded the hole - I assume that the alloy is quite soft as it wasn't a real struglle to screw home. I also used an 8mm socket for all the star bolts which worked fine for me.

On the plus side, I took it for a spin and the temperature rose to the more familiar point above 80 so happy that there was an issue that is now fixed.

Dave
 

Wirral_guy

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simon, what is the purpose of the stubby hose ? I understand its just blanked off so does not supply anything ?
My car does take time to warm up but does reach 80-85 after about 10-15 mins - depends on driving style and speed - If idling then it would be more than this i guess.

A bit of a guess but it looked as though it feeds water through to the oil filter housing so maybe channels the coolant around that. That was my thought whilst I was trying to work out how to put it back.

Dave
 

Peter De La Mare

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The fourth holds a sort of double fuel pipe clip. You will find that the new housing isn't tapped for the fuel pipe clip bolt so you wont be putting that back.

It's intended for you to retap the thread with the bolt as you do it up. This is very common now. On the E320 CDi Thermostat housing there are two blank threads that you tap yourself. I guess it saves production costs.
 

270CDI

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I've had a read through all your threads and it seems like a fairly straightforward job.
One question though, why does the housing need replacing? Can't i just buy a new thermostat and o-ring to do the job? But if i have to replace the housing aswell, how much do MB charge for all this?
 

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The thermostat and housing are all one around £35
 

Peter De La Mare

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Well, I paid £47.:mad:
 

Peter De La Mare

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No, I'm just perpetually skint because I can't find Thermostats for £35.
 

television

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No, I'm just perpetually skint because I can't find Thermostats for £35.

One member posted that we had paid £35,,but finding that post is hard as there are a few post running on this
 

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