Ongoing OMC Problem

[cts122]

I have a '76 Grady White with a OMC 165 I/O. We have been struggling with this engine for about 4 years now. It continually overheats with after running for about 15 minutes. The lastest Rx for the engine is an air blockage in the vent to gas tack. If anybody has had trouble like this in a similar engine and remedied it please let me know.

 

[Walt T]

Re: Ongoing OMC Problem

You have a blockage in the engine somewhere. You may have to pull the engine and clear the passages. I assume you've been the route of manifold, riser, tstats, impeller, sea pump, etc.

 

[Boatist]

Re: Ongoing OMC Problem

OldSalt<br />I agree with walt. From your name sounds like you use it in salt water. My first guess is Exhaust manifold plugged where it goes into riser. They only last 4 to 6 years in salt water before water starts getting in engine thru the exhaust manifold. Pull the riser where it bolts to exhaust manifold and see if it is not all stopped up. If it is you can clean it out and it will not overheat but all the metal means manifold ready to fail and water to leak back into the engine thru exhaust valve. I assume you have check the thermostat and water circulaton pump on engine.<br />Here is a couple of thing you can do to isolate problem. If your engine is like mine it has a hose coming from the outdrive up to the front of the engine near the thermostate. (Starboard side) This is input cooling sea water. First check the water pump indicator where it sprays out on the outdrive. Next pull the hose to front of engine and run into a bucket or overboard and make sure you have good flow at idle. If low flow then it is water pump impeller time in outdrive. <br />On my engine it then has a short hose from thermostate to front of exhaust manifold. This hose is the output from the engine and also excess water from the outdrive. If engine is hot this water can be very hot so be carefull but with engine hot hook a hose to the thermostat output and run over board. Start engine and if motor cools down then your problem is blockage in the exhaust manifold or riser. You can only run it this way for a short time as have no cooling to the exhaust manifold.<br />Hope this helps and good luck. Also please come back and tell us what you find.

 

[Waterbugtoo]

Re: Ongoing OMC Problem

In addition, it could also have a CRACKED manifold. Cracked internally allowing exhaust to enter the cooling system, thus running way hot.<br /><br />

 

[hondon]

Re: Ongoing OMC Problem

When is the last time the water pump in the sterndrive was changed? Yes you have one, and no, it is'nt a fun job.