OMC 305 OVERHEATING AT IDLE & HIGH RPM

[rodbolt]

Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM

hello<br /> remove and check the sea water pump housing. they are prone to warp. do a leak down test. if you supect a cracked head then plug off the saewater in line and place the two water lines for seawater out in a bucket of water. when you apply air look for bubbles. if the boat has power steering or remote oil cooling take both hoses off the coolers. if it has power steering it has a cooler<br /> if the cooler is clogged with debris it will over heat.<br /> good luck slow down and take a systemqaatic approach.

 

[tyvicire]

Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM

thanks guys. I am going to try to check it with a clear hose here soon. The one thing about this problem that seems the strangest is when it overheats. I could go crank it up now and run it for an hour and it will stay cold. Out of the last 10 times that I ran it with muffs its overheated twice. One of those times I couldnt get it to cool with any change in rpm's. Then in the water, it will usually run fine for a while (1 hour or so)at about 160 degrees then all of a sudden high or low rpms will run too hot but comforatable at about 3000 rpms (175 degrees).

 

[rodbolt]

Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM

hello<br /> well I have had many problems with some of the cobra units. would work fine for half a day and hit a swell and the seawater pump would lose its prime. I have seen many stange problems with them. that is why once I know its not engine mechanical I convert it to crank driven jabsco. on the ford engines to use the some of the pumps you have to machine a brass ring to center the pump flange to the crank hub.<br /> good luck and keep posting

 

[navigator336]

Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM

Tyvicire,<br /><br />Post number 11 (one of yours) is interesting. I've never owned an I/O so I am not familiar with much of the inner-workings. I don't know what is meant by the, "idle exhaust relief". Your most recent post is also very interesting. You describe this as an intermittent problem occurring sometimes and sometimes not even given the same set of conditions (load, speed, ear muffs, lake,etc.). Based on this, I personally doubt it's a cracked head. It seems you've got something or several things floating around in your cooling system that occassionally block flow. Maybe others can elaborate on the "idle exhaust relief" thing. Diesel Walt, in post # 12, if I understood correctly, said that at idle most of the discharged water should be coming out near the anodes as you described. Under what conditions should large volumns of water be exiting the idle exhaust relief area? My apologies for rambling here a little and not knowning more about the outdrive portion of an I/O, but the intermittent problem and the apparent lack of flow through an area the manual describes as a common exit path seems suspicious to me.

 

[Ryoken]

Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM

just a tidbit to add to the thread, not sure where this guy is at with this.... <br /><br />make sure you check downline after the pump for old impeller blades.. this can cause the symptoms from the first post. they usually like to get stuck in the front of the oil cooler..

 

[tyvicire]

Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM

Hey guys, I decided to bring the boat to the shop. Tired of messing with it. I will keep you updated. Hopefully he will figure it out before it cost me too much. Thanks, Mike Greene

 

[Peter J Fraser]

Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM

OUCH!!, Do I see a white surrender flag here?<br /><br />Regards<br /><br />Peter

 

[tyvicire]

Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM

Unfortunately Yes, If I was a little more mechanically inclined I would probably keep going. Oh Well.