Re: omc king cobra over heat after water impeller install
hi new to the forum, i have a 93 donzi 22 classic had a 454, i replaced with a built 502, king cobra drive, very low hours on the boat and drive 345, engine has 40, i decided to check the water impeller was running great just me being curious, well the impeller was stiff and had some rough edges so i replaced it anyway reused old oring and used silicone gasket maker to hold oring in place now engine runs cool on the muffs but will slowly over heat in the lake, any ideas as to what this could be i have headers so no manifold issues, thanks in advance.
Howdy,
Welcome aboard!
Overheating issues are most frequently the impeller.
Since you've replaced it and you still have over-heat problems, you've started a process that you'll need to finish.
(those are about $100 a "pop" aren't they? I just found a source of them on ebay that has "more than 10 of them" )
That will include verifying that you have good flow from the raw water supply through the PS and Oil coolers and on through to the T-stat housing.
I had a similar problem with a clogged (with previous impeller failure fragments/debris) that was more or less OK at low power settings but the flow was inadequate at higher power.....
My oil cooler was COMPLETELY PLUGGED with impeller fragments that would NOT dislodge by running water backwards though it! It did however, pass *some* water......just not enough!!
It's all about FLOW. if you cannot get enough flow of cooling water the engine will heat up. Other problems can be clogged riser/manifolds (which prevent the water from exiting =low flow)
Since it's ok on "muffs", (pressurized water supply) you might also have a "leak" that's allowing air into the system. remove the hose from the transom mount that goes to the PS/oil coolers then on to the t-stat housing. install a length of clear hose so you can see if there's any bubbles that will indicate a leak someplace in the raw water pump suction side.
You can also check to see if you have good flow by briefly running the engine with the hose disconnected and dumping water overboard. It should squirt out pretty good even at idle.
Since you have a "new" engine, you could rule out a clogged water jacket (unless you ran it into a sand bar recently)
You probably already know you need to "baby" that drive. Many show stopper parts for them no longer exist.
Cheers,
Rick
