Engine temps running high

One source of raw water restriction you won't see unless you haul out, is marine growth covering the raw water intakes.
 
quote:
Originally posted by Gregory S

One source of raw water restriction you won't see unless you haul out, is marine growth covering the raw water intakes.

Click to expand...


....and inside the intakes and then, pipe up to the seacock and plumbing from seacock to sea strainers, especially if it includes 90* elbows as I found out this spring.

Besides the ones inside the scoop strainer( fortunately I had switched to the Groco type with hinged access doors) I found the main culprit for rise in gauge temp, riser top temp and steaming exhaust was 3 semi-large barnacles which had attached to and grown in/on the 90* bronze elbow before the basket sea strainer , and the barnacles were catching sea weed. Never saw them but could feel and cleaned them out with long flat screw driver and heavy flexible wire. For both engines.
Afterward , temps back at or below t-stat spec., risers cool to the touch , an 0 steam. Happy day!

Water flow had looked good the whole time but was insufficient at elevated RPM before cleanout.
 
I haven't had a chance to use the boat since posting but have since added antifreeze which was very low and water into the batteries. I've started the engines and let them run
at my dock. They showed no signs of overheating so I'm hoping this was the answer. Hope to go out on Sunday.
Thank you all for your excellent advice.
 
You'll know when you put a load on the engines with cruise RPMs. Sounds like your boat has been sitting idle n salt water for three weeks. If the problem is raw water restriction, it could be worse now.
 
I had my mechanic out. He removed golf ball sized chunk of weed from fuel coolers on both motors. See if that is my issue.
Plan to cl an out both motors over winter and add grocco strainers. Volvo D4 motor has a poor design with a strainer after impeller and the basket has larger holes
 
Finally had a chance to run the boat and the temps were fine under load ( 34rpm ) for about 2min but then began to slowly creep up. When backing off they dropped back to normal. This tells me she needs new water pumps as this happened many years ago when I first bought her. Cha
Ching!
 
Can we assume that you can achieve full rated rpm on both engines as a very brief test?
Have the engines been tuned/timed in the last few years?

I guess it could be water pumps - but it does not make sense to me given that these engines/pumps have only seen maybe 100 hrs in 5 years.
Maybe impellers if they have not been replaced in the past 2 years but not typically water pumps.
Things like exhaust elbows, heat exhangers and hoses (especially suction hose) tends to cause problems with low use over many years.
 
That doesn't necessarily mean your engine needs a new water pump, though it ...might... need a new impeller.
If the housing was scored, the engine would tend to overheat at very LOW rpm because the impeller tips would not be able to create enough suction. At higher rpm the impeller tips don't even touch the housing so housing scoring makes no difference.

How hot were the aft tops of riser/elbows when you checked them with your palm? If too warm , besides a possible impeller problem , you could have a restriction anywhere on the RW side or a suction air leak.

Your engine won't run at 34 rpm. ;)
 
agree Sandy, what he describes doesn't sound like a weak pump or impeller. I'd expect those problems to be worse at low RPMs and improve with higher rpms. Sounds like raw water restriction to me. Dirty heat exchanger, oil cooler?
 
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