QuestionQUESTION: I am trying to help a friend get his riding mower (Engine Model OV490EA, Spec 208035B)running correctly. It is hard starting; basically slows down or even stops at the compression stroke it seems when starting. It will start sometimes but not every time. We adjusted the valves to .004 for the intake and .006 for the exhaust. The exhaust clearance was greater than that before we adjusted it. This made it somewhat better but it is still not starting right. Once it does start, it seems to run fine. One other thing is that this mower had gas run out of the tank into the oil. We replaced the fuel pump which was letting gas into the oil and we also replaced the fuel bowl components with a bowl kit. It doesn't have any more gas going into the oil now. Could this condition have caused the flywheel key to partially shear which would have altered the timing? When starting, it does have a tendency to spit back through the carb and make a kind of wheezing noise. If the flywheel key was partially sheared, would it run okay once it did start? What could we be overlooking in determining what the problem is? Thanking you in advance for any help you can give us!
ANSWER: I have not had very many Tecumseh keys partially shear, but I have had it happen on Briggs and Stratton.
Either way I would check the key to know for sure as it will cause kick back and I had some Briggs engines run fine, with a partially sheared key, after they starter.
Did you drain all the old oil and refill with new oil? I am assuming you have had it running since fixing the fuel leak and adjusting the vavles. Is this correct?
Have you dis-connected the battery cables and cleaned the battery terminals and cable ends with a wirebrush to ensure a good connection? I have fixed a lot of hard starting problems just by cleaning the battery connections?
Have you had the battery load tested?
Let me know.
Eric
---------- FOLLOW-UP ----------
QUESTION: Thanks for your response. To answer your questions, we did drain the old oil and refilled with new oil. It has run since I did that but it is hard to start and sometimes just doesn't seem like it wants to turn over or at least it is very slow. The battery cables and terminals have been cleaned with a wire brush. The battery was rundown before we starting working on the mower so we recharged it and then tested it with an Autoxray 6000 which uses Midtronics software to test the battery. The battery tested good; we also keep it on a charge each night to keep the charge up. We checked the voltage at the starter terminal when we cranked the motor and it read approximately 10.2 volts. This was after we had tried cranking it many times.
Today, we ran a compression test and got a reading of 60 psi; this was accomplished after the engine had run for about 2 minutes. We also did a leak down test at 40 and 75 psi. Had a hard time holding the crank from moving but both tests were within 1 or 2 psi of the regulated psi.
One thing that we noticed is that when checking the spark plug after trying to start the engine that it is black but doesn't seem to be really wet with gas. We tested the spark plug using an OK Spark Tester and it shows the plug is getting high voltage and is firing. Another thing we noticed is that there is a sound coming from the top of the motor below the mesh screen on the flywheel that sounds almost like a grinding noise. It doesn't sound like it is the engine though. Not sure what it is, but you hear it when cranking. Don't hear it once the engine starts. I am beginning to wonder whether there are two problems; one being the slow cranking and the other being a fuel problem since the spark plug is not wet with gas after trying to crank it.
Any additional help would be appreciated!
AnswerThe grinding could be bad...pull the top engine shroud off and make sure the ignition module is not hitting the flywheel.
Sounds like you have a lot of tools. If you have an air or electric impact gun I would also remove the flywheel nut, then the flywheel and make sure nothing it grinding on the inside of the flywheel...there are magnets inside the flywheel for the charging system. The flywheel should have three holes in the top for a flywheel puller. You can use any puller that will fit the bolt patter...I use a $10 Harbor Freight steering wheel puller...best money I ever spent.
Does the carburetor have an anti-afterfire solenoid? You can tell as there will be a wire or two running to the carb.
Do you have any way of checking the current draw when cranking the engine? Usually have to have a DC shunt or a really high amp meter.
Eric
