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496 mag ho low sea water psi

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kdjohn1

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"I have a 2005 496 mag ho givi

"I have a 2005 496 mag ho giving me fits. Installed a new sea water pump assembly due to low pressure.
PSI went from .9 max to 2.4 max. Heat Exchanger plugged up; punch out and clean; no improvement in PSI. Remove stern drive assembly, no obstructions found, replace o-rings,etc. and reinstall stern drive assembly; no improvement. Engine will operate within normal temp range at idle but alarm sounds and eventually goes into guardian mode seconds later when accelerating and arriving onto plane at about 3200 to 3400 rpm. what next?"
 
"Belt driven sea water pump, r

"Belt driven sea water pump, right?
Sounds like you have a restriction in your sea water pickup, strainer, or plumbing.
If that all checks out, try disconnecting and diverting your raw cooling water supply hose from your sea water pump at the exchanger inlet, and pump into a bucket for 15 seconds at 1000 rpm. You should get about 7 GPM flowrate. The bucket should fill in about 15 seconds. If not, you have insufficient volume for some reason.
If it's a half system, are your manifolds/risers plugged off?
Do your risers run mildly hot to the hand? They should not be blistering hot.
Maybe your circulating pump is shot?
Have you changed your T'stat?

Rod"
 
"PROPER!
I SPOKE WITH MERCNET

"PROPER!
I SPOKE WITH MERCNET TECH TODAY(AN *******, BY THE WAY)CONFIRMED THAT RESTRICTION IS BETWEEN PICK-UP AND SEA WATER PUMP.(IF RESTRICTION IS AFTER PUMP, THEN PSI WOULD BE HIGH, NOT LOW.)
WILL REMOVE STERN DRIVE UNIT TOMORROW AND RECHECK FOR RESTRICTION."
 
"removed stern drive,no restri

"removed stern drive,no restriction seen from outside. when intake hose is removed from inside transom and elbow removed from transom unit, salt build up has caused black hose to collapse around and crush the plastic insert inside the hose where it enters the engine compartment at the transom.
merc net tech is consulted as to the easiest way to replace the hose and insert. he says engine must be removed, but he's going to send me a new transom unit under warranty and pay 11 hours labor. sweet."
 
"customer has been advised to

"customer has been advised to regularly flush sea water circuit with fresh water after salt water use and proper winterization. i really need a marine tech. anyone out there interested in working in sunny south LA(Louisiana, that is)"
 
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