Help..no water getting thru outdrive (not the impeller)

don't know how to make this short, i'll try without leaving out important information.

Bought a boat with out the upper section of the outdrive. last owner siezed it up, low on fluid(?)
1988 FourWinns with 4.3 V6 connected to an OMC Cobra sterndrive

Bought a used upper half of the outdrive, bolted it to my lower, added fluid, etc bolted it up to the boat.
Fired right up and went in and out of gear nicely. Engine got hot right away on the ear-muffs/hose.
First thought was theremostat since impeller was new.
Upon looking at the thermostat housing (after removing it) I saw that cooling water would run to both exhaust manifolds all the time (before t-stat even opened or was stuck). The manifolds were so hot I couldn't touch em so I figured that water wasn't coming up to the engine at all. I tried to blow down and backwards thru the hose that fed fresh cooling water up to the t-stat housing and could not blow thru it (even with the impeller and its housing off).
Figured I must have a blockage somewhere in the hose, in the power steering cooler or in the outdrive.
I removed the outdrive again and now I could freely blow thru the cooling hose from both the t-stat end of the hose and from the transom thru the gimble housing area where water would enter from the outdrive.
Must be the outdrive, right?

With the outdrive proped upand leaning forward a bit, I poured water in to the area where it meets the gimbal housing to go towards the engine. The water remained there. Didn't seep or leak thru the upper half of the outdrive to the impeller area. Put a rag over hole and used compressed air to try to blow thru the outdrive, no luck.
Seems water cant get thru from impeller area thru the oudrive to get to the intake area in the gimbal housing area. Am I making sense? I know i might be using some wrong terms here.

When I look in the hole where water should come from (after being pushed by the impeller), it looks like a blind hole! No where for water to come thru the outdrive.

help! Lost and not boating

pics for reference as I'm not sure how to say what I mean.
screwdriver is in hole where water would go from outdrive to the engine (thru the gimbal housing?)
If I pour water in there it should flow right thru to the area on the opposite (back) side of the upper gear housing where the impeller would be.
Looking in that hole, it goes no where!
help!


is it possible that I got a gearcase(upper section of outdrive) that is not compatible with the rest of my boat/lower outdrive/gimbal system?
it bolted up perfect to both the lower unit and the gimbal housing.
seemed like a perfect match

Maybe i am crazy but i never saw a cobra painted white.

That lower is not from a stringer unit.

Water tube between the drive halfs in place?You can see that from the front of the drive(flashlight).
Remove the drive and put a hose in the transom side water inlet,start it and see if it cools that way.
Cools that way then the drive is the problem.
Remove the cover off the pump and see if the shaft is turning.
Make sure the impellers center isin't stripped and it's turning.

Just making sure:You fill it from the side?Or the bottom?
It needs to be filled from the side.From the bottom and it will leave it about a 1/2 quart low and burn up the upper.J

not a stringer for sure. no idea why it is painted light grey, fourwinns color maybe

thanks Jerry, ya, can see water tube in place. picture this.. with impeller and impeller housing off, if I pour water down the right side hole (where water would be pulled up by the impeller) it drains out from the water pick up area near the bottom of the lower unit like it should.

but..
if I pour water in the left side hole where the impeller would push the water thru the upper gearcasetowards the engine it just sits there. does not go thru the gearcase. seems blocked with no way thru the gearcase housing.also, looking from front of upper outdrive (where the hole is that lines up with the tube that goes thru the transom) it appears to be a blind hole. no passage for the water to come from the impeller side. How is this possible?

does anyone have a Cobra outdrive off a boat that they can look in this area to see what it looks like?

here is a pic looking into the "d" shaped hole where the water should come from the impeller and into the transom area. I've been calling around and no one has ever heard of a cobra outdrive (upper, gearcase section) that does NOT have a port (or water passage) thru this section. All I keep hearing is that it is there, it was in the casting. Has to be there. only way for water to get to the engine. Poke around with wire, it is blocked. use compressed air and blow it out, etc etc.

I have probed with a long pick, blown it out with my air compressor, filled it with water (it goes nowhere).
There simply does not appear to be a passage for water to flow thru the upper half. Looking in (from transom side) with a bright flashlight I can see the infamous "mystery screw" that is not supposed to be removed and then past it to the dead end of the casting. There should be a hole somewhere here for water to come thru.

Has anyone ever heard of this or seen it?

I'm thinking this upper gearcase will never work for me.
I tried to get a pic looking in with the flashlight on..

been on the phone with techs who say that there has to be a passage for the water to go thru.
there simply is not, on this one.

One person thought this could have been a remote possibility.. when the upper outdrive was cast (brand new) the sand didn't touch together where it should (providing the water passage) and it has been bad since day one. Maybe dealer that sold it on a boat originally replaced it after the boat overheated and it was scrapped.l possibly it has been passed off from one owner to the next over the years and never been good.
seems unlikely to me but remotly possible I guess.

how about this for an option.. drill a hole in the side (back a little further from the cobra logo) and then drill a relief hole for the water to come into the passage where it belongs. This would require a patch on the outside of the case of course or water would simply exit there instead. Seems extreem to me.

anyone have an upper half of a 4.3 V6 Cobra outdrive to sell?

looks like I need one

Take the water pump housing and backing plate off the drive and see if there's anything in there like Bigfoot or some crud. Items 11-13-50-9-12-49:

Don't take out 42-47 as that is the rear oil seal for the shaft.

It could be that the short water hose from the gimbal to the transom plate rigid tube is blown.
Item number 37 in this pic:


Unfortunately no fun to replace if that's the problem.

thanks o2batsea

i know this sounds crazy but there is absolutly no passage from the back to the front of the upper outdrive for water to go thru.

If you look from the transom side of the upper and see tha "d" shaped hole where the water comes from (pushed thru the upper by the impeller) and look in there.. there is no opening. It is a blind (dead end) hole. There is the screw that can be gotten at from outside on the side of the upper drive if you remove the round cobra logo and the plug behind it. That is all that is in there. I have scraped and scratched, poked and prodded in there but there simply is no hole to let water thru. I have been warned..do not remove that screw in there, so I haven't

I have even put a rag over the hole with my air gun from air compressor and nothing comes out the backside where the impeller would be. Poured water in and it sits there. doesn't flow thru to the impeller area.

With the flashlight I can see the entire area in there, nothing but aluminum walls to see. no hole.

sounds impossible but this is what I'm dealing with.

Did they make an OMC Cobra drive for thru-hull water inlet only? Some boats do pull water directly thru a hole in the bottom of the hull...would they have a special upper drive for this with the drive inlet blocked?

nope they did not

I don't have anything to add about the upper passage, but I can add some info about the lower there- that is a GLM aftermarket lower unit. note short and long idle relief slots instead of 6 holes of Cobra. Don't know if that is useful or not, if they did anything different with the water supply etc.

The plug on the side has NO parts #s
It can be removed just don't loose the backing part.
You try to remove the pump mount.#44 and 45 in the first pic?
It looks like it's got a lot of corrosion in there.

Hi Davelobi.
Was this the solution that you describe the end?
I have exactly the same problem as you describe and I try to provide enough info before I start screwing

The raw water inlet is probably full of shells.
Little microorganisms can travel thru the screen and make a beautiful residence in he casting as the urn into big shells.
This will make you think waterump impeller or water pump need replacing. Hook up to hose and let it run an flush passage.