60hp 3cyl overheat following impeller replacement

[Biggieb400]

Hello outboard Wizards!! I am new to this forum and have already found a wealth of knowledge in the 'Top Secret' files and the FAQ's.

Engine Model - TE60TLCEA
Boat - Sun Tracker 24' Party Barge
Model Year - 1989

I picked up a project pontoon a few weeks back with a 60 hp 3cyl engine. I was able to get the engine running with some ignition and neutral safety switch wiring corrections. The tell-tale restrictor was plugged and quickly fixed while running on muffs. Once I had the wiring resolved, I took the pontoon out for a 'sea trial'. Engine ran great!!

Not knowing the engine's history, I decided to proactively replace the impeller. I got the new style kit, 0432955. During the installation, I noticed that the new housing was a 1 piece SS housing as well as the base plate having a smaller inlet opening as noted in NoECM's post - http://forums.iboats.com/showthread.php?t=544170. The engine also had already been updated or built with the tell-tale/vent in the upper part of the exhaust cooling jacket. I also installed the higher rate thermostat spring.

Took the boat out on Memorial day weekend, engine idled like crap. I assume the first trip out loosened up gunk in the carbs. We got the boat outside the no wake zone and I opened it up to WOT - approximately 4000 RPM. Shortly after that, I hit the S.L.O.W. mode and the buzzer came on continuously. The engine cooled down and we were able to continue with the engine running below 2300 RPM, no issues. Got home, looked at the instructions again, and realized I did not remove the restrictor. Removed the restrictor, ran it on the muffs, pulled the thermostat and it looked okay, as did the thermostat seat. There was a couple small pieces of debris in the thermostat from the water inlet screen. Cleaned that out, ran the engine briefly with the muffs and no thermostat or cover to flush it out. Reinstalled thermostat with new spring.

Took it back to the lake, this time with the infared temp gun. At 2300 RPM, the head temp was 150 -155 degF. Within 2-3 minutes of WOT, the buzzer went off and we hit the derate again. Temp gun showed 160, maybe a little higher at the time of derate. We pulled the stat out, against my better judgement, and it ran successfully at WOT for 30 or 45 minutes. Tried the old spring, hoping it would open sooner with the increased water flow and still had the same problem.

One final note, the temp switch appears to be the old style (solid tan wire). I am hesitant to replace it, as I don't like the idea of the alarm triggering at a higher temp and it didn't trip the alarm on the first trip.

I am ready to pull my hair out. Please give me some additional ideas so my entire boating season isn't ruined!!!

Thanks in advance

 

[jbjennings]

Re: 60hp 3cyl overheat following impeller replacement

If the buzzer went off at 160 degrees, you've got a faulty buzzer. 160 degrees should be the correct operating temp. With your infrared thermometer, you should even be able to aim it at the cylinder head and see the temp. rising and falling as the thermostat opens and closes. At least I can with mine.
Good luck,
JBJ

 

[Biggieb400]

Re: 60hp 3cyl overheat following impeller replacement

JBJ

Thanks for the response. When you say 'bad buzzer', are you talking about buzzer in the dash, or the temp switch in the cylinder head?? I can see your logic in the temp sensor being faulty and triggering at an artificially low water temp. The buzzer is a very simple device; power and ground. I don't see the buzzer being the issue.

Do you know what temperature the temp switch should close? I can pull it out and test it in some hot water...

 

[jbjennings]

Re: 60hp 3cyl overheat following impeller replacement

Sorry,
I meant the temp. switch in the head. I believe it should start opening about 140-145 degrees. After rereading your post, I notice that it said over 160. It really shouldn't get over that. You may try to pull your plugs and see if any look steam cleaned. You may have an exhaust cover leak that's letting air into the water jackets. I also hope that someone else checks in on your thread, because cooling problems as you already know won't tolerate any mistakes. If the temp warning switch in the head is going off around 150 or 160 it is bad, however. I don't see a pressure relief valve on your motor which controls water flow at high speed operation---that is what I would think it would be if your temp. was actually getting too high. But if it's only 160 degrees and the alarm is on, it has to be the switch. I think they're about $40.
GOod luck,
JBJ

 

[WernerF]

Re: 60hp 3cyl overheat following impeller replacement

From the 1989 60/70hp OMC manual:
Switch closes at 203 +/- 6?F
Switch opens at 162 +/- 15?F
Engine temp measured at the head's top:
900 rpm: 140 +/- 15?F
5000 rpm: must not exceed 160?F

The thermostat/spring/valve seat combination is the pressure relief valve.

 

[Biggieb400]

Re: 60hp 3cyl overheat following impeller replacement

From the 1989 60/70hp OMC manual:
Switch closes at 203 +/- 6?F
Switch opens at 162 +/- 15?F
Engine temp measured at the head's top:
900 rpm: 140 +/- 15?F
5000 rpm: must not exceed 160?F

The thermostat/spring/valve seat combination is the pressure relief valve.

Thanks for those specifications. Can you clarify whether the temperatures are for the new or old style temp switch? I will pull the temp sensor out and check continuity through the temp range above. I could be wrong, but my gut feeling is that the water inside the engine is not getting that hot.

