2003 C230k M271 - coolant leak at back of engine
tl;dr = What’s the triangle-shaped extra bit that came with my replacement Oil Cooler Water Pipe (A-271-200-13-52)?
SO thankful for this post. You guys saved me a lot of frustration & money spent on topping up coolant all the time.
I wanted to remove the part & double-check the P/N, but I was afraid of all the other components people said they had to remove in order to get to this pipe. I’m either lucky or stupid, but I decided to just go for it & try to remove the pipe without removing anything else.
I had a pretty easy time getting my hand wiggled between the other hoses that make getting to this pipe difficult. My palm-sized articulating ratchet slipped right into the correct space, and made getting the ONE BOLT that holds this thing on easy to remove. (If MB would’ve added another bolt 180° opposite, I’m sure these wouldn’t fail as often)
Total time = 10 min. (+15 min spent looking for something to catch the leaking coolant under the car)
Like many of you, I found I did have a cracked pipe at the o-ring (which was stretched out)...BUT...mine was so brittle I couldn’t put it back on after I removed it. This little Merc is my daily, so I was in a bad place.
I used some Gasket Maker (sold at all the local parts stores) to create a stop-gap solution while I waited for the new part I ordered to arrive. It worked! For about a month, actually....but I’m now experiencing coolant leakage just like before, so it’s time to put the new part in.
BUT!... I don’t know what this extra triangle-shaped boy is for. I’m sure it’s staring me in the face & super obvious, but I’m just not seeing it. A little help?
Also: I’m reusing the hose clip. It’s easy to swap onto the new part: Just pop the inner rod out using an awl/screwdriver/nail, or, in my case: a letter-opener.
Also how did you get the plastc hose clamp to unclamp?
Thanks
Gary
I used a standard ratchet and (once the hose that is clipped on the plastic hose is detached) it worked fine.
I actually managed to get both my hands back there too!
I got the part from Amazon here for $13 TOPAZ 2712001352 Coolant Water Pipe - Oil Cooler to Cylinder Head
But after 4 plus hours finally accepted that the supplied O'ring was too thick and bought this O'ring hit for $11 419pc Universal O-Ring Assortment Set Metric Kit Automotive Seal Rubber Gasket
With the right o'ring, it is actually 15MIN JOB!!!
So here are my arm positions as I lay on the engine
My hand could reach all the way down!!
I undid the hoseclip and clamp 1st. Do Not try and remove the Host clip with force, there is a pin holding it in.
Last edited by garyhgaryh; Oct 29, 2020 at 11:55 PM. Reason: Fix typo




In your case the tab was at the top when looking from the top of the engine? My tab was facing the other direction (down). I hope I'm not confusing you.
Thanks!
Gary
Last edited by garyhgaryh; Oct 30, 2020 at 04:13 PM.
Tab is up
Craftsman 9-41421 1/8" x 2" Slotted Screwdriver
Price: $7.49
Doesn't work. I even have a smaller slotted screw driver... NO go..
Craftsman 9-41421 1/8" x 2" Slotted Screwdriver
Price: $7.49

The Best of Mercedes & AMG




With that said, nothing wrong with snipping off the clip if you're desperate. Like you mention, a replacement is only a few bucks.
No surprise the pipe broke at the o-ring seat since a bunch of you had the same problem. Now i have to clean up the remnants of the old pipe and o-ring.
I hope this $10 pipe replacement is good enough. I got it since jasonMB used the same part. I got the extra O-rings just in case (he had issue with the O-ring being too thick).
With that said, nothing wrong with snipping off the clip if you're desperate. Like you mention, a replacement is only a few bucks.
Last edited by garyhgaryh; Nov 3, 2020 at 06:58 PM. Reason: Fix typo; add title; add more photos




