Troubleshooting Overheating

[Hank285]

Hello all. Last weekend my engine overheated. Had a great summer on the water, No problems. When i overheated i shut down right away. I then restarted with no problem and engine cooled down. While returning to my dock running about 2200 RPM to keep temp at 180, i felt the riser elbo's port was cool but starboard hot. The previouse weekend we hit low water. I raised my drive and crept out. Did i ruin my Impeller or clog up my thermostat or something like that. Has this type of overheating happened to any one here and can you give me some direction to troubleshoot or other ideas. Thanks Hank

02, 350 Mag MPI, BIII

 

[bruceb58]

Re: Troubleshooting Overheating

Have you ever replaced your impeller?

Does it normally run that warm? If it does maybe you picked up a plastic bag on the drive and it fell away when you stopped.

How hot was the starboard riser? Too hot to leave your hand on?

 

[Hank285]

Re: Troubleshooting Overheating

The boat is new to me this spring. Iv had no problems at all with temp for the entire summer. Usually runs at 175 to 180. The engine has around 400 hrs and i have not checked the impeller. It is most likely the original. I took her for a ride this past weekend and it did the same thing, It's not going away. I could not leave my hand on the riser for very long on the starboard side.

 

[bruceb58]

Re: Troubleshooting Overheating

Since you don't know the age of the impeller, I would change that first since you need to do it anyway.

 

[pete963]

Re: Troubleshooting Overheating

merc says to change the impeller every 2 season but depends on how you use your boat i change out every year also do you have closed cooling or RWC

 

[Hank285]

Re: Troubleshooting Overheating

I have raw water cooling system. You guys make allot of sence. Dispite having to be an elf to get to the pump im going to dig into it this weekend. Does the pump come apart from the front or should i just plan on removing the entire unit. Iv just ordered the sevice manuals and have not pulled one before. Looks like fun. Any sugestions would be appreciated. Thanks Hank

 

[QC]

Re: Troubleshooting Overheating

You have to pull the whole pump. Sounds hot for raw water cooled to me. Also, I am not sure why a bad impeller would cool one side and not the other . . . You should change the impeller anyway along with the thermostat, but you have not diagnosed your overheat yet. My .O2.

Here's a C&P from the manual. I bolded my first thought although one side is usually hotter. Don't recall which one . . .

Engine Overheats (Cooling System)
Cause Special Information
IMPORTANT: The first step is to verify if the engine
is actually overheating or the temperature
gauge or sender is faulty.

IMPORTANT: Best way to test gauge or sender is
to replace them.
Loose or broken drive belt
Seawater shutoff valve partially or fully closed
(if equipped)
Clogged or improperly installed sea strainer
Loose hose connections between seawater
pickup and seawater pump inlet (models with
belt driven seawater pump only)
Pump will suck air. Pump may fail to prime or will
force air bubbles into cooling system.
Seawater inlet hose kinked or collapsed
Seawater pickup clogged
Obstruction on boat bottom causing water
turbulence
Obstruction will be in front of seawater pickup,
causing air bubbles to be forced into cooling
system
Defective thermostat
Exhaust elbow water outlet holes plugged
Insufficient seawater pump operation Worn pump impeller
Obstruction in cooling system such as casting
flash, sand, rust, salt, etc.
Refer to water flow diagram for engine type
being serviced
Engine circulating pump defective

 

[Hank285]

Re: Troubleshooting Overheating

Great feedback, Thanks QC. Iv ordered the service manuals for nmy engine and drive from Stemtostern.com.

Based on all the information you all have provided i feel confident in my persuite to begin troubleshooting.

Heres my plan. First im going check the intake flow through drive. Remove the raw water pump and rebuild. Remove the hose on the intake side of the power steering cooler and look for blockage. Replace the thermostat.

Thanks Hank

 

[Hank285]

Re: Troubleshooting Overheating

Great feedback, Thanks QC. Iv ordered the service manuals for nmy engine and drive from Stemtostern.com.

Based on all the information you all have provided i feel confident in my persuite to begin troubleshooting.

Heres my plan. First im going check the intake flow through drive. Remove the raw water pump and rebuild. Remove the hose on the intake side of the power steering cooler and look for blockage. Replace the thermostat.

Thanks Hank

 

[Hank285]

Re: Troubleshooting Overheating (Continued)

Re: Troubleshooting Overheating (Continued)

Hey guys. I am still overheating.

This is what I have done to resolve so far. A couple of you suggested inspecting the impeller and removing hoses from the manifolds and risers. I pulled all the hoses and ran fresh water through them, they all seemed clear. Although I could not reverse flush the power steering cooler. Im still waiting for my manuals to arrive so I believe the power steering cooler is underneath the port side manifold? There is also some sort of plastic valve? Before the cooler. Im assuming that maybe you cannot reverse flush the cooler. Is that right?

I replaced the impeller, it was in great shape, and I think the previous owner must have replaced it. Replaced the thermostat. The old one was pretty ugly.

Can any of you give me some other suggestions as to the next step in troubleshooting?

Oh, I ran fresh water through so it came through the bottom of the manifold and came out the riser, I did not pull these hoses since it seemed to have good flow.

Starboard riser gets pretty hot, Port cool.


Thank Hank

 

[bruceb58]

Re: Troubleshooting Overheating

Remove the hoses that go to the manifolds and run the engine for a short amount of time. Be careful becuase you can overheat the manifolds and the rubber downstream so don't run it long, If you are getting good flow out those hoses your manifolds/risers could be the broblem.

How much has this engine been run in salt water?

 

[Reel Poor]

Re: Troubleshooting Overheating

Check out this link. Trouble shooting overheating

 

[Hank285]

Re: Troubleshooting Overheating

Ill give this a try tomorrow after i get the riser and elbo from the starboard side back on. By the way they look good all passages are open. Do you think a circulating pump cpold cause the starboard side only to get real hot?

Thanks Hank

 

[Reel Poor]

Re: Troubleshooting Overheating

With the elbow off did you notice the flapper in the top of the Y pipe.

 

[Hank285]

Re: Troubleshooting Overheating

With the elbow off did you notice the flapper in the top of the Y pipe.

No, I guess ill have to pull the rubber off to see that. Is there one on each side? Thanks

 

[bruceb58]

Re: Troubleshooting Overheating

The circulating pump has nothing to do with the temperature of the risers.

 

[Reel Poor]

Re: Troubleshooting Overheating

No, I guess ill have to pull the rubber off to see that. Is there one on each side? Thanks

There should be. If there not, it probably would not cause an overheating problem but you may as well check em while your there.

Shouldn't have to pull the rubber hose off, just shine a flash light down there and look.

 

[Hank285]

Re: Troubleshooting Overheating Resolved

Re: Troubleshooting Overheating Resolved

The problem was blockage. Found it in the cooler under the port side of the engine. When i initially flushed it i was not succesful because when back flushing i left the check valve attached that is installed before the cooler. This prevents backflow. (Backflushing)

Thanks for all your help guys. This is a great resource, and i appreciate the way you all take the time to share your exsperience with those in need of help.

Thanks Hank