OMC stringer 400 impeller replacement

[jdman]

How hard is this to replace? i have done a couple of outboards but never sterndrive. thanks, jdman

 

[Boatist]

Re: OMC stringer 400 impeller replacement

Jdman<br />I done outboards also and have the manual for the 400 serries 140 HP 1980 but have not tried this one. Reading thru the manual could never figure how to do the shift cables.<br />Is your pump having problems or are you doing it just because someone reccomended it. I had my 1980 done twice and both times ask for the old parts. When checked the old parts saw no problem with water pump impeller at all. The casting it rides in did have some pitting. Each time I did it was because had other work done in area and was not that much more to do water pump. <br />Good luck.

 

[jdman]

Re: OMC stringer 400 impeller replacement

boatist, thanks for the reply. My water pump is not really giving any trouble, but i have noticed lately that the temp. wants to ease up when cruising. i can slow down momentarily and it will go back down. just increases slowly. i have owned the boat for 3 years and haven't replace it. don't know if previous owner ever replaced it. Thought it would be good preventitive maintenance. I have the original owners manual, and it has a digram of the lower unit but not very detailed. Looks like the water pump is in a different location than a typical outboard. Guess i need to get a shop manual. Thanks again for the reply, Jdman

 

[Boatist]

Re: OMC stringer 400 impeller replacement

Jdman<br />Yes water pump is just below upper gear box. After you pull outdrive must remove the upper gear box then can get to water pump bolts on bottom of upper gear box.<br />The problem you decribed sounds more like a exhaust manifold to me. When they start to go bad get lots of rust and scale plugging up holes between Exhaust manifold and Riser. Motor will run at normal tempature at idel and slow speed but as go faster tempature will rise.<br /><br />Before I pulled unit and did impeller I would do a couple of tests. The first one is easy. Find the hose coming from the outdrive on the starboard side to the thermostat houseing. Pull this hose off engine and put in a bucket or over the side. With outdrive in water not on muffs start engine up and see if you get a good flow of water. If you do then impeller is not the problem. Only reason not to run on muff is want to make sure impeller is pumping water not just water from hose pressure.<br />Next you can pull the riser and check holes in manifold and riser and see if they are plugged up, or you can pull hose coming from Thermostat to exhaust manifold (front port side) and attached another hose to run over the side run motor and see if it cools down fast. Be careful here as this water is hot. Also while hose is off have no cooling for exhaust manifold. If you would like to run longer could put in a T so could hook up exhaust manifold normal and a hose over the side with a valve or way to stop flow. Go out and run your engine until temp starts to rise then open up hose over the side and see if it cools down fast. I bet it will but again be careful as water here is hot.<br /><br />If thermostat is stuck closed will also over heat, also engine water pump must turn and circulate water but I bet it is the manifold.<br /><br />If you do decide to change water pump impeller I would check closely the shaft that drives the water pump. This shaft that drives the water pump also drives lower unit and has a high failure rate. When it goes bad water pump and lower unit do not turn.<br />Good Luck and be sure and let us know what you find.