Cooling problems 2.3l OMC

[Keyboardman]

Hi guys, My 2.3l OMC runs fine and the temp gauge is mid range when idling the boat on muffs. Put it in the water today and after about 15 mins or so I noticed the temp was slowly climbing. It got just up to almost the red (no actual temp reading) and I shut her down. I have installed a new impeller, I checked the t stat in a pot of hot water before installing it on the new engine and the water pump looked fine also. The water hose coming from the outdrive to the engine is cool and the one that goes to the intake manifold is just warm. The exhaust manifold is cool but the engine block seems pretty warm to the touch! Should I try to flush the engine block somehow? I'm not even sure exactly how cooling system works on this engine. Advice? Thanks

 

[Bondo]

I have installed a new impeller,

Ayuh,..... Was the old impeller still all there, intact,..??

If any fins were missin', ya gotta find 'em,.....

 

[Keyboardman]

Yes, the old impeller was all there and in great shape. I flushed the line with a garden hose from where the hose attaches to the t stat housing. It ran clear. Maybe first try a new T stat? This one is I don't know how old but, it did open up in a pan of hot water.

 

[Bondo]

This one is I don't know how old but, it did open up in a pan of hot water.

Ayuh,.... Then that probably ain't it,.....

I don't do OMCs, so I'm shootin' from the hip here,......
Water has to be pumped into the motor, through the system, 'n then be able to get out,......

I'd start by figurin' out the flow pattern of yer system, 'n start pullin' hoses to see where the water is flowin',......
Or ain't flowin',.....

Were there any, Any scorin' or overly polished areas in the raw water pump body,..??
It don't take much, 'n air screws up the pump,.....

 

[Lou C]

Bondo's got a good point the wear plate in the impeller housing, if it gets scored, will cause a good impeller to not pump enough. Was the engine overheating before you changed the impeller?
The OMC Cobra impeller is very easy to change but, that o-ring seal that goes in the housing, can shift out of place when you install it. The impeller will then suck air when the boat's up on plane. To check: remove the plastic cover at the rear of the upper gear housing that covers the impeller housing. Hook up your muffs and water hose, and start the engine. There should be no water leaking out around the impeller housing, if water leaks out, then air can be sucked in. When I do the impeller I like to use a thick grease like OMC triple guard grease (now sold as Evinrude Triple Guard) that will keep that Oring in place when you install it.

Other causes: worn, or partially melted water tube grommets in the lower unit, rusted water tube, both of these require pulling the drive and splitting the upper and lower to fix.

 

[Keyboardman]

This is the first time I've had it in the water at the dock. I replaced the engine and have only run it on the muffs and it's never gotten hot . I replaced the wear plate along with the impeller but, will pull the cover and do the checks on the o ring. Thanks, will let all know what I find.

 

[Scott Danforth]

on the muffs, the hose is forcing water into the system. at the dock, you are relying solely on the impeller drawing up water and pushing it.

 

[Keyboardman]

I think I've identified the problem. The face of the adapter plate that the gasket and wear plate mate to is corroded really bad. I didn't pay much attention to it when I replaced the impeller awhile back. I'm sure that water was going behind the gasket and not sending all it should up to the engine. Line from engine to impeller is clear as well as the intake. Will I need a special puller to get this old one off?

 

[Lou C]

There is a guy on you tube who posted up how to do this, Michael
Romer….he has a lot of youtube vids on OMC repairs.

 

[Keyboardman]

I found the Video online on how to pull the adapter. Pretty sure that this has to be the problem. Nothing else seems to be wrong. Wish me luck with the procedure, I'll post as I go along. Waiting for the parts now. Thanks

 

[Keyboardman]

Got the old adapter out. After screwing 5/16"x 1/2" set screws in the threads in the case I tapped the housing bolt holes. The old one didn't have enough material left in the housing bolt holes to get a 3/8" thread to hold. I ended up tapping one of the adapter bolt holes and that got a good bite but on the bottom one I had to go up to 7/16". I turned the bolts incrementally and it pushed right out.