Cool running Universal 5411

[Alsail27]

Hi everyone; Ericson 28+ (first season that I have the boat) here with the 5411 direct raw water cooled. Engine runs fine, but cold; turns out that the previous owner had completely closed (shut off valve) the return and so the thermostat was never recirculating to get the temp up. Engine temps were around 100F (but again, running smoothly, no issues). When I opened the return and replaced the thermostat (also replaced the raw water pump) the engine comes up nicely to 140-150F and stays there, so all good. Just that it seems that even at full speed there is some recirculation needed to keep the engine temp up, which in turn reduces the water flow into the exhaust, with the result that quite a bit of steam is generated out the exhaust (and the exhaust water is on the warmer side). Anybody have any idea what is going on? - if I restrict the return I get the exhaust to stop steaming, but then the engine temp drops. If I run the engine temps at the correct temp I get steam. Almost looks to me like the cooling system is overdimensioned for the engine?
Thanks for any advice ...
Best
Alex
E28+, Maine.

[tkeithlu]

Without getting too deeply into it, it sounds like you've got a 140 F thermostat when a 165 F would be better. The thermostat should control the steady state temperature with the available water flow fully open.

[GordMay]

Greetings and welcome aboard the CF, Alex.

Evidently, the Seawater Cooled engine uses a 7 PSI CAP.

UNIVERSAL DIESEL MODEL 15 & 25 (EARLY MODELS 5411 & 5421)
Service Manual ➥ https://www.westerbeke.com/technical...hnical_man.pdf
Parts Manual ➥ https://www.westerbeke.com/parts%20m...parts_list.pdf

See page 31: Thermostat Assembly, Part #299624

[JimsCAL]

I had a 5411 jn my previous boat which I owned for 20 years. Yes the 140F thermostat is correct. This is a raw water cooled engine and a higher temp would greatly increased scaling in the cooling passages if in salt water. DO NOT install a 165F or higher temp thermostat unless you convert to fresh water cooling (actually not a bad idea).

Sounds like you understand how the 5411 cooling water recirculation system works. I would get some water vapor (not really steam!) in the spring when the water was cold. As long as the engine is not overheating and the coolong water temp is at 140F, I would not worry about a bit of water vapor. At low loads, only a small amount of cooling water gets delivered to the exhaust as most is recirculated.

On an unrelated issue, the 5411 has the common Universal issue of having "trailer" connectors which are known for causing electrical problems. If they are still there, think strongly about replacing them.