Oil Cooler Thermostat Replacement - Page 3 - PeachParts Mercedes-Benz Forum

funola · #31 08-01-2015, 12:47 PM

How did you take the 2 pieces on the left apart in your pic? I took my T stat out on my spare housing and those 2 pieces won't separate. It looks like they are held together with a black rubber seal. Those 2 pieces make up the T stat assembly (I think), item 86, and is what you get if you buy a new one from Mercedes, which is what I plan on doing. I'll post pics of mine later.

mach4 · #32 08-01-2015, 01:07 PM

I would say yes. I'll do that same test with my good one to confirm.

I think it's a Teflon disc but not certain

I just pressed the two parts apart. It's just a snug fit, nothing special.

funola · #33 08-01-2015, 01:13 PM

Quote:

Originally Posted by mach4

I would say yes. I'll do that same test with my good one to confirm.

I think it's a Teflon disc but not certain

I just pressed the two parts apart. It's just a snug fit, nothing special.

Why did you press them apart? Is the part of the T stat the non bronze piece (with the 4 vent orifices, you called it a piston) that does the sealing between oil pump and oil cooler? I think it is but need to study it more to be sure.

funola · #34 08-01-2015, 01:17 PM

My stat is marked 03X, not sure what that means and not sure what year or what engine the housing came from. I'll get a p/n off the housing later.

funola · #35 08-01-2015, 01:20 PM

The stem extension is 7.5 mm at 90F ambient which I think = failed.

Edit: I think this T stat and housing may have been messed with. The end cap for the stat (item 83, Mercedes calls it a valve seat) was very loose and required no torque to remove.

funola · #36 08-01-2015, 01:40 PM

Quote:

Originally Posted by mach4

.......I'll do that same test with my good one to confirm.............

What test?

mach4 · #37 08-01-2015, 01:46 PM

Quote:

Originally Posted by funola

What test?

Pouring water...

I've got 4.61mm stem extension on my good thermostat.

funola · #38 08-01-2015, 01:52 PM

Quote:

Originally Posted by mach4

Pouring water...

I've got 4.61mm stem extension on my good thermostat.

I don't think that is a valid test after looking at my stat. Those 4 vent holes will let the water through and will also let oil through to the cooler before the stat opens. So I don't understand the FSM test that says you should get a sudden rise in temp at the inlet of the oil cooler when the oil reaches the opening temp of the stat.

Edit: I mis spoke. Those 4 holes are the path of oil flow to the oil cooler. How are they sealed against the housing when the stat is closed? I'll have to take a closer look at the housing.

mach4 · #39 08-01-2015, 01:57 PM

Quote:

Originally Posted by funola

I don't think that is a valid test after looking at my stat..

Yea, I'm agreeing with you on that.

funola · #40 08-01-2015, 05:52 PM

mach4, do you know if p/n 1171800175 is the 110C T stat?

It's $47.50 from mbpartsworld REGULATOR. ENGINE LUBRICATION; OIL FILTER made by Mercedes Benz. #1171800175

but $37.95 from ecstuning
1171800175 - REGULATOR,OI - ES#1644529

Anyone buy from these outfits before?

mach4 · #41 08-01-2015, 06:05 PM

I have no clue...

I was running 180F on the trip back from the junk yard today.

funola · #42 08-01-2015, 06:35 PM

Just spoke to ECS. They will check with their Mercedes specialist on Monday if it's the 110 C stat and if it is available from Mercedes. They also have the gaskets. I don't think it is a good idea to put in a used stat considering what can happen if it fails in the wrong position.

mach4 · #43 08-01-2015, 06:47 PM

Make sure you get the waffle gasket

You want the one on the right...notice the difference in texture and thickness compared to the non-MB one!

funola · #44 08-02-2015, 08:49 AM

Quote:

Originally Posted by mach4

Make sure you get the waffle gasket

You want the one on the right...notice the difference in texture and thickness compared to the non-MB one!

I will thanks.
Have you checked your pressure relief valve? Pushed hard on mine with a stick and it didn't move. Made a tool to get the screw cap off but it's too tight-need to apply more torque to get cap off. Meanwhile took cover off the other ports to look at the pressure relief valve and noticed a rod inside the spring which should not be there per parts diagram. Can you check yours?

mach4 · #45 08-02-2015, 04:42 PM

I tested the pressure relief valve and it works fine. Takes a fair amount of pressure, but that's to be expected given the pressure it's designed to open at. Haven't made a tool to open it up so can't comment on that aspect.