Oil leakage

[ron6785]

I'm chasing down a small oil leak. I've 8/71 naturals and It looks like it might be coming out of the Air intake. Is that possible? My airboxes are operational and I'm getting the residual oil you would expect there. I found oil on top of the engine aft of the intake. doesn't look like its coming out of the crank vent which is in the same proximity but not close enough to be the problem, I think.
I'm show wear grooves on the pistons rings, which would indicate that shouldn't be the problem. Any suggestions ?

 

[SKYCHENEY]

Pictures would help.

 

[Timm]

2 stroke Detroits have airbox drains that typically are routed to the drip pan. Check to make sure the one in question is not plugged up or has come loose.

FYI, Walker Engineering (Airsep folks) make a device specifically designed to capture that oil. You can check it out here: http://walkerairsep.com/product_detail.asp?id=565

If anyone is interested, you can order it from West Marine or Port Supply and get your West Advantage points. The stores don't carry them but they can place a special order (p/n AJ4120KT) and have it delivered to your local store.

 

[yachtsmanbill]

2 stroke Detroits have airbox drains that typically are routed to the drip pan. Check to make sure the one in question is not plugged up or has come loose.

FYI, Walker Engineering (Airsep folks) make a device specifically designed to capture that oil. You can check it out here: http://walkerairsep.com/product_detail.asp?id=565

If anyone is interested, you can order it from West Marine or Port Supply and get your West Advantage points. The stores don't carry them but they can place a special order (p/n AJ4120KT) and have it delivered to your local store.

I just cleaned out the crap cans on my 12-71Ns which were neglected for
30+ years and GRODY to the max. See the chill thred. Also made sure the 2 lines to them were wide open. The Ns also have the vent pipe to the blower inlet which has a screen/filter under the flange. It may be plugged also causing high crankcase pressure. ws

 

[ron6785]

I just cleaned out the crap cans on my 12-71Ns which were neglected for
30+ years and GRODY to the max. See the chill thred. Also made sure the 2 lines to them were wide open. The Ns also have the vent pipe to the blower inlet which has a screen/filter under the flange. It may be plugged also causing high crankcase pressure. ws

Thanks, for the info, yep my accumulator tanks were clogged as well and in a very inacessible area. I cleaned the airboxes extended the hoses and run it into a bottle. What year motors have the screen/filter ? Is the screen on the air intake. I have one on top of the inside of the air intake housing, don't actually know what its function is being that its location isn't covering the air intake manifold. Maybe the air is directed there?

 

[Nonchalant1]

Detroits will ooze oil through every pore at every gasket if not tightened perfectly or painted heavily, which stops oozing sometimes. Also check your airbox drain checkvalves. DDs have a checkvalve in the airbox drain tubes to prevent high airbox air pressure at cruising RPMs from blowing through the drip tube. They open when the engines come down to idle and drip the oil through the tubes. If your airbox checkvalves are stuck shut, you may accumulate oil in the airbox. These checkvalves must be pointed down at least at a 45 degree angle or more. Straight down is best. Some installations have them going sideways and this leads to sticking.

Doug Shuman

 

[Will]

Are you talking about the rectagular air intakes on top of the blower? If so, you may have some crankcase breather tubes with openings facing the air intakes. It's not uncommon for a small about of oil to get into the air intakes from the breathers then seep out when the engies are shut down.
Will

 

[ron6785]

I'm talking about the Air Silencers which are rectangular, they attach to some sort of adapter that attaches to the blower intake. I havn't taken that assembly apart yet but I assume there must be some sort of filter or screen between the adapter and the blower intake. Assuming there is some sort of screen and further that it is clogged which would mean restricted air flow. How would that result in a oil leak? I don't have enough deisel smarts to know if that would cause a oil leak out of the Air Silencers?

 

[yachtsmanbill]

The venturi pipe on Ns comes off the back of the block via a flange. There may or may not be a mesh filter in there to accumulate oil mist. Lots of slow, cold running causes sludge in there along with poor crankcase ventlation. The "fillters" on the intakes are only silencers. DDs make a LOT of intake noise! ws

 

[Will]

I'm more familiar with in-line 6-71s than I am with V8's but I'd assume there is a screen(s) somewhere between the air silencers and the blower. Regardless, I doubt anything in the air intake system is clogged otherwise there would be a lot of smoky exhaust. The air box is on the other side of your blower so I doubt that's the problem. I suspect that oil from the breather gets sucked into the silencer then drips out. Detroits are notorious for weeping oil leaks and if that's all there is, you could just wipe it up from time to time.
Will

