B&S 18HP mower burns oil and stalls when hot
- Thread starter Jerryb
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Put oil in it.
Is it a splash oil or pressure?
Check the oil. Is it overfilled? If so, your needle/seat are not working in the carburetor and it is dumping fuel into the engine.
Also, when was the last time you have changed the oil? What oil are you using? I have seen some engines with REALLY OLD (never changed) oil that do nothing but smoke once warm because the oil is so super thin.
Assuming the oil is freshly changed and is not overfilled, than your float in the carburetor is what I would look at next. Might have a hole in it.
Also, when was the last time you have changed the oil? What oil are you using? I have seen some engines with REALLY OLD (never changed) oil that do nothing but smoke once warm because the oil is so super thin.
Assuming the oil is freshly changed and is not overfilled, than your float in the carburetor is what I would look at next. Might have a hole in it.
Originally Posted By: bubbatime
Check the oil. Is it overfilled? If so, your needle/seat are not working in the carburetor and it is dumping fuel into the engine.
Also, when was the last time you have changed the oil? What oil are you using? I have seen some engines with REALLY OLD (never changed) oil that do nothing but smoke once warm because the oil is so super thin.
Assuming the oil is freshly changed and is not overfilled, than your float in the carburetor is what I would look at next. Might have a hole in it.
+1 Also try replacing the fuel filter.
Check the oil. Is it overfilled? If so, your needle/seat are not working in the carburetor and it is dumping fuel into the engine.
Also, when was the last time you have changed the oil? What oil are you using? I have seen some engines with REALLY OLD (never changed) oil that do nothing but smoke once warm because the oil is so super thin.
Assuming the oil is freshly changed and is not overfilled, than your float in the carburetor is what I would look at next. Might have a hole in it.
+1 Also try replacing the fuel filter.
What load are you putting on this engine?
sounds like it's getting too hot. Pull the shrouds off and clean out any crud in the cooling fins and around the flywheel. Then change the oil and filters.
Originally Posted By: ironman_gq
sounds like it's getting too hot. Pull the shrouds off and clean out any crud in the cooling fins and around the flywheel. Then change the oil and filters.
Agreed...
A float with a hole in it isn't going to care what the temp is... And if it did, it's not going to miraculously purge it's self of the fuel it's absorbed when cooled...
sounds like it's getting too hot. Pull the shrouds off and clean out any crud in the cooling fins and around the flywheel. Then change the oil and filters.
Agreed...
A float with a hole in it isn't going to care what the temp is... And if it did, it's not going to miraculously purge it's self of the fuel it's absorbed when cooled...
I had an old Craftsman w/ 18HP that did that. Found that the breather was blocked up and after 30 mins so much pressure built up in the crankcase that oil started backing up and drenched the air filter. I would check the air filter to see if it is soaked which would verify.
+1 engine is too hot From carb/fueling problem - lean condition. Dont keep using it till you figure it out. Pull the spark plug and look at the electrode/insulator and Google for color pics.
If it is it white and clean that would be overly lean. Which can be caused by a clogged carb passage or fuel filter. In this condition it will run OK but when you load it doing cutting it will overheat.
It should be moderately brown in color. Dark brown or black would be overly rich which can be from a hole in the float.
Could also be as suggested clogged breather but that would also indicate substantial blowby which would make it a bigger problem.
If it is it white and clean that would be overly lean. Which can be caused by a clogged carb passage or fuel filter. In this condition it will run OK but when you load it doing cutting it will overheat.
It should be moderately brown in color. Dark brown or black would be overly rich which can be from a hole in the float.
Could also be as suggested clogged breather but that would also indicate substantial blowby which would make it a bigger problem.
OK. From experience I can tell you these engines have a design flaw that blow head gaskets. That's your problem.
I've done this repair twice now. The last time I did it the only thing I did different was copper sprayed the head gasket. So far, knock on wood, has held up the longest to date (about 5.5 years).
I've done this repair twice now. The last time I did it the only thing I did different was copper sprayed the head gasket. So far, knock on wood, has held up the longest to date (about 5.5 years).
My dad's Cub Cadet with an 18.5 one lunger Intek has also had the head pulled twice for this issue. It burned copious amounts of oil each time. B&S essentially skipped a head bolt location that causes the gasket to fail between the pushrod gallery and the cylinder. On the plus side they are easy to tear down and usually start easier than new after a careful valve adjustment upon reassembly.
I changed oil the end of last season. I also changed oil to 10W-30 and new filter last week. It still stalls. I always check oil before mowing. I cleaned gunk from around the cooling fins. I don't know if it's splash or pressure. The engine is intek OHV 18hp B&S. I will change air filter this week. It sounds like it may be a head gasket like some suggested. I can't work on it this week, but I will get back to you next week. Thanks for all your help.
I would check the valve clearance. The clearance closes up as the engine heats up, and if it is set too close, the valves may not seat as well, causing a loss of compression and thus power. The engine may become difficult to start when hot, and seem to lose power, both of which can be caused by adjustment that is too close.
FWIW, the piston is supposed to be at 1/4" past TDC when setting clearance, from what I have gleaned.
tom
FWIW, the piston is supposed to be at 1/4" past TDC when setting clearance, from what I have gleaned.
tom
I changed the head gasket as some of you suggested. It seemed to be leaking where they skipped a bolt like you said. The piston head and valves were coated with black carbon. I cleaned it and put it back together and now it won't run at all except when I spray starting fluid. Replaced old black plug. I took apart the carb. Needle valve looks new. Float works, no leaks. It seems not to be getting any fuel. There is fuel in the bowl and fuel line flows. Any other suggestions??
That's possible, BUT, it wouldn't start before I took it apart. Do you think I could have made a mistake? Don't answer that.
It is not getting fuel and there is gas in the bowl. I took out the spark plug and it is dry and it starts with starting fluid. Why no fuel to the engine?
It is not getting fuel and there is gas in the bowl. I took out the spark plug and it is dry and it starts with starting fluid. Why no fuel to the engine?
The carb have one of those fuel shutoff solenoids in it?
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