Hi Guys,

Recently, I was using my Generac 5550 generator with a 10HP Briggs & Stratton OHV, model 204412, Type 0142 engine, and it started running rough and puffing black smoke. So I bought the repair manual. Took everything apart to the piston, cleaned the carbon off the pistons and valves. Cleaned everything up on the cylinder head, replaced all gaskets with new ones. Put it back together, and adjusted the valves properly. I changed the air filter and spark plug, changed the carburetor with a new one. Fired it up and it still lacks power, runs rough and spits out some black smoke. I pulled it apart several times readjusting valves, cleaning carbon off the plugs. Put it back together but it still runs rough. The only thing I noticed, and I am not sure about is, there was some oil sitting at the bottom of the valve rods, and noticed that the valve cover which has a breather tube, seemed a bit oily? When I pull the breather tubing off, and smell it, it smells like fuel, and had some oil residue there. Not sure if this could be the problem? Or what it exactly would be? Any ideas are certainly appreciated. Oh and a leak down test, showed minimal leakage, nothing of concern?? Thanks. Mike

If it were a car, I'd say the PCV valve is stuck open.

Have you taken the carb apart yet? You sound like you are flooding, maybe a needle valve or bad float.

I have completely replaced the carburetor, of which I don't believe it is the carb, it is doing the same thing, as with the old carb. It seems like the mixture is too rich, but there is no adjustment for this carb. Briggs & Stratton have a mechanical governor on this particular model, and it is set to full open on the throttle. I called to verify and that is what they said, there is no adjustment, it stays wide open. This is the second carb but same result. Seems like it is running rich. I have seen bits and pieces about the breather and tubing? But not anything very clear about this. It seems like oil did get into the breather and tubing, and I am not sure if this could be it?? Any more ideas??

If the breather is bad, there would be oil on the air filter, and in the air filter housing, and carbs. Throat. I agree with ballengerb1 the carb has a float or needle problem. And is flooding causing it to build excessive carbon and black smoke. As far as minimal leakage, if you used a b&s leak down tester, and followed the procedures step by step, if the gauge did not stay in the green, it is not minimal, and it needs repaired.

As previously stated, I have already changed the carburetor, it is now the second one, with the same problem. I have done a leak test. Everything came back fine. Only 15% leakage which is normal and acceptable. No air from dipstick, breather or any other place that I could hear. I did find what appears as oily residue in the breather and tubing, and also the brand new filter, started to blacken up a bit, though I didn't find oil in the carb. The needle and carb are fine.

Other ideas?

Again black smoke is not from oil burning, it is from the fuel mixture. Good luck.

Well, from what I gathered just now, speaking to Briggs & Stratton, is that it appears to be a vacuum issue, it appears it is going to be the breather, which is located on the valve cover. I just ran air through the tube, and it started hissing, which their book says no air should be escaping. There is also oil residue on the new air filter. In speaking with Briggs, they said it appears to be vacuum related and that would certainly do it. I have done a leak down test and that came back fine no problems. So rings seem to be fine, as well as the other components. If there are any other ideas on this, I would like to hear them. I just ordered the part, $30 bucks from Briggs, ouch! So I am still in need of opinions and ideas. Thanks.

Mike

Be sure to clean the area thouroughly before applying the new gasket between the breather and block.

I seam to be having the same problem I noticed that the exhaust valve was moving about half the distance I talked to a mechanic that informed me that briggs is using plastic camshafts I haven't replaced it yet but I can't find any thing else wrong:confused:

Go for it jeff, let us know where you are on the project and if you need any help.

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Originally Posted by jeff beckwith

I seam to be having the same problem i noticed that the exhaust valve was moving about half the distance I talked to a mechanic that informed me that briggs is using plastic camshafts i havent replaced it yet but I can't find any thing else wrong:confused:

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Wow, thanks for the info. I haven't really been using my generator much do to other things going on, but I don't think I ever got mine fixed either, and have replaced the carb, gas, filters, gaskets, adjusted the valves, etc... but don't think I have ever gotten it really back up to par. So you say they are plastic camshafts?? Let me know if you change yours out. I am a bit afraid to dig to deep and get myself into more trouble, but if you do happen to find it is the problem. Please pass it along. Thanks.

