JRSto

HI again! JIM here!!! I just read and responded to your post re: your holes in your stainless props. Then I read this "Problem". Sounds to me like solving this wiring problem my may also have something to do with the electrolysis situation. Good Luck JIM Vero Beach, Fl, USA

I have a 302CR twin 5.7 DP engines and at the time of my last hual out for bottom and porp paint (the boat is 3 years old) I ran into the exact same situation with my props (all 4 of them). the pictures I took look the same as yours. I consulted two prop rebuilders, neither recommended repair because of the speed they run at and the proxmity to the second prop. I found a couple articles on marine corrosion which helped me locate electrolisis situations that most likely caused "my" prop holes. The articles could possible indicate electrolisis areas of concern for you. http://www.boatus.com/boattech/marinecorrosion.htm http://www.westmarine.com/webapp/wcs/store...ing-Systems.htm also www.Volvopentastore.com has a corrosion protection system you may find useful. part # 41101900 Hope this helps. JIM Vero Beach, Fl, USA

I drive a 2006 302CR (twin 5.7 DP Volvos) and I have experienced that problem many times in the past couple years. Try disconnecting the wire from the sending unit on the riser elbow. If the alarm stops sounding and your temperatures are normal ... you may want to change out the sensor. I carry a spare all the time for that very problem.

here's what I have found... the props most certainly have undergone some extensive galvanic corrosion and installing Volvo QL system in addition to the system Monterey installs, may OVER protect the lower units which will create other problems. I need to determine where the stray current is comming from and treat it accordingly. An excellent article can be found at... http://www.boatus.com/boattech/MarineCorrosion.htm An excerpt.. "Corrosion Protection Testing and Troubleshooting For diagnostic tests, a simple digital volt/ohm meter (multimeter) is necessary. An analog version may be used, but it must be a high-impedance model. Even the most inexpensive digital volt/ohm meter has high impedance. One of the most helpful methods for determining if corrosion below the waterline is occurring is through the measurement of the hull potential. This is done by immersing a reference electrode, usually silver/silver chloride (a silver wire with a coating of silver chloride) into the water about six inches behind the drive. This electrode is connected to the positive terminal of a digital volt/ohm meter. The negative lead from the meter is attached to the battery ground. With the meter on a two-volt DC scale, the hull potential is displayed. When performing tests, be sure to make sure your battery is fully charged. Also, new boats will usually produce higher readings than normal. This is because the drive unit is being protected by a new finish and new sacrifical anodes. To obtain an accurate diagnosis, the test should be performed after the boat has been used at least one or two weeks. All boats should be moored for at least eight hours before performing the test. This is necessary in order to allow the cathode system and sacrificial anodes to polarize the water molecules in direct contact with the drive. Be careful not to rock the boat excessively while boarding to perform the test, as this will alter the reading."

I have a 2004 Monterey 302 with stock Volvo Penta DP outdrives. I keep the boat moored in salt water and have been keeping the bottom and drive units painted and a coating called "Prop Speed" on the props. Here's my challange..when the props were removed this last week for recoating they were found to have extensive apparent galvanic corrosion inside the hub beyond repair. Is this "normal"? Will the "Volvo QL Active Corrosion Protection System" PN # 41101900 eliminate the problem? Help, Please, $760 for each props gets old quick.