Westerbeke trouble; over heating.-gctid823573

[scubadiver#3988]

Advice needed on an 8.0kw generator.

Like every single time, I boarded the boat and started the generator to charge the batteries (I'm on a mooring right now). I peek over the side to confirm water discharge and look at the gauges for proper operation. The water discharge appeared normal. After about 40 minutes of running the generator shut down by itself. Ran fine for 2 hrs last weekend. I knew fuel was not the problem. I felt the raw water pump with my back of my hand and it was very hot. Too hot to touch. I decided to rebuild the raw water pump and started the engine again. Now a week later, the engine started right up. I peeked over the side and the discharge looks normal. After reaching 180 degrees, I removed the fresh water fill cap and watched the water circulate. The temp gauge reached 200 degrees and I shut the generator down.

Here are my questions -

What is the normal operating temperature for this generator? (Could the overheat sensor be faulty)

Can the fresh water pump be tested for proper operation without removal?

Am I getting in over my head to clean out the heat exchanger or is it pretty straight forward?

Thanks for any advice.

[iceclimber]

http://www.westerbeke.com/documentlibrary.htm

You can find the manual for your generator here. If you list the exact model, might be easier to help you. I assume you checked the strainer, anti freeze etc, pretty sure your generator should be operating at 180 degrees. When you say "rebuilt the pump" does that mean a new impeller ? Your symptoms sound like a worn impeller. If you suspect your heat exchanger, pull it and take to a radiator shop and have it pressure tested. They are relatively simple devices and tend to work or not.

[cosmo777]

to me - a hot raw water pump means a lack of seawater. So as mentioned, either the sea strainer is plugged, or the intake/scupper had a blockage. I would check both, and then replace the impeller (checking for loose pieces from previous owners not getting all the impeller chunks out?).

You are probably seeing an overtemp alarm shutting your genny down, you just need to trace to why - normal operation will keep temps in check.

[vinomaker]

Every time I have had an issue with my Westerbeke overheating ( 200+ degrees) it has been the saltwater strainer was not sealing properly so no raw water was being sucked in (which fried the impeller) or it has been the impeller needed replacing.

I would start with the raw water intake and the impeller.

[kev_rm]

"scubadiver#3988" post=823573 wrote:
Advice needed on an 8.0kw generator.

Like every single time, I boarded the boat and started the generator to charge the batteries (I'm on a mooring right now). I peek over the side to confirm water discharge and look at the gauges for proper operation. The water discharge appeared normal. After about 40 minutes of running the generator shut down by itself. Ran fine for 2 hrs last weekend. I knew fuel was not the problem. I felt the raw water pump with my back of my hand and it was very hot. Too hot to touch. I decided to rebuild the raw water pump and started the engine again. Now a week later, the engine started right up. I peeked over the side and the discharge looks normal. After reaching 180 degrees, I removed the fresh water fill cap and watched the water circulate. The temp gauge reached 200 degrees and I shut the generator down.

Here are my questions -

What is the normal operating temperature for this generator? (Could the overheat sensor be faulty)

Can the fresh water pump be tested for proper operation without removal?

Am I getting in over my head to clean out the heat exchanger or is it pretty straight forward?

Thanks for any advice.

Normal temp would be ~175.

Fresh Water Pumps almost never cause overheating - normally they just start leaking.

A lot of WB's You can visually inspect the heat exchanger for blockage by taking the caps off. If its clogged with scale, take to rad shop. I've had mine clogged with impeller parts and zinc bits before but I was able to unclog with it still installed.

[Uncle_Bob]

Removing the heat exchanger is easy and should be part of regular maintenance so I'd start there. There are two clamps that get unscrewed and two hoses to disconnect. You might want to disconnect the coolant hose at the highest point to avoid an antifreeze puddle. Once the cylinder is off, remove the endcaps and the core. The core is many tubes often plugged with zinc that has sloughed off the anode. Best is have a rad shop boil it out but you can use a welding rod to ream each tube. Hold the core lengthway to a bright light to determine how clear the tubes are. Compressed air or high pressure water helps.

[scubadiver#3988]

Thanks for all the help.

Impeller was whole when removed. Sea strainer is clear and plenty of water is coming out through exhaust.

I ordered a fresh water pump due to the age of the old one. Old one not leaking. I know Confucius says "if it works, don't fix it" but age has got me concerned.

I will try to remove the heat exchanger.

[higgins_jr]

Scubadiver, if you have plenty of water coming out the exhaust, it would seem the impeller and heat exchanger are OK. Before changing out the engine coolant pump, just check out the thermostat. If that's not opening correctly, that will certainly cause the temp to rise and shut it down.

I've attached a Westerbeke parts/diagram manual page 46 has the thermostat info. Good luck with it. Cheers

http://www.westerbeke.com/parts%20manual/48220%2035c%20-%2035d%20-%208.0%20-%2010.0%20btda%20parts%20list.pdf

[iceclimber]

read up on this, and with a salt boat it may be the cooling passages inside the generator. You can flush them.

[scubadiver#3988]

Thermostat arrived today

[scubadiver#3988]

It is my understanding the cooling of the interior parts of the engine is through the heat exchanger and the exchanger is filled with antifreeze. The antifreeze is filled to within 1/4" of the fill neck. The cap to the fill neck was also very warm to the touch.

[higgins_jr]

Scubadiver, not sure where you're at with your problem. You're correct with your observations - the coolant is circulated thru the engine then thru the heat exchanger by the "fresh" water pump. The coolant in turn is cooled/maintained at normal operating temp by the raw water pump circulating sea water thru the heat exchanger and exhaust manifold. 175-185 deg F is very warm to the touch.

You said the thermostat had arrived. You will loose some coolant when you remove the thermostat housing cover. Watch that the gasket under the housing cover isn't too damaged - you may need to replace that too or make another to ensure it doesn't leak after the new thermostat is fitted. See if that lowers and maintains your temp to ensure it doesn't overheat.

Cheers

[scubadiver#3988]

Gasket arrived with thermostat. I ordered two.

[capt._ron]

If the thermostat doesn't fix the problem, check the exhaust elbow for starting to plug with carbon. Water flow out the exhaust may look fine but it may be restricted enough to cause overheating, good luck.

[higgins_jr]

Scubadiver, if you can, try to syphon out some of the coolant with a hose down to approx the level of the thermostat housing and put some rags around the area. Just trying to avoid coolant flooding around the alternator/terminals etc. Let us know how you go.

Cheers