Westerbeke 8kv diesel generator overheating-gctid815245

[Smitty]

My boat 1986 model 3870

The generator has run close to the upper end of the green zone since I have owned it....nine years

Now it is slowly creeping into overheat, so I shut it down.

Anti freeze changed end of last season.....just checked the impeller and it is fine.

So, does that only leave the heat exchanger and thermostat?

Should I remove the heat exchanger and take it to a radiator shop?

What other issues whould cause overheating?

Advice welcomed...

[smitty477]

- Are you getting sufficient water out the exhaust?

if not stop right here and look for collapsed hoses, blockages, poor water pump cam etc.

- Are you getting any black smoke out the exhaust under load?

- Have you adjusted the coolant water pump drive belt?

If you have a slipping belt the heat will rise, if you have black smoke you may have a restricted exhaust and that will cause overheat, if your valves are well out of adjustment or your injectors dribble that will add heat.

Have you had the exhaust elbow right after the water injection cleaned or replaced lately? How many hours on the genset?

[Smitty]

Thank you so much S477

Hard for me to know how much exhaust water is enough?

Yes, dark exhaust smoke now

Water Pump V belt is fine.

Have never had timing or injectors checked

So, the exhaust elbow is the small elbow off the collant tank? Large hose goes to muffler and small hose also enters the elbow...also a wire plugged in.....no, have never had that off

Lots of hours....no hour meter...low oil pressure

[Uncle_Bob]

It is really simple to remove the heat exchanger and look through the holes at the sun and see how plugged they are. 25% will raise the temperature. Rad shop will clean it. Total time to remove and replace isn't much more than an hour.

[mmichellich]

Did you purge it of air after anti freeze change.

[mmichellich]

Is the exhaust water hot or just warm a bit which is normal.

[mmichellich]

Check amt of exhaust water. Is it less than normal?

Check strainer and thru hull.

Check belt for slippage.

Replace impeller.

[smitty477]

Thank you so much S477

"Hard for me to know how much exhaust water is enough?"

This is hard o describe but with the stock waterlift muffler you should have a 'whoosh" of outlet water every 2-3 seconds or less.(not 5 seconds)

"Yes, dark exhaust smoke now"

Dark and black with the occasional black soot on top of the water at startup?

"Water Pump V belt is fine."

Great

"Have never had timing or injectors checked"

OK - not likely the problem unless the overheat comes on very slowly and only at higher loads. Could be contributory.

"So, the exhaust elbow is the small elbow off the collant tank? Large hose goes to muffler and small hose also enters the elbow...also a wire plugged in.....no, have never had that off"

Does it run OK for a few minutes or more? Does it then creep up in temps mostly when you are adding loads? Did the problem come on over a longer period of time?

"Lots of hours....no hour meter...low oil pressure"

You still want to look at the water flow and the intercooler tunes being partially blocked but these exhaust elbows load up with carbon soot over time and at about 1,000 or so will be pretty well blocked right after the mixing water goes in. You may also find a whole lot of corrosion in the elbow right after the carbon area which leads to failure of the elbow. If/when you pull the elbow look closely as the carbon almost looks like part of the elbow but the exhaust passageway will be greatly reduced - like in half. The exhaust restriction can cause much higher back pressure, unburnt and latent ignition and a bunch of extra heat in the engine.

[rogerkarenorth]

My exhaust elbow was almost completely plugged from corrosion; might check your elbow.

[Smitty]

So...this morning,I removed the heat exchanger...it doesn't look too bad actually, but I will take it to a radiator shop for cleaning.

Also removed the exhaust elbow, I can get my finger in the smaller inlet...doesn't seem plugged but will have a closer look tomorrow.

Nothing really obvious so far

[Smitty]

What is the normal temps that your Westerbeke's operate at?

[RDH3818]

Attached files

[The_Other_Gary]

That is exactly where mine runs and I have a brand new heat exchanger, rebuilt water pump and new belts.

It seems to be very happy at that temp.

[smitty477]

Yes- that gage look just like all of the ones I have had (3 @ 12.5K and 1 @ 8K).

But they should not have this.....

"Yes, dark exhaust smoke now"

[mmichellich]

"Smitty" post=815398 wrote:
So...this morning,I removed the heat exchanger...it doesn't look too bad actually, but I will take it to a radiator shop for cleaning.

Also removed the exhaust elbow, I can get my finger in the smaller inlet...doesn't seem plugged but will have a closer look tomorrow.

Nothing really obvious so far

Look where the exhaust flows through the elbow. Do you see any carbon build up blocking the exhaust? Have you checked the strainer and impeller?