How to verify no engine damage from broken water pump

[Geek_Guy]

Morning,

I had a mechanic change the water pump">raw water pump on my Yanmar 3HM35F.

Turned out that the unit was not properly put together and somewhere along my 16 hour trip it stopped working. Is there a way to verify that the engine was not harmed?

The engine starts normally and sounds OK. I've replaced the pump. But am a little nervous that there may have been internal damage.

Thanks in advance.

[Calif.Ted]

How hot and for how long was it overheated ? I suppose you could do a compression test but if it starts and runs normally probably not needed. I had an impellor fail once and asked my mechanic about possible damage. When I told him the gauge showed 210 for about 15 minutes until I could shut down he implied you'd need to peg the gauge for longer to damage a diesel.

[Terra Nova]

Originally Posted by Geek_Guy

...raw water pump...was not properly put together and somewhere along my 16 hour trip it stopped working...

What do you mean "not properly put together" and don't you have a temperature gauge or over-temp alarm?

[a64pilot]

Usually the first thing to go in an overheating is the head gasket.
Monitor your oil and see if it starts to look milky, you can also watch your coolant to see if the overflow tank, overflows and possibly starts bubbling, both signs of a head gasket leak.
However as I assume your overheat alarm didn’t sound, I doubt there is a problem, but if you really lost all raw water, which I doubt, your exhaust system needs inspecting as the hose and muffler could easily have been overheated.
Usually losing raw water flow causes such a different exhaust sound, that you know something is wrong

[Geek_Guy]

Guys,

Thanks for the replies and thoughts.

It was an odd combination of happenings.


Apparently the bulb burned out for the hot water idiot light, and the buzzer was turned off. Further the last of the trip was in a pounding rain and wind storm.

I noticed the bulb was burned out after getting to our destination. It was working the morning when we left.

The pump was installed without the washer or spacer that is supposed to be behind the pulley. It worked fine till it rubbed off the straight sides. Then it just started spinning. However I don't know when that happened.

But thanks a64, that was what I was asking for.

[Jammer]

a64pilot correctly points out that leakage across the head gasket is usually the first sign of damage from overheating.



It is not unusual for there to be latent problems from overheating that only show up after a period of operation. I would suggest paying close attention and exercising caution for the next 25 hours or so of operation.



Other failures are possible and may manifest themselves as a reduced engine life rather than an out-and-out failure. I disassembled an engine once that had a hole in one piston because of local overheating. Coolant flow between the cylinder walls and the head was blocked by the use of the incorrect head gasket, which I believe was the root cause. I disassembled another engine (in a car) that finally failed 40,000 miles after being run without oil for several miles.

[a64pilot]

If you lost all water flow, check your exhaust closely, it’s usually fiberglass or plastic and rubber, none of which handle Diesel exhaust temps very well, if it’s not burnt completely up, then I think you had some water flow.

[JOHNMARDALL]

I'm sorry to hear about your problem. To emphasize what others have said, if your engine ran for more than about fifteen seconds with no raw water flow, the exhaust system is damaged. Even if you can't see anything obvious, the hoses will be burnt on the inside, reducing their flexibility, leading to cracking, and the waterlock and other exhaust system components will probably have pinholes, at a minimum. Don't take a chance on having exhaust leaks suffocate a crew member or guest who is asleep down below.


Sorry to be the bearer of bad news.

John Mardall
Vetus Maxwell Boat Equipment

[ski69sail]

Hi There

You may want to get your engine oil tested. It will show up any damage in the form of lead and iron filings etc. There is an initial test .Then do a oil/filter change and have a follow up oil test after a recommended number of running hours.

[Dove1955]

Good advice already given. Any kind of overheating would have created obvious damage already. Cast iron engine blocks and heads are pretty tough. Overheating damage occurs more on blocks or heads made out of aluminum.
If the engine sounds good, no water in the oil you are probably fine.