I have a 1989 Sundancer 268 with a 7.4l GM big block V8 and a Bravo One drive. I put new plugs in last year and on the last trip of last year, my engine was running rough. It started out with me wondering if the timing was off, but it got progressively worse to the point where it was missing, shuddering and generally unhappy. I pulled the plugs when I got home and they all looked normal... except for cylinder #3 - completely fouled with oil. I changed the #3 plug and put it away for the winter.
We got a late start this year, but I had it out for the first time yesterday and immediately noticed the same rough running. It was hesitating, surging and I was getting more vibration than normal. I decided not to stress things and stayed off plane and putted around. Got home and pulled the plugs out of cylinder #3 and #5. #5 looked fine and #3 was oily. Here is a picture of the two plugs, #3 is a new plug with only 5 hours of running:
My googling says it could be the valve stem seal or maybe the rings. What do you guys thing I'm dealing with here? How does one diagnose this?
Thanks for any help!
We got a late start this year, but I had it out for the first time yesterday and immediately noticed the same rough running. It was hesitating, surging and I was getting more vibration than normal. I decided not to stress things and stayed off plane and putted around. Got home and pulled the plugs out of cylinder #3 and #5. #5 looked fine and #3 was oily. Here is a picture of the two plugs, #3 is a new plug with only 5 hours of running:
My googling says it could be the valve stem seal or maybe the rings. What do you guys thing I'm dealing with here? How does one diagnose this?
Thanks for any help!