Omc cobra 4.3 running hot

[Trackertrucker]

Took the boat out last weekend and she was running hotter than normal. Got up around 200 and I shut her down, she is only used in fresh water and is stored in the water as well. The week before I got into a shallow channel and I think I sucked some muck up. I'm taking a stab at an impeller kit change but was wondering if there is a way to flush the PS cooler out to be sure I don't have anything stuck in there. Lou C do you have any pointers on this? Thanks

 

[Bondo]

Ayuh,..... Disconnect the water line from the drive, at the t-stat housin', 'n back-flush from there,.....

 

[Trackertrucker]

Ok cool, I'm planning to flush it while I have the impeller housing off so hopefully I'll flush some crap out if there's anything in it. Thank you Bondo

 

[Trackertrucker]

Ok so I took everything apart yesterday evening, went to flush everything and I pushed out a big glob of grandma hair. So apparently I had sucked that up due to one of my intake screens being broken out. Impeller was in good shape. Reassembled with new parts, put her in the water today and she runs cool as a cucumber now. Thanks for all the help, Bondo have you ever changed the intake screens on a Cobra?

 

[Bondo]

Nope,.... I've never even touched a cobra,.....

 

[Lou C]

It is exactly the same as any other similar size Evinrude or Johnson outboard lower unit. You have to split the upper and lower drive housings, remove the water passage cover and it just pulls out with a needle nose pliers. I actually had to remove mine for good because my boat is moored in salt water and no matter what I did with painting it with anti fouling, I had marine growth that would cause gradual increase in running temps. I had barnacles growing on that screen and up into the water intake passage.
So at one point I just decided to remove it and have not had trouble with stuff getting sucked in really and even if I did I'd have to fab up an external screen of some kind that was easily removeable. Some aftermarket lower units for the Cobra actually came that way (external screens) and they were also used on later model Evinrude/Johnson OBs.
Sometimes it can be tough to get the upper and lower gear housings to separate but I have a trick for that one too...

 

[Lou C]

https://www.crowleymarine.com/johnson-evinrude/parts/55307.cfm?mdl=PBMYAP

the screen is part # 5 in the diagram, you remove part # 58 to get at it....I'd replace gasket # 63 while you're at it and make sure the water tube grommets part # 75 are in good shape.

 

[Scott Danforth]

FWIW......the holes in the screen are larger than the inside of the tubes in the PS cooler.

so no mater what, crap will get stuck in the PS cooler.

 

[Trackertrucker]

Thanks for the replies, appreciate the advice greatly

 

[Lou C]

In the future if you want to back flush it from the t stat housing, just remove the impeller housing on the upper gear housing and flush away. Then you can flush the other way with the muffs on the lower unit water intakes. All the years I had the Cobra, I never had a blockage in the P/S cooler, it has always been crap growing on that water screen. BTW, Merc Alphas and Bravos don't have screens but they have smaller water intake holes and more of them. The Cobra had the screen and 4 much larger holes. I don't think the Volvo SX had screens either, but more holes (6 vs 4) and they were smaller.

 

[Scott Danforth]

either way lou, the .2" diameter holes in the PS cooler are smaller than the .25 or.31" diameter holes in the pickup rock strainer