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Craftsman lawn mower is dumping its oil

#1

T

TBm

Hello again, Robert and others. :biggrin:


Same mower, different problem...(shakes head) This is it:

craftsman_id.jpg



I was able to repair (rather than replace) the gear box thanks to the help you provided in THIS GEARBOX THREAD from two months ago. THANKS

I had to flip the mower entirely upside down to work on the gear box. I tried to empty all the oil prior to flipping the machine, but a lot more drained out while it was upside down (it seemed to be coming not from the fill spout but from the top of the engine, under the plastic pull rope cover(?).

When the repair was complete, I refilled the oil and gave the gearbox a ten-minute test run. No problems, BUT...I've been finding oil on the garage floor ever since...


Today I put the mower out in the yard and just let it run, to empty the remaining gas in the tank and carberator for Winter. When I went out to check on it (while running) it was smoking quite a bit. I noticed a LOT of oil had collected in the circular depression in the sheet metal (like a moat) around the motor.

Lots of oil had collected in this sheet metal "moat":
oil_moat.jpg



While it was running, I unscrewed the oil filler cap/dipstick. It almost blew off! 'Not sure if that's normal or not...I never took the oil cap off a running engine before.

I had filled it with oil after the gearbox repair, but now the dipstick indicates "ADD".

It appears the oil is coming from high on the engine, up under the plastic covers:
oil_from_up_under.jpg



Any ideas on what's up with this thing?

Could some BLOCKAGE have been caused by me flipping it upside down and leaving it that way for a couple of weeks?

Very frustrated here,
Tom :confused2:


#2

K

KennyV

There is a crankcase breather that may be open and allowing oil to be pushed out... (some disassembly required) remove the top cover and look around, clean things up and you will find the problem under there... :smile:Kenny


#3

JDgreen

JDgreen

KennyV said:
There is a crankcase breather that may be open and allowing oil to be pushed out... (some disassembly required) remove the top cover and look around, clean things up and you will find the problem under there... :smile:Kenny
Click to expand...

I've got the same model and engine...it has always leaked oil badly where the dipstick/oil fill tube enters the block. Try using some kind of sealant there, clean the metal well first.


#4

T

TBm

Kenny and JD ==

Thanks. It's getting C-C-C-C-C-COLD here, but I'm encouraged enough by your comments to go ahead and dive in anyway. I disassembled a bunch of the upper assemblies two years ago for something else. If I can solve this problem with that level of knucklebustin' I'm up to it.


#5

T

TBm

Another question before I begin:

While the mower was running (burning the remaining gas as prep for winter storage), I removed the oil fill cap/dipstick: it kinda POPPED up, under what seemed like a LOT of internal pressure, and oil spatter was exiting of the fill tube.

Is that normal, or is it an indication of Kenny's suggested crankcase breather issue, or perhaps some other specific issue?


#6

rekees

rekees

JDgreen said:
I've got the same model and engine...it has always leaked oil badly where the dipstick/oil fill tube enters the block. Try using some kind of sealant there, clean the metal well first.
Click to expand...

Ditto ... I've also had an oil leak where the fill tube enters the housing. Fixed the problem by ordering a new rubber washer that slips around the bottom of the fill tube. I think those washers dry out over time and loose their seal allowing oil to leak out, accumulate on the deck and then dip down on the floor. The part number should be in the owner's manual.


#7

K

KennyV

TBm said:
I removed the oil fill cap/dipstick: it kinda POPPED up, under what seemed like a LOT of internal pressure, and oil spatter was exiting of the fill tube.

Is that normal
Click to expand...

That will be normal... there is a lot, LOT of air moving around in the relatively small crank case on a small engine...
There are not a lot of places that will leak oil, a clean up and look will find the source quickly... :smile:KennyV


#8

M

Mean Machine

It sounds like something may not be quite right with your crankcase. Is your dipstick or dipstick tube properly seated? The engine breather assembly could possibly be defective, as well.


#9

JDgreen

JDgreen

rekees said:
Ditto ... I've also had an oil leak where the fill tube enters the housing. Fixed the problem by ordering a new rubber washer that slips around the bottom of the fill tube. I think those washers dry out over time and loose their seal allowing oil to leak out, accumulate on the deck and then dip down on the floor. The part number should be in the owner's manual.[


My mower was on clearance at Sears, someone returned it, most likely becuz of the oil leak. Since it was a clearance price, there was no manual included, I didn't know there was supposed to be a gasket under the tube, so I just used sealant.
Click to expand...


#10

T

TBm

I uploaded a scan of the manual's exploded diagram.

I don't see any washer, seal or gasket where the oil filler tube enters - but I might be missing something...

HERE'S A LINK TO THE IMAGE FILE (too big to post it here in this forum)
Internet Explorer will (usually) shrink an image so the whole thing fits on your screen. This one's a BIG image, so try clicking on the image. That will (usually) force Internet Explorer to return it to its true, original (big) size.

Please let me know what you guys think. And if you can, point out the OIL BREATHER.

My fingers are crossed that it's NOT part 20, the rubber oil seal at the top of the shaft...

Tom


#11

K

KennyV

TBm said:
I don't see any washer, seal or gasket where the oil filler tube enters - but I might be missing something...



My fingers are crossed that it's NOT part 20, the rubber oil seal at the top of the shaft...

Tom
Click to expand...

I don't think there is a seal at the fill tube... I believe that screws into the crankcase... It could be loose.

