Engine ran hot today

[chaparral442]

Volvo penta 4.3 (2003) - Started normal took off from dock and engine never really cooled down. Normally runs under 200 -- today it got up to 225 and would not cool down. Ran it for about 15 minutes before I noticed and shut it down
What is the problem and could I have hurt the engine?

Also when I tried to turn it off the engine "dieseled and would not stop- had to pull the coil wire to shut it off

 

[Don S]

Re: Engine ran hot today

The engine would not shut down because it was hot. You REALLY need to restart it NOW. Make sure when it was dieseling that it didn't suck water back into the engine thru the exhaust. Which happens when they diesel.
If it won't turn over or starts to turn over and stops suddenly, pull the spark plugs and crank the engine till the water is out of the cylinders. Dry the plugs put them back in and start it. DO NOT let it set overnight.
You don't need to hook water up if it's not possible, only run if for a few seconds (10 or less) at idle or just above idle to make sure the water is out of the system.
Now, the cause of the overheat.
When was the last time the impeller in the raw water pump was replaced. That is the first place to check on any overheat problem on any boat.
What is your full engine model number? Carbed or EFI?

 

[chaparral442]

Re: Engine ran hot today

The engine would not shut down because it was hot. You REALLY need to restart it NOW. Make sure when it was dieseling that it didn't suck water back into the engine thru the exhaust. Which happens when they diesel.
If it won't turn over or starts to turn over and stops suddenly, pull the spark plugs and crank the engine till the water is out of the cylinders. Dry the plugs put them back in and start it. DO NOT let it set overnight.
You don't need to hook water up if it's not possible, only run if for a few seconds (10 or less) at idle or just above idle to make sure the water is out of the system.
Now, the cause of the overheat.
When was the last time the impeller in the raw water pump was replaced. That is the first place to check on any overheat problem on any boat.
What is your full engine model number? Carbed or EFI?

I did re crank it and it ran ok - I thought maybe I picked up trash so I let it idle for a while and it still would not cool down. IT is Carbed 4.3GL volvo penta in a caravelle 187

 

[Don S]

Re: Engine ran hot today

Well, at least you know it doesn't have water in the cylinders. That's great.
Now, check the impeller. If you picked up a plastic bag, when you shut the engine off it would fall off the drive. But the damage was already done.
Pull the impeller and check it.