4.3L OMC overheating

had the boat out last weekend and the water intakes got plugged. motor ran fine, but got hot. temperature gauge did not max out, but motor locked - up and would not turnover until it cooled. once it cooled down I took it back to the dock. pulled the dipstick out and oil on disptick was good. I decided to change it anyways. oil was homogenized so I pulled the filter and flushed everything. put new oil in it and ran it in the yard with the hose attachment. pulled oil out again and it looked good - no water signs but slightly darker than new. filled it again and ran it in the lake for a little bit checking dipstick constantly. dipstick looked good so pumped oil out of the pan and it also looked good - no water, slightly darker than new. annual service was done this year and impeller was replaced - still in good condition. with the water in the oil I asumed heads got warped, but looking at the oil after flushing and running it I am questioning what to do next.

Re: 4.3L OMC overheating

[color=lt blue]Be sure to check all rubber exhaust componants. With the engine running without water the rubber exhaust parts can be cooked from the inside. Check for brittle rubber and hardness. All the rubber should be flexable. If you havent checked and replaced the raw water pump impeller, it would be the next thing to do. [/color]

Re: 4.3L OMC overheating

would you pull the heads, machine them and replace the gaskets even though the oil right now looks good?

Re: 4.3L OMC overheating

Pulling the heads at this point is premature. The issue that's most concerning is the impellor and possibly the temper of the rings. Generally a bad overheat will make the rings lose their temper and down goes compression and oil usage goes up. Since the motor locked up, do as reel poor says and check the impellor as well as run a compression check and/or leakdown test. Thus will give you a better idea of the condition of the heads and cylinders.

Re: 4.3L OMC overheating

thanks. I already pulled the impeller and it still looks new. it had less than 5 hours on it when the overheating occurred.