26 hp intek belching after getting hot

[Scrubcadet10]

I don't guess a worn cam lobe could cause this, could it?
That would probably be more constant.

 

[Tinkerer200]

Just now got through mowing for about an hour with this machine. When riding on it, and mowing at higher rpm, you don't notice any problem. It starts instantly, and idles smoothly. But, when it is sitting still, and you get behind it, while increasing rpms, it starts with frequent hic up, and even a subtle back fire now and then. After having checked the valve clearances, compression, and putting in new plugs, I was wondering if these symptoms might indicate too high a fuel level in the float bowl. Thanks for suggestons.

Sounds more like a lean condition to me, I would try spraying WD40 or carb cleaner around manifold to block/ carb to manifold gasket areas to see if it makes a difference in rpm indicating a leak. Also makes me wonder about head gasket.

Walt Conner

 

[sgkent]

If you would have stopped at a gas station back in the days In a volts wagon and filled it up with gas. Then going down the interstate and got behind a semi truck and followed it for several miles I would almost bet your engine would over heat and blow up and your gas tank would almost be still full of fuel. ... .

to set the record straight. Going to a race in Atlanta back in the 70's, in Texas, and pulling a small camping trailer into a very strong 50 mph head wind in a 1971 VW bus we could not get over 40 mph. We found a semi that could not get over 40 mph either and he had no problem with us sitting 4' off the back of his truck for about 2 hours since both of us were able to speed up to about 60 that way. He used his turn signals to tell us what was going on at a distance ahead. With a full set of gauges on the bus - oil pressure, oil temp, cyl head temp etc., I can assure you that we actually ran cooler because their was less effort pushing into the headwind. Air cooled engines need air volume to cool, and the best benefit comes at a spot where the fan is most efficient. A heavy load at low RPM is hardest on air cooled engines.

As to the OP - probably changing the air filter, and fuel filter would be where I would go with this. That said, I have seen this behavior in some of my air cooled engines around the landscape and garden. In each case it turned out to be a worn out fuel pump (diaphragm) or loose carb jet. Modern fuels attack many of the fuel diaphragms and this causes an inconsistent supply of fuel - which in turn causes the surging.

 

[SlopeMan2]

I don't guess a worn cam lobe could cause this, could it?
That would probably be more constant.

Thanks Scrubcadet10. I hadn't thought about a worn cam lobe. Since it started this snorting all at once, I wouldn't think it was that. But, since it has over 1000 hours on it, I might check that. It only takes one little thing. Sure a good feeling when they run nice and smooth. Thanks

 

[SlopeMan2]

Sounds more like a lean condition to me, I would try spraying WD40 or carb cleaner around manifold to block/ carb to manifold gasket areas to see if it makes a difference in rpm indicating a leak. Also makes me wonder about head gasket.

Walt Conner

Ok Walt, will try spraying some WD around the intake. I remember having a friend that did that to my 250 Honda that was fussy. One cylinder did have a little oil coverage around the head, which had happen over time. It wasn't fresh. The other cylinder was dry. I forget which cylinder had the highest compression, but they showed 150 and 160. If it were a head gasket, wouldn't the compression be much lower? I mowed again with it tonight. When I am mowing at higher revs, you hardly notice it. And, at idle, it sounds fine. But at about 1/4th throttle, it starts to spit, and sort of has a lope to it. I really hate it, because it was so perfect before last week. I will check the compression again. I will try the WD and check the compression again.

 

[SlopeMan2]

to set the record straight. Going to a race in Atlanta back in the 70's, in Texas, and pulling a small camping trailer into a very strong 50 mph head wind in a 1971 VW bus we could not get over 40 mph. We found a semi that could not get over 40 mph either and he had no problem with us sitting 4' off the back of his truck for about 2 hours since both of us were able to speed up to about 60 that way. He used his turn signals to tell us what was going on at a distance ahead. With a full set of gauges on the bus - oil pressure, oil temp, cyl head temp etc., I can assure you that we actually ran cooler because their was less effort pushing into the headwind. Air cooled engines need air volume to cool, and the best benefit comes at a spot where the fan is most efficient. A heavy load at low RPM is hardest on air cooled engines.

