Just wanted to add my experience for posterity of the forum. My '03 c230 has 110k miles on her and I just had to replace this pipe - the one above the exhaust manifold. I replaced the coolant pipe and vacuum pump at the rear of the engine last summer due to leaks, but had to add water several time over the past year and located a (hopefully 'the') leak where this pipe enters the head. The pipe had cracked at the groove for the o-ring. Had to pull the cracked off part of the pipe out of the head. I would definitely pull the heat shield to remove the pipe. I also used a piece of bailing wire to keep the hose clamp from slipping down the hose which runs behind the engine. I also used a very, very small amount of waterproof grease to lube the o-ring to make it easier to get in place. It took about 2 hours including putting the car up on ramps, removing bottom pan to drain coolant (reused coolant, still fresh from last summer), and letting cool down enough to do the work. Hoping this was the last of the coolant leaks. If I could find a suitable adapter I would pressure test - or a suitable vacuum system which would work on this car I might consider getting on of those.

 

 

Hello guys..
Doing a mini invasion on that topic so i share my issue here hence is the most relevant i found.
I have a w204 C200 Kompressor (204.041) (135 KW / 184 PS)
I had the top up coolant index yesterday,did a ~150kms route.
Later in the night as i was reurning home, I saw some "smoke".
Turns out it was the antifreeze fluid evaporating as it was leaking on hot surface of the engine.
Tank was 1/3 full at this time.
I was "hoping" it was a hose or an o-ring but i might be in deeper trouble.
Can you tell me by your experience if that is a crack on the engine block?
Or this "line" is the way the aluminum is casted and the leakage comes from above,where the hose contacts?
video:

leakage point

 

Here's the photo of mine ... unfortunately I didn't take a very clear photo so it's hard to tell ... but it does look like a casting flange in there. If you are the original owner of this car and never had an overheating problem, then I would assume no reason to think you've cracked the head. It's not a huge amount of work to replace that o-ring ...

2005 M271

 

Hi Justap,
Are you sure it is leaking from that area? If you are sure, then most likely it is the old o-ring, not the block. That line is just from casting.
One way to make sure is to start the car, get the cooling system up to pressure, then stop the car and observe; as the engine cools down, you should start seeing something.
I notice some stains on the front and also on the power steering reservoir. Check it it is not from the water pump - there is a little weep hope, IIRC toward the top of the pump casing by the pulley.

 

Hi guys!
So let's say I got lucky in my unlucky situation.
Only the horizontal tube needed replacement.
Flush of the system, new fluids, all done to the steelership because i wanted to be sure and have the guarantee hence its a weak point of our engines.
Thank you all for the answers and interest you shown, I appreciate it!

 

does anybody know what this is called even the auto part store can’t tell me. It’s leaking from there and it’s the top left of my radiator.

 

That looks like the transmission cooler line. There is a small o-ring in there that probably needs to be replaced. It was part #C-019-997-57-45 when I bought it 10 years ago to do the tranny fluid flush ... retailed for $5 each and they gave it to me for about half that. Look like FCP Euro, for one, still carries it ... https://www.fcpeuro.com/products/mer...ing-0199975745

To remove the fitting, first there are a couple of clamps on the line that are holding it against the radiator, you will have to unfasten them ... then simply slide that clip out of the fitting about a half inch and then pull the fitting straight out away from the radiator ... it's a round tube with an o-ring on it ... you might need to wiggle it a bit as the o-ring makes it a tight fit.

You are at the top of the circuit so little if any tranny fluid will leak out ... but put a few paper towels under there to catch any drips.

Enjoy!

-- John

 

So after a few years of having a weird intermittent leak at the front of the engine, I decided to replace the front pipe again.

Some notes:

The current OEM (dealer) PN for the thermostat is A271-203-05-75, and is made by Wahler. It is rated to open at 88C, while the aftermarket (Wahler) units I purchased in the past were rated at 90C. Not a big deal, but worth mentioning.

The OEM thermostat does not include any of the o-rings (one between the pipe and thermostat, and one where the pipe fits into the motor). For this reason I would recommend buying a reputable aftermarket unit (most of which include both o-rings) instead to save a few bucks. As long as the actual unit is made by Wahler (OE brand), it'll be fine. From personal experience, most aftermarket thermostats for this car are repackaged Wahler units.

A029-997-21-48 o-ring between pipe and motor (included with coolant pipe)
A271-997-00-45 o-ring between pipe and thermostat

The front coolant pipe is PN A271-200-12-56, which is unchanged from before. This pipe includes the o-ring between pipe and motor, but not the o-ring between pipe and thermostat. While the old pipe had not completely failed (ie broken in half), I did notice that the inside was warped, as if it was melting from the heat. Unfortunately the part has not been updated (exact same material as the previous one), so I imagine these pipes will just have to be replaced every few years. Also I noticed that the plastic ridge that sits against the thermostat o-ring had turned soft and was starting to crumble like a cookie. The pipe was definitely on its way out.


Warped pipe interior

I also had a weird problem where the o-ring between the pipe and motor would swell and stretch (resulting in leaks) within a few months of installation. When I removed the 2 screws, both were covered in a mixture of engine oil and coolant. I also found smudges of caked engine oil in the hole where the pipe goes. I suspect that the o-ring material is compatible with coolant but not with the engine oil, and was reacting with residual oil from when I had the leaking can sensor magnets. This time I cleaned out the screw holes as best as I could. Hopefully this permanently fixes the problem.

 

whats the part number for the long tube on top

 

I need some help I dropped both the screws for this job and need help finding the part number. They dropped somewhere and I cannot find or see them. Can you tell me what part #160 in the diagram is?

 

Your local dealer will know. Guessing most people here won't have those PNs handy as we would've just reused the screws.

With that said, if you didn't move your car, just remove the underbody tray and find them both. A magnetic pickup tool would also help. Wouldn't that be easier?

 

I need part number for #160 I dropped the bolts trying to get them back in. Greatly appreciate it.

 

Looks like today's your lucky day. Someone else posted the PNs for the diagram.

According to the link, the screw you want is PN N910143-3006001 aka M6x16 screw. I think there's a typo though - I think the PN is actually N910143-006001 (notice the missing "3").

 

@slammer111 Thank you muh for the help. This coolant pipe and these screws are driving me crazy. The screws are not at the bottom they are somewhere on the back of the engine. Just a 30 min job has turned into a problem. LOL thank again man.

 

Heres a link to the parts diagrams. Pick your model then submodel. https://nemigaparts.com/cat_spares/epc/mercedes/1/

Water pump diagrams found under Engine > Engine Cooling > Water Pump