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Oil leak

Tiny
CP313
  • MEMBER
  • 2004 CHEVROLET MONTE CARLO
  • 3.4L
  • V6
  • AUTOMATIC
  • 225,000 MILES
My car is leaking oil from this part of the engine in the picture. When that yellow piece is plugged into that hole and I start the car out oil steadily drips from there. Does anyone know what that part is called or how to fix it?
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Tuesday, November 17th, 2020 AT 10:58 AM

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Tiny
CP313
  • MEMBER
  • 19 POSTS
This is what I’m talking about, when that yellow piece is in and I start car up oil leaks there? What is that?
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Tuesday, November 17th, 2020 AT 11:03 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Can you do a couple things? First, can you remove the sensor so we can see the tip and that will confirm what I think it is. It looks like that is the engine coolant temperature sensor. So if that is the case then your coolant and oil are mixing. The oil does look thin and milky but not as bad as I would expect for it to be leaking out of this. It could also be the oil pressure sensor but it doesn't look like it is in the correct location.

Also, can you check the oil and coolant and see if they are mixed?

https://www.2carpros.com/articles/coolantantifreeze-in-the-engine-oil

Let us know this info and we can go from there. Thanks
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Tuesday, November 17th, 2020 AT 12:13 PM
Tiny
CP313
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  • 19 POSTS
Thanks for your help. When you say remove sensor you mean take the yellow piece off?
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Tuesday, November 17th, 2020 AT 1:37 PM
Tiny
CP313
  • MEMBER
  • 19 POSTS
Or you mean unscrew the piece the yellow part plugs into?
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Tuesday, November 17th, 2020 AT 1:51 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Sorry. Yes I mean to unscrew the sensor itself that I am pointing at in the picture.

However, before you do, can you get a picture of it a little further away and I may be able to confirm that it is the coolant temperature sensor? It looks like it is in the side of the block but it is hard to tell. Thanks
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Wednesday, November 18th, 2020 AT 6:01 PM
Tiny
CP313
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  • 19 POSTS
Here’s more pictures:
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Thursday, November 19th, 2020 AT 9:08 AM
Tiny
CP313
  • MEMBER
  • 19 POSTS
It’s like up under where you see the oil dipstick.
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Thursday, November 19th, 2020 AT 9:09 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Got it. That is just above the starter which makes that the oil pressure sensor. I am attaching the process on how to replace that. This is good news because that is not uncommon and does not mean any other issues are with the engine. The sensor should have a seal on the sensor part that goes into the engine and they fail and it starts leaking. You can just replace the sensor or sometimes you can even find the seal and just replace that but the sensor is probably not that expensive.
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Thursday, November 19th, 2020 AT 5:43 PM
Tiny
CP313
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  • 19 POSTS
Thank you so much! I’m going to replace it tomorrow.
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Thursday, November 19th, 2020 AT 11:29 PM
Tiny
CP313
  • MEMBER
  • 19 POSTS
Do you think I can do it without lifting vehicle? I think I can reach it from the top. Do you know what I need to unscrew the sensor? I tried with my hand no luck.
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Thursday, November 19th, 2020 AT 11:31 PM
Tiny
CP313
  • MEMBER
  • 19 POSTS
I went and got a deep socket today and the sensor switch, but I can’t get the old one off. The deep socket won’t reach.
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Friday, November 20th, 2020 AT 10:22 AM
Tiny
CP313
  • MEMBER
  • 19 POSTS
Thanks bro. I changed the switch today and the leak is gone! At 230,000 miles she drove great all day. :) Thanks
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Friday, November 20th, 2020 AT 10:54 PM
Tiny
KASEKENNY
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Sorry I didn't get back to you earlier. Yeah deep sockets would work great but they normally don't reach. Normally a wrench is the only thing that works. So glad you got it replaced and everything is doing well.

Please come back to 2CarPros in the future. Thanks
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Saturday, November 21st, 2020 AT 9:57 AM
Tiny
CP313
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Yes, I will come here with future questions. They make a socket just for the oil sensor switch, cost me $12.00 at O'Riley’s and the sensor switch was $10.00. Drove her today for like 8 hours straight 230,000 miles. Rides very nice.
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Saturday, November 21st, 2020 AT 9:58 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Oh. Good. Yeah, they make all sorts of special tools for almost everything so I am glad you mentioned that. I am sure others will benefit from that in the future if they need to replace this as well. Thanks again.
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Sunday, November 22nd, 2020 AT 6:04 PM

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