OMC 3.0 Overheating Problem! Need Advice.

[gking]

OMC 3.0 Liter Cobra in a Four Winns Boat.<br />I bought the boat this summer and sat for 2 years.<br />Boat overheated and I brought the temp. down slowly. I replaced a chewed up impeller. Tested it out again and it ran hot again. When I travel slow it runs at 178 to 180. When I put a load or put some speed on it it quickly raises to 200 or more degrees in minutes. I have to slow it down to a crawl to cool it back down again tp 180. I am not sure what the problem is. I think I have restriction in the coolant system. I am wondering if anyone has ever had parts of an old impellar cause problems somewhere else in the cooling system. I have a restriction of some type. Another boat was on the lake and I was able to compare. At no wake speed... I was 180 and same boat and model was 156 degrees. <br /><br />A new problem also has occured. Beside the manifold and engine. A hairline area has water bubbiling out of it now. I first thought it was oil but it is water. This area is very tiny pin holes of water bubbling out. Only in certain spots. This area is like a seam between engine and manifold. Is this an area that is a weld or gasket? Do I have a bad manifold now? Engine runs great. I thought about tightening manifold down to see if it was loose or something. But I think I need to check manifold by elbow to see if something is restricting water in their so it will not carry heat out.<br /><br />Any advice, I would greatly appreciate it!<br /><br />I have a cooling problem and now this pin hole bubbling along the seam between engine and manfold. <br /><br />Is it time to go the shop? I am not sure I can fix this one myself. <br /><br />I have read forums, I do not think water is in the oil. Oil looks ok. Engine is running great but I do not want to lose the engine over this. <br /><br />I think I might be at a critical point. What is the story on manifolds and how do you know they are bad. I read that if they can crack inside and water goes to the gaseous side and that water might be bubling out in that area?<br /><br />I want to save money but doing it myself might lead to ruining the engine if I do not take care of this one right. <br /><br />Greg

 

[gking]

Re: OMC 3.0 Overheating Problem! Need Advice.

Well, <br /><br />I have pulled the manifold off. It looks like there is no cracks. I am getting some water throught the manifold when I put a garden hose. It does not however appear to let all the water out of the elbow evenly. I still have not detached it. It is coming out in front more than back side of elbow. What is the best way to clean this out?<br /><br />What other places may I have an obstruction?

 

[gking]

Re: OMC 3.0 Overheating Problem! Need Advice.

Well,<br /><br />I pulled elbow and manifold etc. Water flow good. <br /><br />I found bits and pieces of old impellar lodged up before the thermostat housing. I do not feel I have wasted my time with this because I still need to replace valve cover gasket and manifold gasket. It was worth the piece of mind to know that the water is circulating now.<br /><br />Anyone else with experience with this problem. First time for me. I have always had outboards. This is all new to me.<br /><br />Greg

 

[piedmarin]

Re: OMC 3.0 Overheating Problem! Need Advice.

need help also. We have same kind of trouble, but it occur only when we stop and lift the propeller out of the water. <br /><br />It's like if the cooling system had been drained, and there is no water coming in. 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 is behind all this.

 

[Walter]

Re: OMC 3.0 Overheating Problem! Need Advice.

Piedmarin...<br /><br />Post your topic on a separate thread. Include all the necessary information (year, make, model, etc.) and describe the problem. That'll avoid a lot of confusion when folks try to supply answers to the both of you on the same thread.<br /><br />Walt

 

[rocksingerca]

Re: OMC 3.0 Overheating Problem! Need Advice.

I had the same trouble. Mine was a lot of rust in the heads. The engine was never winterized properly and the heads were pluged. When I ran slowly it was warm but would burn up when I tryed to run up on plane. Last fall I blew a piston and when I took the heads off the head was cracked.So it was a combination of water going into the #8 piston and the lack of flow.

 

[kdmiller8251]

Re: OMC 3.0 Overheating Problem! Need Advice.

I just got done (I THINK) with the same sort of problems...<br /><br />1. I replaced Impeller<br />2. I replaced Manifolds.<br />3. I replaced Waterpump<br />4. I replaced Thermostat<br /><br />After Completing all the above repairs I finally got it to cool down the right way (SO FAR)<br /><br />Did you see any gummed up passages or anything ing the boat cooling areas like where the thermostat goes or the manifolds??? Mine was terrible.. its amazing that it even cooled it.<br /><br />is this a saltwater boat?<br />Also check the lower unit for obstructions or build up in any of the passages there<br /><br />Tallman

 

[P.V.]

Re: OMC 3.0 Overheating Problem! Need Advice.

Check out my reply to the basic question to a 3.o Cobra cooling -problem om Aug. 5th.

 

[gking]

Re: OMC 3.0 Overheating Problem! Need Advice.

Update on problem for any of those that might have this problem of overheating. I replaced impellar, thermastat. Make sure that you get out the rubber parts that may have been sucked up all the way to the thermostat housing. I found that the rubber was sucking up through the hose that leads to the thermostat housing and building a rubber bits and pieces dam that would keep the water from flowing through thermostat housing. Once I removed the bits and pieces no problem. No more overheating!!!