Oil Leak (Where Would It Be Coming From)

For the last 4 or so years I have had an oil leak draining down the passenger side rear of the motor on my 94 K2500HD 6.5L Diesel. It leaks down the side of the bell housing on the starter then to the ground. I am trying to figure out potential sources of the leak. I can see some oil residue in the valley toward the rear of the engine as well. At first I was thinking it could be the OPS, but I have read that it located on the driver side, so I am thinking that is not the issue. I am almost positive it is not the valve cover either as I had my transmission and bell housing off about 4 months ago and I had a pretty good view of the back side of the valve cover. It appeared to be coming from somewhere up in the valley of the motor at the rear. Can anyone point me at some common items that may be the source of this oil leak.

The fuel injector return lines on mine caused that exact symptom as you described. Get yourself a complete kit, as it has all of the pieces needed.These are made of heat and fuel resistent material which will last many years. Since you are new here you may want to fill in the information in your signiture which appears at the bottom of all posts. You can see an example of it at the bottom of my reply. Let me be the first person here to welcome you to The Diesel Page!

Crawl up into the engine bay and peek down into the valley area and get a light in there.

The IP could be seeping oil where it bolts to the front cover.

OIL AND FUEL CAN DRAIN down the hole in the back of the valley, but this will drip out of the hole at the lower bell housing cover.

Dripping off the RH rear side almost has to be a VC leaking.

The turbo oil drain line runs down the front side and into the block... possibly blowing back ???

Can you get it on a hoist and get a good peek at it from the bottom ???

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Originally Posted by Warren96

The fuel injector return lines on mine caused that exact symptom as you described. Get yourself a complete kit, as it has all of the pieces needed.These are made of heat and fuel resistent material which will last many years. Since you are new here you may want to fill in the information in your signiture which appears at the bottom of all posts. You can see an example of it at the bottom of my reply. Let me be the first person here to welcome you to The Diesel Page!

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Thanks for the welcome. I am almost certain it is actually oil and not fuel, but I will smell a sample tonight and see if there is a Diesel odor to it. How much of a pain is it to change out those lines? They mush be packed back in there.

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Originally Posted by Robyn

Crawl up into the engine bay and peek down into the valley area and get a light in there.

The IP could be seeping oil where it bolts to the front cover.

OIL AND FUEL CAN DRAIN down the hole in the back of the valley, but this will drip out of the hole at the lower bell housing cover.

Dripping off the RH rear side almost has to be a VC leaking.

The turbo oil drain line runs down the front side and into the block... possibly blowing back ???

Can you get it on a hoist and get a good peek at it from the bottom ???

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Thanks for the reply. When I had the transmission off a while ago I could see that it appeared to be coming from the valley somewhere and following the top of the bell housing down the passenger side. I could also see some residue where it looked like it followed the head gasket seam around the back of the motor and down the rear. I do have a leak on the turbo oil return line due to a bad gasket and I have ruled it out as the cause of this leak.

I too have the same scenario on my '94 K2500, 324K. I'm replacing head gaskets this week. Passenger head gasket removed (failed at front water jacket) and indicates oil seepage above rear most lifter/pushrod cavity. The block in that area is shaded in oil, whereas the remaining areas appear in normal mill finish. I am convinced this is the culprit. I too thought it had to be VC's; not so. They were snug and sealed. I may be proven wrong when I run the engine soon. I'll post a follow-up.

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Originally Posted by 6.5_Diesel

Thanks for the reply. When I had the transmission off a while ago I could see that it appeared to be coming from the valley somewhere .

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Op sending unit,.?