 

[ron6785]

The venturi pipe on Ns comes off the back of the block via a flange. There may or may not be a mesh filter in there to accumulate oil mist. Lots of slow, cold running causes sludge in there along with poor crankcase ventlation. The "fillters" on the intakes are only silencers. DDs make a LOT of intake noise! ws

Thanks, the crank (Venturi) on my 8v's is not as long and doesn't come as close to the air intake as yours. My philosophy with DD's is if you arn't going somewhere don't start'em. Alot of guys in the marina come down periodically and start the engines and let them run for 20-30 min. I don't think that's not very good for DD's. We're in the south and the boat is in the water year round, we don't run the boat alot in the winter not because of the weather, but just my own idea is that if I'm not going on a trip there is no reason to run the boat unless we have guests. Because, like the folks in florida, we have a long boating season we tend to day cruise only if we have company or the marina gang wants to go for a ride.

 

[ron6785]

I'm more familiar with in-line 6-71s than I am with V8's but I'd assume there is a screen(s) somewhere between the air silencers and the blower. Regardless, I doubt anything in the air intake system is clogged otherwise there would be a lot of smoky exhaust. The air box is on the other side of your blower so I doubt that's the problem. I suspect that oil from the breather gets sucked into the silencer then drips out. Detroits are notorious for weeping oil leaks and if that's all there is, you could just wipe it up from time to time.
Will

Thanks, yea they all seem to weep, I got off my backside and took off the air silencers and there is a screen designed to block only the largest of stuff. In effect you're pumping whatever air is in the engine room directly into the blower. As mentioned earlier, my air boxes are operating normally and the leak is not coming from there. My consern is that I have oil on top of the engine and just aft of the Air silencers. I'll have to run the engines and see if it's comming out of the Venturi pipe although mine is not plumbed to feed back into the air intake like yachtsmanbill.

 

[mike]

FWIW, check the hose clamps that cover the blower drive coupling at the rear of the housing. There are two clamps on a ~3" dia hose that may need tightening, esp if the hose is getting old and dryed out. I had some weeping in the same area on 8v71N, it may fix the problem. While your looking in area check to see if it's a leaking oil line (1/4" dia tube) between the blower and housing. Also, you may have a blower drive seal that is leaking, but it usually shows up inside the blower not on the outside.

 

[Genesis]

The coupler between the blower and the gear train is enclosed by a rubber "boot" that can deteriorate and leak. If its leaking from there and the clamps are not damaged the boot is probably deteriorated. It can be changed without removing the blower by cutting the new one and then gluing it back together, placing the repaired "split" on the top. If you have oil pooling under the blower drive shaft boot that is PROBABLY where its coming from; this is a fairly common place for a very annoying oil leak.

If the blower is disturbed the engine must be retuned as loosening the holddown bolts on the blower will change the geometry slightly between the governor pushrods and the control arms under the rocker covers.

 

[ron6785]

FWIW, check the hose clamps that cover the blower drive coupling at the rear of the housing. There are two clamps on a ~3" dia hose that may need tightening, esp if the hose is getting old and dryed out. I had some weeping in the same area on 8v71N, it may fix the problem. While your looking in area check to see if it's a leaking oil line (1/4" dia tube) between the blower and housing. Also, you may have a blower drive seal that is leaking, but it usually shows up inside the blower not on the outside.

Thanks for the info, will check it out.Ron

 

[ron6785]

The coupler between the blower and the gear train is enclosed by a rubber "boot" that can deteriorate and leak. If its leaking from there and the clamps are not damaged the boot is probably deteriorated. It can be changed without removing the blower by cutting the new one and then gluing it back together, placing the repaired "split" on the top. If you have oil pooling under the blower drive shaft boot that is PROBABLY where its coming from; this is a fairly common place for a very annoying oil leak.

If the blower is disturbed the engine must be retuned as loosening the holddown bolts on the blower will change the geometry slightly between the governor pushrods and the control arms under the rocker covers.

Thanks, Ron

 

[Genesis]

BTW if you decide to remove the blower you will need a new gasket and you must remove the driveshaft for it from the REAR of the gear train before pulling the blower. If you have a flange-mounted alternator it is behind that - if not, there's just a cover there.

It is not a big deal to remove BUT there is an inside C-clip that retains it. DO NOT DROP IT IN THE GEAR TRAIN; it is hardened spring steel and if you DO, you're SEVERELY screwed as there is a high probability of it going somewhere that will do SEVERE damage. Worse, getting access to where it will probably go if you DO drop it is going to be NO FUN.