Replaced the tired 671 in my Wabco 777 with a 671T.The oil pan needed to be changed,on the turbo motor the turbo oil drain went into the pan above the static oil level.The grader pan had a extra plug on the side but it is below static oil level,I ran the return oil in there.Problem is until it warms up,the oil backs up and leaks into the exhaust side of the turbo,and drips onto the engine.A couple of older Detroit guys have told me it's "cold stacking" I don't know what that means.My return line is half inch.Maybe going to a three quarter inch line mite fix it.Any one ever run into this before?
What we used to call cold stacking was oil going up the stack from out of the turbo. It was caused by idling for long periods of time. Black heavy smoke would poor out when you ran the engine hard again and caught that sludge on fire. Generally though the oil didn't come from the turbo charger. It came right out of the cylinders.
Normally the drain line off the turbo needs to be above the oil level in the pan. With it cold I'd guess the oil is pretty thick so it's blocking the turbo drain. (I'm assuming cold in Michigan is about what cold in Alaska is and you don't mean 65*) Oil is still going to feed into the turbo and it's got to go somewhere so it's blowing out of the exhaust side. Without seeing the oil pan and it's placement it's hard to give an idea on a solution, but I would imagine it wouldn't be too tough to weld in a drain inlet higher up on the pan.... or perhaps use the two pans you have to make one pan that fits in the machine and allows the turbo to drain correctly.
Thanks guys,I'm thinking that between cold oil,and slight crankcase pressure the drain cannot overcome the resistance.The pan is a giant cast iron one,and is part of the mounting system.I should have Bored a hole in it during the conversion,but you know,got in a hurry.So my old mentors saying "Bob you Won't make time to do it right the first time,but will always make time to do it the second time". Comes to mind. ----- EVERYONE HAVE MERRY AND SAFE HOLIDAY!!!!!!!:usa
Try putting an extra breather on the valve cover, engine blow may be making excessive crankcase pressure an extra breather may be your fix, it may pay to check your injector settings and injector type, the wrong injectors and or wrong timing will make a gm smoke and breathe like an asmatic gypsy.
Its probably different around the country but here in the nations refrigerator what we called wet stacking on the 2 stroke Detroit's, was that when they idled when it was winter cold, they did not generate enough heat for good combustion and and unburnt fuel would collect and drool out the top and drip down the stack. This was a common occurance on the old non turboed models. Sometimes it would take a half a mile when you started going to clear out the loaded condition and get them to screaming again. The old cranes had the same issues if doing hoist work along with a heater that blew cold air.
I agree with all the advice to get your oil drain above the static oil level. It certainly wouldn't hurt to run a larger return line as 1/2" seems pretty small to me and you don't want any restriction in that return line whatsoever.
I agree you may need a larger return line above the static oil level. most off the 12V71Ts I work on have a full 1 inch return for each turbo. But they also slobberstack if they are allowed to idle to long in the cold. My rule of thumb is "build air pressure and drive off easy til it builds some heat" then cob it to the max and dont let up. Jmo.
Any chance you can move the drain into the block somewhere?
Well MAYBE we have turned the corner with winter, and it's starting to warm up.I picked up a dozer (D3B) and trailer,this winter so I've been busy with them.Now that the paint is drying,I can maybe get time to work on the grader again.Many thanks to those that replied.
outasite, in any other engine that is called "slobbering" just tie a sack over the radiator and drive it like you stole it.
Ya,the old saying here is,to get the most out of a old Detroit you need to slam your finger,or something, in the door first!!!
I've always felt the reason the old 2 stroke Detroits had more of a problem with "cold stacking" was due to the blower(s) pushing the same amount of air through then engine at light load of full load. A four stroke engine with a turbo more or less takes in air in relation to the load, more load more boost more air...... I have been told that if you had a 2 stroke Detroit that was being used at low power much of the time the way to stop or at least reduce the "cold stacking" was to remove the exhaust manifold(s) and make up a plate to go between the head(s) and manifold(s) with a bunch of say 3/8 inch holes in it. This would create a resriction that would cut back the air going through and cooling down the cyliners. Best thing for the old Detroits is to run them like you wanted them to explode, keeps things nice and warm and cleans out the exhaust system.
Interesting take on it kshanson . The house engine in my crane will cold stack as it idles allot on a job site . Oil will dribble out around the muffler clamp . Engine starts & runs great , don't think there is anything wrong with it ... Just the nature of the beast .
Yair . . . td25c . I reckon you are right there, there is nothing worse than a Detroit on a gen. set running loose . . . man they are messy. Wind the load up to about 80% and they are a different engine. Cheers.
Maybe mine is not that unusual,I blamed the turbo thinking that the oil return line was to small.But it sounds like the non turbo ones do it as well!!!
Yair . . . Outasite . They do . . . I would be still inclined to try and get your turbo oil return above oil level though. Cheers.