temp alarm after coolant change

[Ken13559]

I helped a friend to change his coolant for his 3YM30. We drain the coolant totally then top up the coolant. Ran the engine hot then fill in more coolant. However, we kept getting the temperature alarm. May be got some air lock somewhere inside. Any idea what the problem is and how to burp the system? Thanks.

 

[Saillife]

Start with the obvious - Is the raw water intake open & is water flowing out? After that I'd be looking at the temp sensor and see if the engine really overheating.

 

[John T1594]

Burp

Happens all the time when you drain or change the coolant. Try to remove an air purge vent screw (if you have one) near the fresh water pump, or from one of the hoses on the high side of the system. If you keep the overflow tank full, the engine will likely burp itself when it cools down

 

[s sauer]

'burping' the system

Generally you will get an air bubble trapped somewhere; in ours it was typically under the T-Stat, so the overheat alarm would sound; we'd shut it down and let it cool off. It is easier to find a hose at a high point (our 28.5 has a hose running to the water heater) and loosen the clamp and hose enough to let the air out, but be very careful if you've already run the engine as you may release steam or hot water.

 

[jviss]

Doesn't the thermostat housing have a bleed valve on it?

What I do is start and run with the pressure cap off, and when the temp comes up and thermostat opens, fill it up, and cap it. Make sure there's enough in the overflow tank so the system doesn't suck air.

 

[Ken13559]

Ok, raw water intake was opened, that's the 1st thing. I'm sure its over heating 'cos beside the alarm, I see alittle smoke coming from fresh water water pump area. I've the overflow tank top to full mark so hopefully by now the cooled down engine would have drawn in some coolant. Noted that I should look for high point hose to disconnect to burp the sysytem. Should I remove the thermostat to pour in some coolant?