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Oil Burning on Startup

#1

G

Guggenheim24

I have a Briggs 9L902 0284-E1 3.5 that smokes on startup. This past winter I replaced the intake valve seal with an OE one since usually smoking on startup only is caused by that. Valve does not have play in guide either. Still smokes on startup. When I initially pulled off the head, there was a little oil collected between the piston and head. Sitting on the cylinder wall closest to the deck obviously. Not alot. I just find it odd if it was a cylinder wear/out-of-round or ring issue, it would smoke constantly and have low compression. Engine has good compression from the feel of it, and will start first pull; which makes me kind of doubt I have a compression issue. And it doesn't smoke alot and not for long. 2 seconds tops. After that it does not smoke anymore and if I restart hot will not smoke. Only when it sits for a week. We've had the mower since new and the engine has been meticulously maintained with oil changes every fall and clean air filters its whole life. Any ideas? Thanks


#2

R

Richard Milhous

Are you sure the smoke is oil, not gas?


#3

Scrubcadet10

Scrubcadet10

Yep, what color smoke we talking about, Blueish/whiteish or black?


#4

StarTech

StarTech

Could simply be over filled with oil and it seeping pass the rings when sitting long periods. Or the cylinder being lower the normal oil level when stored.


#5

O

olgeezershonda

Your symptoms sound exactly like a valve stem seal leak to me too. I had a 1980 Pontiac with a 305 that did the same thing - replaced all the valve stem seals and the bit of blue smoke at start up went away. Odd that it would happen so soon after a replacement last winter but worth looking into


#6

VRR.DYNDNS>BIZ

VRR.DYNDNS>BIZ

StarTech said:
Could simply be over filled with oil and it seeping pass the rings when sitting long periods. Or the cylinder being lower the normal oil level when stored.
Click to expand...
The above is most likely the cause. If oil at the level of the piston because plug is doen hill or slightly over full, oil will weep past rings when stored before next use. If overhead valve engine could be he3ad gasket. All this is assuming the smoke is blue. One last possibility is float failure leaking gas into crankcase and over filling which then causes issues. Also a dirty airfilter or wet will draw hard on the breather and suck oil.


#7

B

bertsmobile1

As others have said, smoke on start up only is oil seeping into the combustion space that gets burned off just after it starts.
The problem no one has mentioned is oil that is too thin will also cause this to happen'
Thin oil happens because the engine is overheating or fuel has leaked down into the sump & diluted it.
So check your oil and remove the blower housing & clean the fins .


#8

S

slomo

SAE 30 oil is supposed to be at the TOP of the threads at the yellow oil cap. As in nearly over flowing. Make sure the block is level like the pic below when checking.

1635428498971.png


#9

S

slomo

Take a white paper towel. Hold it near the muffler. You are looking for oil or black soot.

Normally smoking on start up only is intake valve seals. Does your engine have one?

Might do a valve adjustment while you are at it.

Also remove the head. Decarbon the cylinder, head and valves. This is in your engine manual.

Clean those filthy engine block cooling fins while you are there too. Again in your engine manual as a yearly to-do.


#10

StarTech

StarTech

slomo said:
SAE 30 oil is supposed to be at the TOP of the threads at the yellow oil cap. As in nearly over flowing. Make sure the block is level like the pic below when checking.

View attachment 58801
Click to expand...
Please check your post information vs the engine in this post. I think you are advising the OP to hydro-lock his engine but it may just be my brain being flooded with all the rain here this morning.


#11

E

enigma-2

If nothing else is at fault, check the crankcase breather for a blockage.


#12

S

slomo

StarTech said:
Please check your post information vs the engine in this post. I think you are advising the OP to hydro-lock his engine but it may just be my brain being flooded with all the rain here this morning.
Click to expand...
I can't pull up his engine on the Briggs site. Looked to me as a 9ci 3.5hp engine??? You might be on to something Star Tech?? I don't know if he has a H or V crank either??

1635462392619.png


#13

S

slomo

Guggenheim24 said:
I have a Briggs 9L902 0284-E1 3.5 that smokes on startup. This past winter I replaced the intake valve seal with an OE one since usually smoking on startup only is caused by that. Valve does not have play in guide either. Still smokes on startup. When I initially pulled off the head, there was a little oil collected between the piston and head. Sitting on the cylinder wall closest to the deck obviously. Not alot. I just find it odd if it was a cylinder wear/out-of-round or ring issue, it would smoke constantly and have low compression. Engine has good compression from the feel of it, and will start first pull; which makes me kind of doubt I have a compression issue. And it doesn't smoke alot and not for long. 2 seconds tops. After that it does not smoke anymore and if I restart hot will not smoke. Only when it sits for a week. We've had the mower since new and the engine has been meticulously maintained with oil changes every fall and clean air filters its whole life. Any ideas? Thanks
Click to expand...
Is your engine like the one in the picture I posted?

Put of a picture of your engine on here. Or a video would be even better.


#14

StarTech

StarTech

Briggs Numerical Designation cheat sheet


#15

B

bertsmobile1

slomo said:
I can't pull up his engine on the Briggs site. Looked to me as a 9ci 3.5hp engine??? You might be on to something Star Tech?? I don't know if he has a H or V crank either??

View attachment 58808
Click to expand...
Did you put the leading 0 in there to make it 09L9d2-0284-e1


#16

peteco

peteco

Don´t worry for a little smoke, go ahead


#17

S

slomo

bertsmobile1 said:
Did you put the leading 0 in there to make it 09L9d2-0284-e1
Click to expand...
I did now at your suggestion. 0 results. I'm not a repair shop. No access to the pro site.

1635516408994.png


#18

StarTech

StarTech

That is a routing error on Briggs site due to having select what the engine is on. Kinda dumb idea on Briggs part by programming the search engine that way when we don't what the engine is on. You kinda have to take an educated guess as to what it is on.

If you select "pressure washer" instead of "push mower" it will come up with 12 results.
1635519922927.png


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