Are there any markings on the new pipe you ordered? Wondering if they changed the material (which they did for the OEM part).
Now that you mention it I realize I have a pix of the front side but not the backside of the arm. If you look closely at the part it look like the markings are shaved off on my part. Weird. Wonder if that implies anything? Like perhaps I have an older part.
I should have deburred the inside of the pipe where the restriction was. Anyways, the car is running great now with no leaks. Putting it all together took only a few minutes. That hose strap took so much of my time I could have done several cars if those car has the release tab facing up. Breaking the bracket that holds the strap to the coolant pipe tool a few minutes. Should have done that instead.
I'm glad i found this thread and thanks to you slammer, jasonMB, and the rest of you for an informative thread. Buying that extra o-ring set was a blessing as I had to use a smaller/thinner o-ring. It was labelled R2 on my container. I hope that info helps someone in the future reading this. That's my contribution to this thread
.
Done!
Last edited by garyhgaryh; Nov 3, 2020 at 09:52 PM.




Sounds like you used a lower quality knockoff part for the replacement. If the part was identical to the genuine article, the o-ring would not have had any fitment problems. Also, there is no way to tell if the knockoff used a newer (ie improved) material like the genuine updated part. In any case, time will tell if the part holds up. Glad you got everything fixed.
Sounds like you used a lower quality knockoff part for the replacement. If the part was identical to the genuine article, the o-ring would not have had any fitment problems. Also, there is no way to tell if the knockoff used a newer (ie improved) material like the genuine updated part. In any case, time will tell if the part holds up. Glad you got everything fixed.

Now I have to work on a 535i with a similar problem - coolant leak from back of engine. I know the turbo coolant line in the back are common issues so I'm sure it's that. Dealer wants $3k to fix it as it involves dropping the subframe..
... Onto my next project.Last edited by garyhgaryh; Nov 3, 2020 at 10:51 PM.
The placement of the pipe makes it painful to do. I had to remove the pesky vacuum tube and motor mount to have more space. Would have been quicker if I didn't drop the ratchet - had to lift the car, remove the splash guards hoping to find the tool but nope! It's stuck there by transmission, LOL


Any ideas where I should start looking, before I throw more parts at the car? And MB is supposed to be over-engineered..

In this diagram, the hose that goes closest to the leak isn't shown. It's right where the number 124 is (ie connects to the "lower branch" of 130). Anyone have the diagram that would show that hose?
Heater Hose Part no. 2098300093
Last edited by cmpong; Aug 23, 2021 at 09:38 AM.





https://www.aliexpress.com/i/1005001413124169.html
Last edited by slammer111; Aug 22, 2023 at 09:51 AM.
A decent video I found explaining the issue:
My biggest worry is going to be the piece broken inside. IT not that I wont be able to get it, it that my old *** is going to be sore trying to get this out LOL




Coolant on bell housing
I had previously replaced the coolant pipe above the exhaust manifold and the one leading to the water pump. Fortunately, I recalled reading Slammer's thread at that time, and I was able to find it again with a search. (I probably should have replaced the pipe that is leaking now at the same time. I looked at it but decided it would be painful to do the job and hoped for the best.) I can't confirm whether the coolant pipe is the source of the leak, but it does appear my symptoms are similar to those of everyone who posted on this thread.
I ordered the OEM Mercedes pipe from AutohausAZ. (There are less expensive non-OEM options, but I decided not to save a few bucks at the expense of having to do this job twice.)
I am planning to replace the pipe this weekend and I was taking a look at the situation in my engine compartment. I did notice one oddity:
Hose clip not engaged in the hose.
It looks like the hose clip that holds the coolant pipe to the hose is not engaged properly around the hose. I can't tell whether it is broken or whether someone who previously worked on the car didn't reinstall it correctly. Based on one of the earlier posts in this thread, it appears that the part number for the clip is 209-546-02-43. I may go to the dealer and buy a clip next week just in case I need to replace it. This would delay my work a few days, but I would rather have the clip available and do the job right the first time.
Thanks to everyone who contributed to this thread and to Slammer for initiating the discussion. If anyone thinks I'm on the wrong track, please don't hesitate to speak up.
Last edited by KevinH2000; Mar 22, 2024 at 08:16 PM.


