Mikeymagoo
Cadet
- Joined
- Oct 8, 2011
- Messages
- 12
So a little history. I bought this boat a month ago, previous owner said engine was rebuilt last spring and boat was taken out twice this summer. We replaced the rocker arm cover (cracked 3 places) and the intake manifold gasket to stop the leaking oil. Once we got the leaks stopped we put it in the water.
It idled fine in harbor, but when we took the rpms to 3000, the engine was sluggish and wouldn't come on plane. About 30-45 seconds later, big clacking noises and we shut it down. The distributor hadn't moved, so we started back up. It was backfiring out the carb, but we limped in on 3 cylinders.
We found a broken rocker arm on the #4 cylinder exhaust valve and a bent pushrod on the #4 intake valve. The other 3 cylinders and components were fine. We pulled the head and found a small mark on the #4 piston. The #4 valves moved freely and the oil came from the lifters when compressed. The timing chain didn't seem to have jumped. There isn't a flapper in the exhaust tube.
We can't figure out what happened, if the timing jumped why didn't all valves hit the pistons? If the pushrods are too long, why only #4 cylinder issues?
We don't want to put it back together just to have it blow up again. Any ideas? The pistons look okay, could the previous rebuild been done incorrectly to cause this?
It idled fine in harbor, but when we took the rpms to 3000, the engine was sluggish and wouldn't come on plane. About 30-45 seconds later, big clacking noises and we shut it down. The distributor hadn't moved, so we started back up. It was backfiring out the carb, but we limped in on 3 cylinders.
We found a broken rocker arm on the #4 cylinder exhaust valve and a bent pushrod on the #4 intake valve. The other 3 cylinders and components were fine. We pulled the head and found a small mark on the #4 piston. The #4 valves moved freely and the oil came from the lifters when compressed. The timing chain didn't seem to have jumped. There isn't a flapper in the exhaust tube.
We can't figure out what happened, if the timing jumped why didn't all valves hit the pistons? If the pushrods are too long, why only #4 cylinder issues?
We don't want to put it back together just to have it blow up again. Any ideas? The pistons look okay, could the previous rebuild been done incorrectly to cause this?
