OM642 C207 2012 Running Temperature

[MrGundam]

Had a good look around the forum and think this is hopefully just the thermostat. Despite a few good 30 minute runs on the motorway my engine doesn't seem to go past 80 and usually sits around 65 - 70c:

I have a genuine MB thermostat arriving tomorrow (£154!!!) but wondered if there are any other things which could cause a cool engine if this does not fix the issue? Thanks

 

[Flash]

It will be the thermostat.

It's getting stuck in the open position.

 

[MrGreedy]

should be rock solid at something like 89 degrees.

Good move with the new thermostat

 

[markjay]

[/IMG]..I have a genuine MB thermostat arriving tomorrow (£154!!!) but wondered if there are any other things which could cause a cool engine if this does not fix the issue? Thanks

Nope... nothing else, just the thermostat.

And, depending on where it is located on the engine, you might need to top up the coolant.

One way of tacking it is by siphoning-out the coolant from the expansion bottle, which will lower the level, then pouring it back in once the job is done.

 

[OneForTheRoad]

Was the previous owner called trotter by any chance ?

 

[MrGundam]

Was the previous owner called trotter by any chance ?

Believe it or not the car has had yearly services at first MB the a specialist indie. It was garaged for nearly 2 years before I bought it, covering only 500 Miles.

Luckily I got it for a good price, and bitcoin has been very good to me this year

 

[OneForTheRoad]

Believe it or not the car has had yearly services at first MB the a specialist indie. It was garaged for nearly 2 years before I bought it, covering only 500 Miles.

Luckily I got it for a good price, and bitcoin has been very good to me this year

You'll have a good car and peace of mind once you get it sorted. You seem a bit like many others on here and enjoy DIY. Good on ya .

Garaged for 2 years probably explains the rotten brake pipe .

 

[MrGreedy]

I'm just posting this as a question, and something that @markjay will probably know better, but if you bought this from a car trader/garage, if there is a fault does the trader have to offer a repair or offer to replace the vehicle under your consumer rights by law?

I can't remember and had a quick look, but did you buy privately or from a trader?

 

[markjay]

Offer a repair, unless the fault is substantial, or several faults keep appearing repeatedly.

In any event you can't reject a car before you've given the seller the reasonable opportunity to sort-out the problem.

 

[MrGreedy]

Thanks markjay

MrGundam, you seem to be fixing a few things. If you bought from a trader it might be worth seeing if they'll do their lawful duty and help you out here?

 

[MrGundam]

Thanks markjay

MrGundam, you seem to be fixing a few things. If you bought from a trader it might be worth seeing if they'll do their lawful duty and help you out here?

Hi Greedy,

This was a private sale, and to be fair to the guy everything he said was true and it was a good price. He was selling on behalf of his son who moved abroad and the car had very little use the past 2 years, just sat in his garage. The service history stacks up each year and has had the AT filter / fluid done at 80,000 which was a good sign.

Most motors I have had the temp gets up to about 83c so on the test drive the temp I was getting didn't seem out of reasonable expectations. The burst brake pipe was a bit of a shock but luckily I found the cause. Unfortunately these modern vehicles have so much plastic covering everything that when buying it is not viable to have a full look about behind everything. Even the MOT misses many of these issues.

Fortunately I am fairly confident at DIY mechanics and so have most tools needed and to be honest tackling these issues now is peace of mind and has given me the opportunity to get to know the vehicle a little. Tackling the jobs myself saves a lot of money that I then use for other maintenance items as a precaution. So far I have installed carplay, done oil change / filter, fuel filter, cabin filter, PCV, thermostat, turbo inlet gaskets, brake fluid flush and soon to do power steering flush.

My only concern is what the EGR tract holds as I am aware these things gunk up over time. Further down the line I envisage inlet removal and clean / swirl flap delete with oil cooler seals done whilst I am in there.

