OMC 3.0 Overheating

To All, I'm just a newbie here, tried to search first before posting but could not find anything related to my problem. Bought a boat 3 weeks ago everything was fine the first time we took it out and when it was dock at the marina but 2 days ago we decided to go fishing and after a half hour the boat starts to overheat, light smoke fumes coming out of the vent and the temp shoots to over 225 so we decided to turn it off and cool it down, tried it again after an hour and and it did overheat again and decided to towed it back to the marina. Tried to figure out the water pump on this 4 cyl looks like ford motor, I thought it might be behind the belt pulley next to the alternator but somebody told me it's not there, since we bought this boat used and not the original owner now we are confused and lost and don't have a mannual, somedbody also told me that it might be by the drive assembly since it has an outboard drive, anybody know exactly where the water pump is and what to look for, I disconnected the 5/8" diameter hose the blows air to it and it's not clogged, removed also the thermostat but still overheating, I would like to inspet the water pump but not sure it's location, any help is greatly appreiated.
BTW the motor say's OMC cobra 3.0, 4 cylinder, looks like ford engine. and it is a 1989 bayliner 2145 sunbridge, thanks again

Re: OMC 3.0 Overheating

On my Cobra outdrive, there was a plastic cover at the top of the outdrive held on by a few bolts. Behind that cover was my impeller. I'm assuming yours is the same, but I'm not versed on years/models. That impeller would be circulating water into the motor. You should check to be sure it's in good shape. it's easy to get to, so worth taking a look.

Re: OMC 3.0 Overheating

Thanks for your quick reply, do we need to take the boat out of the water or can we service it while it's dock at the marina

Old Yeller Boater said:

On my Cobra outdrive, there was a plastic cover at the top of the outdrive held on by a few bolts. Behind that cover was my impeller. I'm assuming yours is the same, but I'm not versed on years/models. That impeller would be circulating water into the motor. You should check to be sure it's in good shape. it's easy to get to, so worth taking a look.

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Re: OMC 3.0 Overheating

The drive has to be up out of the water, either by a lift or on the trailer.

Re: OMC 3.0 Overheating

We finally got the impeller out of the shaft, the bolt are easy to find and was able to remove it without any special tools. Now we will figure out the impeller rotation if it's clockwise or counter clockwise, because the instruction says to starts like 90 degrees from the left when to install the cover back, correct me if I'am wrong that means the rotation is clockwise looking at the impeller, any info is greatly appreciated.

Re: OMC 3.0 Overheating

you could take the coil wire off the engine, watch the impeller shaft, and crank the starter. That will tell you which way it is rotating. I changed mine, but I took note of which way the inpeller blades were bent.

Re: OMC 3.0 Overheating

We finally replaced a defective rubber impeller and start up the engine, the problem still overheats without the thermostat with the engine idling, we haven't try running it yet above idling speed.
I have one more question because the engine temp still goes above normal and I don't see any water coming out of the hose while disconnected from the thermostat manifold and the mannual doesn't say the water flow direction, can anybody enlighten me what the role of the rubber impeller, if its supply water to the engine or pull the water away from the engine. Also, is there another pump besides this impeller,a any help is greatly appreciated.
BTW we checked the hose and it's not clogged, just confused if there should be water flowing during idling or what the idling speed should be at.

Re: OMC 3.0 Overheating

you should have water flowing all the time. The impeller pulls water from the outdrive, and supplies it to the engine. The engine mounted pump then circulates the water through the engine to cool it. If your transom to engine hose is not plugged, and you have a new impeller, I would check for plugs between the impeller housing and the water intake in the outdrive. Then make sure everything is sealed properly so you are not sucking air.

Re: OMC 3.0 Overheating

wcasey5, thanks for your reply, so breaking the rubber hose from the thermostat manifold I should be seeing a water coming out of the hose if the engine is running, very interesting, this is my first time owning a boat..We did not check the impeller housing for plugs but when I blows air from the rubber hose we saw the air coming out of the housing, I guess we should disconnect the hose from the transom (new word). BTW when we put it bak together we did not put any gasket sealant on that housing, instead we used a grease, the boat is still in the water. Also any idea what that little hose by the impeller housing is for, trying to learm as much as I can from the forum because the mannual doesn't say much about troubleshooting, thanks again and will post what we found.

Re: OMC 3.0 Overheating

Sounds like you still have a restriction somewhere. Could be below the rubber impeller in the drive. Also sometimes pieces of the old impeller break off and restrict water flow, even though you can still blow through. You could have a badly worn impeller housing. Another reason for overheating, probably not your problem since you are not getting water, sometimes the flapper valve in the back side of the exhaust riser breaks off and drops down and blocks the exhaust passage. Mine did.

Re: OMC 3.0 Overheating

You can go to bestboat parts.com, click on OMC, put in your E-mail and then find your mod # and then you can get a good exploded vue of your drive along with part numbers. I have had no luck ordering parts from this site. Many others have had the same problem.
Just good to see how it comes apart.

Re: OMC 3.0 Overheating

Thanks for the info, I'll visited that websites and they have a very good drawings but haven't found the right one yet, probably need to give the right info so I can find our cooling system drawings. Yesterday we decided to disconnect the hose from the gimbal but very little water coming out from that connection while it's idling and not enough presure to push the water to the top of the manifold so we dicded to blow the line with pressurized air and we saw some rubber parts from the impeller came out of the port, hopefully we cleanered all the parts from the housing and will put it back once we replaced the gasket and the housing rubber o-ring.

Lodgepole said:

You can go to bestboat parts.com, click on OMC, put in your E-mail and then find your mod # and then you can get a good exploded vue of your drive along with part numbers. I have had no luck ordering parts from this site. Many others have had the same problem.
Just good to see how it comes apart.

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