 

[Biggieb400]

Re: 60hp 3cyl overheat following impeller replacement

Sorry,
I meant the temp. switch in the head. I believe it should start opening about 140-145 degrees. After rereading your post, I notice that it said over 160. It really shouldn't get over that. You may try to pull your plugs and see if any look steam cleaned. You may have an exhaust cover leak that's letting air into the water jackets. I also hope that someone else checks in on your thread, because cooling problems as you already know won't tolerate any mistakes. If the temp warning switch in the head is going off around 150 or 160 it is bad, however. I don't see a pressure relief valve on your motor which controls water flow at high speed operation---that is what I would think it would be if your temp. was actually getting too high. But if it's only 160 degrees and the alarm is on, it has to be the switch. I think they're about $40.
GOod luck,
JBJ

JBJ

I'm not quite following everything above. I did replace exhaust gasket between the drive and mid section during the impeller repair. This is the only exhaust joint that was disturbed during the impeller replacement. I carefully checked the parts side by side and everything looked good based on my visual inspection.

Can you help me better understand how this exhaust is getting into the cooling system? I checked the spark plugs following the Memorial Day weekend trip and they appeared dry, but black.

 

[jbjennings]

Re: 60hp 3cyl overheat following impeller replacement

It doesn't sound like exhaust is getting into the cooling system. It's possible it can get in there if the exhaust cover seals on the port side of the engine are bad---unrelated to any lower unit work. But they if they get hot during an overheat, they can leak exhaust into the cooling system. Usually if that is the case you'll get an intermittent stream in the water pump indicator stream, and even steam.
I would replace the temp. switch and see what happens, keeping a close eye on the powerhead after and during a nice long run with your infrared thermometer.
Good luck,
JBJ

 

[WernerF]

Re: 60hp 3cyl overheat following impeller replacement

Can you clarify whether the temperatures are for the new or old style temp switch? ...

This is a little ambiguous in the manual. There isn't any hint about two different temp switch versions. But the table lists additional temperatures for a second switch inside (white/black wire, 96 and 89 +/- 3?F) which the 1989 model doesn't have (used for warm-up spark timing advance in the later models, 1993 and up).

 

[Biggieb400]

Re: 60hp 3cyl overheat following impeller replacement

I checked the temp switch last night. It closed at ~200 degF, which is in spec. The switch opened at about 140 degF.

Is it possible there is some sort of internal restriction? In another post I read that the engine runs on the thermostat at low engine speeds, and the thermostat opens at 143 degF. I've recorded ~150 degF at idle on the back/top of the head. At higher engine speeds, the spring allows the thermostat to lift off of the seat, allowing more water flow, and in theory, the engine should operate cooler. Is that correct?

Besides an internal restriction, I have 2 additional thoughts. The engine is running lean at WOT, causing higher than expected combustion temps or there is something unique about this engine/water pump combo. I am tempted to change back to the original water pump impeller plate with the larger opening.

I don't think the engine is running lean on oil, as it still has the VRO connected and I've even added oil to the fuel as 'insurance'...

Desperate for some additional thoughts...

 

[WernerF]

Re: 60hp 3cyl overheat following impeller replacement

In your posts I didn't read that you changed the thermostat, did you? If it is 23 years old, replace it.

 

[Biggieb400]

Re: 60hp 3cyl overheat following impeller replacement

I did not replace the thermostat, only the spring between the thermostat and the cover. I've ordered a new one to see if it makes a difference. I am a bit skeptical, as the thermostat should be off of the seat at higher engine speeds.

When I ordered the t-stat, it appears you can buy the internal components individually. Does that mean I can disassemle the old t-stat? I ordered a complete assembly, just curious if I can disassemble the old one and inspect it for debris.

 

[WernerF]

Re: 60hp 3cyl overheat following impeller replacement

The thermostat assembly is the vernatherm, a spring, and the plasic housing creating a valve with the seat which can be disassembled. I think replacing the complete assembly is the right thing, because the plastic or the spring might have deformed.

Yes, the thermostat should be off the seat at higher rpm. You didn't mention the strength and the temperature of the tell tale. Is the water pressure ok, so that you can expect the valve to work? I do not know without the restrictor, but with it the water stream is almost straight at idle.

As far as I have understood, the modifications mean more cooling of the engine exhaust part (big tell tale from the exhaust top), but less (over-)cooling of the cylinder head (stronger thermostat spring) in order to maintain a round cylinder. I'm not sure if the temperature will still drop at higer speeds.

 

[Biggieb400]

Re: 60hp 3cyl overheat following impeller replacement

Werner

I feel like the water stream from the tell-tale is strong. With the restrictor removed, it seems to be flowing a solid stream of water from the 3/16 ID tubing. I don't notice any sputtering of air or steam from the discharge. Next time I have it in the water, I might see if I can submerge the tube into a bucket, which would allow me to determine if there are air pockets.

I stole the picture below from NoECM's post. Can you explain what the 2 ports in the picture below are for? I've seen water erratically flow from these and I don't know what they are connected to in the upper part of the drive.

 

[WernerF]

Re: 60hp 3cyl overheat following impeller replacement

These are the exhaust relief ports. At idle the exhaust pressure wouldn't be high enough to push away the water in the leg and so the engine would die at idle without the ports. Maybe they also help resonsance tuning of the exhaust.
Water or spray is supposed to come out there. Some of the cooling water is mixed to the exhaust gases, so you can see it there.
If you have to look that hard for air bubbles, I think there can't be enough to affect cooling.