Export thread

Kawi 601V crankcase pressure/black oil

#1

H

Hayward51

I've rebuilt this engine with all new internals, including crankshaft, new. I reused the heads and bought aftermarket carb. The PO had hacked the old Nikki carb. It fired up initially and for 4 hours breaking in rings, it ran perfect. I noticed oil leaking around drain plug and replaced O ring there and the dip stick tube. When draining oil, I noticed it was black metallic. Filled with fresh oil, warmed up engine, checked stick, it was foamy. ?? I started up after topping off oil and ran at different RPMs for about 3 or 4 min. with clutch engaged and it just died. I got it to start again on full choke. It would stall off choke. I checked oil again and there was a lot of pressure released unscrewing the dip stick. I assume that pressure may have caused the O ring problems. Do you have any suggestions on the black and foamy oil ? And the crankcase pressure ?


#2

T

txmowman

Pressure release from the crankcase when the engine is stopped? If so, the crankcase may not be venting through the breather system. The reed valve might be stuck. This would prevent fuel pump operation resulting in not being able to keep the engine running. Black oil is caused by blow-by of hydrocarbons. This could be from not venting the crankcase as well.


#3

H

Hayward51

Thanks for that, txmowman. that makes sense. I also noticed it was slow to pour oil down dip stick chute. It would fill tube and sort of burp back. Is the breather filter necessary? I saw that new kit has none.


#4

T

txmowman

The breather filter is not necessary and should be discarded if you get in there.


#5

H

Hayward51

txmowman said:
The breather filter is not necessary and should be discarded if you get in there.
Click to expand...
I pulled the breather, discarded the oily filter, and found port to the carb tube to be stopped up. ?? I used a good spare crankcase during rebuild that was sitting around. I'm assuming a dirtdobber nested in that port.? All seems normal with vent now. Thanks txmowman !


#6

T

txmowman

Great job finding that. I have heard of those pests causing issues before. Glad you got it fixed up. Thank you for reporting back.


#7

H

Hayward51

Hayward51 said:
I pulled the breather, discarded the oily filter, and found port to the carb tube to be stopped up. ?? I used a good spare crankcase during rebuild that was sitting around. I'm assuming a dirtdobber nested in that port.? All seems normal with vent now. Thanks txmowman !
Click to expand...
txmowman, you seem to be knowledgable,I have one other question. Once i cleared vent tube, I started it up and still have a throttle problem, not related to crankcase pressure (I hope). When I try to Rev it up, it stalls around mid-throttle. If I ease it up, it seems OK but will surge at mid-throttle only. ? Aftermarket carburetor. I tried pilot screws and static governor setting. Any suggestions ?


#8

T

txmowman

When it is surging, if you slowly apply the choke, does it tend to want to smooth out? How does it run at full throttle?


#9

H

Hayward51

txmowman said:
When it is surging, if you slowly apply the choke, does it tend to want to smooth out? How does it run at full throttle?
Click to expand...
I'll check that out tomorrow. It doesn't seem as bad under a load. It sounds smooth a WOT.


#10

T

txmowman

So at high idle under load is sounds good? WOT on a governed engine is when the engine is under heavy load and losing RPM. If the engine runs fine with the PTO engaged, then the idle jet likely is incorrect for this engine or debris in the idle circuit. The engine has no purpose at mid-throttle anyway. If it doesn't surge and runs fine while mowing, that is what you want.


#11

H

Hayward51

txmowman said:
So at high idle under load is sounds good? WOT on a governed engine is when the engine is under heavy load and losing RPM. If the engine runs fine with the PTO engaged, then the idle jet likely is incorrect for this engine or debris in the idle circuit. The engine has no purpose at mid-throttle anyway. If it doesn't surge and runs fine while mowing, that is what you want.
Click to expand...
the problem is mainly acceleration. It will bog down and die shoving it home under no load. If I'm easy on the throttle, it doesn't stumble. Under a load, with PTO on, it seems fine.


#12

T

txmowman

The only thing I do know about aftermarket carburetors is that usually they don't work well. What is the problem with the original carburetor? The Nikki carburetor has transition ports that provide enough fuel during the transition from low to high idle. Maybe the aftermarket carburetor does not have them? You also wrote that you "tried pilot screws". What does "tried" mean?


#13

H

Hayward51

txmowman said:
The only thing I do know about aftermarket carburetors is that usually they don't work well. What is the problem with the original carburetor? The Nikki carburetor has transition ports that provide enough fuel during the transition from low to high idle. Maybe the aftermarket carburetor does not have them? You also wrote that you "tried pilot screws". What does "tried" mean?
Click to expand...
The original Nikki carb was corroded,pitted and throttle shaft was altered by PO (looked like hacksaw was used). I 'tried' adjusting pilot screws at idle. I didn't count turns(?), just tuned by ear for best/highest idle. It made no difference above idle.


#14

H

Hayward51

Hayward51 said:
The original Nikki carb was corroded,pitted and throttle shaft was altered by PO (looked like hacksaw was used). I 'tried' adjusting pilot screws at idle. I didn't count turns(?), just tuned by ear for best/highest idle. It made no difference above idle.
Click to expand...
I checked the surging at mid-throttle and added half choke and it did smooth out. I can live with that. Will the blackened oil (less than 4 hrs old) hurt anything to leave for a few more hours of break-in ?


#15

T

txmowman

The black oil may be temporarily ok as long as the oil level is not over full. You may smell fuel out the exhaust as at operating temp, some of those hydrocarbons will burn off.


#16

H

Hayward51

txmowman said:
The black oil may be temporarily ok as long as the oil level is not over full. You may smell fuel out the exhaust as at operating temp, some of those hydrocarbons will burn off.
Click to expand...
Thank you, txmowman, for all your advice !


#17

T

txmowman

Glad I could help.


#18

S

slomo

txmowman said:
The breather filter is not necessary and should be discarded if you get in there.
Click to expand...
Are you sure about that? Are you cutting grass only in a clean room?


#19

T

txmowman

Absolutely sure. This unneeded element is inside the crankcase. Its purpose was to help separate air and oil droplets, keeping the oil in the engine while letting the air out of the crankcase. Has nothing to do with the engines outside environment.


#20

S

slomo

txmowman said:
Absolutely sure. This unneeded element is inside the crankcase. Its purpose was to help separate air and oil droplets, keeping the oil in the engine while letting the air out of the crankcase. Has nothing to do with the engines outside environment.
Click to expand...
That's right. You are correct. Had to think about that one. Just didn't want any more dirt inside the engine.


#21

T

txmowman

I appreciate that, sir.


Footer Links 1

Top