18.5 hp B@S single cylinder, overhead valves. Intake valve is needing adjustment every time you try to start it. Adjust it and it will start and run fine for the hour it takes to mow the yard. Go to start it the next day and it is compression locked. Pull valve cover and intake valve is at about 20 thousands. What am I looking for?
- Thread starter ArleninOr
- Start date
Tom in TN
Well-known Member
- Location
- Southern Middle Tennessee
Arlen,
I have the same engine in my Huskee brand riding mower, and I've had the same problem you've described here. The valve train in this engine is really poorly designed.
I finally fixed mine last year. I replaced the rocker arm, the push rod, and the funky little bracket that is supposed to keep the push rod aligned with the end of the rocker arm. I also found that the stud that the rocker arm "rocks" on was loose in the head. I put some Locktite on the stud and tightened it into the head.
So far, I haven't had to readjust the valve clearance since I did this stuff.
Hope you find a solution for your particular problem.
Tom in TN
I have the same engine in my Huskee brand riding mower, and I've had the same problem you've described here. The valve train in this engine is really poorly designed.
I finally fixed mine last year. I replaced the rocker arm, the push rod, and the funky little bracket that is supposed to keep the push rod aligned with the end of the rocker arm. I also found that the stud that the rocker arm "rocks" on was loose in the head. I put some Locktite on the stud and tightened it into the head.
So far, I haven't had to readjust the valve clearance since I did this stuff.
Hope you find a solution for your particular problem.
Tom in TN
Sounds like the other poster has some good ideas.
In addition to that, are you setting the valve as is outlined in a factory service manual?
Some Briggs OHV engines need to have the valves set at a certain piston position just (I can't remember, offhand) before or after TDC, .25" of piston travel, perhaps?
ANYHOW, be sure you have the proper service instructions for the engine model number, and follow the valve setting procedure exactly.
In addition to that, are you setting the valve as is outlined in a factory service manual?
Some Briggs OHV engines need to have the valves set at a certain piston position just (I can't remember, offhand) before or after TDC, .25" of piston travel, perhaps?
ANYHOW, be sure you have the proper service instructions for the engine model number, and follow the valve setting procedure exactly.
Adjusted per service manual. Checked the rocker and stud, pushrod and bracket. All look good. Just the intake valve doing this. This mower has very few hrs on it. Less than 30 hours. Will check it out again tomorrow. Driving me to start drinking something stronger than water and coffee.
Janicholson
Well-known Member
I would use a caliper to find out where the wear is happening. if the pushrod, or cam follower, replacing them might make the difference. I assume there is oil getting to the rockers. Measure the valve height, measure the pushrod socket to head distance. Find the wear point to make a good repair. Jim
Has the mower ever had an oil change?
I recall one that came back 3 consecutive months with the valves out of adjustment. The second time, I figured I must have gotten the adjustment wrong. I made SURE it was right that time. The third time I finally figured out that nobody had ever changed the oil and the dirty oil had helped the tappets to wear through the hardening on the camshaft. It was taking about a month for it to get enough clearance to the point where it would not start.
I recall one that came back 3 consecutive months with the valves out of adjustment. The second time, I figured I must have gotten the adjustment wrong. I made SURE it was right that time. The third time I finally figured out that nobody had ever changed the oil and the dirty oil had helped the tappets to wear through the hardening on the camshaft. It was taking about a month for it to get enough clearance to the point where it would not start.
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