Topping up engine coolant after slight overheat

[PhillM]

Beta 14, new last year, 50 hours on the clock:

Last weekend we ran our engine for about 30 seconds with the seacock blocked. Realized quickly, stopped it, cleared the blockage and carried on.

The engine smelt a little hot and I saw steam coming out of the engine bay. Not much, just a bit of vapor.

The engine overheat light did not come on but I think that the coolant got hot, expanded and blew out of the cap / overflow tube onto hot engine parts.

My plan is to need to check / replace the impeller, top up the coolant and run under load for 15 minutes, leave to go cold and then check the coolant again - all as per the manual.

Is there anything else I should do?

I ask because today when I was buying coolant at the local marine engineers, they suggested that there could now be air bubbles in the system and I might need to drain the system and refill.

 

[vyv_cox]

I doubt very much that you have done any harm at all in 30 seconds. When rebuilding engines I always run them for that length of time with no coolant in case there is a problem that might need me to open the engine up. The biggest harm you might have done is to burn the impeller but even that is unlikely in such a short time.

 

[GrahamM376]

There will be more than a few bubbles in the system if you drain it. Sounds as though you shouldn't have a problem if the overheat alarms didn't go off so I would just do as you say - clear blockage, check impeller, top up and run it. I would also extend the expansion pipe so it blows off into a bottle or into the bilge under the engine. One question - what coolant have you been buying? Normal antifreeze is fine as an inhibitor and usually cheaper if not badged "marine".

 

[PhillM]

The engineer who commissioned the engine put in "Volvo Coolant". I didn't want to mix different brands or colours, so that is what I have brought today, ready for Friday when I can next get down to the boat.

 

[fuss]

If it was 30 seconds then it will have done no engine damage at all. However the steam might have been from around the raw water pump as the rubber impeller would have got hot.

I would suggest that you remove the impellor and inspect it as you said you would

 

[PhillM]

OK so got to the boat for an extended lunch hour. Opened the cap to top up the coolant and found the tank EMPTY. Filled the tank then went on to check the impeller. All looked fine, but I replaced it anyway - to be on the safe side.

Ran the engine under load and watched carefully. Large green puddle after about 5 minutes. I found a leak from the pipe connection from the engine into to the heat ex-changer.

I cleaned up, tightened up the jubilee clip and then ran the engine again - no leaks this time.

have come back to work and will go back down tomorrow and top up the coolant again.

I really should have been checking the coolant every time out - Lesson learned - I should have know better especially as I only did the RYA course last year :hororr:

 

[sailorman]

OK so got to the boat for an extended lunch hour. Opened the cap to top up the coolant and found the tank EMPTY. Filled the tank then went on to check the impeller. All looked fine, but I replaced it anyway - to be on the safe side.

Ran the engine under load and watched carefully. Large green puddle after about 5 minutes. I found a leak from the pipe connection from the engine into to the heat ex-changer.

I cleaned up, tightened up the jubilee clip and then ran the engine again - no leaks this time.

have come back to work and will go back down tomorrow and top up the coolant again.

I really should have been checking the coolant every time out - Lesson learned - I should have know better especially as I only did the RYA course last year :hororr:

when servicing the engine, always check the hose clips too. i bet its mentioned in the maintenance schedule too