QuestionQUESTION: I have a Briggs and Stratton 12.5 HP, which is a 2004 model on an MTD riding mower. The last time I used it, the mower was operating at a much reduced power level. It sounded and felt like it was going to kill at any minute. About 30 minutes into the cutting, the mower killed. No loud bang or anything. Now it won't start. It was low on oil and has blown white/blue smoke at times on inclines. I showed it to a small engine guy and he said it was toast, that the piston rod is broken. However, I do not hear any problems with the piston and it still cranks but doesn't fire up. I have a brand new spark plug as well.
Any Ideas.
Thanks
Dave
ANSWER: Pull the spark plug and stick a wooden dowel or pencil in the cylinder and turn the engine over by hand. This will verify if the rod is broken as the piston won't move. Let me know what yopu find from that and we can go from there. Thanks, PK.
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QUESTION: Yes the piston is working. I also tried starter fluid in the cylinder and no change. I checked the spark and I do have spark. I checked the flywheel and the key is fine. I did a compression check and it is 60.
So then i checked valves and they are operating. So I then opened the cylinder and the piston is not in great shape but working. There was a bit of oil that drained out when I opened it. So I closed everything up and still no change and not firing up. I am stumped.
Thanks
Dave
Answer60 psi may be borderline. It's difficult to say without a reference from previous compression tests on your particular engine because of the compression release.
As you have two of the threwe things needed for combustion, properly timed spark and fuel, (ether) that just leaves compression. In the shop we would perform a leakdown test to determine the sealing ability of the engine.
A little oil in the cylinder is normal when you pull the head, maybe a fourth of a tablespoon. More than that might point to a problem. Thanks, PK.
