QuestionQUESTION: I'm not mechanic so please forgive if I don't understand the terminology or workings of the motor but I'll do the best I can. I've got a 1962 3.5 hp. Briggs & Stratton motor on my lawnmower. It has the pulsa jet suction lift carburetor. The mower was running but very hard starting and the exhaust was heavy with smoke. My goal was to replace the worn rings around the piston which I believed was causing the smoke. I just like the mower and didn't want to get a new one. I hoped by replacing the rings I could extend the life of the mower and stop the smoking or oil burning. When taking apart I noticed how corroded the sides of the flywheel were and the opposite side where you are suppose to be able to fit two sheets of paper. I sanded both sides to hopefully improve the starting and checked the points gap. It seems to have good spark. I also took apart the fuel line and took out the idle adjusting screw to blow out with air and that seems to be fine.
I went ahead and replaced the rings which was an endeavor in itself. I had never taken a motor apart. When going back together now I've got spark but no chance of getting the machine to start.
My brother-inlaw checked the compression and said it was very low or non-existent. So he checked the valves and took one out that is on the right, can't remember if it was intake or outtake. He checked it with a feeler gauge and he didn't think it was the right gap and I think he said that he shouldn't be able to spin the valve around when it was in the extended position. He felt that this could be where we were losing the compression. He took the valve out cleaned it up and ground it down to get the correct gap. We also cleaned up the area where the head gasket meets the head because some of the old gasket was stuck to the metal when we took it off, so we cleaned it up and reinstalled it. He got compression up to 20 on his gauge but he said it should be up around 100. We tried to start it anyway but nothing.
He doesn't have time to look at it anymore so I'm on my own. So he thinks it could be in the rings I installed. Is there anything I should look for in the rings? The machine was running before I put the new rings on so I don't think it was the valves even if they weren't exactly how they should be or should be cleaned. I think the machine would at least start with the valves in the condition they were in.
Back to the rings, I tried to follow the instructions on the small sheet of paper that came with the rings. Hopefully I got the correct rings or thought I did, but the sheet of paper shows the TOP, CENTER and OIL ring. I made sure that the CENTER ring had the outside groove facing down. When I look at the Briggs and Stratton book I have I noticed in the section on piston rings that TOP ring has a groove on the inside as well. I hadn't been looking for this, it didn't show this on the piece of paper that came with the rings. I could have installed the TOP ring upside down with the inside groove facing down. Would this make a difference with the compression? As I mentioned, it didn't show this inside groove on the TOP ring in the instructions that came with the rings. Maybe I have the wrong wrings or maybe they didn't think it was important? I was looking at the rings I took out and I can see that there is a bevel on the inside of one them which must have been the TOP ring.
Do you have any advice about what to look for to solve this compression problem or does it sound like a lost cause or just too old of an engine to save?
ANSWER: Never a lost cause. The top ring installation does affect the compression. When you installed the rings, did you make sure the ring gap were staggered from each other?
Eric
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QUESTION: The model number was 6052 type 941193 serial 6219206.
I know what you were saying about making sure the ring gaps weren't all lined up but when putting the rings back in. I attempted to do this but I didn't have a ring compressor. I just worked on one at a time and they kept moving around as I tried to pinch them together. I would work on it for awhile and get frustrated and quit and go back to it again at another time, so when I when I would get one in the cycliner I wasn't sure where the gap was in relation to the prvious. I just hoped they didn't end up all lined up.
Yes, my brother-inlaw checked the gap on the valves he thought they were alright. Do you think taking the rings back out is the only option? I have my doubts that even if I did that I got them back in again that it will improve anything, but if that is the last think I should do before discarding the machine I will do it. Please advise.
Thank you.
ANSWER: I doubt the rings are the issue. If you rotate the engine counter clockwise does the engine snap back to a clockwise rotation?
Briggs never publishes compression readings as they vary with each engine. The recommend method for checking compression these days is to use a leakdown tester. This will tell you which component, if anyy, is causing the compression leak.
Does you brother-inlaw have a leakdown tester or a friend with one?
One tip for installing rings without a ring compressor it to use some hose clamps, screwed together, to use to compress the rings.
Let me know if you have access to a leakdown tester.
Eric
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QUESTION: I tried to e-mail the last few days but kept I was told you were maxed out otherwise I would have gotten back to you sooner. No, my brother-inlaw doesn't have the leakdown tester and I don't know where I could get one. I wonder how much a repair shop would charge to do the test?
When I turn the flywheel counter clockwise it doesn't bounce back clockwise. To help me understand, are there only likely three places where I could be losing compression, 1.) Through the valve gap. 2.)Through the rings, and 3.)Through the head gasket? Are these the only places where it could be happening.
I've got good spark and I've put ether in the chamber. There are some puffs of smoke but it doesn't quite ignite it or fire it. I don't know how to say it. Anything else I can do at this point? Thank you for your help.
AnswerWhat is the point gap set at? Are you certain the camshaft and timing gear on properly lined up?
The point plunger, part number 65704, is it flat on both ends? I have seen these wear on really old engines and would cause a timing problem.
Eric
