OMC 3.0 Running Hot

shadowdwpp

Seaman
Joined
Jul 10, 2003
Messages
57
At the end of the season last year when at Idle and also when revving in neutral My temp gauge showed 220-240 until underway after noticing this I brought it in and asked the marina mechanic to take a look he said he would but never did I brought it back this spring to the dealer I bought the boat from. I had them check and replace the thermostat and water pump and told them to flush the cooling system. It is still running hot at idle are there any suggestions I could have them look at to lower the amount of time they spend diagnosing the problem. I told them to check the temp gauge on Monday I'm going to tell them to make sure the sending unit works ok. It seems to be taking a long time they've had the boat since 5/13 I'm hoping to at least get it on the water before July 4th I've already lost the whole spring season.
 

Cliff24

Cadet
Joined
Apr 28, 2004
Messages
6
Re: OMC 3.0 Running Hot

Looks like we are in the same boat (no pun intended) My problem was just the opposite from yours. it would run fine at idle but overheat when running down the lake. I found this site and thought there may be someone who could help, but I got little response. Ended up taking it to the shop and thats where it still sits today! so don't expect to much help here unless your one of the boys!! Good Luck!
 

Bayrider

Petty Officer 2nd Class
Joined
Apr 4, 2004
Messages
113
Re: OMC 3.0 Running Hot

Hi shadowdwpp.My guess is the out drive impeller is near shoot.When at idle it is struggling to push enough water to the engine water pump.When under way the water is getting forced into the impeller making it easier to push the water to the engine.Hope this helps.Oh! and by the way,cliff24 I don,t think there is a boys club on this site.All the guys do their very best to help everyone who post.There are no favourites here.
 

rattana

Chief Petty Officer
Joined
Jun 12, 2003
Messages
413
Re: OMC 3.0 Running Hot

Shadow do you have closed cooling with a heat exchanger, or do you have a raw water system?
 

shadowdwpp

Seaman
Joined
Jul 10, 2003
Messages
57
Re: OMC 3.0 Running Hot

I should have been more specific<br />it's a 1991 OMC 3.0 with cobra outdrive using raw water cooling.
 

rattana

Chief Petty Officer
Joined
Jun 12, 2003
Messages
413
Re: OMC 3.0 Running Hot

Can you pull the raw water line that goes to your manifold to see if there is any flow at idle? It should shoot up about 4" to 5" out of the hose. Any less and you have a restriction or worn out impellor.
 

mitchcole

Cadet
Joined
Jun 15, 2004
Messages
6
Re: OMC 3.0 Running Hot

Overheating problems in order of liklihood:<br /><br />1. Raw water impeller (this is super easy on the Cobra drive)<br /><br />2. Exhaust manifold corrosion. The manifolds can corrode internally and the corrosion can flake off and block the water flow into the exhaust. This is the only way to get the water out of the engine - so it can prevent cool water from coming in.<br /><br />3. Thermostat: unlikely - but possible<br /><br />4. Water pump on engine - usually these just fail and leak water into the bilge.
 

Cliff24

Cadet
Joined
Apr 28, 2004
Messages
6
Re: OMC 3.0 Running Hot

Wow! Look at the replies! good info I would guess...wish you guys would of helped me out!
 

shadowdwpp

Seaman
Joined
Jul 10, 2003
Messages
57
Re: OMC 3.0 Running Hot

It turned out to be rubber seals<br /> part #12 <br /><br />one of them was split down 95% of it's length so I needed to be underway to pull water in also the raw water pump was replaced and blades of the impeller were found in the system. it took them 6 hours to find the rubber seal at $68 an hour the other points I had allready told them to check on I gave them a list (at the bottom)<br />consisting of things that were actually problems and things that I read on here as being problems for them to check on. It took them 2 hours to do everything on the list but it took them 7 hours to find the seals I told them to let me know about any cost over $300 before doing it. the last time I checked it was $375 total and that was adding in a guestimated additional hour to install the water pump that was on order. Thier service manager was on vacation when he got back and I found out about the seals I also found the price jumped to $873 at this point they were to recieve the parts on Friday the boat still isn't done the've had it 6 weeks at this point. They told me about 3 weeks into it that if they ran into a problem they couldn't handle they would reccomend I take to another dealer that specializes in OMC repairs I think they got to that point because they apparently charged for 2 hours phone consulations with that dealer as well.<br />they only called me once during the 6 weeks that's when I found their estimated price of $375 <br />I figured worse case scenario would be under $500<br />I'm dissapointed with the lack of communication and definitly feel I shouldn't have to pay for all 7 hours of troubleshooting since it' wasn't authorized. If it did fix the problem they should get paid but I don't think I should have to pay for what seems like training apparently it took 1/2 hour to put it all back together. So 7 hours seems excessive especially since 2 of it was phone time talking to another dealer 20 miles away. That dealer isn't in the phone book but now that I know about them I'll go there from now on.<br /><br />************************************************<br />Temp runs very hot (as high as 220 at the end of the season) at idle speed cooling doesn’t engage unless shifted in gear at least ¼ throttle.<br /><br />Check the thermostat<br />New impeller or possibly water pump Make sure there are no missing blades from existing impeller.<br />Drain antifreeze from winterizing. Flush hoses with fresh water verify they are clean.<br />New Battery Cables<br />Check alternator<br />Check starter<br />Check Starter Solenoid.<br />Check tach gauge it seems to show higher rpm’s than recommended settings. <br />Check Temp gauge.<br />Check Blower<br />Check Bilge Pump <br />Check Spark plugs, distributor cap for carbon<br />Check the risers and manifold <br /><br />Trailer <br />check hubs and bearings add grease where necessary.<br />Install bearing buddies
 
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