No water flow on port engine

B

Bill Z

New Member
Nov 27, 2004
150
Clifton Park N.Y.
Boat Info
320 Sundancer
Engines
Twin 6.2 Horizons
Went to visit the boat today. I just cleaned all strainers for engines, genset and A/C last Thursday and engine strainers were clear. Start port engine and no water flow ! Starboard was fine. Did I miss something ? Ran the port for a few minutes to see if it would pick up but did not want to heat up so shut it down. Any idea's ? I am running with Mercruiser 6.2 Horizons. V drives.
 
You opened the seacock right? Sometimes you can get an airlock in the lines, find a way to suck seawater past your raw water pump, and start the engine and you should be set. I've used my suction type oil changer to do my a/c pump...

Bill
 
You may have a blocked inlet caused by alge or sea weed at the hull inlet. Pull the strainer again and see if you have flow with the top off it. If no you will need to back flush the line from the hull. I had this happen once and used a water hose to blow the stuff out of the line.
 
Don.

What do you mean if it wasn't a problem before it is now ? The impellers were replaced last year. I did not run after I determined no water flow ? Thanks for the advice !
 
if your sea cock was closed the short run could have toasted your impellers. They don't last if you run them without water cooling and "lubricating" them and burn up to shreds very quickly if run without water flow.
 
Running without water flow for any length of time will destroy the impeller.
 
Does that include running and seeing that there was no water flow and shutting down after a minute or two ? Never left the dock.
 
You need to replace the impeller as everyone stated above if you ran for "a few minutes" dry.

Seawater pumps are self-priming, they can't "airlock". IF the seacock was open (and the strainer was clear as you say), it could only be a clogged scoop strainer or thru-hull. Easy way to check: Close seacock. Loosen clamps and remove hose; have an appropriate size tapered wood plug on hand. Place your hand or a small bucket over the hose nipple- you're hoping for a strong stream of water to come shooting upwards when you open the seacock. Then open the seacock, confirm a small geyser of water should be shooting up...then close the seacock. The tapered plug is for emergency use if for some reason, you can't shut the seacock.

If water isn't shooting out strongly when you open the seacock something is restricting flow- likely growth outside/inside the thru-hull.
 
Bill Z said:
Does that include running and seeing that there was no water flow and shutting down after a minute or two ? Never left the dock.
Click to expand...

Whenever I do any impellors, I always put them together with plenty of vaseline, to get them over the hurtle of running dry until the water gets there......

Billy
 
My two 454s take maybe 30 seconds before they start to discharge water out the exhaust. The time they plugged up with alge I feel I ran them near dry or dry for 10 minutes as it took that long before I got an over heat indication on the gauges and the buzzer went off. After I shut them down and went back to the marina I pulled both impeller form the pumps and they looked fine. No cracks and no burnt areas. I put them back in and backed flushed the lines and all was well. I changed the impellers this year after 450 hours (2 years running). They were cracked but no burnt parts. Will now change them every 200 hours. You may have put the impeller in with the vanes in the wrong direction. I feel I sucked in the alge when I started the boat as I backed up before going forward. I now always put both engine in forward when the boat is still teid up then back up.
 
Well I am thankful for all of the input !

Turns out that that there was an obstruction in the thru hole. Cleared and started and water is flowing well ! Ran her up to 3100 rpm for 15 minutes and no temp problems. It seems that the impellers were not destroyed as expected based on the comments. I will pay close attention to temps to be sure the impeller is functioning !

I really was hopeful that just starting with no water and shutting down in a minute would not destroy them otherwise any dry start would blow them.
 
Bill Z said:
Well I am thankful for all of the input !

Turns out that that there was an obstruction in the thru hole. Cleared and started and water is flowing well ! Ran her up to 3100 rpm for 15 minutes and no temp problems. It seems that the impellers were not destroyed as expected based on the comments. I will pay close attention to temps to be sure the impeller is functioning !

I really was hopeful that just starting with no water and shutting down in a minute would not destroy them otherwise any dry start would blow them.
Click to expand...

I'm glad things worked out. It's a through-hull fitting. You may not be out of the woods. I'm sure there are others like me that seemed to have good water flow, but when replacing impellers, learned that they were torn up and parts were missing. These parts are known to get lodged in critical areas that need water flow.

Not to make you panic, but just to keep you cautious and aware, it may be worth taking a look at them. If you're looking at them, it's time to replace them. The labor is the hard part. If there are parts missing, many people back-flush the hoses starting at the heat exchanger for fresh-water cooled blocks to try to piece the impellers back together to ensure all parts are removed.
 
You must log in or register to reply here.

Forum statistics

Threads
113,219
Messages
1,428,827
Members
61,115
Latest member
Gardnersf
Back
Top