Super Jr. 25hp CH730 engine issues sent me home today! Lil help?

[Hoosier]

I had an issue last time out with the engine belching out white/grey smoke and nearly dying when I was grinding some stumps on a short but steep incline, the back wheels were on the base of the hill but the machine was going up hill slightly.. I was pointing directly up the hill when this happened. I went home and drained / changed the oil as it seemed over full and it also smelled of gas, so I ordered a carb kit. So while waiting on that kit I went back out today to grind on a flat yard and as soon as I tipped the cutter down it blew enough smoke to make shade and nearly died several times. It ran pretty good back to the trailer but I cant work with it like this. Am I on the right track thinking it's the carb or float or should I consider other issues? The compression on the motor cold is the same on both sides at 180 (If I remember correctly) however today I pulled the dipstick while it was blowing smoke and had a little oil spatter come out of the dipstick tube.

Thoughts?

 

[74inchshovel]

Verify compression first, check plugs and see if, how they're fouled. I kitted same motors carb, did not get good results, bought a factory new carb on EBay for 130ish. Ignition on these motors is pretty rock solid, so if compression checks your on the right track with carb kit. For me at least, white smoke a bit odd on an air cooled motor. Let me know what shakes out on this

 

[Eq Broker]

White/Grey smoke usually indicates a fuel issue. There should be an inline fuel filter and they become clogged over time. I would recommend replacing the fuel filters. Also, I would clean the fuel cell as well. There could be a lot of trash in the tank. If you're getting fuel in the oil, there could be a front seal issue.

Hope this helps!

Dave
Global Equipment Exporters
770-420-6400

 

[Hoosier]

Thanks guys, the kit came in today but using the Alpine Magnum kicked my but, so I will try and get it in this week and test it out and report back what I learn. Compression was tested on a cold engine and was balanced and pretty high. Of course that could change at temperature, but my gas smell is back in the oil so if it aint the carb I may just repower, cant be down long this time of year..

 

[Hoosier]

Well, I put it back together and it seemed to run fine and had vacuum at the dipstick tube and I ran it on a test stump here at the house and it really seemed like I had a qualified repair...then I drove it back to the garage and was moving some stuff out of the way so I could park it and while at a high idle it just puked a huge plume and died. It did not restart right away, the oil level showed fine so I let it sit for a bit and it restarted, however now it wants to run rougher if I pull the dipstick and also spits out oil vapor now instead of vacuum. Is there a breather that has a check valve that could be the culprit?

 

[Eq Broker]

Have you changed the inline fuel filter? The symptoms you are describing are really pointing me in that direction. It's not a costly item. When it's running rough I really believe it's a fueling issue. When an inline fuel filter is bad, it will do exactly what you're describing. I don't know about the breather.

Hope this helps!

Dave
Global Equipment Exporters
770-420-6400

 

[Hoosier]

Really? I would not think low fuel input would cause the oil dipstick tube to go from vacuum to output? I will go eliminate it and see what happens, it's a clear in-line and seems fairly clean at a glance.

 

[Eq Broker]

I've seen the dipstick push out on diesel engines and this happens due to crankcase pressure as the oil is bypassing the rings and the engine needs rebuilding. I hope this isn't the case with your engine. You may also want to check the fuel line as well. I've seen where the engine will run fine for a minute and then the trash hits the inline fuel filter and then causes the issues. We had a machine a few years ago that was doing the same thing as yours. After we changed the inline fuel filter it was still doing it. We then check the fuel line and come to find out there was a dead wasp in the fuel line blocking the fuel flow. I've seen many strange things with equipment over 15 years. Good luck and let's hope it's something that simple.

 

[Hoosier]

So, the other day after I replaced the needle and soaked the carb overnight and put it together it ran and ground OK, and then belched when I got back to the garage and that's when I noticed the light spray out of the dipstick and found it had no real vacuum at the dipstick like it did when it was cold...(That led me to think head gasket etc..) but I forgot to change the oil and it still had gas in it and was over filled. I just now remembered and changed it and kept the level to the low side if half of the crosshatch on the dipstick and it ran a LOT better. I ground on a cherry stump for a while and it behaved properly. I will smell the gas in a while and see if I have that issue resolved. I am starting to think that if the crankcase is overfilled with a really thin oil with gas mixed in it will not run properly (Go figure right). I will work it next week and report back. It could have just been that bad float needle dumping gas into the crank and that would certainly jack with the crank case breather and air volumes etc.. Stay tuned.

 

[74inchshovel]

As far as fuel in the oil, it will have nothing to do with front seal, and if the carb is that rich that it's dumping fuel into cylinders and getting past rings into the crankcase the motor would be blowing black smoke like a coal train, if it ran at all. The lift pump should be sitting on top of valve cover, if internal diaphragm leaks it will certainly put fuel into oil.

 

[Hoosier]

Where did "Front seal" come into this? I agree on the fuel pump, but I can tell you from direct experience that it was overfull with thin oil with a strong gas smell and it only presented as a problem when the motor was tilted. Once you change the oil and have the correct amount it no longer seems to have an issue...at least no so far. If the next job puts gas in the oil I may swap out the fuel pump.