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Discussion Starter #1
Hi folks, top site and full of good info!

Just doing some preventative maintenance on the car.
Was quoted $275 (plus $51 for the thermostat itself) to change the thermostat on the car.
I am assuming the thermostat housing is the top radiator hose connection to the engine, located just above and to the right of the water pump, as you look at the engine.

Given the dealer wants to have a go..... I thought I'd have a go myself and fit it. Looks to be a very simple task which should take a short period of time.

Am I correct?

Thanks!
 

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Just doing some preventative maintenance on the car.
Was quoted $275 (plus $51 for the thermostat itself) to change the thermostat on the car.
That's a lot of money for the 'comfort' of having done preventative maintenance on a part that was not faulty in the first place.

I would save that money for when something really goes wrong.

But, it's your money sir.
 

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Hi folks, top site and full of good info!

Just doing some preventative maintenance on the car.
Was quoted $275 (plus $51 for the thermostat itself) to change the thermostat on the car.
I am assuming the thermostat housing is the top radiator hose connection to the engine, located just above and to the right of the water pump, as you look at the engine.

Given the dealer wants to have a go..... I thought I'd have a go myself and fit it. Looks to be a very simple task which should take a short period of time.

Am I correct?

Thanks!
It is two bolts and a hose clamp. You can do it.
 

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Discussion Starter #5
That's a lot of money for the 'comfort' of having done preventative maintenance on a part that was not faulty in the first place.
There's only one part that can create a catastrophic engine failure without warning, and it's a thermostat.

I always replace them at 5 years.

My clients and brother didn't though. Both in Mercs and BMW's (same manufacturer of thermostats, Behr).
They've all had engine failures. It's a bit like waiting for a timing belt to snap, rather than changing it before it does. Besides $51 ain't much in deference to a $3,000 engine. It's the $275 that sounds like garbage.

Thanks for the PDF, don't suppose the rest of that manual is somewhere I can snag it?

Cheers!
 

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I changed the thermostat for a friend and it took me less than 30 minutes. Part of the time was spent negotiating whether he would buy me a bag of Cheetos and a soda for my work. Seeing how your dealer wants $275, I think I should have asked for a Snickers too.
 

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There's only one part that can create a catastrophic engine failure without warning, and it's a thermostat.
I understand the importance of Thermostat. I am trying to understand what happens when (a) thermostat failed and it is open permanently, (b) thermostat failed and it is closed permanently.

In the case where it is permanently open, I think the coolant doesn't get hot for a long long time. This is bad if you need heat (during the winter). Other than that, will the engine be damaged in this scenario?

How about scenario (b)?
 

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When it goes bad, it is permanently open and it takes very very long to get hot upto the normal operating temperature. More gas, less efficiency. But drivers can see it quickly and can fix when it goes bad.

That's what I know about bad thermostat.

But in case of scenario (b), temperature needle on your dash will go up to the top very quickly.
 

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Discussion Starter #9
Spot on, unfortunately they usually fail closed.............

And the lady will be driving this, and she's not so good with gauges :surrender:
 

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Make sure you use MB colant and distilled water..

Just a small thing, your tap water down there tends to be alkaline so make sure you use distlled water for the coolant mix..

We really-really don't have thermostat failures here in the US, since our water ph is much more regulated to neutral.

In other areas, including your's and the Middle East, tap water tends to be alkaline and with the dissimilar materials in these modern engines a lot of freaky things can happen internally..

Keep the beat mate..
 

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Mine gone bad last weekend and it stuck open. My old old old car had also the thermostat problem and it was stuck open. I guess... they usually fail open. ;)
 

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I changed the thermostat for a friend and it took me less than 30 minutes. Part of the time was spent negotiating whether he would buy me a bag of Cheetos and a soda for my work. Seeing how your dealer wants $275, I think I should have asked for a Snickers too.
hahahaha awesome. Please post more often.
 

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Mine gone bad last weekend and it stuck open. My old old old car had also the thermostat problem and it was stuck open. I guess... they usually fail open. ;)
I'm speechless.


Am I the only person here who runs the truck with no thermostat installed?
 

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boardboy, seriously? no thermostat?
Without the thermostat, the heater may not function properly (if you live in a place where you wouldn't need heat, that shouldn'e be a problem).

With the thermostat removed, how is the upper radiator hose connected to the hole where thermostat was supposed to be?

I know that the coolant temperature is monitored by ECU. Are there any other side effects of not having the thermostat?
 

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The thermostat only closes the water loop in the motor and radiator long enough to heat the motor up. So basically without running a thermostat...my truck runs colder for about 15 minutes...then is completely warmed up. I do the same thing on every vehicle I had. I know those little $4 parts fail often...so I see no reason to leave my $5K motor to chance. Now that being said...if you live in cold climate...like Jersey, NY basically any place up north...not a good idea. But in Florida, Georgia, and the Carolinas I was fine.
 

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When full cooling is needed thermostat closes bypass to water pump and all coolant flows through radiator. Without thermostat cooling system operates in mixed mode.
 

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And yet again...Witek FTW. You know more about my truck than I know about...anything.
 

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Apologies for resurrecting an ancient thread :surrender:!

But I was about to replace the stuck open thermostat on my ML350 and something in the Coolant Circuit PDF posted above caught my eye. The entry "S Windshield washer fluid reservoir, coolant heated". Was this an option, or do all ML's heat the washer fluid?

Also the heater core speaks of twin "duovalves". What are these and what are their function?
 
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