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I have a nasty oil leak in my 1998 E 320 Wagon, rear wheel Drive, V6 engine. I pulled and resealed the driver's side and passenger side valve covers. They now look fine. I also pulled the bottom oil pan and that looks fine too. The oil appears to be leaking near or above some sort of fluid pump that is bolted to the engine block on the driver's side of the lower oil pan. Do I need to take this pump off and get at something behind it?
I thought the leak might be from the low oil level sensor. I found something on the passenger side of the engine on the back of the oil pan that looks like a sensor. The alternator is next to it. No oil leaking there though.
The engine oil is leaking somewhere that allows it to get on the serpentine belt and then spray all over the front of the engine. What a mess!!
I am a DIY mechanic and could really use the expert advice of someone who has had the same problem. Any and all assistance is appreciated.
I love my car but the oil leak has me standing still.:frown
 

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Easiest way is to clean the area up with a de-greaser , and pinpoint the exact area where it is leaking.

And take some pictures to post here.
 

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I have same car.

Where you see the oil, is not always where it originates. I went through an oil leak search last Fall and it is documented here. In my case, it was mainly the breather covers on top of the valve covers, the oil cooler/filter housing o-rings and a small power steering hose leak.

I too had oil on serpentine belt. It and the fan distribute the oil all over they place. It wasn't my source of leak, but the oil test port on front of engine is said to leak as is the connection from PS reservoir to the PS pump.

If you can see the leak after cleaning off the engine, you could try putting UV dye into oil and seeing if that helps locate leak. I did that when I thought I still had a leak, but turned out any oil still dripping was there from earlier, so had no dye. I used dye in PS fluid as well.

This was my thread - maybe you will find some clues somewhere among the posts.
 

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Most likely it's from the bottom of the oil filter housing or the oil pressure test port. Your engine doesn't have an oil cooler so it's not from that.

It could also be leaking from the power steering reservoir and the dirt and grease on the engine makes it look like it's oil.
 

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Discussion Starter #6
I will be working on this on Sunday(after church)

Thanks to everyone who responded. I live in the woods in Montana and can only use this 2 wheel drive car in the summer which starts when the snow melts. I will clean the engine tomorrow with degreaser. I inspected it closely today after reading all of your very helpful comments. It is definitely an engine oil leak. I pulled about a 1/2 cup out of the plastic skid plate cover that goes beneath the lower oil pan. I found a good buildup of dirt and oil underneath the oil filter canister. There was a nice path of oil to the driver's side of the engine down by the pump or A/C compressor.
I searched Pelican parts and they show rubber gaskets for the oil canister housing. I suspect I need a new one of those. Has anyone done this job or know of a DIY link by someone who has replaced the oil canister gaskets?
No oil cooler on this engine but Pelican does list one for this car.
I will keep everyone posted.
Thanks again for the very helpful advice. I really appreciate everyone's assistance.
 

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You take out the oil filter. Then if you look at the bottom of the housing you will see a 46mm bolt holding the oil filter housing in place.

You will need a 46mm socket. Some people say to get a 12 point socket. But I say you should get a 6 point. The 12 point doesn't fit tight and it can be easy to strip the 46mm bolt holding the oil filter housing. Remember the oil filter housing is on an angle. So when you apply pressure to loosen it, you may slip or you may apply force in an awkward angle that could cause you to slip. So I recommend the 6 point but It's up to you though.

Make sure you get a genuine Mercedes gasket. Also when I did mine I had a very hard time getting that bolt loose. I ended up having to use an impact gun because it was just too tight. Also be careful re-installing that bolt. It can be very easy to strip the threads because it's difficult to reach your hand all the way down there to start the bolt.

One more warning: the threads that hold the oil filter in the housing are razor sharp. So watch your hand near the threads. I ended up cutting my hand in a few spots and I didn't even feel it. I only noticed it when I saw red drops of liquid on the radiator hose and the surrounding area. Then I looked down and saw my hand bleeding. Lesson learned!!
 

