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Discussion Starter · #1 ·
Hey All,

I have a 2008 CIvic LX with 253k miles. All maintenance is done (could use a thermostat, water pump and tensioner for preventative but I haven't gotten around to that). I just got my results back from testing my used oil and Blackstone is telling me that there is a small amount of coolant in my oil.
I started to notice the smell of coolant in the cabin, but only when the engine is warm/hot already and I start it. Like if I drive to the supermarket, get something real quick and come back to the car to start it, that's when I smell it. It goes away pretty quick.
So far I have put a dye in the coolant and used a UV light to look around, but I can't find anything.
I also borrowed a pressure tester from Advance Auto. Pumped up to 16psi and the came back after 10 mins to find the needle didn't move

Yesterday I changed the starter....I decided to take the UV light out and look for any evidence of the coolant leak and I think I found something. Right under the throtttle body and where the intake manifold meet it looked like the leak starts from there.

Questions:
Does coolant run through that area?
Does coolant and oil come into contact with each other anywhere in that area?

Posting a pic from a diagram of where I saw the coolant coming from:
Any help is appreciated.
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For the Si, the throttle body has two little metal coolant lines that are built into the assembly to cool it down (I’m assuming?). I actually had a leak in that area and it ended up being a small ring clip around the TB line that was loose. Perhaps the r18 has the same TB setup, but that doesn’t explain how it could get in your oil… that’s very concerning
 

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Hey All,

I have a 2008 CIvic LX with 253k miles. All maintenance is done (could use a thermostat, water pump and tensioner for preventative but I haven't gotten around to that). I just got my results back from testing my used oil and Blackstone is telling me that there is a small amount of coolant in my oil.
I started to notice the smell of coolant in the cabin, but only when the engine is warm/hot already and I start it. Like if I drive to the supermarket, get something real quick and come back to the car to start it, that's when I smell it. It goes away pretty quick.
So far I have put a dye in the coolant and used a UV light to look around, but I can't find anything.
I also borrowed a pressure tester from Advance Auto. Pumped up to 16psi and the came back after 10 mins to find the needle didn't move

Yesterday I changed the starter....I decided to take the UV light out and look for any evidence of the coolant leak and I think I found something. Right under the throtttle body and where the intake manifold meet it looked like the leak starts from there.

Questions:
Does coolant run through that area?
Does coolant and oil come into contact with each other anywhere in that area?

Posting a pic from a diagram of where I saw the coolant coming from:
Any help is appreciated.
View attachment 247748
bye a jdm (r18 from japan) engine with low mileage. u'll spare time and money...if you buy it, buy with transmission.. easy swap...just did it 2 months ago (same leakage from oe engine issue [06 to 08]) and it runs great now... feels like a brand new car...
 

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Discussion Starter · #4 ·
bye a jdm (r18 from japan) engine with low mileage. u'll spare time and money...if you buy it, buy with transmission.. easy swap...just did it 2 months ago (same leakage from oe engine issue [06 to 08]) and it runs great now... feels like a brand new car...
Would love to swap out an engine as a project, but just don't have the time. Next chance I get I'll take off the throttle body, give it a good cleaning and do some investigating. As far as the oil in the coolant, it's trace amounts, so I'm gonna ride it till the wheels fall off.
 

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Discussion Starter · #5 ·
For the Si, the throttle body has two little metal coolant lines that are built into the assembly to cool it down (I’m assuming?). I actually had a leak in that area and it ended up being a small ring clip around the TB line that was loose. Perhaps the r18 has the same TB setup, but that doesn’t explain how it could get in your oil… that’s very concerning
Next couple of days off I get, I'll take off the throttle body for a cleaning and do some investigating. Thanks
 
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