Westerbeke W21 overheating - possible airlock?

[Makeitone]

Hi Everyone,

I have a Hunter 34.5 (have never known what that .5 means btw) with a Westerbeke W21 engine. The engine runs fine however recently my temp creeps up very quickly - at 2,000 rpm 210-220F - under load or idle.

My raw water system is working fine - impeller checked, water discharging and heat exchanger clear of impeller bits. Alternator and belt are fairly new and appear to be working fine. Prop has not been checked but since I overheat under idle I am not concerned with it at the moment.

I feel the fresh water system (coolant side) is the issue as the heat exchanger remains cool while the thermostat reads 200-200F, the thermostat housing temp is 170-180F and the cylinder head bolts 200F. I was wondering if anyone knew of a simple check to see if the freshwater system is working properly? and possibly best way to bleed an airlocked system?

I also have hoses running to my water heater and I have read this is a common source of an airlock - if I disconnected the water heater and just ran a 4-5inch loop hose would this cause any complications?

Any advice would be helpful - thank you

Paul

 

[Stu Jackson]

Paul, you need to Burp your freshwater coolant system. Here's how, similar to yours.

Engine Overheating 101 - How to Burp Your Engine (Reply #6) http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462

 

[Bill Roosa]

If you have a coolant expansion tank "burping" is handled for you over several cycles of heating the engine up to operating temp and letting it cool down. The coolant expansion tank lets the air out as the engine heats up and the tank tube sucks more anti in as she cools down.
Also, upon initial filling of the engine with anti you should leave the coolant pressure cap OFF and run the engine adding coolant till she reaches operating temp. If you just fill and close it up you will trap a lot of air in the cooling passages. This will come out via the expansion tank but you would have to add a lot of coolant and the tank most likley would get sucked dry (which kinda defeats the whole idea of having the tank in the first place.)

 

[kloudie1]

The 34.5 is not really its official name, but 34 is.. The boat is 34' 6" overall length (34.5 feet) so it is a "bonus" 34!

 

[Makeitone]

The 34.5 is not really its official name, but 34 is.. The boat is 34' 6" overall length (34.5 feet) so it is a "bonus" 34!

Thank you - I like the new name....My bonus H34...and when the dock master asks she's 34, when my neighbour ask she's 34'6"

 

[Makeitone]

Thank you for the tips - I'll try this weekend to get all the air out....and burp my freshwater system. Cheers, Paul

 

[kloudie1]

Yep.. the neighbor gets 35 and the guy charging by the foot for dockage gets 34.. they get 34 !! When I had mine surveyed many years back, I wondered if the surveyor would pick that up and sure enough, the charge was for 34 1/2 feet.. You have one of the kinda rare ones, Paul.. that Westerbeke was not installed on many of the 34's..