It would be more likely that# 75 leaks before #20... lower seal gets more abuse.. :smile:KennyV


#12

M

Motorman

Oil leaks around the dipstick area are common. First clean the area around the dipstick tube and remove the tube. There will be either an o-ring at the bottom of the tube where it fits into the crankcase or a rubber grommet that the tube slides into.


#13

T

TBm

Motorman: There will be either an o-ring at the bottom of the tube where it fits into the crankcase or a rubber grommet that the tube slides into.
KennyV: I don't think there is a seal at the fill tube... I believe that screws into the crankcase... It could be loose.

You guys are really making me curious. Gonna have to tear it apart and see who's right... :biggrin:


HERE'S THE PARTS DIAGRAM LINK AGAIN

KennyV said:
It would be more likely that #75 leaks before #20... lower seal gets more abuse.. :smile:KennyV
Click to expand...
I'm seeing no leaks under the engine, so no problems with #75 (lower seal). LOGIC: If lower seal is more likely to fail than upper seal, and lower seal is good, then upper seal should still be very good.

I think I had pulled the flywheel off last time I saw #20 upper seal. That was NO FUN because I don't own the correct puller :eek: I hope to avoid that this time...


OIL BREATHER System:
#6 Breather Element - is this thing soft like a filter, or is it hard plastic, or metal?
#10 Breather Valve Body
#12 Breather Tube

#6 and #10 appear in the diagram just above the engine block. The #12 Breather Tube is at lower left, attached to #240, the air cleaner body. My paper air filter got ruined by crankcase oil while the mower was upside down.

QUESTION: If the Breather Tube (#12) became clogged, or kinked or in any way obstructed during the gearbox repairs, would it cause the engine to blow its oil out? If so, from where is the oil exiting the engine? Maybe right where that oil fill tube enters the crankcase?

COULD IT BE AS SIMPLE AS THIS: THE AIR FILTER is TOO DIRTY (or clogged with oil)?

If the crankcase can't "breath" properly, maybe that would explain the extreme pressure (or so it appeared to me) when I removed the oil fill cap while the engine was running...?


#14

T

TBm

Nobody...? :frown:


#15

K

KennyV

TBm said:
If the crankcase can't "breath" properly, maybe that would explain the extreme pressure (or so it appeared to me) when I removed the oil fill cap while the engine was running...?
Click to expand...

A small engine will have such a large pulse in the crank case that you can never remove the oil fill cap with the engine running...
It is vented into the intake manifold with a tube... But it is always going to blast out a lot of air if you open it with the thing running... KennyV


#16

T

TBm

Thanks for the confirmation, Kenny.

The other points in my earlier post are:

Q1. Could a blocked paper air filter build up enough crankcase pressure to cause oil to exit the crankcase?

Q2. Could a blockage in the oil breather hose that runs to the air filter housing cause a build-up of pressure, enough for oil to exit the crankcase?

If either answer is YES, where is the oil blowing out from?
This whale's definitely got a "blow hole" somewhere... :biggrin:


#17

M

Motorman

There is definately an o-ring style seal at the end of the dip stick tube. You may not have found it because it blew out or it was never installed.


#18

T

TBm

Motorman said:
There is definately an o-ring style seal at the end of the dip stick tube. You may not have found it because it blew out or it was never installed.
Click to expand...
Motorman ==
Thanks. I don't see one on the exploded diagram from the manual, so I'll have to dig in and see for myself. Been dragging my feet because it's so blasted cold here. Not sure how I'll purchase a new one without a part number, though...

P.S. How's Maryland these days? I used to live in Prince George's County, in Greenbelt and also in Croom. Fond memories, mostly.


#19

adan

adan

Hi TBm! I'm trying to follow the discussion with the wide eyes of a college student trying to learn engineering. It's quite tough to follow without seeing an actual unit. I just wonder if you ever brought this thing to a technician nearby?

P.S. How's Nebraska today?


#20

T

TBm

adan said:
Hi TBm! I'm trying to follow the discussion with the wide eyes of a college student trying to learn engineering. It's quite tough to follow without seeing an actual unit. I just wonder if you ever brought this thing to a technician nearby?

P.S. How's Nebraska today?
Click to expand...
This would be a tough way to learn Engineering, but on the other hand, I applaud your interest in gaining a PRACTICAL understanding of Engineering principals. I wonder how many graduate each year with heads full of theory, and nothing more...:wink:

Local Technicians are expensive. As long as it's something basic (outside the combustion chamber and carburator) I should be able to handle it.

As for Nebraska, it's frigid winter blasts from Canada and seething summer heat from Texas and Oklahoma, with nothing to slow it down but a few barbed wire fences along the way. :biggrin: I much prefer Maryland for climate and scenery, but not for politics or social norms. Turns out I'm midwestern at heart, just can't seem to get used to the scrubby little trees...:biggrin:.

Adan, are you a college student or are you somenone looking to retire soon? Maybe you were using the "college student" reference merely to describe the extent of your interest in the topic? Either way, the more the merrier.


#21

M

mois25

I have had an oil leak before and just as reekes, ordered a new rubber washer. Yours seems like a gravitated issue though I am also assuming you have got the know-how as well.


#22

T

TBm

mois25 said:
Yours seems like a gravitated issue though.
Click to expand...

Thanks for the reply. What do you mean by a "gravitated" issue?


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