View Full Version : 4.3 l Mercruiser Locked up and now turns over very slow

08-06-2013, 11:02 PM
Hi everyone. I have a problem that I need some help with. I had the boat out and was towing the kids on a tube. I took a sharp turn and when we straightened out the boat seemed to have less power. When I throttled down the engine quit and would not turn over at all any more. When I lifted the engine cover it seemed to be ticking and popping like it was over heated. This is what I did to try and check what could be wrong.

1. Checked cooling lines and all had water coming out of drain plugs.
2. Checked engine oil and no water present in oil.
3. Removed spark plugs and serpentine belt and the engine turned over very very slowly no water on pistons.
4. Checked battery voltage and it was fine.

Thanks in advance any and all help from you guys out there would be greatly appreciated it was our first trip on the water this year.

08-07-2013, 08:45 PM

First off, your post would have been best if it were in the Mercruiser forum....

If the engine turns over by hand, you may be ok...it likely did overheat....the job now is to find out why and then fix it.

water coming out of the drain plugs in the manifolds doesn't really mean anything.

is it raw water cooled or do you have a heat exchanger?

when was the last time the water pump impeller was changed?

how old are the exhaust elbows and what type of water does the boat see?

08-09-2013, 11:29 AM
The engine does turn over by hand. It is turning very slowly even with the starter. It is raw water cooled and the impeller was changed last year. I bought the engine last year as a TKS or turn key system and it ran excellent. This was the first time we were able to take it out this year and it started and ran perfectly. after about 10 mins it just seemed to be losing power as if it were running out of gas and when I powered it down it was completely locked up and I could not turn it over. After removing the plugs and belt I got it to start to turn again.

08-09-2013, 11:50 AM
For the turning over part, I'd suggest load testing the battery and making sure both ends of both cables are clean and tight.

for the overheat part, you didn't answer the Q's on the age of the elbows and the water you boat on. You also should verify the water pump has adequate flow

as far as why it died, it could have been the overheat or a fuel delivery problem.