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S550 Never ending oil leak

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10
7
Exp. Type
HPDE
Exp. Level
Under 3 Years
Maricopa, AZ
For about a month or so I’ve been trying to fix an oil leak. Started off as just 5-6 drops on the garage floor after driving it. At first I thought it was the filter and changed it, then the oil pressure switch and changed that. I took the car out for a ~300 mile cruise on Sunday (today’s tuesday) and the car didn’t miss a beat. Clean garage floor on Monday morning when I took it to work and back. Did not drive the car today and my garage floor looks like the picture, with splatters dripping off of it down the drivers side of the car. The car sees the track once a month so it always has fresh oil (the oil on the floor looks fresh but hard to tell). It seems too random to just be old leftover oil from leaking before, but laying below it while it’s running I can’t find any obvious leaks. Any other parts worth checking or replacing that could be causing this?4D26AC6C-4432-4F3C-AB98-CEAB636DC3C9.jpeg
 
37
58
Exp. Type
Time Attack
Exp. Level
3-5 Years
Gilbert SC
On drivers side like that I would think something in the oil filter area. The oil filter has a factory water to oil cooler that is sandwiched between the engine block and the oil filter. Check the connection / seal between the cooler and the block, if the filter to cooler connection is not leaking. If you look inside the threaded tube your oil filter screws onto it should be hex shaped and you can tighten it with a Allen wrench if my memory is correct.

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6,455
8,381
I would agree with that assesment, I just replaced mine in my 06. same thing, mystery oil leak that I could not find, even on the rack, but always left a puddle under the car.
 

Mad Hatter

Gotta go Faster
5,288
4,292
Santiago, Chile
I had the same thing, the oil cooler on my Boss leaked. It was from where the elbow joined the cooling stack. It actually happen twice and was one of the reasons we switched to a Setrab setup.

1680104342052.png
 
10
7
Exp. Type
HPDE
Exp. Level
Under 3 Years
Maricopa, AZ
On drivers side like that I would think something in the oil filter area. The oil filter has a factory water to oil cooler that is sandwiched between the engine block and the oil filter. Check the connection / seal between the cooler and the block, if the filter to cooler connection is not leaking. If you look inside the threaded tube your oil filter screws onto it should be hex shaped and you can tighten it with a Allen wrench if my memory is correct.

View attachment 85234

View attachment 85232

View attachment 85233
Thank you all for the help, I’m going to see if I can try this later today. Is there any specific torque spec for the hex inside or just snug?
 

ArizonaBOSS

Because racecar.
Moderator
8,734
2,737
Arizona, USA
Thank you all for the help, I’m going to see if I can try this later today. Is there any specific torque spec for the hex inside or just snug?
On the S197 it's 43 ft-lbs and you will need a 14mm hex to do it.
 
10
7
Exp. Type
HPDE
Exp. Level
Under 3 Years
Maricopa, AZ
On drivers side like that I would think something in the oil filter area. The oil filter has a factory water to oil cooler that is sandwiched between the engine block and the oil filter. Check the connection / seal between the cooler and the block, if the filter to cooler connection is not leaking. If you look inside the threaded tube your oil filter screws onto it should be hex shaped and you can tighten it with a Allen wrench if my memory is correct.

View attachment 85234

View attachment 85232

View attachment 85233
Ok so I believe I have located the source of the leak. Last time I was under there I cleaned up everything and now it seems there’s an oil waterfall coming from behind the cooler (highlighted yellow below). I have checked the 14mm and it was tight.1680226704502.png
 
37
58
Exp. Type
Time Attack
Exp. Level
3-5 Years
Gilbert SC
The connection between the oil cooler and engine block is like the connection of the oil filter to the engine. Sounds like you have debris on the o ring or a damaged o ring. If you use the 14mm allen and remove the pipe in the middle the oil cooler will pull down so you can look at the o ring.
 
10
7
Exp. Type
HPDE
Exp. Level
Under 3 Years
Maricopa, AZ
The connection between the oil cooler and engine block is like the connection of the oil filter to the engine. Sounds like you have debris on the o ring or a damaged o ring. If you use the 14mm allen and remove the pipe in the middle the oil cooler will pull down so you can look at the o ring.
That’s kind of what I did. I took it off and cleaned the whole area and put it back together. I did not see any leaks above it on the engine block, but if it continues would it be best to just replace the oil cooler? It doesn’t look like there’s a separate part to just replace the o ring, it’s kinda built into the cooler1680271667133.png
 

Dave_W

Cones - not just for ice cream
1,016
1,326
Exp. Type
Autocross
Exp. Level
20+ Years
Connecticut
Thinking off the top of my head, YMMV. Since the oil coller is bolting up to the face on the bock where an oil filter would attach if you didn't have the cooler, maybe the o-ring in the cooler is the same as an o-ring in the proper-size oil filter?

Does the cooler o-ring come out easily? If so, and you've got a second car, you could bring it to an industrial supply house that handles o-rings to see if they have something. These folks are in Chandler, maybe give them a call to see if they can help (they could be too big but point you to someone else in the area) - https://www.azseal.com/
 
356
310
Exp. Type
Time Attack
Exp. Level
Under 3 Years
Bulgaria
That’s kind of what I did. I took it off and cleaned the whole area and put it back together. I did not see any leaks above it on the engine block, but if it continues would it be best to just replace the oil cooler? It doesn’t look like there’s a separate part to just replace the o ring, it’s kinda built into the cooler
better yet remove that shiznit and buy a proper oil cooler this ones especially in early Gen 2 cars have a tendency to fail and take your engine with them. Mishimoto Oil Cooler have a sandwich plate to get rid of the factory Oil cooler. I would go that route if I was OP and get rid while improving the engine cooling in the process.
 
349
364
I installed this cooler on my '11 GT and in my experience you really have to get all of the 43 ft/lbs as noted by @ArizonaBOSS above. At first I just cranked it down "snug" tight, thought it was good enough but I was totally wrong and it leaked like crazy. Then I tightened it to spec and all was good.

The cooler goes on way, way tighter than you would tighten an oil filter.
 
10
7
Exp. Type
HPDE
Exp. Level
Under 3 Years
Maricopa, AZ
Wanted to thank you all again for your help. So far so good, I took the cooler off and cleaned the entire surface and put it all back together and torqued it down and no more new drops on the floor or on the car that I can tell. Fingers crossed it’ll stay like that
 

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