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Discussion Starter #9
Photo of the Oil Dripping

I cleaned the engine well and then checked again for oil leaks. There was a good buildup of oil and dirt under the filter canister but no leaks were present. I crawled underneath the car and snapped a photo of the oil dripping. It is coming from the drivers side front (near bumper) of the oil pan. It looks like I have to pull the pan again and RTV seal it. I am a little mystified about the oil dripping from the torx head bolt though. That is above the oil pan and separated from it.
Any thoughts? Anyone seen this before and have advice?

Here is a link to the photo:
www.timslife.com/oil_leak.jpg

The last time I pulled the pan I used a 1/8 continuous bead of genuine mercedes silcone. This time I may use a tube of blue silcone. Any suggestions or links are appreciated.

Thanks to everyone. I will keep you posted.
Tim in Montana
 

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Since you have been down there exploring and have removed the oil pan, can you advise me as to where the oil sensor is located. Mine is defective ( so it indicates on the display ) and I want to do a visual inspection of the connectors 1st. I have crawled around under mine but without the use of as lift it is difficult. Would like to have a starting point to start my inspection.
 

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The starting point should be your battery condition. I had the same fault from time to time, and after I replaced the battery (one of the cells was very low in electrolyte), the problem disappeared. The connector for the oil sensor is at the passenger side. near the alternator.
 

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Hey Tim...

I have a nasty oil leak in my 1998 E 320 Wagon, rear wheel Drive, V6 engine. I pulled and resealed the driver's side and passenger side valve covers. They now look fine. I also pulled the bottom oil pan and that looks fine too. The oil appears to be leaking near or above some sort of fluid pump that is bolted to the engine block on the driver's side of the lower oil pan. Do I need to take this pump off and get at something behind it?
I thought the leak might be from the low oil level sensor. I found something on the passenger side of the engine on the back of the oil pan that looks like a sensor. The alternator is next to it. No oil leaking there though.
The engine oil is leaking somewhere that allows it to get on the serpentine belt and then spray all over the front of the engine. What a mess!!
I am a DIY mechanic and could really use the expert advice of someone who has had the same problem. Any and all assistance is appreciated.
I love my car but the oil leak has me standing still.:frown
Hey Tim:

Any progress fixing the leak ?

Does your wagon have the Self Leveling Rear Suspension with separate Hydraulic / power steering fluid reservoir (at front DS immediately behind headlight) ?

If so, I don't think its your power steering pump leaking.

But saying it hits your serpentine belt and goes backwards suggests a front engine leak location, not behind that point.

I believe the Oil Filter housing has a large O-ring (prob not just a gasket) underneath. As others stated you pull Oil Filter cover off, remove filter & mount, then look inside - very large nut 46mm holds housing onto block.

Tip: Tractor Supply has the 1 13/16" socket in stock in their Tools Section and it's just $12 fits perfectly. Much easier than ordering a 'Benz Service Socket 46mm'.

I imagine if that nut has worked loose, isn't torqued right or if O-ring has failed, that would make a huge oil leak, especially at high speed & pressure like Highway driving.

I replaced mine on our V-8 / M113 engined ML500, is how I know. On that rig, it also has the leak prone Oil Cooler (finned alimuminum sink looking assy) which mounts immediatly beside said Oil Filter Housing.

My housing O-ring wasn't leaking, but you have to remove that Housing to do the Oil Cooler O-ring replace, so I did both. I think the O-rings came together anyhow.

Our m112 3.2 V-6 in the e320 wagon didn't have the Oil Cooler, and our Housing doesn't leak, so I haven't messed with it.

Also, I did research if that 'Oil Pressure Test Port' on our V-6 was leaking, and determined it wasn't. But if yours is, that also could be the issue.

Of course, we all have leaking Valve Cover gaskets....mandatory feature on all MB V engines, right ?

Hope this helps....

David in East Texas
 
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