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-   -   Hot engine won't start (http://www.sailnet.com/forums/gear-maintenance/45976-hot-engine-wont-start.html)

threeofakind 08-11-2008 09:30 PM

Hot engine won't start
 
Hi,
I ran in a strange problem last WE on my Beneteau: The engine was running when I got the temperature alarm. I immediately shut off the engine, and let it cool.
I then checked the oil level which was low and added some.
I tried to restart the engine, but it wouldn't (still too hot?). I could hear a 'click' but no cranking.
Back at the mooring a few hours later, I gave it another try, and it did start right away... This got me very confused.
Any idea at what may be going on?
Thanks,
Thomas

HoneyDoII 08-11-2008 09:42 PM

I'll offer one sugestion, since the engine was overheated some of this heat was also transferred to your starter. A hot engine is hard to crank and a hot starter is much less efficient electrically than a cold one - it's possible it simply couldn't muster up the power to turn the engine over. Later with everything cool (relatively) it was again no problem. I would also suggest that you watch it for the cause of the overheating problem, I don't think it was oil if you were just a little low.

erps 08-11-2008 09:44 PM

The click you heard was the starter solenoid switch closing. Two things are possible. Either the engine was so hot that it was partially seized, and the starter couldn't budge it or the hot starter had high resistance and couldn't pass enough current through the contacts to spin the motor. I think the second was more likely.

Were there any other problems with the cooling system that may have caused the over heat problem? An overheat due to low oil is quite a bit more serious than a overheat due to low water.

cruisingdream 08-11-2008 09:50 PM

cooling concern
 
You may have partially seized the engine from being too hot and loosened up enough when it cooled down.
This is a cooling water concern, a slightly low oil level would not cause an overheat , most likely the oil pressure alarm would go off first ,check your fresh water cooling system, drive belts, sea strainers, valves, thru hulls for blockage.
Your engine may have survived but with a couple of years taken out of its life.

jrd22 08-11-2008 10:02 PM

I would agree with the posts above that this is a water/coolant issue rather than oil. What was the water temp (if there is a guage) when the alarm went off? I would determine if you are getting enough raw water flow through the exhaust and also check your coolant level. I always change thermostats if an engine overheats, and changing the impeller on the raw water pump, or at least checking it would be a good idea.

John

alan83054 08-11-2008 10:05 PM

Ditto John's post above...all of his suggestions are great!

Rockter 08-12-2008 02:33 AM

three...
When you say that the oil level was low, do you mean right off the dipstick, or low on the dipstick?
If the motor was running when you shut down, it will not have siezed.
I don't think the starter cooked. The engine is likely to have been in flames before that happened.
Check the wire to the starter solenoid. It may be loose or have fallen off.

threeofakind 08-12-2008 12:24 PM

Thank you all for all your good tips.

I could not see any trace of oil on the dipstick (because of the heel?). After I added about 2 quarts (more than 'some') the dipstick showed oil within the range.
There is no gauge, only a temperature alarm.

The engine is cooled with raw water. I always check the exhaust for water coming out. There was water at all times, but I understand I need to check the pump as maybe the flow wasn't enough.

I am obviously not very skilled when it comes to engines because I always thought that the raw water was doing all the cooling.
But reading your post, I am now guessing that my engine (Volvo Penta 2002) also uses fresh water. There is a reservoir which looks low as well. I will refill it with fresh water. Hopefully this was the cause of the overheating. With these hot days, maybe the water did evaporate faster than usual...

Thanks again for your suggestions.

Boasun 08-12-2008 12:42 PM

Gauge your engine!! You'll want; Oil Temp, Coolant Temp, Engine Oil Pressure, and transmission temp & pressure (if possible). All of this along with the Tachometer. Then add in the if you can the low level oil and coolant alarms along with the other temp alarms.
With the gauges you can log your engine's operation temp & Oil pressures, while in use. Then any changes will stand out like a sore thumb.
An Hour meter also for those pesky oil changes at regular intervals.

RAGTIMEDON 08-12-2008 01:09 PM

If yur engine is "fresh water cooled" which is common for anything over about 10 HP, the fresh water is not really water, but is a mixture of water and antifreeze. Since you said there is a reservior, chances are that is what you have. The sea water goes thru a heat exchanger, to cool that antifreeze/water mix, just like an auto radiator is cooled by air flow thru it. The heat exchanger is a honeycomb with lots of little tubes to transfer the heat from the engine coolant to the sea water. If the pump impeller is a couple years old, pieces of it can break off and plug up the heat exchanger, causing overheating. sometimes it doesn't affect the flow of sea water significantly, so you think you have cooling, but if the engine coolant is not flowing freely, it overheats! If you have not changed your impeller for two years, do it now. If there are any pieces of rubber missing from the old impeller, take your heat exchanger apart and clean it. BTW, before you start your engine EVERY DAY, check the oil! If you change oil every 100-150 hours, which most engine manufacturers reccommend, the oil should not be below the dipstick unless there is a leak. Checking oil level every day you use your engine will let you know if there is a leak. It can happen any time, due to the inherent vibration in a boat.


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