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-   -   Overheating Perkins 4-108 (http://www.sailnet.com/forums/gear-maintenance/18374-overheating-perkins-4-108-a.html)

Eleanna 07-19-2006 11:24 PM

Overheating Perkins 4-108
 
Engine is newly rebuilt but is overheating, the mecanic was going crazy because he couldn't find anything wrong with the engine. I ended up taking the boat out of the marina ($70.00/hr)....
Q. would a bad prop cause overheating?
Reason for asking is when i increase the rpm the rudder shakes, i went under the boat to see but i'm such a lousy diver so i didn't have enough time to really see the prop.

I'm thankful for any responses.

E.

triangle32 07-19-2006 11:32 PM

overheating perkins 4108
 
My perkins also overheats if i run it too hard, if i push the throttle to full the rpm's stop at 1500 when in gear eventually overheating...from what i've been told it is definately the prop...I'll let you know how it works out after I change it...that of course after I find a new oil cooler..it is way to corroded and spewed oil all over my engine room and bilge ***gross*** if you know where I can get a new oil cooler. it is attatched to my heat exchanger/expansion tank and seems pretty tough to find...it is a marinised perkins 4108 so any direction here would be greatly appreciated.

thanks,

ted
s/v cybele
halifax NS

Eleanna 07-19-2006 11:40 PM

if you only get 1500 rpm something is wrong the 4-108 should atleast go up to 23-2400 rpm. I know a place here in ft. lauderdale that specializing in perkins. I will get back to you with more info.

DynaMeme 07-20-2006 08:36 AM

I can't speak to the vibration, But there is something you need to check re overheating. I owned a 1980 Perkins 4-108 from 1996 to 2004. Carbon deposits built up where the water injects into the exhaust elbow. At low rpm and on short jaunts, no problem. Higher rpm and longer running periods, problem. The effect is subtle enough it is very hard to detect by watching the waterflow ejected from the exhaust. If the engine was old enough to rebuild you may have replaced this elbow. If not, take a look. Also make sure you don't have hoses that are delaminating or collapsing from the inside out.

camaraderie 07-20-2006 10:40 AM

Triangle...Try this link for a Perkins compatible oil cooler...they are great folks.
http://www.tadiesels.com/oil-coolers.html

Eleanna...sounds like same symptoms I get when I pick up a crab trap! Suggest you check your cutlass bearing for binding/wear as this could be responsible for the vibration and engine problems.
I assume you HAVE checked that you have good water flow in out of your exhaust AND that this water flow increases as you increase the throttle RPM's. If the flow does not increase then you could have the problem DynaMeme describes OR you could have a restricted flow somewhere in your water INTAKE line/filter/through hull. I would check this before hauling the boat to check cutlass bearing and prop.

Eleanna 07-20-2006 05:55 PM

well I did have somebody go under the boat and the prop is in good condition. Now the bearing that camarederie mentioned, I assume its the bearing that sits between the prop and hull? its infact not sitting up against the hull. its just sitting halfway to the prop. And I do have steady fast drop from the prop axle. The water flow increase as the rpm increase.
DynaMeme might be right about the carbon buildup its definitely worth taking a look, also replace some of the hoses sounds like a good start aswell.

Thanks for your reply's.
E.

eaudela 07-20-2006 07:33 PM

Quote:

Originally Posted by Eleanna
Engine is newly rebuilt but is overheating, the mecanic was going crazy because he couldn't find anything wrong with the engine. I ended up taking the boat out of the marina ($70.00/hr)....
Q. would a bad prop cause overheating?
Reason for asking is when i increase the rpm the rudder shakes, i went under the boat to see but i'm such a lousy diver so i didn't have enough time to really see the prop.

I'm thankful for any responses.

E.

Eleana...I had heating problem too. If you have a water heater on bord,
each time you add water to the engine you have to fill the hose at the water tank with water because the new heather tank have a valve , if there is air in the hose the valve won t open and the engine is overeathing. You will have you install a bypass valve to let the water go back to the engine.
the temperature in tank is 142 F. a lot less than the engine EAUDELA

Eleanna 07-20-2006 07:41 PM

Hmm, the water heater isn't even hooked up to the engines cooling system. Could that be it?
Thanks
E

cman2crew 07-20-2006 07:49 PM

engine overheat
 
Have you looked at the prop shaft and engine alignment.
Possibility that they are not aligned?
Also possibility of prop bent or not set properly.
Ray

Eleanna 07-20-2006 10:02 PM

The engine-shaft is properly aligned, prop is not bent or mis aligned.
I even had it cleaned from growth today.
E.


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