OMC 3.0 cobra overheating

[piedmarin]

This is a 1990 engine in a ponton<br /><br />The engine overheat only after the sterndrive had been out of water (full trim up). This is usually when we stop for lunch. <br /><br />It's like if the cooling system had been drained, and there is no water coming in ( we don't have any water at the hydraulic cooler inlet). <br /><br />Impeller is new because earlier this summer the old one was burnt after we had started the engine and forgot that the propeller was out of water, we clean all the debris in the impeller case.<br /><br />We had unpluged all the cooling hose, try to recharge them with water without really success.<br />We been stuck 4 times and each times the cooling system finnaly start to works after moore than 1 hours both hands in it . But we still don't know what we did good, luck was behind us.<br /><br />Is there any place in the strendrive where debris can cumulate?<br />--------------------------------------------------------------------------------

 

[Walter]

Re: OMC 3.0 cobra overheating

If the only time your engine is overheating is when the outdrive is in the fully raised position....the answer is really quite simple. Don't run your engine with the outdrive in the fully raised position! I'm not trying to be cute, but the truth is...you shouldn't do that! The reason is because it puts the u-joints at a severe angle which causes them to wear very quickly. I can't tell you why your engine overheats in the raised position...but if everything is ok otherwise...I think the solution to your problem is simple.<br /><br />Walt

 

[piedmarin]

Re: OMC 3.0 cobra overheating

Walter,<br /><br />sorry to be misundertood, i'm from the french part of canada, english being my second language.<br /><br />I know the boat should not even be started the outdrive full raised.<br /><br /> This is my stepfather's boat we are talking about, and he bought in may. On is second ride, he forgot to lower the drive before sarting the engine after lunch stop. It let it idling few minute before he tought about the drive been full raised. It was definitively too late for the impeller. Lesson was learned. Need to be towed to the closest marina, to sleep there, to find a impeller on a sunday morning...short long story<br /><br />This is the only time engine had run the drive full raised.The drive had always been raised after engine had been turned off. <br /><br />The boat is in a marina in deep water, no need to raise the drive there. So we don't have any overheating problem when we leave the marina.<br /><br />Like i was trying to said we raise the drive only when we stop on a island or close to the shore,engine not runing, there is a lot of rocks all around this lake.<br /><br />Then, when we go back for the ride, we hand push the boat from the shore, lower the drive and then starting the engine. But every time Coling system it's like if it had been flushed and he doesn't want to take new water. every time we had remove the impeller and blow in the vent hose and tube, also we had try to recharge the system from the water pump hose.<br /><br />So from what i may understand now there is may be still some debris ine the upper gear case or some where else in the sterndrive.<br /><br />But we are very newbie about marine mechanics.<br /><br />There is a way to clean the cooling system or it need or do we need to take the sterndrive apart.<br /><br />Thanks for your help

 

[sea wolf]

Re: OMC 3.0 cobra overheating

check the seal on the water pump housing. it may have come loose or wasen't put back on allowing the pump to suck air. it's behind the plastic cover where the impeller is located. put some gasket sealer on the seal when u replace it.

 

[sea wolf]

Re: OMC 3.0 cobra overheating

check the seal on the water pump housing. it may have come loose or wasen't put back on allowing the pump to suck air. it's behind the plastic cover where the impeller is located. put some gasket sealer on the seal when u replace it.

 

[P.V.]

Re: OMC 3.0 cobra overheating

OK, let'e go over this. You say the impellor was replaced on a Sunday morning??? What was the condition OF the impellor?? If the "vanes" of the impellor (the tips) were gone, did you try to get them out ??? By this I mean , you should have removed the inlet hose at the thermostat housing prior to restarting the motor in water. This is to let the pieces flow out into the bilge (while checking for proper water flow) and not get stuck inside the thermostat housing. But, I believe you should take off the water pump housing again and look for the following. Inside the plastic housing is the stainless liner. This liner is pressed in by hand but secured by the tight fit and a little adhesive called Adhesive "M". Often, the liner can slip (in the direction of impellor rotation) and block off the water inlet ports and also the outlet ports. Commom if the housing has been damaged by lack of water and the resulting heat build-up. If you look for it, you will see it if it's moved or not. The housing and the liner will need to be replaced. OMC makes a rebuild kit but you must purchase the housing seperatly. Also, You will find that OMC came out later with a modified water pump liner and impellor that updates the orginal. It seems the standard impellor pumped too much water and over-cooled the motor so when you purchase the correct pump kit it will look somewhat different than what you may have.