Coolant leak.. I Think I found the source
#51
MBWorld Fanatic!
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.
The following users liked this post:
biker349 (07-21-2022)
#52
Look under your own bonnet - I did and easily found it! It's obviously the water pipe
#53
Junior Member
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:
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:
The following users liked this post:
biker349 (07-21-2022)
#54
Super Member
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
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
2005 M271
The following users liked this post:
biker349 (07-21-2022)
#55
MBWorld Fanatic!
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.
Last edited by VVF; 02-03-2019 at 07:17 PM. Reason: typo
The following users liked this post:
biker349 (07-21-2022)
#56
Junior Member
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!
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!
Last edited by justapstar7; 02-04-2019 at 01:08 PM.
The following users liked this post:
biker349 (07-21-2022)
#58
Super Member
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
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
Last edited by jkowtko; 01-30-2022 at 09:39 AM.
The following users liked this post:
biker349 (07-21-2022)
#59
MBWorld Fanatic!
Join Date: Dec 2003
Location: Vancouver, BC, Canada
Posts: 3,122
Likes: 0
Received 210 Likes
on
201 Posts
2003 C230K Coupe Orion Blue
Front coolant pipe replaced again
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.
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.
Last edited by slammer111; 06-11-2024 at 03:24 AM.