 

[MrGreedy]

Ah, okay then.
I bought mine private too and I'm fine with doing the fixing as well, and like you a lot of it is preventative as I intend to keep the car a good while, so the bits will need doing anyway and my view is if I get them done earlier, I will personally get more benefit from my money during my ownership.

 

[mbmb123]

My car was running cold, not as much as yours. What alerted me was the failure of the stop/start to enable itself.
Apparently being up to temperature and having a good battery are required before it will engage.

But back to the thermostat. It will be interesting to see the internals. You can actual remove the thermostat from its housing.
(So MB could sell this item, but they'd make less money)

Looking at mine I realized the "rubber" sealing ring had failed, there's only a small piece remaining.
I wonder where the rest of it is???

 

[Flash]

For sake of a few quid imo it's best to replace the whole unit supplied genuine from MB.

I changed mine myself and quite a straight forward job to do but little bit of stripping involved.

Autodoc do sell the thermostat individual though.

 

[MrGundam]

All sorted now. Replaced the entire unit (didn't know you could replace the actual thermostat part).

Sits around 92c now which is spot on. First time I have ever had a car where the temp issue was actually the thermostat, usually something else.

 

[MrGundam]

My car was running cold, not as much as yours. What alerted me was the failure of the stop/start to enable itself.
Apparently being up to temperature and having a good battery are required before it will engage.

But back to the thermostat. It will be interesting to see the internals. You can actual remove the thermostat from its housing.
(So MB could sell this item, but they'd make less money)

Looking at mine I realized the "rubber" sealing ring had failed, there's only a small piece remaining.
I wonder where the rest of it is???

Couldn't see anything obviously wrong with it. Mine didn't have a o-ring and had a rubber base that looked in good condition.

 

[MrGreedy]

That thermostat shaped gasket where it bolts to the inlet manifold is £16!!!!! from Merc. A complete rip-off of a gasket by Merc standards which usually aren't too bad usually.

If you did go for the just innards, you would (should) have to add that to the total cost, whereas I bet it was provided with a new thermostat.


Edit: corrected. I previously said water pump, but I meant thermostat

 

[OneForTheRoad]

Hi Greedy,

This was a private sale, and to be fair to the guy everything he said was true and it was a good price. He was selling on behalf of his son who moved abroad and the car had very little use the past 2 years, just sat in his garage. The service history stacks up each year and has had the AT filter / fluid done at 80,000 which was a good sign.

Most motors I have had the temp gets up to about 83c so on the test drive the temp I was getting didn't seem out of reasonable expectations. The burst brake pipe was a bit of a shock but luckily I found the cause. Unfortunately these modern vehicles have so much plastic covering everything that when buying it is not viable to have a full look about behind everything. Even the MOT misses many of these issues.

Fortunately I am fairly confident at DIY mechanics and so have most tools needed and to be honest tackling these issues now is peace of mind and has given me the opportunity to get to know the vehicle a little. Tackling the jobs myself saves a lot of money that I then use for other maintenance items as a precaution. So far I have installed carplay, done oil change / filter, fuel filter, cabin filter, PCV, thermostat, turbo inlet gaskets, brake fluid flush and soon to do power steering flush.

My only concern is what the EGR tract holds as I am aware these things gunk up over time. Further down the line I envisage inlet removal and clean / swirl flap delete with oil cooler seals done whilst I am in there.

The egr itself can be hard to get out. You need a chisel and a few taps of a hammer to get it shifted . Turning it as you go. Mr.muscle in an old coffee mug and let it to soak.

That water pump shaped gasket where it bolts to the inlet manifold is £16!!!!! from Merc. A complete rip-off of a gasket by Merc standards which usually aren't too bad usually.

If you did go for the just innards, you would (should) have to add that to the total cost, whereas I bet it was provided with a new water pump.

Water pump ?

 

[MrGreedy]

Water pump ?

Thermostat.
Corrected my post

 

[mbmb123]

Interesting, despite our cars being the same year and basic engine OM642, your thermostat is a different design.
My spindle comes off the internal diaphragm, yours comes off the housing.