Michael

I was hoping that some could answer my question if the cam lobes on the intake and exhaust are the same hight, if so then I have a cam with a flat lobe on the exhaust. Michael you can check to see if your valves are doing the same thing, I going to try to find a new cam to see if the cam lobes are the same ,If anyone has any information I would apprecate it. Thanks

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Originally Posted by latinprince

Wow, thanks for the info. I haven't really been using my generator much do to other things going on, but I don't think I ever got mine fixed either, and have replaced the carb, gas, filters, gaskets, adjusted the valves, etc.... but don't think I have ever gotten it really back up to par. So you say they are plastic camshafts??? Let me know if you change yours out. I am a bit afraid to dig to deep and get myself into more trouble, but if you do happen to find it is the problem. Please pass it along. Thanks.

Michael

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Michael I pulled the generator apart the cam was flat replaced and runs fine, the problem was the same as you have. My generator is model 204412 code 146 check to see if valve move the same distance

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Originally Posted by jeff beckwith

michael i pulled the generator apart the cam was flat replaced and runs fine, the problem was the same as you have. my generator is model 204412 code 146 check to see if valve move the same distance

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Hi Jeff,

I think you are right on. Because like I said, I haven't really tried since I did the carb, the adjustment etc... When I did try it, it didn't sound like it got back up to full power. So I am going to guess that my problem is the same that you experienced. Was it a plastic cam as you thought it was??

How difficult was it to replace out the cam?


Mike

Hi mike when I pulled the generator apart I found out the cam was steel ,but it was still flat the hardest part of replacing the cam is getting the stator off if you have problems them take it to a shop and let them pull it I used a slide hammer but make sure that you can see a difference in the movement of the exhust veres the intake valve if they both look like they move the same then that may not be the problem . Good luck

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Originally Posted by jeff beckwith

hi mike when I pulled the generator apart I found out the cam was steel ,but it was still flat the hardest part of replacing the cam is getting the stator off if you have problems them take it to a shop and let them pull it I used a slide hammer but make sure that you can see a differance in the movement of the exhust veres the intake valve if they both look like they move the same then that may not be the problem . good luck

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Hi Jeff,

Thanks for the response. Yea, I think my valves are not even in movement. I think you are right about it being the cam. So it is definitely steel,, mmmm... I do have a slide hammer. I bought the repair book for this thing, but it is very confusing because it includes all the models for the series. How did you get the generator separated from the engine portion? Also, if you could explain how you used the slide hammer to get the thing out of there? I appreciate your input, as truth be told, I am a little bit worried about digging myself into something that I might not be able to do. But I am almost sure you are on to something because my valves aren't moving evenly, and I thought that seemed strange. I think if I remember correctly, one of the valves, don't remember which one, but it only opened just barely and the other seemed to open quite a bit more.


Mike

Hi mike the generator comes off if you remove the four bolt in the front they are short with nots on the back side then pull the housing off then there is a bolt in the center of the rotor the bolt is about 4 inchs long . You may trying losing the bolt and taping on the end of the bolt and pulling on the rotor at the same time. Make sure the bolt is screwed in most of the way.so you don't mess up the threads . Sounds like the same problem. Once you get started it not that hard the worst part is removing the rotor . It helped that I am a mechanic . But I did not find it to hard once the rotor was off it took about 15 min to get it all apart the manual should help. Jeff

I have been follwing this question and I'm having a problem with the B&S 10hp ohv. My engine is mounted on a "little wonder leaf blower". The engine might have overheated and caused the bronze valve guide to move inside the cylinder head assembly causing limited travel for the exhaust valve. If you find limited valve travel with the exhaust valve the guide may have moved. The guide is pressed in at the factory. This has happened twice to me in 3 years and one of my local repairman says this has happened with this application on "little wonder blowers" Any replies would be appreciated. Thanks, SkipB

What may behapening in your case, is the valves are bending and taking out the bushing. If your setup vacuums leaves, then it all makes sense. If it gets heavily loaded, the valves might bend by bringing up a sudden stick.

I's guess that lowering the RPM or going to a lower viscosity oil might help.