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Oil seeping from exhaust

trukfan

Well-Known Member
Joined
Jul 26, 2009
Messages
45
Location
S.E. Wisconsin
Occupation
Maintenance Tech for a machine shop
Hi all. As the title states, I've got an oil seepage issue on an engine. I say seepage because it's not leak per se, but I still have oil where I shouldn't. Engine in question is a turbo'd 6 cylinder 401ci in a Ford 9700 ag tractor, the same I had oil cooler issues with in another post.

While running, I have oil seeping out of where the turbo bolts onto the exhaust manifold. I say seeping because it takes 20 minutes for it to form a trickle and it is barely visible until then. I also have the same seepage where the boot from the down pipe meets the intake manifold. Engine has less than 3k hours since a complete rebuild with new turbo, and I am unsure how long this issue has existed.

I had originally thought leaky oring or seal in the turbo, but I noticed yesterday my tractor with a non turbo'd 401 seems to be doing the same thing. Similar hours on rebuild, but I had to tear it down completely 2 years ago for a coolant leak in a cylinder wall. Both tractors have a removable crankcase vent tube in the valve cover, but nothing resembling a PVC valve. Does this sound like crankcase vent issue, or something else?

On the turbo'd tractor, it will puff blue smoke while running, but not constantly which I assume is from oil being forced through the intake by the turbo. On my other tractor, it only smokes a little at start up. Once I'm in the throttle, she burns clean unless I'm really working her.

The only other thing I've been told to check is the oil return line from the turbo, since my other tractor isn't turbocharged, that may or may not solve anything. Thanks in advance.
 

Delmer

Senior Member
Joined
Jan 3, 2013
Messages
8,865
Location
WI
I don't have any idea what it is. Is it definitely motor oil? or possibly gunky unburned fuel?

First thing I'd check is the breathers for a buildup of dirt on the bottom. See how much crankcase blowby is coming out of the tube when the engine is warmed up. And take the intake off the turbo and see how much play is in the shaft, axially and radially. Spins free and no rubbing too.
 

RZucker

Senior Member
Joined
Jul 7, 2013
Messages
4,077
Location
Wherever I end up
Occupation
Mechanic/welder
Are you getting these droolies at full load or just loafing around the yard? And by full load. I mean hot working not just full throttle. Cold weather and light loads will cause exactly what you are describing. I would check the turbo discharge on the one for excess oil just for the heck of it though.
 

Queenslander

Senior Member
Joined
Apr 5, 2009
Messages
1,228
Location
Australia
Sounds a little like a problem we had recently with an M11 truck engine.
Would seep small amounts of oil past the clamp on the turbo plumbing etc., and make smoke intermittently.
Turned out to be a mesh pad covering the crankcase breather, inside the tappet cover, was gummed up leading to excessive crankcase pressure.
 
Last edited:

56wrench

Senior Member
Joined
Dec 4, 2016
Messages
2,074
Location
alberta
Check for a fiber mesh crankcase vent filter in the valve cover . Remove the vent tube from the valve cover and it should be under a lip around the hole if it has one. Some ford diesels are more prone to plugging this filter than others; it may depend on the engine application and operating conditions. I'm not sure if all ford diesels had this filter. Another symptom is leaking crankshaft seals.
 
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