94 OMC 90hp Turbojet cooling ?

I have an issue right now where my Boston Whaler Rage heats up. I can put the boat on a hose in the drive way and it seems to be fine. A stream of water shoots from the back of the boat, very little water is coming from the exhaust ports. Is water ever mixed with the exhaust or does it just circulate around the muffler then exit the port on the back of the jet drive? When I put it in the water here in FL, the alarm goes off within about 5 min and water will boil off of the muffler. I have removed the thermostats completly and that has not changed anything. I tried to remove the screw to view the pressure relief spring and ball in the jet pump housing, but it is seized. Any thoughts? Is the exhaust supposed to be "wet" or is the dry exhaust expected??

As always, thanks for the help!

Exhaust is wet !---------Motor must idle at at least 1200 RPM ( floating in water ) in order to get water pressure from the jet pump for cooling.-------Be very careful running one of those on the hose adapter.-----------------------It could be a problem with water deflectors ( guides ) that direct cooling water in the block.---------Post the results of a compression test as well.--------Blown head gaskets can have an affect on cooling too.

I didnt realize that there were water defectors. Can you give me an idea as to where these are located and how to check them. I have a parts diagram, if you have a part number, I can look it up and that will give me a better idea as to what to check. Thanks for the help!!

You'll have to remove the cyl heads to look at them. Make sure they are not swelled up and blocking any water passages. They are in the block and part # is 322411

Ok thanks. On other question, at what point does water enter the exhaust on this thing? For the life of me I cannot find it. To me it looks like the water just circles the muffler then exits the muffler via a 1/2 hole in the transom.

Anybody? Back on the hose again today. Flush from the transom plate back with no issues. Flush transom plate forward and no issues but only a drip from the exhaust. A stream of water from the hole above the jet pump thought. Any ideas as to where water actually enters the exhaust? I believe this is where my problem lies. Thanks

Maybe , maybe I will have a look at the adapter housings of my 115 HP Turbo Jet later this week and see how it all works, just for you.

It would be greatly appreciated!!

Looked at the waterflow diagram of the block and compared the parts diagrams of outboard and turbo jet housings.---Water enters the exhaust flow from the thermostat / poppit valve housing just below the block.------Will still look at the muffle and adapter housing on shop floor later.

Thanks so much for checking!! That helps me narrow down where I should look.

Be very , very careful running this machine on a hose !!-----------Read your manuals.

Fixed it!! Want to post follow up for any others that may be troubleshooting this issue. At the top of the cyls are water lines that run to a "T" adapter then it runs to the top of the muffler. The "T" is plastic and looked fine from the outside. I disconnected all the lines and that revealed that the tips of the plastic had gotten so hot at some point that it melted inwards and completely cut off any water flowing thru them. As soon as I replaced, water began flowing out of the exhaust and not just the hole thru the transom. Boat now runs cool and no alarms!!!! Thanks for everyone's help! -Scott.

n36511 said:

Fixed it!! Want to post follow up for any others that may be troubleshooting this issue. At the top of the cyls are water lines that run to a "T" adapter then it runs to the top of the muffler. The "T" is plastic and looked fine from the outside. I disconnected all the lines and that revealed that the tips of the plastic had gotten so hot at some point that it melted inwards and completely cut off any water flowing thru them. As soon as I replaced, water began flowing out of the exhaust and not just the hole thru the transom. Boat now runs cool and no alarms!!!! Thanks for everyone's help! -Scott.

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Trying to trace down an overheat on this same engine. I have good flow through everything except through the exhaust out this 1/2" hole you mention. It's completely blocked. Flow through the valve covers and jackets is fine, but nothing will go through the exhausts middle cooling section and out the hole. Question on your is does it always come out that hole or is there some pressure regulator on route?