Boring question for teccies

[Renegade_Master]

Going along nicely about 3000 revs, take her up to 3400/3500 for only about 2/3 mins, port engine temperature goes up, have to turn it off for a few of mins. Start up keep to 3000 no probs.

Not using any water, checked before leaving and upon return (45nm), raw water intake filter clean. Ok I had 7 peeps on board well eight wiv fat Dave but what could it be? KAMD43's F36

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[Talbot]

Barnacle bill is making you overpropped?

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[Renegade_Master]

dont think so boat does 800hrs a year out 4-5 days a week, anyway stb engine ok

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[ccscott49]

possibly partially blocked heat exchanger, or anywhere in the raw water side.


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[Renegade_Master]

yes that sounds likely Colin

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[Riggy]

Had simalar overheating prob on my Kad 43 (singular...can only afford the one)few months ago. Like the more knowlegable chaps in the previous replies, can't disagree.....but if not that...possibly (this was my problem) rubber impeller at the front of the lump, that pulls in the raw water? (Mine WAS supposed to have been replaced during a routine full service just before I bought it but a disreputable broker in Portland Dorset never replaced it) Even fairly new ones are known to have weathered/split/perished before expected.

<hr width=100% size=1>Scheme me up Botty..........there's no intelligent life down here!!!!!!!!

 

[studgies]

Also check the water injection elbow, if it is blocked it will restrict the flow through the whole raw water system

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[paulineb]

I agree with Colin /forums/images/icons/laugh.gif

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[Talbot]

Figgured that you would already have looked at water impellor, only other non-water related problem that might raise temp of one engine is possibly a partially blocked injector, thus causing the other cylinders to work harder than designed?

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[Dave_Snelson]

A question of calories...

...and not for fat Dave (and hey, he sounds like me!). The non-linear use of motors means that when you pass a certain speed, you achieve diminishing returns for increasing throttle usage. Up from 3000 to 3400 means a huge increase in calorific output of any engine - maybe twice as much as you are near WOT.

Any defect in cooling will show up - not as a fault of the engine, but as a fault of the cooling system trying, and failing to remove the huge increase in generated heat.

So...as Colin says:- Heat exchanger / Raw water intake / impellor etc. Go through them, and while you are at it, you have 2 motors...do 'em both!

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[ArthurWood]

Clive - agree with others, but would look in this order:
impeller, raw water intake under boat, heat exchanger. As someone else mentioned, do both impellers while you are at it and make a practice of changing them every 100-150 hr.

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[ccscott49]

Have to disagree with the 100-150 hours on the impellors, in my experience, they last considerably longer than that, I change mine yearly, have never had a failure and keep the old ones (if in good nick) for spares, and throw them away every other year.

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[Renegade_Master]

Dave & Arthur thanks for the advise re doing both engines and regularly. Erm she is the school boat and does hundreds of hrs a year and has a full service every 100hrs (both engines)/forums/images/icons/smile.gif which includes checking the impellors.

Inclined to agree with one comment re impellors life span, had some go prematurely on the Gobbi recently, only lasted about 100 hrs. However some can last far more as Colin says.



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[Riggy]

RE; impellers

One other tip if re-newing impellers....don't know about other makes... but on Volvo's...they need to be Volvo parts. Friend recently had overheating on one engine on a Sealine 30-something after just having had a FULL service. Turned out the Company doing the service fitted a non-pattern impeller on one engine and the rubber was too soft. Fitted a Volvo impeller and all was ok. Hope you get it sorted.

<hr width=100% size=1>Oh a drop of Nelson's blood wouldn't do us any harm....

 

[ArthurWood]

Colin - I have the same experience. i.e. never had one go, but I change/inspect then every 100 hr or so. What I do always see however is that they have suffered permanent set in that the 'teeth' remain bent in one direction and don't spring back as when they are new. Even when kept for some time after, the old ones don't recover (sounds like me!).Efficiency must therefore be reduced by this.





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[TrueBlue]

Umm, nobody's seemed to have mentioned - check the raw water filter / strainer?

I assume you salt water boaters have such a thing fitted. I have a girt big one fitted to my ditch crawler, no probs for x years, then all of a sudden thing fills up - and I mean <font color="blue">fills up </font> with composted dead tree bits, amazing that even though strainer now thoroughly constipated big time, that any water gets through.

The result is similar to that described; normal use OK, go for a plane on the Thames, engine gets hot.....

 

[Renegade_Master]

check my post again...