I have a 12 or 13 year old Scotts (by john deer) self propelled mower with a 3 speed rear drive gear box and a B&S Intek 6.5hp OHV motor.
The mower has always done a decent job pf cutting the lawn. My lot size is 10K sq ft with a 1388sq ft house, double car garage, shed and graveled dual wide RV parking on one side. The lawn is not huge so I dont want a riding mower. Takes me maybe 1-1.5 hours to mow everything on the slowest speed. It's all flat.
Recently I checked the oil level in the engine and it was barley registering on the stick. I added a little oil to get it between the low and high mark. Since then the mower spews blue smoke out the muffler. I drained the oil and refilled thinking I had inadvertently overfilled it but after carefully measure the oil amount and verifying it was right between the low and high mark on the stick I still get huge clouds of smoke out the pipe. The plug is very oily.
I hooked up a compression tester and gave the cord a few yanks and it went up to 90psi. From what I have been reading that seems good given the auto decompression cams in these things. Maybe I am wrong though.
Anyhow, it is probably time for a rebuild or replacement. One of the output shafts on the transmission is seized and I had to take the gears out of the wheel so it is now a one wheel drive. The cost for a replacement transmission for this is over $200 alone. Combine that with the cost of rebuilding and I am starting to think maybe its time to get a new mower.
If I got a new mower I would be looking at the $450 or less price range.
So if this were your mower would you rebuild the engine and fix tranny or just toss it and get a new mower? It doesn't seem like they sell any push mowers with a 6.5hp engine anymore. I may miss the extra power.
Sounds like you may have a valve problem. If you are handy I would pull the the valve cover off and maybe the head and see what the problem is. What would you have to lose. If you are not handy with engines trade it in on a new unit. Would cost to much in labor to repair. Remember that this is only my opinion, as there are professionals on this forum who feel that I am an old fart who does not know much.
I am handy with tools and I would be doing all work myself. I have replaced the crank in it once already (ran over a hidden stump in the first year I bought it).
I did plan on popping the valve cover but I have been pretty busy.
I pulled off the head over the weekend. The cylinder walls look great. No scoring. I did not see an obvious failure in the head gasket. I noticed the exhaust valve does not have a stem seal nor is there one shown in the engine diagram. The intake valve stem seal seemed to seal good on the shaft.
What else should I be looking for? The air cleaner has no oil in it so I know it is not sucking it in through the breather. I do notice the piston rocks ever so slightly at the bottom of its stroke when the crank changes angles.
Sorry I haven't gotten back to you sooner. There is no seal on exhaust valve. I would replace the seal on the intake. As long as you have it apart, I would take it to a good repair shop and have them recondition the valves and seats. Shouldn't cost a lot and I feel worth the cost. Replace the head, intake and exhaust gaskets. I would also consider cleaning and rebuilding the carb at this time. Slight play of the piston is normal and I have no concerns about that. Clean the top of the piston and cylinder walls before reassembly. If you have any more questions post back.
I do agree with Honda engines, I have a CRV and is great, but with small engines I would recommend nothing but Briggs and Stratton. They seem to go forever if you maintain them.
