Fuel Injector O-Ring Lubrication
Thread Starter
Member
Joined: Jul 2012
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From: San Francisco, CA
2003 C230 Sedan Manual
Fuel Injector O-Ring Lubrication
Replacing the fuel injectors (one of them is leaking) on my 2003 C230. The WIS recommends Lubricating paste, rubber parts 2.5 kg, DB supply specification 6867.00 part number A 000 989 01 60. It sells in bulk for about $100 at the dealerships. Which aftermarket product do you recommend? I hear all kind of conflicting advice online. Thanks
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From: BC, Canada
2003 C230K Coupe Orion Blue
Just curious, how did you know an injector was leaking?
When I had to remove the injectors as part of the crankcase breather hoses and check valve replacement I didn't even know any lubrication was required. I just hammered them back into the engine.
If you think about it, the lube is really just for ease of installation/removal. The stock holes are already super tight. I imagine any grease that doesn't eat o-rings will also work. Unfortunately I can't tell you what those would be. I should also mention that the o-rings were completely dry when I pulled them out, so whatever they used was long gone.
You may also want to look at the job above if you haven't done so already.
When I had to remove the injectors as part of the crankcase breather hoses and check valve replacement I didn't even know any lubrication was required. I just hammered them back into the engine.
If you think about it, the lube is really just for ease of installation/removal. The stock holes are already super tight. I imagine any grease that doesn't eat o-rings will also work. Unfortunately I can't tell you what those would be. I should also mention that the o-rings were completely dry when I pulled them out, so whatever they used was long gone.You may also want to look at the job above if you haven't done so already.
Last edited by slammer111; May 17, 2025 at 06:52 PM.
Thread Starter
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Joined: Jul 2012
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From: San Francisco, CA
2003 C230 Sedan Manual
An independent shop diagnosed a slow crank due to too much fuel and found out that injector #1 is leaking. I have already replaced the hoses and check valve at least twice over the life of the car, so will likely leave these alone for now unless they look suspect upon closer look. Just trying not to damage the o-rings putting the new injectors in, or using lubricant that might weaken the seals over time. I see mentions in other posts of Chemours Krytox GPL 105 being repacked by MB for use on the sunroof, but seems to be a liquid and not a paste so am a bit hesitant to use that one.
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C230K
Do you literally mean the cranking is slow, or is the car hard to start (cranks for a long time before the engine fires up)?
And be sure to use a genuine MB or Bosch injector. I know someone who replaced their injectors with cheap Amazon junk and it resulted in poor drivability.
And be sure to use a genuine MB or Bosch injector. I know someone who replaced their injectors with cheap Amazon junk and it resulted in poor drivability.
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w203cl
Krytox GPL 205 is the corresponding grease. Very expensive.
I use a silicon grease and never had problems so far. You can clean injectors usually very good. Put them in a vice (I bored a hole in a wood piece) connected to 12V and a switch, a syringe full of carb cleaner and pressed it through.
I use a silicon grease and never had problems so far. You can clean injectors usually very good. Put them in a vice (I bored a hole in a wood piece) connected to 12V and a switch, a syringe full of carb cleaner and pressed it through.
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2003 C230 Sedan Manual
Thanks will use the Krytox then. This small tube is still a lot cheaper than at the dealer.
https://a.co/d/6fNe9uv
https://a.co/d/6fNe9uv
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Thread Starter
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Joined: Jul 2012
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From: San Francisco, CA
2003 C230 Sedan Manual
Takes about 3 sec to start-up the car, longer than it used to. Ordered the injectors from Germany through MB. Took several weeks to arrive as they were on back order.
Do you literally mean the cranking is slow, or is the car hard to start (cranks for a long time before the engine fires up)?
And be sure to use a genuine MB or Bosch injector. I know someone who replaced their injectors with cheap Amazon junk and it resulted in poor drivability.
And be sure to use a genuine MB or Bosch injector. I know someone who replaced their injectors with cheap Amazon junk and it resulted in poor drivability.
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Thread Starter
Member
Joined: Jul 2012
Posts: 90
Likes: 2
From: San Francisco, CA
2003 C230 Sedan Manual
Just curious, how did you know an injector was leaking?
When I had to remove the injectors as part of the crankcase breather hoses and check valve replacement I didn't even know any lubrication was required. I just hammered them back into the engine. If you think about it, the lube is really just for ease of installation/removal. The stock holes are already super tight. I imagine any grease that doesn't eat o-rings will also work. Unfortunately I can't tell you what those would be. I should also mention that the o-rings were completely dry when I pulled them out, so whatever they used was long gone.
You may also want to look at the job above if you haven't done so already.
When I had to remove the injectors as part of the crankcase breather hoses and check valve replacement I didn't even know any lubrication was required. I just hammered them back into the engine.
If you think about it, the lube is really just for ease of installation/removal. The stock holes are already super tight. I imagine any grease that doesn't eat o-rings will also work. Unfortunately I can't tell you what those would be. I should also mention that the o-rings were completely dry when I pulled them out, so whatever they used was long gone.You may also want to look at the job above if you haven't done so already.
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Joined: Dec 2003
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From: BC, Canada
2003 C230K Coupe Orion Blue
Thanks for the suggestion to replace the crankcase check valve and hoses as part of the job. I experienced a blown crankcase gasket not too long ago, without any obvious root-cause. Now I wonder if a malfunctioning check valve could have contributed to a high crankcase pressure and subsequent gasket leak?
When I replaced the hoses and check valve, I do remember finding that a brass nipple with a pinhole had completely plugged up. Might want to look into this too. The good news is this nipple is relatively easy to access, and only requires removal of the air box.
Last edited by slammer111; May 19, 2025 at 04:41 AM.
Thread Starter
Member
Joined: Jul 2012
Posts: 90
Likes: 2
From: San Francisco, CA
2003 C230 Sedan Manual
I always assumed that the check valve fails open. Internally it's basically a plug that is pushed closed by a spring. In theory I guess the plug can get jammed (oil gunk) but I imagine the valve is more likely to fail open (spring failure). If you have a high crankcase pressure, I would look more into problems such as excessive blowby. Have you had a compression test done on the engine?
When I replaced the hoses and check valve, I do remember finding that a brass nipple with a pinhole had completely plugged up. Might want to look into this too. The good news is this nipple is relatively easy to access, and only requires removal of the air box.
When I replaced the hoses and check valve, I do remember finding that a brass nipple with a pinhole had completely plugged up. Might want to look into this too. The good news is this nipple is relatively easy to access, and only requires removal of the air box.
Will definitely clean the pinhole and probably replace the check-valve too while I am in there.
