Raw water pump is not pumping any water

[mbaud]

I've melted 2 impellers (and the housing) on my OMC outdrive while taking a couple spins around the lake. It never overheated last year, and after backflushing and checking all hoses for flow, I've run out of ideas. I can hook up the muffs when the lower unit is in the water and everything's good, but for some reason I seem to be sucking air when I take them off - the pump just won't prime. Are there other seals in these units that need to be replaced? I'd appreciate any advice the experts on the forum can give me - I'm about ready to take it in.

 

[mbaud]

Sorry, it's a Cobra (non SX) with a 15 spline prop shaft matched to a 5.0L

 

[HT32BSX115]

Sorry, it's a Cobra (non SX) with a 15 spline prop shaft matched to a 5.0L

Howdy,

Welcome aboard!

"Cobra(Non SX)" covers a LOT of models from 1986 the mid 90's Can you be a tad more specific? (like actual model number?)

 

[Lou C]

If the o ring seal on the impeller housing does not seal perfectly it can suck air; and that little nipple must be open to allow air out of the housing. Try this: remove the cover on the rear of the upper gear unit and disconnect the little hose at the nipple. Then hook up the water muffs and run it. There should be no water leaking from around the housing and there should be a strong stream of water from the nipple. You should see a lot of water coming out under the transom mount.
Also did you replace the wearplate
?If you still have trouble it could be an obstruction in the lower unit water passages or in the ps cooler (broken off impeller blades).

 

[mbaud]

Thanks for the replys, I'll get the serial number off the lower unit and post back what I find.  I did replace the wear plate, and the housing seems pretty well sealed up - there is a stream of water coming out of the nipple when the muffs are on.  The boat came with a rubber hull plug in the 'dummy screw' hole, so we took that out to test flow - with the lower unit up, I can stick a garden hose up to it, and water will come out the intake, and visa versa, with the muffs on, clean water comes out that hole - the lower unit does not appear to have a blockage.

 

[mbaud]

Found this while reading thru a ton of 'overheating' threads - "hook up the hose and watch to make sure water doesn't leak out from around the anode on the front of the case if it does your drive isn't together right like mine and you need to split it and get the water uptake tube to connect and seal properly."
I have this, muffs on, engine off, water coming out by the anode. I'm guessing that is not normal.

 

[mbaud]

I'm hoping someone can reply back on whether water should be coming out by the anode on the front of the drive case when the muffs are hooked up, engine is not running. Thanks

Model #987348

Serial #70766902

OMC DRIVE SYSTEMS OUTBOARD MARINE CROP WAUKEGAN IL

ENGINE 5.0.

 

[HT32BSX115]

I'm hoping someone can reply back on whether water should be coming out by the anode on the front of the drive case when the muffs are hooked up, engine is not running. Thanks

Model #987348

Serial #70766902

OMC DRIVE SYSTEMS OUTBOARD MARINE CROP WAUKEGAN IL

ENGINE 5.0.

By model number, I mean a number like the following.

502AMLPWS 1990
502APRPWS 1990
502BPRPWS 1990

If you have a Dog-Clutch Cobra, your problem sounds like the following one. There's a picture in there too. You must separate the lower from the upper to fix this problem.

http://forums.iboats.com/forum/engi...4-3-over-heating-new-impeller-still-overheats

Regards,


Rick

 

[Lou C]

No there should not be water coming out of the area above the anode....
It could be those water transfer grommets inside the drive, or.....

Could be been a cracked water transfer nipple in the transom mount.