(GOT IT!!!) Help, no cooling water getting to engine, blockage? Not impeller.

88 4.3 chevy OMC Cobra outdrive.
Getting hot.
Had outdrive off for several weeks as last owner locked up the upper half solid being low on gear lube.
Installed used outdrive, impeller, fluid, etc. Fired right up with muffs on.
Got hot quickly, exhaust manifolds quite hot. Thought stuck t-stat. Pulled housing and it looks to me that cooling water can bypass a not yet open (or stuck) t-stat and still cool the exhaust manifolds. Right?

Cooling line that comes up to engine from outdrive seems to be blocked. I can't blow air thru it even with the impeller and housing off. Clamped garden hose to top end of fresh-in water hose to try to backflush it. Still blocked.

Read a ton of postings here but couldn't locate this exact issue. Heard mention of power steering cooling, could blockage be there? How do I get to it? Mighty tight down there with v6 vs an inline 4.

Thinking I'll have to remove outdrive again to try to find blockage from that end. It's heavy.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

I think I found the issue/blockage!
I pulled the outdrive off again. Now I can blow freely thru the hose that feeds cooling water to the t-stat housing and also in the other direction from the water inlet at the gimble. Eliminated obstructionsi in all the hoses and thru the power steering cooler as well.

Blockage has to be in the upper half of my outdrive.

When I look in to the outdrive from the gimbal side where the water would come from (after the impeller) , it looks like a blind hole. No where for water to come from. I poured water in and it sat there, didn't dribble thru to where I had removed the impeller and housing. Blind hole. Upon closer look with flashlight, I see a large screw with washer and rubber grommet going in to the side of the outdrive down in this pocket. It can be accessed if I pop of the welsh (sp) plug on the outside if the upper outdrive that used to be covered with a cobra logo.

Why would this plug be in there?
Is it the problem? It has to be.
I got this upper outdrive used so I don't know the history.
Previous owner pull cooling water into his boat engine some other way and blocked this off?
I suspect I'll destroy that plug on the outside of the outdrive when I attempt to remove it. Are they easily gotten and easy to install? Drill a hole in it and pry it out?

Wanted to add a pic of this but to much of a rookie to figure out how to post a pic

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

bet im too late but do not mess with that screw behind the cobra logo. theres nothing but a hole behind it and a square nut that holds the screw to cover that hole. and its a ***** to get back in place. and will have to take the drive off to get it back proper. and if o rings etc get messed up may not be able to get new. i got lucky and found new old stock parts last year. but theyre no new ones made.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Randy J said:

bet im too late but do not mess with that screw behind the cobra logo. theres nothing but a hole behind it and a square nut that holds the screw to cover that hole. and its a ***** to get back in place. and will have to take the drive off to get it back proper. and if o rings etc get messed up may not be able to get new. i got lucky and found new old stock parts last year. but theyre no new ones made.

Click to expand...

Thanks Randy! Not to late, still messing around on my phone (quasi computer).

If that isn't it, then how does water get through the upper outdrive from impeller area thru to the gimble area? Not quite sure how to describe this in my rookie (non-technical) terms.
Am I showing you where I mean? With outdrive removed from boat there is what looks like a plastic (pvc?) pipe on the boat side in the gimble housing. This feeds cooling water to the engine that came from the outdrive, right? With the impeller housing off, if I pour water down one of the holes (behind impeller) it runs out down near the bottom of the lower unit where the fresh water intake screens are. Good that direction. If I pour water in the other side, it should come out where the outdrive meets the gimble housing to provide cooling water to the engine. None comes out. Even with a rag to cover the rest if the hole and compressed air, there is no flow thru the upper part of the outdrive.

What is going on. Has this upper been sabatoged?

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

View attachment 111067
View attachment 111068
I hope the pics work now.
screwdriver in hole where water should flow from outdrive to the engine (thru the gimbal housing?)
Looking in with a flashlight, there is no where for water to come from. Looks like a dead end in there.
Is it possible I have a non-compatible gear housing for my boat?
Lower unit bolted up perfect. Upper half bolted up to boat perfect as well.
How, where does the water get thru the upper half from the impeller side to the gimbal side?
Am I missing something simple (done that before)

also, is it possible that this upper half of the outdrive (gearcase?) that I bought is not the correct one for my engine/gimbal housing/lower unit ?
lower lined up perfect and bolted up nice.
installed on the backl of the boaqt perfect also.

why doesnt water go thru from impeller area towards engine?

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

can't believe it, I think I solved the blind hole mystery.

From the bottom of the gearcase (lower removed and looking at bottom inside of upper gearcase) there is 5 bolts holding a plate over the water jacket. removed that and saw an expandable rubber freeze plug in the hole to my cooling passage that was blocked that didn't let water thru the gearcase. I had to remove the welsh plug from the port side of the gearcase to back out the screw in the freeze plug to remove it. now I magically have water passage from the pressure side of the impeller towards the transom.

I was afraid to mess with that screw because of all the warnings about "don't touch that screw on the side of the gearcase". I hope removing the plug was the right thing. I think (someone please verify) that the screw not to mess with is on the starboard side of the gearcase. both of these are hidden with the cobra logo sticker.

going to throw it back together now and see what happens. Local carQuest had a welsh plug for 63 cents when the marina failed to come up with a part number for such a thing and had no part available.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

0307450 0 ring omc
0912314 plug-gear
0314491 0 ring
0912315 washer
0911848 cobra medallion

these are orignal omc part #'s total $24.18

ps i dont have orignal screw #. or the rectangler nut. As i didnt need that. but im sure can be found.. get at a omc dealer

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Randy J said:

0307450 0 ring omc
0912314 plug-gear
0314491 0 ring
0912315 washer
0911848 cobra medallion

these are orignal omc part #'s total $24.18

ps i dont have orignal screw #. or the rectangler nut. As i didnt need that. but im sure can be found.. get at a omc dealer

Click to expand...

Thanks Randy, bu I think those numbers are all for the starboard side of the gearcase. port side gets plug and medallion and thats it.
Marina and online , couldnt find a part number anywhere to fill the hole that I plugged with a welsh plug (1 1/8 inch).
Been running in the driveway now for 15 minutes, staying right at 160 degrees.

Headed to the lake now!

Re: Help, no cooling water getting to engine, blockage? Not impeller.

Re: Help, no cooling water getting to engine, blockage? Not impeller.

yep left side