As to the OP - probably changing the air filter, and fuel filter would be where I would go with this. That said, I have seen this behavior in some of my air cooled engines around the landscape and garden. In each case it turned out to be a worn out fuel pump (diaphragm) or loose carb jet. Modern fuels attack many of the fuel diaphragms and this causes an inconsistent supply of fuel - which in turn causes the surging.

Thanks sgkent. Enjoyed reading about drafting with the VW bus, ha. I remember tucking behind a travel trailer on a 90cc Honda in 1965. When we stopped at a station, I thanked him, and said I was getting over 100 mpg. He laughed, and I should have, because he was pulling me, ha.

I will check the fuel filter, since you said it sounded like a fuel supply problem. I does surge. And, yes, the fuel pump. That is original, so I will check that. I love this engine, so hope you are right. It doesn't knock, or have mechanical noises, and the compression tested 150 and 160. I did recheck the valve clearance. Thanks a lot. Will let you know what I find.

 

[Tinkerer200]

Ok Walt, will try spraying some WD around the intake. I remember having a friend that did that to my 250 Honda that was fussy. One cylinder did have a little oil coverage around the head, which had happen over time. It wasn't fresh. The other cylinder was dry. I forget which cylinder had the highest compression, but they showed 150 and 160. If it were a head gasket, wouldn't the compression be much lower? I mowed again with it tonight. When I am mowing at higher revs, you hardly notice it. And, at idle, it sounds fine. But at about 1/4th throttle, it starts to spit, and sort of has a lope to it. I really hate it, because it was so perfect before last week. I will check the compression again. I will try the WD and check the compression again.

Head gasket starting to leak will not show drastic compression loss. Just trying to think of something which might result from getting hot under load. Long shot, might run some SeaFoam thru it per instructions on container.

Walt Conner

 

[SlopeMan2]

Head gasket starting to leak will not show drastic compression loss. Just trying to think of something which might result from getting hot under load. Long shot, might run some SeaFoam thru it per instructions on container.

Walt Conner

I rigged a small temporary gas tank, and mixed gas and seafoam half and half. I mowed some with it last night. Will try this a few time before I dig further. I do remember doing this to a 250 Honda, and it did the trick then. I had forgotten about that, but never had any more problems with the Honda. Thanks, and will let you know.

 

[SlopeMan2]

Was mowing tall grass on a 90 degree day, with throttle nearly open, and afterwards noticed that this 26 hp intek started belching frequently. It doesn't exactly sound like a back fire, but on that order. It starts and mows fine, and when running at slow speeds, or idle, it is not as noticeable. I had just been bragging about this engine, which has over 1000 hours on it. It has been well maintained, uses no oil, and has always run perfectly. I will do some checking tomorrow, but wondered if others had experience this.

Well guys, finally got the 26 hp B&S to quit belching. A new carburetor solved the problem. Some of you suggested that it was a lean problem. Well, I guess it was. I checked everything else first - leaks, valves, new fuel pump, lines, filter, plugs etc. I understand the little o rings around the jets go bad. It seemed easier to find a new carb. on-line, than parts. So - got it all back together, prayed and turned the starter. Oh what a feeling. It started quick, and was it's old self. Sounds great. Mowed 2 hours with it today without a hic-up. What puzzles me, is why it started that all at once, while mowing on that hot day. The only thing I can figure, is that some extra heat affected the little o rings - or, that it was just time for one of them to get distorted.

Thanks again to all you guys. These little engines can make you pull your hair - kinda complicated like human bodies. Much better that the problem was just a motor, than a problem in one of us that the doctor has to figure out. Thanks, and hope you all get help with your problems.

 

[Scrubcadet10]

Glad you got her going!