Westerbeke 44A4 - Overheat

[Richwink]

Hi

My first marine engine problem...

My engine overheated even at 1100 RPM while I was heating the oil up for a oil change. There was raw water flow, what seemed like a normal amount.

The engine has been using a little bit of coolant over the last 6 months but lately hasn't used any. I figured out that the line was plugged between the reservoir and the cap. I cleaned that out and then started the engine back up. I had a continuous stream of bubbles coming up the reservoir line.

Where could the coolant be going? What is the best way to bleed the air out of the system.

Thanks

Richard

[mcerdos]

There could be a lot going on here. The coolant should not be filled at the expansion reservoir. If you are doing this it could be the cause of your bubbling. It should be filled at the cap. Some bubbling, at first, is normal.

It is differcult to help without knowing the age of the engine and the mainteince performed.

Here are some common things to check:

1. Raw Water Impeller – the most common source. A spoke of the plastic impeller breaks off and clogs the raw water flow. Easy fix: buy a new impeller. Be sure to find and remove any missing impeller blades
2. Mixing Elbow – Corrosion here blocks the flow. Solution is a new or boiled out elbow.
3. Heat Exchanger – Scale builds up in the heat exchanger. Solution is to snake with a wire and dip in acid.
4. Thermostat Sensor/Receiver – Is the thermostat stuck? Or is the engine even overheating? Check the exhaust temperature. How hot is the water? Shoot a heat sensor on the water reservoir.
5. Fresh Water Tank/Coolant – Is it leaking?
6. Hoses – Delamination inside engine hoses restricts the flow, causing the engine to overheat.
7. Fresh Water Pump – An aluminum impeller inside the pump can corrode and limit flow.
8. Oil Cooler – Similar to the heat exchanger. You cannot snake her out because the tubes narrow at the ends but dipping the cooler in an acid bath does the job.
9. Over-propped – Too large a diameter or too much pitch can cause an engine to overheat prematurely. Correlates with not reaching full RPM’s. Is the prop clean and have any changes been made?
10. Aeration – Air getting in from a leak in the line anywhere can lead to overheating.

Hope this helps get you started.

[Scott Berg]

Open the cap, start the engine and run up the temp till the thermostat opens (use a thermometer in the coolant) and watch to see if it 'burps' and the level drops. After the burp, kill the engine, top up, fill the overflow to the cool line, and try again.... If that doesn't work you need to go step by step as above; I'm just pointing you to the easy fix....


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[mcerdos]

Originally Posted by Scott Berg

Open the cap, start the engine and run up the temp till the thermostat opens (use a thermometer in the coolant) and watch to see if it 'burps' and the level drops. After the burp, kill the engine, top up, fill the overflow to the cool line, and try again.... If that doesn't work you need to go step by step as above; I'm just pointing you to the easy fix....


Sent from my iPad using Cruisers Sailing Forum

Yes. A very easy way to check the thermostat.

[Richwink]

Hi

Will do the cap test tomorrow. The overheat occurred at the dock in neutral at 1100.

The raw water was flowing really good coming out of the boat. There was some debris in the raw water heat exchanger so I cleaned that out.

The engine is 2002 with only 2100 hours on it. Normally runs like a top.

Hoperfully that cures it. Will let you know.

Richard

[Richwink]

Hi

Cap test worked... Got all the air out and ran the engine for about 1/2 half hour. Also got a infrared thermometer which made checking this much easier.

Thanks Forum for all the help.

Richard

[mcerdos]

Originally Posted by Richwink

Hi

Cap test worked... Got all the air out and ran the engine for about 1/2 half hour. Also got a infrared thermometer which made checking this much easier.

Thanks Forum for all the help.

Richard

Glad to have helped. Also glad it was a simple fix and not expensive. The infrared thermometer is a great tool. I have a log book of "normal" temps.